---
_id: '605'
abstract:
- lang: eng
text: 'Position based cryptography (PBC), proposed in the seminal work of Chandran,
Goyal, Moriarty, and Ostrovsky (SIAM J. Computing, 2014), aims at constructing
cryptographic schemes in which the identity of the user is his geographic position.
Chandran et al. construct PBC schemes for secure positioning and position-based
key agreement in the bounded-storage model (Maurer, J. Cryptology, 1992). Apart
from bounded memory, their security proofs need a strong additional restriction
on the power of the adversary: he cannot compute joint functions of his inputs.
Removing this assumption is left as an open problem. We show that an answer to
this question would resolve a long standing open problem in multiparty communication
complexity: finding a function that is hard to compute with low communication
complexity in the simultaneous message model, but easy to compute in the fully
adaptive model. On a more positive side: we also show some implications in the
other direction, i.e.: we prove that lower bounds on the communication complexity
of certain multiparty problems imply existence of PBC primitives. Using this result
we then show two attractive ways to “bypass” our hardness result: the first uses
the random oracle model, the second weakens the locality requirement in the bounded-storage
model to online computability. The random oracle construction is arguably one
of the simplest proposed so far in this area. Our results indicate that constructing
improved provably secure protocols for PBC requires a better understanding of
multiparty communication complexity. This is yet another example where negative
results in one area (in our case: lower bounds in multiparty communication complexity)
can be used to construct secure cryptographic schemes.'
alternative_title:
- LNCS
author:
- first_name: Joshua
full_name: Brody, Joshua
last_name: Brody
- first_name: Stefan
full_name: Dziembowski, Stefan
last_name: Dziembowski
- first_name: Sebastian
full_name: Faust, Sebastian
last_name: Faust
- first_name: Krzysztof Z
full_name: Pietrzak, Krzysztof Z
id: 3E04A7AA-F248-11E8-B48F-1D18A9856A87
last_name: Pietrzak
orcid: 0000-0002-9139-1654
citation:
ama: 'Brody J, Dziembowski S, Faust S, Pietrzak KZ. Position based cryptography
and multiparty communication complexity. In: Kalai Y, Reyzin L, eds. Vol 10677.
Springer; 2017:56-81. doi:10.1007/978-3-319-70500-2_3'
apa: 'Brody, J., Dziembowski, S., Faust, S., & Pietrzak, K. Z. (2017). Position
based cryptography and multiparty communication complexity. In Y. Kalai &
L. Reyzin (Eds.) (Vol. 10677, pp. 56–81). Presented at the TCC: Theory of Cryptography
Conference, Baltimore, MD, United States: Springer. https://doi.org/10.1007/978-3-319-70500-2_3'
chicago: Brody, Joshua, Stefan Dziembowski, Sebastian Faust, and Krzysztof Z Pietrzak.
“Position Based Cryptography and Multiparty Communication Complexity.” edited
by Yael Kalai and Leonid Reyzin, 10677:56–81. Springer, 2017. https://doi.org/10.1007/978-3-319-70500-2_3.
ieee: 'J. Brody, S. Dziembowski, S. Faust, and K. Z. Pietrzak, “Position based cryptography
and multiparty communication complexity,” presented at the TCC: Theory of Cryptography
Conference, Baltimore, MD, United States, 2017, vol. 10677, pp. 56–81.'
ista: 'Brody J, Dziembowski S, Faust S, Pietrzak KZ. 2017. Position based cryptography
and multiparty communication complexity. TCC: Theory of Cryptography Conference,
LNCS, vol. 10677, 56–81.'
mla: Brody, Joshua, et al. Position Based Cryptography and Multiparty Communication
Complexity. Edited by Yael Kalai and Leonid Reyzin, vol. 10677, Springer,
2017, pp. 56–81, doi:10.1007/978-3-319-70500-2_3.
short: J. Brody, S. Dziembowski, S. Faust, K.Z. Pietrzak, in:, Y. Kalai, L. Reyzin
(Eds.), Springer, 2017, pp. 56–81.
conference:
end_date: 2017-11-15
location: Baltimore, MD, United States
name: 'TCC: Theory of Cryptography Conference'
start_date: 2017-11-12
date_created: 2018-12-11T11:47:27Z
date_published: 2017-11-05T00:00:00Z
date_updated: 2021-01-12T08:05:53Z
day: '05'
department:
- _id: KrPi
doi: 10.1007/978-3-319-70500-2_3
ec_funded: 1
editor:
- first_name: Yael
full_name: Kalai, Yael
last_name: Kalai
- first_name: Leonid
full_name: Reyzin, Leonid
last_name: Reyzin
intvolume: ' 10677'
language:
- iso: eng
main_file_link:
- open_access: '1'
url: https://eprint.iacr.org/2016/536
month: '11'
oa: 1
oa_version: Submitted Version
page: 56 - 81
project:
- _id: 258AA5B2-B435-11E9-9278-68D0E5697425
call_identifier: H2020
grant_number: '682815'
name: Teaching Old Crypto New Tricks
publication_identifier:
isbn:
- 978-331970499-9
publication_status: published
publisher: Springer
publist_id: '7200'
quality_controlled: '1'
scopus_import: 1
status: public
title: Position based cryptography and multiparty communication complexity
type: conference
user_id: 3E5EF7F0-F248-11E8-B48F-1D18A9856A87
volume: 10677
year: '2017'
...
---
_id: '609'
abstract:
- lang: eng
text: Several cryptographic schemes and applications are based on functions that
are both reasonably efficient to compute and moderately hard to invert, including
client puzzles for Denial-of-Service protection, password protection via salted
hashes, or recent proof-of-work blockchain systems. Despite their wide use, a
definition of this concept has not yet been distilled and formalized explicitly.
Instead, either the applications are proven directly based on the assumptions
underlying the function, or some property of the function is proven, but the security
of the application is argued only informally. The goal of this work is to provide
a (universal) definition that decouples the efforts of designing new moderately
hard functions and of building protocols based on them, serving as an interface
between the two. On a technical level, beyond the mentioned definitions, we instantiate
the model for four different notions of hardness. We extend the work of Alwen
and Serbinenko (STOC 2015) by providing a general tool for proving security for
the first notion of memory-hard functions that allows for provably secure applications.
The tool allows us to recover all of the graph-theoretic techniques developed
for proving security under the older, non-composable, notion of security used
by Alwen and Serbinenko. As an application of our definition of moderately hard
functions, we prove the security of two different schemes for proofs of effort
(PoE). We also formalize and instantiate the concept of a non-interactive proof
of effort (niPoE), in which the proof is not bound to a particular communication
context but rather any bit-string chosen by the prover.
alternative_title:
- LNCS
author:
- first_name: Joel F
full_name: Alwen, Joel F
id: 2A8DFA8C-F248-11E8-B48F-1D18A9856A87
last_name: Alwen
- first_name: Björn
full_name: Tackmann, Björn
last_name: Tackmann
citation:
ama: 'Alwen JF, Tackmann B. Moderately hard functions: Definition, instantiations,
and applications. In: Kalai Y, Reyzin L, eds. Vol 10677. Springer; 2017:493-526.
doi:10.1007/978-3-319-70500-2_17'
apa: 'Alwen, J. F., & Tackmann, B. (2017). Moderately hard functions: Definition,
instantiations, and applications. In Y. Kalai & L. Reyzin (Eds.) (Vol. 10677,
pp. 493–526). Presented at the TCC: Theory of Cryptography, Baltimore, MD, United
States: Springer. https://doi.org/10.1007/978-3-319-70500-2_17'
chicago: 'Alwen, Joel F, and Björn Tackmann. “Moderately Hard Functions: Definition,
Instantiations, and Applications.” edited by Yael Kalai and Leonid Reyzin, 10677:493–526.
Springer, 2017. https://doi.org/10.1007/978-3-319-70500-2_17.'
ieee: 'J. F. Alwen and B. Tackmann, “Moderately hard functions: Definition, instantiations,
and applications,” presented at the TCC: Theory of Cryptography, Baltimore, MD,
United States, 2017, vol. 10677, pp. 493–526.'
ista: 'Alwen JF, Tackmann B. 2017. Moderately hard functions: Definition, instantiations,
and applications. TCC: Theory of Cryptography, LNCS, vol. 10677, 493–526.'
mla: 'Alwen, Joel F., and Björn Tackmann. Moderately Hard Functions: Definition,
Instantiations, and Applications. Edited by Yael Kalai and Leonid Reyzin,
vol. 10677, Springer, 2017, pp. 493–526, doi:10.1007/978-3-319-70500-2_17.'
short: J.F. Alwen, B. Tackmann, in:, Y. Kalai, L. Reyzin (Eds.), Springer, 2017,
pp. 493–526.
conference:
end_date: 2017-11-15
location: Baltimore, MD, United States
name: 'TCC: Theory of Cryptography'
start_date: 2017-11-12
date_created: 2018-12-11T11:47:28Z
date_published: 2017-11-05T00:00:00Z
date_updated: 2021-01-12T08:06:04Z
day: '05'
department:
- _id: KrPi
doi: 10.1007/978-3-319-70500-2_17
editor:
- first_name: Yael
full_name: Kalai, Yael
last_name: Kalai
- first_name: Leonid
full_name: Reyzin, Leonid
last_name: Reyzin
intvolume: ' 10677'
language:
- iso: eng
main_file_link:
- open_access: '1'
url: https://eprint.iacr.org/2017/945
month: '11'
oa: 1
oa_version: Submitted Version
page: 493 - 526
publication_identifier:
isbn:
- 978-331970499-9
publication_status: published
publisher: Springer
publist_id: '7196'
quality_controlled: '1'
scopus_import: 1
status: public
title: 'Moderately hard functions: Definition, instantiations, and applications'
type: conference
user_id: 3E5EF7F0-F248-11E8-B48F-1D18A9856A87
volume: 10677
year: '2017'
...
---
_id: '6196'
abstract:
- lang: eng
text: PMAC is a simple and parallel block-cipher mode of operation, which was introduced
by Black and Rogaway at Eurocrypt 2002. If instantiated with a (pseudo)random
permutation over n-bit strings, PMAC constitutes a provably secure variable input-length
(pseudo)random function. For adversaries making q queries, each of length at most
l (in n-bit blocks), and of total length σ ≤ ql, the original paper proves an
upper bound on the distinguishing advantage of Ο(σ2/2n), while the currently
best bound is Ο (qσ/2n).In this work we show that this bound is tight by giving
an attack with advantage Ω (q2l/2n). In the PMAC construction one initially XORs
a mask to every message block, where the mask for the ith block is computed as
τi := γi·L, where L is a (secret) random value, and γi is the i-th codeword of
the Gray code. Our attack applies more generally to any sequence of γi’s which
contains a large coset of a subgroup of GF(2n). We then investigate if the security
of PMAC can be further improved by using τi’s that are k-wise independent, for
k > 1 (the original distribution is only 1-wise independent). We observe that
the security of PMAC will not increase in general, even if the masks are chosen
from a 2-wise independent distribution, and then prove that the security increases
to O(q<2/2n), if the τi are 4-wise independent. Due to simple extension attacks,
this is the best bound one can hope for, using any distribution on the masks.
Whether 3-wise independence is already sufficient to get this level of security
is left as an open problem.
author:
- first_name: Peter
full_name: Gazi, Peter
id: 3E0BFE38-F248-11E8-B48F-1D18A9856A87
last_name: Gazi
- first_name: Krzysztof Z
full_name: Pietrzak, Krzysztof Z
id: 3E04A7AA-F248-11E8-B48F-1D18A9856A87
last_name: Pietrzak
orcid: 0000-0002-9139-1654
- first_name: Michal
full_name: Rybar, Michal
id: 2B3E3DE8-F248-11E8-B48F-1D18A9856A87
last_name: Rybar
citation:
ama: Gazi P, Pietrzak KZ, Rybar M. The exact security of PMAC. IACR Transactions
on Symmetric Cryptology. 2017;2016(2):145-161. doi:10.13154/TOSC.V2016.I2.145-161
apa: Gazi, P., Pietrzak, K. Z., & Rybar, M. (2017). The exact security of PMAC.
IACR Transactions on Symmetric Cryptology. Ruhr University Bochum. https://doi.org/10.13154/TOSC.V2016.I2.145-161
chicago: Gazi, Peter, Krzysztof Z Pietrzak, and Michal Rybar. “The Exact Security
of PMAC.” IACR Transactions on Symmetric Cryptology. Ruhr University Bochum,
2017. https://doi.org/10.13154/TOSC.V2016.I2.145-161.
ieee: P. Gazi, K. Z. Pietrzak, and M. Rybar, “The exact security of PMAC,” IACR
Transactions on Symmetric Cryptology, vol. 2016, no. 2. Ruhr University Bochum,
pp. 145–161, 2017.
ista: Gazi P, Pietrzak KZ, Rybar M. 2017. The exact security of PMAC. IACR Transactions
on Symmetric Cryptology. 2016(2), 145–161.
mla: Gazi, Peter, et al. “The Exact Security of PMAC.” IACR Transactions on Symmetric
Cryptology, vol. 2016, no. 2, Ruhr University Bochum, 2017, pp. 145–61, doi:10.13154/TOSC.V2016.I2.145-161.
short: P. Gazi, K.Z. Pietrzak, M. Rybar, IACR Transactions on Symmetric Cryptology
2016 (2017) 145–161.
date_created: 2019-04-04T13:48:23Z
date_published: 2017-02-03T00:00:00Z
date_updated: 2023-09-07T12:02:27Z
day: '03'
ddc:
- '000'
department:
- _id: KrPi
doi: 10.13154/TOSC.V2016.I2.145-161
ec_funded: 1
file:
- access_level: open_access
checksum: f23161d685dd957ae8d7274132999684
content_type: application/pdf
creator: dernst
date_created: 2019-04-04T13:53:58Z
date_updated: 2020-07-14T12:47:24Z
file_id: '6197'
file_name: 2017_IACR_Gazi.pdf
file_size: 597335
relation: main_file
file_date_updated: 2020-07-14T12:47:24Z
has_accepted_license: '1'
intvolume: ' 2016'
issue: '2'
language:
- iso: eng
month: '02'
oa: 1
oa_version: Published Version
page: 145-161
project:
- _id: 258AA5B2-B435-11E9-9278-68D0E5697425
call_identifier: H2020
grant_number: '682815'
name: Teaching Old Crypto New Tricks
publication: IACR Transactions on Symmetric Cryptology
publication_identifier:
eissn:
- 2519-173X
publication_status: published
publisher: Ruhr University Bochum
quality_controlled: '1'
related_material:
record:
- id: '838'
relation: dissertation_contains
status: public
status: public
title: The exact security of PMAC
tmp:
image: /images/cc_by.png
legal_code_url: https://creativecommons.org/licenses/by/4.0/legalcode
name: Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)
short: CC BY (4.0)
type: journal_article
user_id: 3E5EF7F0-F248-11E8-B48F-1D18A9856A87
volume: 2016
year: '2017'
...
---
_id: '635'
abstract:
- lang: eng
text: Memory-hard functions (MHFs) are hash algorithms whose evaluation cost is
dominated by memory cost. As memory, unlike computation, costs about the same
across different platforms, MHFs cannot be evaluated at significantly lower cost
on dedicated hardware like ASICs. MHFs have found widespread applications including
password hashing, key derivation, and proofs-of-work. This paper focuses on scrypt,
a simple candidate MHF designed by Percival, and described in RFC 7914. It has
been used within a number of cryptocurrencies (e.g., Litecoin and Dogecoin) and
has been an inspiration for Argon2d, one of the winners of the recent password-hashing
competition. Despite its popularity, no rigorous lower bounds on its memory complexity
are known. We prove that scrypt is optimally memory-hard, i.e., its cumulative
memory complexity (cmc) in the parallel random oracle model is Ω(n2w), where w
and n are the output length and number of invocations of the underlying hash function,
respectively. High cmc is a strong security target for MHFs introduced by Alwen
and Serbinenko (STOC’15) which implies high memory cost even for adversaries who
can amortize the cost over many evaluations and evaluate the underlying hash functions
many times in parallel. Our proof is the first showing optimal memory-hardness
for any MHF. Our result improves both quantitatively and qualitatively upon the
recent work by Alwen et al. (EUROCRYPT’16) who proved a weaker lower bound of
Ω(n2w/ log2 n) for a restricted class of adversaries.
alternative_title:
- LNCS
author:
- first_name: Joel F
full_name: Alwen, Joel F
id: 2A8DFA8C-F248-11E8-B48F-1D18A9856A87
last_name: Alwen
- first_name: Binchi
full_name: Chen, Binchi
last_name: Chen
- first_name: Krzysztof Z
full_name: Pietrzak, Krzysztof Z
id: 3E04A7AA-F248-11E8-B48F-1D18A9856A87
last_name: Pietrzak
orcid: 0000-0002-9139-1654
- first_name: Leonid
full_name: Reyzin, Leonid
last_name: Reyzin
- first_name: Stefano
full_name: Tessaro, Stefano
last_name: Tessaro
citation:
ama: 'Alwen JF, Chen B, Pietrzak KZ, Reyzin L, Tessaro S. Scrypt is maximally memory
hard. In: Coron J-S, Buus Nielsen J, eds. Vol 10212. Springer; 2017:33-62. doi:10.1007/978-3-319-56617-7_2'
apa: 'Alwen, J. F., Chen, B., Pietrzak, K. Z., Reyzin, L., & Tessaro, S. (2017).
Scrypt is maximally memory hard. In J.-S. Coron & J. Buus Nielsen (Eds.) (Vol.
10212, pp. 33–62). Presented at the EUROCRYPT: Theory and Applications of Cryptographic
Techniques, Paris, France: Springer. https://doi.org/10.1007/978-3-319-56617-7_2'
chicago: Alwen, Joel F, Binchi Chen, Krzysztof Z Pietrzak, Leonid Reyzin, and Stefano
Tessaro. “Scrypt Is Maximally Memory Hard.” edited by Jean-Sébastien Coron and
Jesper Buus Nielsen, 10212:33–62. Springer, 2017. https://doi.org/10.1007/978-3-319-56617-7_2.
ieee: 'J. F. Alwen, B. Chen, K. Z. Pietrzak, L. Reyzin, and S. Tessaro, “Scrypt
is maximally memory hard,” presented at the EUROCRYPT: Theory and Applications
of Cryptographic Techniques, Paris, France, 2017, vol. 10212, pp. 33–62.'
ista: 'Alwen JF, Chen B, Pietrzak KZ, Reyzin L, Tessaro S. 2017. Scrypt is maximally
memory hard. EUROCRYPT: Theory and Applications of Cryptographic Techniques, LNCS,
vol. 10212, 33–62.'
mla: Alwen, Joel F., et al. Scrypt Is Maximally Memory Hard. Edited by Jean-Sébastien
Coron and Jesper Buus Nielsen, vol. 10212, Springer, 2017, pp. 33–62, doi:10.1007/978-3-319-56617-7_2.
short: J.F. Alwen, B. Chen, K.Z. Pietrzak, L. Reyzin, S. Tessaro, in:, J.-S. Coron,
J. Buus Nielsen (Eds.), Springer, 2017, pp. 33–62.
conference:
end_date: 2017-05-04
location: Paris, France
name: 'EUROCRYPT: Theory and Applications of Cryptographic Techniques'
start_date: 2017-04-30
date_created: 2018-12-11T11:47:37Z
date_published: 2017-01-01T00:00:00Z
date_updated: 2021-01-12T08:07:10Z
day: '01'
department:
- _id: KrPi
doi: 10.1007/978-3-319-56617-7_2
ec_funded: 1
editor:
- first_name: Jean-Sébastien
full_name: Coron, Jean-Sébastien
last_name: Coron
- first_name: Jesper
full_name: Buus Nielsen, Jesper
last_name: Buus Nielsen
intvolume: ' 10212'
language:
- iso: eng
main_file_link:
- open_access: '1'
url: https://eprint.iacr.org/2016/989
month: '01'
oa: 1
oa_version: Submitted Version
page: 33 - 62
project:
- _id: 258AA5B2-B435-11E9-9278-68D0E5697425
call_identifier: H2020
grant_number: '682815'
name: Teaching Old Crypto New Tricks
publication_identifier:
isbn:
- 978-331956616-0
publication_status: published
publisher: Springer
publist_id: '7154'
quality_controlled: '1'
scopus_import: 1
status: public
title: Scrypt is maximally memory hard
type: conference
user_id: 4435EBFC-F248-11E8-B48F-1D18A9856A87
volume: 10212
year: '2017'
...
---
_id: '637'
abstract:
- lang: eng
text: For many cryptographic primitives, it is relatively easy to achieve selective
security (where the adversary commits a-priori to some of the choices to be made
later in the attack) but appears difficult to achieve the more natural notion
of adaptive security (where the adversary can make all choices on the go as the
attack progresses). A series of several recent works shows how to cleverly achieve
adaptive security in several such scenarios including generalized selective decryption
(Panjwani, TCC ’07 and Fuchsbauer et al., CRYPTO ’15), constrained PRFs (Fuchsbauer
et al., ASIACRYPT ’14), and Yao garbled circuits (Jafargholi and Wichs, TCC ’16b).
Although the above works expressed vague intuition that they share a common technique,
the connection was never made precise. In this work we present a new framework
that connects all of these works and allows us to present them in a unified and
simplified fashion. Moreover, we use the framework to derive a new result for
adaptively secure secret sharing over access structures defined via monotone circuits.
We envision that further applications will follow in the future. Underlying our
framework is the following simple idea. It is well known that selective security,
where the adversary commits to n-bits of information about his future choices,
automatically implies adaptive security at the cost of amplifying the adversary’s
advantage by a factor of up to 2n. However, in some cases the proof of selective
security proceeds via a sequence of hybrids, where each pair of adjacent hybrids
locally only requires some smaller partial information consisting of m ≪ n bits.
The partial information needed might be completely different between different
pairs of hybrids, and if we look across all the hybrids we might rely on the entire
n-bit commitment. Nevertheless, the above is sufficient to prove adaptive security,
at the cost of amplifying the adversary’s advantage by a factor of only 2m ≪ 2n.
In all of our examples using the above framework, the different hybrids are captured
by some sort of a graph pebbling game and the amount of information that the adversary
needs to commit to in each pair of hybrids is bounded by the maximum number of
pebbles in play at any point in time. Therefore, coming up with better strategies
for proving adaptive security translates to various pebbling strategies for different
types of graphs.
alternative_title:
- LNCS
author:
- first_name: Zahra
full_name: Jafargholi, Zahra
last_name: Jafargholi
- first_name: Chethan
full_name: Kamath Hosdurg, Chethan
id: 4BD3F30E-F248-11E8-B48F-1D18A9856A87
last_name: Kamath Hosdurg
- first_name: Karen
full_name: Klein, Karen
id: 3E83A2F8-F248-11E8-B48F-1D18A9856A87
last_name: Klein
- first_name: Ilan
full_name: Komargodski, Ilan
last_name: Komargodski
- first_name: Krzysztof Z
full_name: Pietrzak, Krzysztof Z
id: 3E04A7AA-F248-11E8-B48F-1D18A9856A87
last_name: Pietrzak
orcid: 0000-0002-9139-1654
- first_name: Daniel
full_name: Wichs, Daniel
last_name: Wichs
citation:
ama: 'Jafargholi Z, Kamath Hosdurg C, Klein K, Komargodski I, Pietrzak KZ, Wichs
D. Be adaptive avoid overcommitting. In: Katz J, Shacham H, eds. Vol 10401. Springer;
2017:133-163. doi:10.1007/978-3-319-63688-7_5'
apa: 'Jafargholi, Z., Kamath Hosdurg, C., Klein, K., Komargodski, I., Pietrzak,
K. Z., & Wichs, D. (2017). Be adaptive avoid overcommitting. In J. Katz &
H. Shacham (Eds.) (Vol. 10401, pp. 133–163). Presented at the CRYPTO: Cryptology,
Santa Barbara, CA, United States: Springer. https://doi.org/10.1007/978-3-319-63688-7_5'
chicago: Jafargholi, Zahra, Chethan Kamath Hosdurg, Karen Klein, Ilan Komargodski,
Krzysztof Z Pietrzak, and Daniel Wichs. “Be Adaptive Avoid Overcommitting.” edited
by Jonathan Katz and Hovav Shacham, 10401:133–63. Springer, 2017. https://doi.org/10.1007/978-3-319-63688-7_5.
ieee: 'Z. Jafargholi, C. Kamath Hosdurg, K. Klein, I. Komargodski, K. Z. Pietrzak,
and D. Wichs, “Be adaptive avoid overcommitting,” presented at the CRYPTO: Cryptology,
Santa Barbara, CA, United States, 2017, vol. 10401, pp. 133–163.'
ista: 'Jafargholi Z, Kamath Hosdurg C, Klein K, Komargodski I, Pietrzak KZ, Wichs
D. 2017. Be adaptive avoid overcommitting. CRYPTO: Cryptology, LNCS, vol. 10401,
133–163.'
mla: Jafargholi, Zahra, et al. Be Adaptive Avoid Overcommitting. Edited by
Jonathan Katz and Hovav Shacham, vol. 10401, Springer, 2017, pp. 133–63, doi:10.1007/978-3-319-63688-7_5.
short: Z. Jafargholi, C. Kamath Hosdurg, K. Klein, I. Komargodski, K.Z. Pietrzak,
D. Wichs, in:, J. Katz, H. Shacham (Eds.), Springer, 2017, pp. 133–163.
conference:
end_date: 2017-07-24
location: Santa Barbara, CA, United States
name: 'CRYPTO: Cryptology'
start_date: 2017-07-20
date_created: 2018-12-11T11:47:38Z
date_published: 2017-01-01T00:00:00Z
date_updated: 2023-09-07T13:32:11Z
day: '01'
department:
- _id: KrPi
doi: 10.1007/978-3-319-63688-7_5
ec_funded: 1
editor:
- first_name: Jonathan
full_name: Katz, Jonathan
last_name: Katz
- first_name: Hovav
full_name: Shacham, Hovav
last_name: Shacham
intvolume: ' 10401'
language:
- iso: eng
main_file_link:
- open_access: '1'
url: https://eprint.iacr.org/2017/515
month: '01'
oa: 1
oa_version: Submitted Version
page: 133 - 163
project:
- _id: 258AA5B2-B435-11E9-9278-68D0E5697425
call_identifier: H2020
grant_number: '682815'
name: Teaching Old Crypto New Tricks
publication_identifier:
isbn:
- 978-331963687-0
publication_status: published
publisher: Springer
publist_id: '7151'
quality_controlled: '1'
related_material:
record:
- id: '10035'
relation: dissertation_contains
status: public
scopus_import: 1
status: public
title: Be adaptive avoid overcommitting
type: conference
user_id: 3E5EF7F0-F248-11E8-B48F-1D18A9856A87
volume: 10401
year: '2017'
...
---
_id: '640'
abstract:
- lang: eng
text: 'Data-independent Memory Hard Functions (iMHFS) are finding a growing number
of applications in security; especially in the domain of password hashing. An
important property of a concrete iMHF is specified by fixing a directed acyclic
graph (DAG) Gn on n nodes. The quality of that iMHF is then captured by the following
two pebbling complexities of Gn: – The parallel cumulative pebbling complexity
Π∥cc(Gn) must be as high as possible (to ensure that the amortized cost of computing
the function on dedicated hardware is dominated by the cost of memory). – The
sequential space-time pebbling complexity Πst(Gn) should be as close as possible
to Π∥cc(Gn) (to ensure that using many cores in parallel and amortizing over many
instances does not give much of an advantage). In this paper we construct a family
of DAGs with best possible parameters in an asymptotic sense, i.e., where Π∥cc(Gn)
= Ω(n2/ log(n)) (which matches a known upper bound) and Πst(Gn) is within a constant
factor of Π∥cc(Gn). Our analysis relies on a new connection between the pebbling
complexity of a DAG and its depth-robustness (DR) – a well studied combinatorial
property. We show that high DR is sufficient for high Π∥cc. Alwen and Blocki (CRYPTO’16)
showed that high DR is necessary and so, together, these results fully characterize
DAGs with high Π∥cc in terms of DR. Complementing these results, we provide new
upper and lower bounds on the Π∥cc of several important candidate iMHFs from the
literature. We give the first lower bounds on the memory hardness of the Catena
and Balloon Hashing functions in a parallel model of computation and we give the
first lower bounds of any kind for (a version) of Argon2i. Finally we describe
a new class of pebbling attacks improving on those of Alwen and Blocki (CRYPTO’16).
By instantiating these attacks we upperbound the Π∥cc of the Password Hashing
Competition winner Argon2i and one of the Balloon Hashing functions by O (n1.71).
We also show an upper bound of O(n1.625) for the Catena functions and the two
remaining Balloon Hashing functions.'
alternative_title:
- LNCS
author:
- first_name: Joel F
full_name: Alwen, Joel F
id: 2A8DFA8C-F248-11E8-B48F-1D18A9856A87
last_name: Alwen
- first_name: Jeremiah
full_name: Blocki, Jeremiah
last_name: Blocki
- first_name: Krzysztof Z
full_name: Pietrzak, Krzysztof Z
id: 3E04A7AA-F248-11E8-B48F-1D18A9856A87
last_name: Pietrzak
orcid: 0000-0002-9139-1654
citation:
ama: 'Alwen JF, Blocki J, Pietrzak KZ. Depth-robust graphs and their cumulative
memory complexity. In: Coron J-S, Buus Nielsen J, eds. Vol 10212. Springer; 2017:3-32.
doi:10.1007/978-3-319-56617-7_1'
apa: 'Alwen, J. F., Blocki, J., & Pietrzak, K. Z. (2017). Depth-robust graphs
and their cumulative memory complexity. In J.-S. Coron & J. Buus Nielsen (Eds.)
(Vol. 10212, pp. 3–32). Presented at the EUROCRYPT: Theory and Applications of
Cryptographic Techniques, Paris, France: Springer. https://doi.org/10.1007/978-3-319-56617-7_1'
chicago: Alwen, Joel F, Jeremiah Blocki, and Krzysztof Z Pietrzak. “Depth-Robust
Graphs and Their Cumulative Memory Complexity.” edited by Jean-Sébastien Coron
and Jesper Buus Nielsen, 10212:3–32. Springer, 2017. https://doi.org/10.1007/978-3-319-56617-7_1.
ieee: 'J. F. Alwen, J. Blocki, and K. Z. Pietrzak, “Depth-robust graphs and their
cumulative memory complexity,” presented at the EUROCRYPT: Theory and Applications
of Cryptographic Techniques, Paris, France, 2017, vol. 10212, pp. 3–32.'
ista: 'Alwen JF, Blocki J, Pietrzak KZ. 2017. Depth-robust graphs and their cumulative
memory complexity. EUROCRYPT: Theory and Applications of Cryptographic Techniques,
LNCS, vol. 10212, 3–32.'
mla: Alwen, Joel F., et al. Depth-Robust Graphs and Their Cumulative Memory Complexity.
Edited by Jean-Sébastien Coron and Jesper Buus Nielsen, vol. 10212, Springer,
2017, pp. 3–32, doi:10.1007/978-3-319-56617-7_1.
short: J.F. Alwen, J. Blocki, K.Z. Pietrzak, in:, J.-S. Coron, J. Buus Nielsen (Eds.),
Springer, 2017, pp. 3–32.
conference:
end_date: 2017-05-04
location: Paris, France
name: 'EUROCRYPT: Theory and Applications of Cryptographic Techniques'
start_date: 2017-04-30
date_created: 2018-12-11T11:47:39Z
date_published: 2017-04-01T00:00:00Z
date_updated: 2021-01-12T08:07:22Z
day: '01'
department:
- _id: KrPi
doi: 10.1007/978-3-319-56617-7_1
ec_funded: 1
editor:
- first_name: Jean-Sébastien
full_name: Coron, Jean-Sébastien
last_name: Coron
- first_name: Jesper
full_name: Buus Nielsen, Jesper
last_name: Buus Nielsen
intvolume: ' 10212'
language:
- iso: eng
main_file_link:
- open_access: '1'
url: https://eprint.iacr.org/2016/875
month: '04'
oa: 1
oa_version: Submitted Version
page: 3 - 32
project:
- _id: 258AA5B2-B435-11E9-9278-68D0E5697425
call_identifier: H2020
grant_number: '682815'
name: Teaching Old Crypto New Tricks
publication_identifier:
isbn:
- 978-331956616-0
publication_status: published
publisher: Springer
publist_id: '7148'
quality_controlled: '1'
scopus_import: 1
status: public
title: Depth-robust graphs and their cumulative memory complexity
type: conference
user_id: 3E5EF7F0-F248-11E8-B48F-1D18A9856A87
volume: 10212
year: '2017'
...
---
_id: '648'
abstract:
- lang: eng
text: 'Pseudoentropy has found a lot of important applications to cryptography and
complexity theory. In this paper we focus on the foundational problem that has
not been investigated so far, namely by how much pseudoentropy (the amount seen
by computationally bounded attackers) differs from its information-theoretic counterpart
(seen by unbounded observers), given certain limits on attacker’s computational
power? We provide the following answer for HILL pseudoentropy, which exhibits
a threshold behavior around the size exponential in the entropy amount:– If the
attacker size (s) and advantage () satisfy s (formula presented) where k is the
claimed amount of pseudoentropy, then the pseudoentropy boils down to the information-theoretic
smooth entropy. – If s (formula presented) then pseudoentropy could be arbitrarily
bigger than the information-theoretic smooth entropy. Besides answering the posted
question, we show an elegant application of our result to the complexity theory,
namely that it implies the clas-sical result on the existence of functions hard
to approximate (due to Pippenger). In our approach we utilize non-constructive
techniques: the duality of linear programming and the probabilistic method.'
alternative_title:
- LNCS
author:
- first_name: Maciej
full_name: Skórski, Maciej
id: EC09FA6A-02D0-11E9-8223-86B7C91467DD
last_name: Skórski
citation:
ama: 'Skórski M. On the complexity of breaking pseudoentropy. In: Jäger G, Steila
S, eds. Vol 10185. Springer; 2017:600-613. doi:10.1007/978-3-319-55911-7_43'
apa: 'Skórski, M. (2017). On the complexity of breaking pseudoentropy. In G. Jäger
& S. Steila (Eds.) (Vol. 10185, pp. 600–613). Presented at the TAMC: Theory
and Applications of Models of Computation, Bern, Switzerland: Springer. https://doi.org/10.1007/978-3-319-55911-7_43'
chicago: Skórski, Maciej. “On the Complexity of Breaking Pseudoentropy.” edited
by Gerhard Jäger and Silvia Steila, 10185:600–613. Springer, 2017. https://doi.org/10.1007/978-3-319-55911-7_43.
ieee: 'M. Skórski, “On the complexity of breaking pseudoentropy,” presented at the
TAMC: Theory and Applications of Models of Computation, Bern, Switzerland, 2017,
vol. 10185, pp. 600–613.'
ista: 'Skórski M. 2017. On the complexity of breaking pseudoentropy. TAMC: Theory
and Applications of Models of Computation, LNCS, vol. 10185, 600–613.'
mla: Skórski, Maciej. On the Complexity of Breaking Pseudoentropy. Edited
by Gerhard Jäger and Silvia Steila, vol. 10185, Springer, 2017, pp. 600–13, doi:10.1007/978-3-319-55911-7_43.
short: M. Skórski, in:, G. Jäger, S. Steila (Eds.), Springer, 2017, pp. 600–613.
conference:
end_date: 2017-04-22
location: Bern, Switzerland
name: 'TAMC: Theory and Applications of Models of Computation'
start_date: 2017-04-20
date_created: 2018-12-11T11:47:42Z
date_published: 2017-04-01T00:00:00Z
date_updated: 2021-01-12T08:07:39Z
day: '01'
department:
- _id: KrPi
doi: 10.1007/978-3-319-55911-7_43
editor:
- first_name: Gerhard
full_name: Jäger, Gerhard
last_name: Jäger
- first_name: Silvia
full_name: Steila, Silvia
last_name: Steila
intvolume: ' 10185'
language:
- iso: eng
main_file_link:
- open_access: '1'
url: https://eprint.iacr.org/2016/1186.pdf
month: '04'
oa: 1
oa_version: Submitted Version
page: 600 - 613
publication_identifier:
isbn:
- 978-331955910-0
publication_status: published
publisher: Springer
publist_id: '7125'
quality_controlled: '1'
scopus_import: 1
status: public
title: On the complexity of breaking pseudoentropy
type: conference
user_id: 3E5EF7F0-F248-11E8-B48F-1D18A9856A87
volume: 10185
year: '2017'
...
---
_id: '650'
abstract:
- lang: eng
text: 'In this work we present a short and unified proof for the Strong and Weak
Regularity Lemma, based on the cryptographic tech-nique called low-complexity
approximations. In short, both problems reduce to a task of finding constructively
an approximation for a certain target function under a class of distinguishers
(test functions), where dis-tinguishers are combinations of simple rectangle-indicators.
In our case these approximations can be learned by a simple iterative procedure,
which yields a unified and simple proof, achieving for any graph with density
d and any approximation parameter the partition size. The novelty in our proof
is: (a) a simple approach which yields both strong and weaker variant, and (b)
improvements when d = o(1). At an abstract level, our proof can be seen a refinement
and simplification of the “analytic” proof given by Lovasz and Szegedy.'
alternative_title:
- LNCS
author:
- first_name: Maciej
full_name: Skórski, Maciej
id: EC09FA6A-02D0-11E9-8223-86B7C91467DD
last_name: Skórski
citation:
ama: 'Skórski M. A cryptographic view of regularity lemmas: Simpler unified proofs
and refined bounds. In: Jäger G, Steila S, eds. Vol 10185. Springer; 2017:586-599.
doi:10.1007/978-3-319-55911-7_42'
apa: 'Skórski, M. (2017). A cryptographic view of regularity lemmas: Simpler unified
proofs and refined bounds. In G. Jäger & S. Steila (Eds.) (Vol. 10185, pp.
586–599). Presented at the TAMC: Theory and Applications of Models of Computation,
Bern, Switzerland: Springer. https://doi.org/10.1007/978-3-319-55911-7_42'
chicago: 'Skórski, Maciej. “A Cryptographic View of Regularity Lemmas: Simpler Unified
Proofs and Refined Bounds.” edited by Gerhard Jäger and Silvia Steila, 10185:586–99.
Springer, 2017. https://doi.org/10.1007/978-3-319-55911-7_42.'
ieee: 'M. Skórski, “A cryptographic view of regularity lemmas: Simpler unified proofs
and refined bounds,” presented at the TAMC: Theory and Applications of Models
of Computation, Bern, Switzerland, 2017, vol. 10185, pp. 586–599.'
ista: 'Skórski M. 2017. A cryptographic view of regularity lemmas: Simpler unified
proofs and refined bounds. TAMC: Theory and Applications of Models of Computation,
LNCS, vol. 10185, 586–599.'
mla: 'Skórski, Maciej. A Cryptographic View of Regularity Lemmas: Simpler Unified
Proofs and Refined Bounds. Edited by Gerhard Jäger and Silvia Steila, vol.
10185, Springer, 2017, pp. 586–99, doi:10.1007/978-3-319-55911-7_42.'
short: M. Skórski, in:, G. Jäger, S. Steila (Eds.), Springer, 2017, pp. 586–599.
conference:
end_date: 2017-04-22
location: Bern, Switzerland
name: 'TAMC: Theory and Applications of Models of Computation'
start_date: 2017-04-20
date_created: 2018-12-11T11:47:42Z
date_published: 2017-01-01T00:00:00Z
date_updated: 2021-01-12T08:07:46Z
day: '01'
department:
- _id: KrPi
doi: 10.1007/978-3-319-55911-7_42
editor:
- first_name: Gerhard
full_name: Jäger, Gerhard
last_name: Jäger
- first_name: Silvia
full_name: Steila, Silvia
last_name: Steila
intvolume: ' 10185'
language:
- iso: eng
main_file_link:
- open_access: '1'
url: https://eprint.iacr.org/2016/965.pdf
month: '01'
oa: 1
oa_version: Submitted Version
page: 586 - 599
publication_identifier:
issn:
- '03029743'
publication_status: published
publisher: Springer
publist_id: '7119'
quality_controlled: '1'
scopus_import: 1
status: public
title: 'A cryptographic view of regularity lemmas: Simpler unified proofs and refined
bounds'
type: conference
user_id: 3E5EF7F0-F248-11E8-B48F-1D18A9856A87
volume: 10185
year: '2017'
...
---
_id: '6526'
abstract:
- lang: eng
text: 'This paper studies the complexity of estimating Rényi divergences of discrete
distributions: p observed from samples and the baseline distribution q known a
priori. Extending the results of Acharya et al. (SODA''15) on estimating Rényi
entropy, we present improved estimation techniques together with upper and lower
bounds on the sample complexity. We show that, contrarily to estimating Rényi
entropy where a sublinear (in the alphabet size) number of samples suffices, the
sample complexity is heavily dependent on events occurring unlikely in q, and
is unbounded in general (no matter what an estimation technique is used). For
any divergence of integer order bigger than 1, we provide upper and lower bounds
on the number of samples dependent on probabilities of p and q (the lower bounds
hold for non-integer orders as well). We conclude that the worst-case sample complexity
is polynomial in the alphabet size if and only if the probabilities of q are non-negligible.
This gives theoretical insights into heuristics used in the applied literature
to handle numerical instability, which occurs for small probabilities of q. Our
result shows that they should be handled with care not only because of numerical
issues, but also because of a blow up in the sample complexity.'
article_number: '8006529'
arxiv: 1
author:
- first_name: Maciej
full_name: Skórski, Maciej
id: EC09FA6A-02D0-11E9-8223-86B7C91467DD
last_name: Skórski
citation:
ama: 'Skórski M. On the complexity of estimating Rènyi divergences. In: 2017
IEEE International Symposium on Information Theory (ISIT). IEEE; 2017. doi:10.1109/isit.2017.8006529'
apa: 'Skórski, M. (2017). On the complexity of estimating Rènyi divergences. In
2017 IEEE International Symposium on Information Theory (ISIT). Aachen,
Germany: IEEE. https://doi.org/10.1109/isit.2017.8006529'
chicago: Skórski, Maciej. “On the Complexity of Estimating Rènyi Divergences.” In
2017 IEEE International Symposium on Information Theory (ISIT). IEEE, 2017.
https://doi.org/10.1109/isit.2017.8006529.
ieee: M. Skórski, “On the complexity of estimating Rènyi divergences,” in 2017
IEEE International Symposium on Information Theory (ISIT), Aachen, Germany,
2017.
ista: 'Skórski M. 2017. On the complexity of estimating Rènyi divergences. 2017
IEEE International Symposium on Information Theory (ISIT). ISIT: International
Symposium on Information Theory, 8006529.'
mla: Skórski, Maciej. “On the Complexity of Estimating Rènyi Divergences.” 2017
IEEE International Symposium on Information Theory (ISIT), 8006529, IEEE,
2017, doi:10.1109/isit.2017.8006529.
short: M. Skórski, in:, 2017 IEEE International Symposium on Information Theory
(ISIT), IEEE, 2017.
conference:
end_date: 2017-06-30
location: Aachen, Germany
name: 'ISIT: International Symposium on Information Theory'
start_date: 2017-06-25
date_created: 2019-06-06T12:53:09Z
date_published: 2017-08-09T00:00:00Z
date_updated: 2021-01-12T08:07:53Z
day: '09'
department:
- _id: KrPi
doi: 10.1109/isit.2017.8006529
ec_funded: 1
external_id:
arxiv:
- '1702.01666'
language:
- iso: eng
main_file_link:
- open_access: '1'
url: https://arxiv.org/abs/1702.01666
month: '08'
oa: 1
oa_version: Preprint
project:
- _id: 258AA5B2-B435-11E9-9278-68D0E5697425
call_identifier: H2020
grant_number: '682815'
name: Teaching Old Crypto New Tricks
publication: 2017 IEEE International Symposium on Information Theory (ISIT)
publication_identifier:
isbn:
- '9781509040964'
publication_status: published
publisher: IEEE
quality_controlled: '1'
scopus_import: 1
status: public
title: On the complexity of estimating Rènyi divergences
type: conference
user_id: 3E5EF7F0-F248-11E8-B48F-1D18A9856A87
year: '2017'
...
---
_id: '6527'
abstract:
- lang: eng
text: "A memory-hard function (MHF) ƒn with parameter n can be computed in sequential
time and space n. Simultaneously, a high amortized parallel area-time complexity
(aAT) is incurred per evaluation. In practice, MHFs are used to limit the rate
at which an adversary (using a custom computational device) can evaluate a security
sensitive function that still occasionally needs to be evaluated by honest users
(using an off-the-shelf general purpose device). The most prevalent examples of
such sensitive functions are Key Derivation Functions (KDFs) and password hashing
algorithms where rate limits help mitigate off-line dictionary attacks. As the
honest users' inputs to these functions are often (low-entropy) passwords special
attention is given to a class of side-channel resistant MHFs called iMHFs.\r\n\r\nEssentially
all iMHFs can be viewed as some mode of operation (making n calls to some round
function) given by a directed acyclic graph (DAG) with very low indegree. Recently,
a combinatorial property of a DAG has been identified (called \"depth-robustness\")
which results in good provable security for an iMHF based on that DAG. Depth-robust
DAGs have also proven useful in other cryptographic applications. Unfortunately,
up till now, all known very depth-robust DAGs are impractically complicated and
little is known about their exact (i.e. non-asymptotic) depth-robustness both
in theory and in practice.\r\n\r\nIn this work we build and analyze (both formally
and empirically) several exceedingly simple and efficient to navigate practical
DAGs for use in iMHFs and other applications. For each DAG we:\r\n*Prove that
their depth-robustness is asymptotically maximal.\r\n*Prove bounds of at least
3 orders of magnitude better on their exact depth-robustness compared to known
bounds for other practical iMHF.\r\n*Implement and empirically evaluate their
depth-robustness and aAT against a variety of state-of-the art (and several new)
depth-reduction and low aAT attacks. \r\nWe find that, against all attacks, the
new DAGs perform significantly better in practice than Argon2i, the most widely
deployed iMHF in practice.\r\n\r\nAlong the way we also improve the best known
empirical attacks on the aAT of Argon2i by implementing and testing several heuristic
versions of a (hitherto purely theoretical) depth-reduction attack. Finally, we
demonstrate practicality of our constructions by modifying the Argon2i code base
to use one of the new high aAT DAGs. Experimental benchmarks on a standard off-the-shelf
CPU show that the new modifications do not adversely affect the impressive throughput
of Argon2i (despite seemingly enjoying significantly higher aAT).\r\n"
author:
- first_name: Joel F
full_name: Alwen, Joel F
id: 2A8DFA8C-F248-11E8-B48F-1D18A9856A87
last_name: Alwen
- first_name: Jeremiah
full_name: Blocki, Jeremiah
last_name: Blocki
- first_name: Ben
full_name: Harsha, Ben
last_name: Harsha
citation:
ama: 'Alwen JF, Blocki J, Harsha B. Practical graphs for optimal side-channel resistant
memory-hard functions. In: Proceedings of the 2017 ACM SIGSAC Conference on
Computer and Communications Security. ACM Press; 2017:1001-1017. doi:10.1145/3133956.3134031'
apa: 'Alwen, J. F., Blocki, J., & Harsha, B. (2017). Practical graphs for optimal
side-channel resistant memory-hard functions. In Proceedings of the 2017 ACM
SIGSAC Conference on Computer and Communications Security (pp. 1001–1017).
Dallas, TX, USA: ACM Press. https://doi.org/10.1145/3133956.3134031'
chicago: Alwen, Joel F, Jeremiah Blocki, and Ben Harsha. “Practical Graphs for Optimal
Side-Channel Resistant Memory-Hard Functions.” In Proceedings of the 2017 ACM
SIGSAC Conference on Computer and Communications Security, 1001–17. ACM Press,
2017. https://doi.org/10.1145/3133956.3134031.
ieee: J. F. Alwen, J. Blocki, and B. Harsha, “Practical graphs for optimal side-channel
resistant memory-hard functions,” in Proceedings of the 2017 ACM SIGSAC Conference
on Computer and Communications Security, Dallas, TX, USA, 2017, pp. 1001–1017.
ista: 'Alwen JF, Blocki J, Harsha B. 2017. Practical graphs for optimal side-channel
resistant memory-hard functions. Proceedings of the 2017 ACM SIGSAC Conference
on Computer and Communications Security. CCS: Conference on Computer and Communications
Security, 1001–1017.'
mla: Alwen, Joel F., et al. “Practical Graphs for Optimal Side-Channel Resistant
Memory-Hard Functions.” Proceedings of the 2017 ACM SIGSAC Conference on Computer
and Communications Security, ACM Press, 2017, pp. 1001–17, doi:10.1145/3133956.3134031.
short: J.F. Alwen, J. Blocki, B. Harsha, in:, Proceedings of the 2017 ACM SIGSAC
Conference on Computer and Communications Security, ACM Press, 2017, pp. 1001–1017.
conference:
end_date: 2017-11-03
location: Dallas, TX, USA
name: 'CCS: Conference on Computer and Communications Security'
start_date: 2017-10-30
date_created: 2019-06-06T13:21:29Z
date_published: 2017-10-30T00:00:00Z
date_updated: 2021-01-12T08:07:53Z
day: '30'
department:
- _id: KrPi
doi: 10.1145/3133956.3134031
ec_funded: 1
language:
- iso: eng
main_file_link:
- open_access: '1'
url: https://eprint.iacr.org/2017/443
month: '10'
oa: 1
oa_version: Submitted Version
page: 1001-1017
project:
- _id: 258AA5B2-B435-11E9-9278-68D0E5697425
call_identifier: H2020
grant_number: '682815'
name: Teaching Old Crypto New Tricks
publication: Proceedings of the 2017 ACM SIGSAC Conference on Computer and Communications
Security
publication_identifier:
isbn:
- '9781450349468'
publication_status: published
publisher: ACM Press
quality_controlled: '1'
scopus_import: 1
status: public
title: Practical graphs for optimal side-channel resistant memory-hard functions
type: conference
user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87
year: '2017'
...
---
_id: '1187'
abstract:
- lang: eng
text: We construct efficient authentication protocols and message authentication
codes (MACs) whose security can be reduced to the learning parity with noise (LPN)
problem. Despite a large body of work—starting with the (Formula presented.) protocol
of Hopper and Blum in 2001—until now it was not even known how to construct an
efficient authentication protocol from LPN which is secure against man-in-the-middle
attacks. A MAC implies such a (two-round) protocol.
article_processing_charge: No
article_type: original
author:
- first_name: Eike
full_name: Kiltz, Eike
last_name: Kiltz
- first_name: Krzysztof Z
full_name: Pietrzak, Krzysztof Z
id: 3E04A7AA-F248-11E8-B48F-1D18A9856A87
last_name: Pietrzak
orcid: 0000-0002-9139-1654
- first_name: Daniele
full_name: Venturi, Daniele
last_name: Venturi
- first_name: David
full_name: Cash, David
last_name: Cash
- first_name: Abhishek
full_name: Jain, Abhishek
last_name: Jain
citation:
ama: Kiltz E, Pietrzak KZ, Venturi D, Cash D, Jain A. Efficient authentication from
hard learning problems. Journal of Cryptology. 2017;30(4):1238-1275. doi:10.1007/s00145-016-9247-3
apa: Kiltz, E., Pietrzak, K. Z., Venturi, D., Cash, D., & Jain, A. (2017). Efficient
authentication from hard learning problems. Journal of Cryptology. Springer.
https://doi.org/10.1007/s00145-016-9247-3
chicago: Kiltz, Eike, Krzysztof Z Pietrzak, Daniele Venturi, David Cash, and Abhishek
Jain. “Efficient Authentication from Hard Learning Problems.” Journal of Cryptology.
Springer, 2017. https://doi.org/10.1007/s00145-016-9247-3.
ieee: E. Kiltz, K. Z. Pietrzak, D. Venturi, D. Cash, and A. Jain, “Efficient authentication
from hard learning problems,” Journal of Cryptology, vol. 30, no. 4. Springer,
pp. 1238–1275, 2017.
ista: Kiltz E, Pietrzak KZ, Venturi D, Cash D, Jain A. 2017. Efficient authentication
from hard learning problems. Journal of Cryptology. 30(4), 1238–1275.
mla: Kiltz, Eike, et al. “Efficient Authentication from Hard Learning Problems.”
Journal of Cryptology, vol. 30, no. 4, Springer, 2017, pp. 1238–75, doi:10.1007/s00145-016-9247-3.
short: E. Kiltz, K.Z. Pietrzak, D. Venturi, D. Cash, A. Jain, Journal of Cryptology
30 (2017) 1238–1275.
date_created: 2018-12-11T11:50:37Z
date_published: 2017-10-01T00:00:00Z
date_updated: 2023-09-20T11:20:58Z
day: '01'
ddc:
- '000'
department:
- _id: KrPi
doi: 10.1007/s00145-016-9247-3
ec_funded: 1
external_id:
isi:
- '000410788600007'
file:
- access_level: open_access
checksum: c647520d115b772a1682fc06fa273eb1
content_type: application/pdf
creator: dernst
date_created: 2020-05-14T16:30:17Z
date_updated: 2020-07-14T12:44:37Z
file_id: '7843'
file_name: 2017_JournalCrypto_Kiltz.pdf
file_size: 516959
relation: main_file
file_date_updated: 2020-07-14T12:44:37Z
has_accepted_license: '1'
intvolume: ' 30'
isi: 1
issue: '4'
language:
- iso: eng
month: '10'
oa: 1
oa_version: Submitted Version
page: 1238 - 1275
project:
- _id: 258AA5B2-B435-11E9-9278-68D0E5697425
call_identifier: H2020
grant_number: '682815'
name: Teaching Old Crypto New Tricks
- _id: 258C570E-B435-11E9-9278-68D0E5697425
call_identifier: FP7
grant_number: '259668'
name: Provable Security for Physical Cryptography
publication: Journal of Cryptology
publication_status: published
publisher: Springer
publist_id: '6166'
quality_controlled: '1'
related_material:
record:
- id: '3238'
relation: earlier_version
status: public
scopus_import: '1'
status: public
title: Efficient authentication from hard learning problems
type: journal_article
user_id: c635000d-4b10-11ee-a964-aac5a93f6ac1
volume: 30
year: '2017'
...
---
_id: '1177'
abstract:
- lang: eng
text: Boldyreva, Palacio and Warinschi introduced a multiple forking game as an
extension of general forking. The notion of (multiple) forking is a useful abstraction
from the actual simulation of cryptographic scheme to the adversary in a security
reduction, and is achieved through the intermediary of a so-called wrapper algorithm.
Multiple forking has turned out to be a useful tool in the security argument of
several cryptographic protocols. However, a reduction employing multiple forking
incurs a significant degradation of (Formula presented.) , where (Formula presented.)
denotes the upper bound on the underlying random oracle calls and (Formula presented.)
, the number of forkings. In this work we take a closer look at the reasons for
the degradation with a tighter security bound in mind. We nail down the exact
set of conditions for success in the multiple forking game. A careful analysis
of the cryptographic schemes and corresponding security reduction employing multiple
forking leads to the formulation of ‘dependence’ and ‘independence’ conditions
pertaining to the output of the wrapper in different rounds. Based on the (in)dependence
conditions we propose a general framework of multiple forking and a General Multiple
Forking Lemma. Leveraging (in)dependence to the full allows us to improve the
degradation factor in the multiple forking game by a factor of (Formula presented.).
By implication, the cost of a single forking involving two random oracles (augmented
forking) matches that involving a single random oracle (elementary forking). Finally,
we study the effect of these observations on the concrete security of existing
schemes employing multiple forking. We conclude that by careful design of the
protocol (and the wrapper in the security reduction) it is possible to harness
our observations to the full extent.
acknowledgement: "We are grateful to the anonymous reviewers for their insightful
comments. The\r\ndetailed reports helped us a lot to address the technical mistakes
as well as to improve the overall presentation of the paper."
author:
- first_name: Chethan
full_name: Kamath Hosdurg, Chethan
id: 4BD3F30E-F248-11E8-B48F-1D18A9856A87
last_name: Kamath Hosdurg
- first_name: Sanjit
full_name: Chatterjee, Sanjit
last_name: Chatterjee
citation:
ama: 'Kamath Hosdurg C, Chatterjee S. A closer look at multiple-forking: Leveraging
(in)dependence for a tighter bound. Algorithmica. 2016;74(4):1321-1362.
doi:10.1007/s00453-015-9997-6'
apa: 'Kamath Hosdurg, C., & Chatterjee, S. (2016). A closer look at multiple-forking:
Leveraging (in)dependence for a tighter bound. Algorithmica. Springer.
https://doi.org/10.1007/s00453-015-9997-6'
chicago: 'Kamath Hosdurg, Chethan, and Sanjit Chatterjee. “A Closer Look at Multiple-Forking:
Leveraging (in)Dependence for a Tighter Bound.” Algorithmica. Springer,
2016. https://doi.org/10.1007/s00453-015-9997-6.'
ieee: 'C. Kamath Hosdurg and S. Chatterjee, “A closer look at multiple-forking:
Leveraging (in)dependence for a tighter bound,” Algorithmica, vol. 74,
no. 4. Springer, pp. 1321–1362, 2016.'
ista: 'Kamath Hosdurg C, Chatterjee S. 2016. A closer look at multiple-forking:
Leveraging (in)dependence for a tighter bound. Algorithmica. 74(4), 1321–1362.'
mla: 'Kamath Hosdurg, Chethan, and Sanjit Chatterjee. “A Closer Look at Multiple-Forking:
Leveraging (in)Dependence for a Tighter Bound.” Algorithmica, vol. 74,
no. 4, Springer, 2016, pp. 1321–62, doi:10.1007/s00453-015-9997-6.'
short: C. Kamath Hosdurg, S. Chatterjee, Algorithmica 74 (2016) 1321–1362.
date_created: 2018-12-11T11:50:33Z
date_published: 2016-04-01T00:00:00Z
date_updated: 2021-01-12T06:48:52Z
day: '01'
department:
- _id: KrPi
doi: 10.1007/s00453-015-9997-6
intvolume: ' 74'
issue: '4'
language:
- iso: eng
main_file_link:
- open_access: '1'
url: http://eprint.iacr.org/2013/651
month: '04'
oa: 1
oa_version: Submitted Version
page: 1321 - 1362
publication: Algorithmica
publication_status: published
publisher: Springer
publist_id: '6177'
quality_controlled: '1'
status: public
title: 'A closer look at multiple-forking: Leveraging (in)dependence for a tighter
bound'
type: journal_article
user_id: 3E5EF7F0-F248-11E8-B48F-1D18A9856A87
volume: 74
year: '2016'
...
---
_id: '1179'
abstract:
- lang: eng
text: "Computational notions of entropy have recently found many applications, including
leakage-resilient cryptography, deterministic encryption or memory delegation.
The two main types of results which make computational notions so useful are (1)
Chain rules, which quantify by how much the computational entropy of a variable
decreases if conditioned on some other variable (2) Transformations, which quantify
to which extend one type of entropy implies another.\r\n\r\nSuch chain rules and
transformations typically lose a significant amount in quality of the entropy,
and are the reason why applying these results one gets rather weak quantitative
security bounds. In this paper we for the first time prove lower bounds in this
context, showing that existing results for transformations are, unfortunately,
basically optimal for non-adaptive black-box reductions (and it’s hard to imagine
how non black-box reductions or adaptivity could be useful here.)\r\n\r\nA variable
X has k bits of HILL entropy of quality (ϵ,s)\r\nif there exists a variable Y
with k bits min-entropy which cannot be distinguished from X with advantage ϵ\r\n\r\nby
distinguishing circuits of size s. A weaker notion is Metric entropy, where we
switch quantifiers, and only require that for every distinguisher of size s, such
a Y exists.\r\n\r\nWe first describe our result concerning transformations. By
definition, HILL implies Metric without any loss in quality. Metric entropy often
comes up in applications, but must be transformed to HILL for meaningful security
guarantees. The best known result states that if a variable X has k bits of Metric
entropy of quality (ϵ,s)\r\n, then it has k bits of HILL with quality (2ϵ,s⋅ϵ2).
We show that this loss of a factor Ω(ϵ−2)\r\n\r\nin circuit size is necessary.
In fact, we show the stronger result that this loss is already necessary when
transforming so called deterministic real valued Metric entropy to randomised
boolean Metric (both these variants of Metric entropy are implied by HILL without
loss in quality).\r\n\r\nThe chain rule for HILL entropy states that if X has
k bits of HILL entropy of quality (ϵ,s)\r\n, then for any variable Z of length
m, X conditioned on Z has k−m bits of HILL entropy with quality (ϵ,s⋅ϵ2/2m). We
show that a loss of Ω(2m/ϵ) in circuit size necessary here. Note that this still
leaves a gap of ϵ between the known bound and our lower bound."
acknowledgement: "K. Pietrzak—Supported by the European Research Council consolidator
grant (682815-TOCNeT).\r\nM. Skórski—Supported by the National Science Center, Poland
(2015/17/N/ST6/03564)."
alternative_title:
- LNCS
author:
- first_name: Krzysztof Z
full_name: Pietrzak, Krzysztof Z
id: 3E04A7AA-F248-11E8-B48F-1D18A9856A87
last_name: Pietrzak
orcid: 0000-0002-9139-1654
- first_name: Skorski
full_name: Maciej, Skorski
last_name: Maciej
citation:
ama: 'Pietrzak KZ, Maciej S. Pseudoentropy: Lower-bounds for chain rules and transformations.
In: Vol 9985. Springer; 2016:183-203. doi:10.1007/978-3-662-53641-4_8'
apa: 'Pietrzak, K. Z., & Maciej, S. (2016). Pseudoentropy: Lower-bounds for
chain rules and transformations (Vol. 9985, pp. 183–203). Presented at the TCC:
Theory of Cryptography Conference, Beijing, China: Springer. https://doi.org/10.1007/978-3-662-53641-4_8'
chicago: 'Pietrzak, Krzysztof Z, and Skorski Maciej. “Pseudoentropy: Lower-Bounds
for Chain Rules and Transformations,” 9985:183–203. Springer, 2016. https://doi.org/10.1007/978-3-662-53641-4_8.'
ieee: 'K. Z. Pietrzak and S. Maciej, “Pseudoentropy: Lower-bounds for chain rules
and transformations,” presented at the TCC: Theory of Cryptography Conference,
Beijing, China, 2016, vol. 9985, pp. 183–203.'
ista: 'Pietrzak KZ, Maciej S. 2016. Pseudoentropy: Lower-bounds for chain rules
and transformations. TCC: Theory of Cryptography Conference, LNCS, vol. 9985,
183–203.'
mla: 'Pietrzak, Krzysztof Z., and Skorski Maciej. Pseudoentropy: Lower-Bounds
for Chain Rules and Transformations. Vol. 9985, Springer, 2016, pp. 183–203,
doi:10.1007/978-3-662-53641-4_8.'
short: K.Z. Pietrzak, S. Maciej, in:, Springer, 2016, pp. 183–203.
conference:
end_date: 2016-11-03
location: Beijing, China
name: 'TCC: Theory of Cryptography Conference'
start_date: 2016-10-31
date_created: 2018-12-11T11:50:34Z
date_published: 2016-10-22T00:00:00Z
date_updated: 2021-01-12T06:48:53Z
day: '22'
department:
- _id: KrPi
doi: 10.1007/978-3-662-53641-4_8
ec_funded: 1
intvolume: ' 9985'
language:
- iso: eng
main_file_link:
- open_access: '1'
url: https://eprint.iacr.org/2016/159
month: '10'
oa: 1
oa_version: Preprint
page: 183 - 203
project:
- _id: 258AA5B2-B435-11E9-9278-68D0E5697425
call_identifier: H2020
grant_number: '682815'
name: Teaching Old Crypto New Tricks
publication_status: published
publisher: Springer
publist_id: '6175'
quality_controlled: '1'
scopus_import: 1
status: public
title: 'Pseudoentropy: Lower-bounds for chain rules and transformations'
type: conference
user_id: 3E5EF7F0-F248-11E8-B48F-1D18A9856A87
volume: 9985
year: '2016'
...
---
_id: '1653'
abstract:
- lang: eng
text: "A somewhere statistically binding (SSB) hash, introduced by Hubáček and Wichs
(ITCS ’15), can be used to hash a long string x to a short digest y = H hk (x)
using a public hashing-key hk. Furthermore, there is a way to set up the hash
key hk to make it statistically binding on some arbitrary hidden position i, meaning
that: (1) the digest y completely determines the i’th bit (or symbol) of x so
that all pre-images of y have the same value in the i’th position, (2) it is computationally
infeasible to distinguish the position i on which hk is statistically binding
from any other position i’. Lastly, the hash should have a local opening property
analogous to Merkle-Tree hashing, meaning that given x and y = H hk (x) it should
be possible to create a short proof π that certifies the value of the i’th bit
(or symbol) of x without having to provide the entire input x. A similar primitive
called a positional accumulator, introduced by Koppula, Lewko and Waters (STOC
’15) further supports dynamic updates of the hashed value. These tools, which
are interesting in their own right, also serve as one of the main technical components
in several recent works building advanced applications from indistinguishability
obfuscation (iO).\r\n\r\nThe prior constructions of SSB hashing and positional
accumulators required fully homomorphic encryption (FHE) and iO respectively.
In this work, we give new constructions of these tools based on well studied number-theoretic
assumptions such as DDH, Phi-Hiding and DCR, as well as a general construction
from lossy/injective functions."
alternative_title:
- LNCS
author:
- first_name: Tatsuaki
full_name: Okamoto, Tatsuaki
last_name: Okamoto
- first_name: Krzysztof Z
full_name: Pietrzak, Krzysztof Z
id: 3E04A7AA-F248-11E8-B48F-1D18A9856A87
last_name: Pietrzak
orcid: 0000-0002-9139-1654
- first_name: Brent
full_name: Waters, Brent
last_name: Waters
- first_name: Daniel
full_name: Wichs, Daniel
last_name: Wichs
citation:
ama: 'Okamoto T, Pietrzak KZ, Waters B, Wichs D. New realizations of somewhere statistically
binding hashing and positional accumulators. In: Vol 9452. Springer; 2016:121-145.
doi:10.1007/978-3-662-48797-6_6'
apa: 'Okamoto, T., Pietrzak, K. Z., Waters, B., & Wichs, D. (2016). New realizations
of somewhere statistically binding hashing and positional accumulators (Vol. 9452,
pp. 121–145). Presented at the ASIACRYPT: Theory and Application of Cryptology
and Information Security, Auckland, New Zealand: Springer. https://doi.org/10.1007/978-3-662-48797-6_6'
chicago: Okamoto, Tatsuaki, Krzysztof Z Pietrzak, Brent Waters, and Daniel Wichs.
“New Realizations of Somewhere Statistically Binding Hashing and Positional Accumulators,”
9452:121–45. Springer, 2016. https://doi.org/10.1007/978-3-662-48797-6_6.
ieee: 'T. Okamoto, K. Z. Pietrzak, B. Waters, and D. Wichs, “New realizations of
somewhere statistically binding hashing and positional accumulators,” presented
at the ASIACRYPT: Theory and Application of Cryptology and Information Security,
Auckland, New Zealand, 2016, vol. 9452, pp. 121–145.'
ista: 'Okamoto T, Pietrzak KZ, Waters B, Wichs D. 2016. New realizations of somewhere
statistically binding hashing and positional accumulators. ASIACRYPT: Theory and
Application of Cryptology and Information Security, LNCS, vol. 9452, 121–145.'
mla: Okamoto, Tatsuaki, et al. New Realizations of Somewhere Statistically Binding
Hashing and Positional Accumulators. Vol. 9452, Springer, 2016, pp. 121–45,
doi:10.1007/978-3-662-48797-6_6.
short: T. Okamoto, K.Z. Pietrzak, B. Waters, D. Wichs, in:, Springer, 2016, pp.
121–145.
conference:
end_date: 2015-12-03
location: Auckland, New Zealand
name: 'ASIACRYPT: Theory and Application of Cryptology and Information Security'
start_date: 2015-11-29
date_created: 2018-12-11T11:53:16Z
date_published: 2016-01-08T00:00:00Z
date_updated: 2021-01-12T06:52:16Z
day: '08'
ddc:
- '000'
department:
- _id: KrPi
doi: 10.1007/978-3-662-48797-6_6
ec_funded: 1
file:
- access_level: open_access
checksum: a57711cb660c5b17b42bb47275a00180
content_type: application/pdf
creator: system
date_created: 2018-12-12T10:12:05Z
date_updated: 2020-07-14T12:45:08Z
file_id: '4923'
file_name: IST-2016-677-v1+1_869.pdf
file_size: 580088
relation: main_file
file_date_updated: 2020-07-14T12:45:08Z
has_accepted_license: '1'
intvolume: ' 9452'
language:
- iso: eng
month: '01'
oa: 1
oa_version: Submitted Version
page: 121 - 145
project:
- _id: 258C570E-B435-11E9-9278-68D0E5697425
call_identifier: FP7
grant_number: '259668'
name: Provable Security for Physical Cryptography
publication_status: published
publisher: Springer
publist_id: '5497'
pubrep_id: '677'
quality_controlled: '1'
scopus_import: 1
status: public
title: New realizations of somewhere statistically binding hashing and positional
accumulators
type: conference
user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87
volume: 9452
year: '2016'
...
---
_id: '1479'
abstract:
- lang: eng
text: "Most entropy notions H(.) like Shannon or min-entropy satisfy a chain rule
stating that for random variables X,Z, and A we have H(X|Z,A)≥H(X|Z)−|A|. That
is, by conditioning on A the entropy of X can decrease by at most the bitlength
|A| of A. Such chain rules are known to hold for some computational entropy notions
like Yao’s and unpredictability-entropy. For HILL entropy, the computational analogue
of min-entropy, the chain rule is of special interest and has found many applications,
including leakage-resilient cryptography, deterministic encryption, and memory
delegation. These applications rely on restricted special cases of the chain rule.
Whether the chain rule for conditional HILL entropy holds in general was an open
problem for which we give a strong negative answer: we construct joint distributions
(X,Z,A), where A is a distribution over a single bit, such that the HILL entropy
H HILL (X|Z) is large but H HILL (X|Z,A) is basically zero.\r\n\r\nOur counterexample
just makes the minimal assumption that NP⊈P/poly. Under the stronger assumption
that injective one-way function exist, we can make all the distributions efficiently
samplable.\r\n\r\nFinally, we show that some more sophisticated cryptographic
objects like lossy functions can be used to sample a distribution constituting
a counterexample to the chain rule making only a single invocation to the underlying
object."
acknowledgement: "This work was partly funded by the European Research Council under
ERC Starting Grant 259668-PSPC and ERC Advanced Grant 321310-PERCY.\r\n"
author:
- first_name: Stephan
full_name: Krenn, Stephan
id: 329FCCF0-F248-11E8-B48F-1D18A9856A87
last_name: Krenn
orcid: 0000-0003-2835-9093
- first_name: Krzysztof Z
full_name: Pietrzak, Krzysztof Z
id: 3E04A7AA-F248-11E8-B48F-1D18A9856A87
last_name: Pietrzak
orcid: 0000-0002-9139-1654
- first_name: Akshay
full_name: Wadia, Akshay
last_name: Wadia
- first_name: Daniel
full_name: Wichs, Daniel
last_name: Wichs
citation:
ama: Krenn S, Pietrzak KZ, Wadia A, Wichs D. A counterexample to the chain rule
for conditional HILL entropy. Computational Complexity. 2016;25(3):567-605.
doi:10.1007/s00037-015-0120-9
apa: Krenn, S., Pietrzak, K. Z., Wadia, A., & Wichs, D. (2016). A counterexample
to the chain rule for conditional HILL entropy. Computational Complexity.
Springer. https://doi.org/10.1007/s00037-015-0120-9
chicago: Krenn, Stephan, Krzysztof Z Pietrzak, Akshay Wadia, and Daniel Wichs. “A
Counterexample to the Chain Rule for Conditional HILL Entropy.” Computational
Complexity. Springer, 2016. https://doi.org/10.1007/s00037-015-0120-9.
ieee: S. Krenn, K. Z. Pietrzak, A. Wadia, and D. Wichs, “A counterexample to the
chain rule for conditional HILL entropy,” Computational Complexity, vol.
25, no. 3. Springer, pp. 567–605, 2016.
ista: Krenn S, Pietrzak KZ, Wadia A, Wichs D. 2016. A counterexample to the chain
rule for conditional HILL entropy. Computational Complexity. 25(3), 567–605.
mla: Krenn, Stephan, et al. “A Counterexample to the Chain Rule for Conditional
HILL Entropy.” Computational Complexity, vol. 25, no. 3, Springer, 2016,
pp. 567–605, doi:10.1007/s00037-015-0120-9.
short: S. Krenn, K.Z. Pietrzak, A. Wadia, D. Wichs, Computational Complexity 25
(2016) 567–605.
date_created: 2018-12-11T11:52:16Z
date_published: 2016-09-01T00:00:00Z
date_updated: 2023-02-23T11:05:09Z
day: '01'
ddc:
- '004'
department:
- _id: KrPi
doi: 10.1007/s00037-015-0120-9
ec_funded: 1
file:
- access_level: open_access
checksum: 7659296174fa75f5f0364f31f46f4bcf
content_type: application/pdf
creator: system
date_created: 2018-12-12T10:13:29Z
date_updated: 2020-07-14T12:44:56Z
file_id: '5012'
file_name: IST-2017-766-v1+1_678.pdf
file_size: 483258
relation: main_file
file_date_updated: 2020-07-14T12:44:56Z
has_accepted_license: '1'
intvolume: ' 25'
issue: '3'
language:
- iso: eng
month: '09'
oa: 1
oa_version: Submitted Version
page: 567 - 605
project:
- _id: 258C570E-B435-11E9-9278-68D0E5697425
call_identifier: FP7
grant_number: '259668'
name: Provable Security for Physical Cryptography
publication: Computational Complexity
publication_status: published
publisher: Springer
publist_id: '5715'
pubrep_id: '766'
quality_controlled: '1'
related_material:
record:
- id: '2940'
relation: earlier_version
status: public
scopus_import: 1
status: public
title: A counterexample to the chain rule for conditional HILL entropy
tmp:
image: /images/cc_by.png
legal_code_url: https://creativecommons.org/licenses/by/4.0/legalcode
name: Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)
short: CC BY (4.0)
type: journal_article
user_id: 3E5EF7F0-F248-11E8-B48F-1D18A9856A87
volume: 25
year: '2016'
...
---
_id: '1592'
abstract:
- lang: eng
text: A modular approach to constructing cryptographic protocols leads to simple
designs but often inefficient instantiations. On the other hand, ad hoc constructions
may yield efficient protocols at the cost of losing conceptual simplicity. We
suggest a new design paradigm, structure-preserving cryptography, that provides
a way to construct modular protocols with reasonable efficiency while retaining
conceptual simplicity. A cryptographic scheme over a bilinear group is called
structure-preserving if its public inputs and outputs consist of elements from
the bilinear groups and their consistency can be verified by evaluating pairing-product
equations. As structure-preserving schemes smoothly interoperate with each other,
they are useful as building blocks in modular design of cryptographic applications.
This paper introduces structure-preserving commitment and signature schemes over
bilinear groups with several desirable properties. The commitment schemes include
homomorphic, trapdoor and length-reducing commitments to group elements, and the
structure-preserving signature schemes are the first ones that yield constant-size
signatures on multiple group elements. A structure-preserving signature scheme
is called automorphic if the public keys lie in the message space, which cannot
be achieved by compressing inputs via a cryptographic hash function, as this would
destroy the mathematical structure we are trying to preserve. Automorphic signatures
can be used for building certification chains underlying privacy-preserving protocols.
Among a vast number of applications of structure-preserving protocols, we present
an efficient round-optimal blind-signature scheme and a group signature scheme
with an efficient and concurrently secure protocol for enrolling new members.
acknowledgement: The authors would like to thank the anonymous reviewers of this paper.
We also would like to express our appreciation to the program committee and the
anonymous reviewers for CRYPTO 2010. The first author thanks Sherman S. M. Chow
for his comment on group signatures in Sect. 7.1.
author:
- first_name: Masayuki
full_name: Abe, Masayuki
last_name: Abe
- first_name: Georg
full_name: Fuchsbauer, Georg
id: 46B4C3EE-F248-11E8-B48F-1D18A9856A87
last_name: Fuchsbauer
- first_name: Jens
full_name: Groth, Jens
last_name: Groth
- first_name: Kristiyan
full_name: Haralambiev, Kristiyan
last_name: Haralambiev
- first_name: Miyako
full_name: Ohkubo, Miyako
last_name: Ohkubo
citation:
ama: Abe M, Fuchsbauer G, Groth J, Haralambiev K, Ohkubo M. Structure preserving
signatures and commitments to group elements. Journal of Cryptology. 2016;29(2):363-421.
doi:10.1007/s00145-014-9196-7
apa: Abe, M., Fuchsbauer, G., Groth, J., Haralambiev, K., & Ohkubo, M. (2016).
Structure preserving signatures and commitments to group elements. Journal
of Cryptology. Springer. https://doi.org/10.1007/s00145-014-9196-7
chicago: Abe, Masayuki, Georg Fuchsbauer, Jens Groth, Kristiyan Haralambiev, and
Miyako Ohkubo. “Structure Preserving Signatures and Commitments to Group Elements.”
Journal of Cryptology. Springer, 2016. https://doi.org/10.1007/s00145-014-9196-7.
ieee: M. Abe, G. Fuchsbauer, J. Groth, K. Haralambiev, and M. Ohkubo, “Structure
preserving signatures and commitments to group elements,” Journal of Cryptology,
vol. 29, no. 2. Springer, pp. 363–421, 2016.
ista: Abe M, Fuchsbauer G, Groth J, Haralambiev K, Ohkubo M. 2016. Structure preserving
signatures and commitments to group elements. Journal of Cryptology. 29(2), 363–421.
mla: Abe, Masayuki, et al. “Structure Preserving Signatures and Commitments to Group
Elements.” Journal of Cryptology, vol. 29, no. 2, Springer, 2016, pp. 363–421,
doi:10.1007/s00145-014-9196-7.
short: M. Abe, G. Fuchsbauer, J. Groth, K. Haralambiev, M. Ohkubo, Journal of Cryptology
29 (2016) 363–421.
date_created: 2018-12-11T11:52:54Z
date_published: 2016-04-01T00:00:00Z
date_updated: 2021-01-12T06:51:49Z
day: '01'
department:
- _id: KrPi
doi: 10.1007/s00145-014-9196-7
intvolume: ' 29'
issue: '2'
language:
- iso: eng
month: '04'
oa_version: None
page: 363 - 421
publication: Journal of Cryptology
publication_status: published
publisher: Springer
publist_id: '5579'
quality_controlled: '1'
scopus_import: 1
status: public
title: Structure preserving signatures and commitments to group elements
type: journal_article
user_id: 3E5EF7F0-F248-11E8-B48F-1D18A9856A87
volume: 29
year: '2016'
...
---
_id: '1365'
abstract:
- lang: eng
text: A memory-hard function (MHF) f is equipped with a space cost σ and time cost
τ parameter such that repeatedly computing fσ,τ on an application specific integrated
circuit (ASIC) is not economically advantageous relative to a general purpose
computer. Technically we would like that any (generalized) circuit for evaluating
an iMHF fσ,τ has area × time (AT) complexity at Θ(σ2 ∗ τ). A data-independent
MHF (iMHF) has the added property that it can be computed with almost optimal
memory and time complexity by an algorithm which accesses memory in a pattern
independent of the input value. Such functions can be specified by fixing a directed
acyclic graph (DAG) G on n = Θ(σ ∗ τ) nodes representing its computation graph.
In this work we develop new tools for analyzing iMHFs. First we define and motivate
a new complexity measure capturing the amount of energy (i.e. electricity) required
to compute a function. We argue that, in practice, this measure is at least as
important as the more traditional AT-complexity. Next we describe an algorithm
A for repeatedly evaluating an iMHF based on an arbitrary DAG G. We upperbound
both its energy and AT complexities per instance evaluated in terms of a certain
combinatorial property of G. Next we instantiate our attack for several general
classes of DAGs which include those underlying many of the most important iMHF
candidates in the literature. In particular, we obtain the following results which
hold for all choices of parameters σ and τ (and thread-count) such that n = σ
∗ τ. -The Catena-Dragonfly function of [FLW13] has AT and energy complexities
O(n1.67). -The Catena-Butterfly function of [FLW13] has complexities is O(n1.67).
-The Double-Buffer and the Linear functions of [CGBS16] both have complexities
in O(n1.67). -The Argon2i function of [BDK15] (winner of the Password Hashing
Competition [PHC]) has complexities O(n7/4 log(n)). -The Single-Buffer function
of [CGBS16] has complexities O(n7/4 log(n)). -Any iMHF can be computed by an algorithm
with complexities O(n2/ log1 −ε(n)) for all ε > 0. In particular when τ = 1
this shows that the goal of constructing an iMHF with AT-complexity Θ(σ2 ∗ τ )
is unachievable. Along the way we prove a lemma upper-bounding the depth-robustness
of any DAG which may prove to be of independent interest.
alternative_title:
- LNCS
author:
- first_name: Joel F
full_name: Alwen, Joel F
id: 2A8DFA8C-F248-11E8-B48F-1D18A9856A87
last_name: Alwen
- first_name: Jeremiah
full_name: Blocki, Jeremiah
last_name: Blocki
citation:
ama: 'Alwen JF, Blocki J. Efficiently computing data-independent memory-hard functions.
In: Vol 9815. Springer; 2016:241-271. doi:10.1007/978-3-662-53008-5_9'
apa: 'Alwen, J. F., & Blocki, J. (2016). Efficiently computing data-independent
memory-hard functions (Vol. 9815, pp. 241–271). Presented at the CRYPTO: International
Cryptology Conference, Santa Barbara, CA, USA: Springer. https://doi.org/10.1007/978-3-662-53008-5_9'
chicago: Alwen, Joel F, and Jeremiah Blocki. “Efficiently Computing Data-Independent
Memory-Hard Functions,” 9815:241–71. Springer, 2016. https://doi.org/10.1007/978-3-662-53008-5_9.
ieee: 'J. F. Alwen and J. Blocki, “Efficiently computing data-independent memory-hard
functions,” presented at the CRYPTO: International Cryptology Conference, Santa
Barbara, CA, USA, 2016, vol. 9815, pp. 241–271.'
ista: 'Alwen JF, Blocki J. 2016. Efficiently computing data-independent memory-hard
functions. CRYPTO: International Cryptology Conference, LNCS, vol. 9815, 241–271.'
mla: Alwen, Joel F., and Jeremiah Blocki. Efficiently Computing Data-Independent
Memory-Hard Functions. Vol. 9815, Springer, 2016, pp. 241–71, doi:10.1007/978-3-662-53008-5_9.
short: J.F. Alwen, J. Blocki, in:, Springer, 2016, pp. 241–271.
conference:
end_date: 2016-08-18
location: Santa Barbara, CA, USA
name: 'CRYPTO: International Cryptology Conference'
start_date: 2016-08-14
date_created: 2018-12-11T11:51:36Z
date_published: 2016-08-01T00:00:00Z
date_updated: 2021-01-12T06:50:11Z
day: '01'
department:
- _id: KrPi
doi: 10.1007/978-3-662-53008-5_9
intvolume: ' 9815'
language:
- iso: eng
main_file_link:
- open_access: '1'
url: http://eprint.iacr.org/2016/115
month: '08'
oa: 1
oa_version: Preprint
page: 241 - 271
publication_status: published
publisher: Springer
publist_id: '5876'
quality_controlled: '1'
scopus_import: 1
status: public
title: Efficiently computing data-independent memory-hard functions
type: conference
user_id: 3E5EF7F0-F248-11E8-B48F-1D18A9856A87
volume: 9815
year: '2016'
...
---
_id: '1366'
abstract:
- lang: eng
text: 'We study the problem of devising provably secure PRNGs with input based on
the sponge paradigm. Such constructions are very appealing, as efficient software/hardware
implementations of SHA-3 can easily be translated into a PRNG in a nearly black-box
way. The only existing sponge-based construction, proposed by Bertoni et al. (CHES
2010), fails to achieve the security notion of robustness recently considered
by Dodis et al. (CCS 2013), for two reasons: (1) The construction is deterministic,
and thus there are high-entropy input distributions on which the construction
fails to extract random bits, and (2) The construction is not forward secure,
and presented solutions aiming at restoring forward security have not been rigorously
analyzed. We propose a seeded variant of Bertoni et al.’s PRNG with input which
we prove secure in the sense of robustness, delivering in particular concrete
security bounds. On the way, we make what we believe to be an important conceptual
contribution, developing a variant of the security framework of Dodis et al. tailored
at the ideal permutation model that captures PRNG security in settings where the
weakly random inputs are provided from a large class of possible adversarial samplers
which are also allowed to query the random permutation. As a further application
of our techniques, we also present an efficient sponge-based key-derivation function
(which can be instantiated from SHA-3 in a black-box fashion), which we also prove
secure when fed with samples from permutation-dependent distributions.'
alternative_title:
- LNCS
author:
- first_name: Peter
full_name: Gazi, Peter
id: 3E0BFE38-F248-11E8-B48F-1D18A9856A87
last_name: Gazi
- first_name: Stefano
full_name: Tessaro, Stefano
last_name: Tessaro
citation:
ama: 'Gazi P, Tessaro S. Provably robust sponge-based PRNGs and KDFs. In: Vol 9665.
Springer; 2016:87-116. doi:10.1007/978-3-662-49890-3_4'
apa: 'Gazi, P., & Tessaro, S. (2016). Provably robust sponge-based PRNGs and
KDFs (Vol. 9665, pp. 87–116). Presented at the EUROCRYPT: Theory and Applications
of Cryptographic Techniques, Vienna, Austria: Springer. https://doi.org/10.1007/978-3-662-49890-3_4'
chicago: Gazi, Peter, and Stefano Tessaro. “Provably Robust Sponge-Based PRNGs and
KDFs,” 9665:87–116. Springer, 2016. https://doi.org/10.1007/978-3-662-49890-3_4.
ieee: 'P. Gazi and S. Tessaro, “Provably robust sponge-based PRNGs and KDFs,” presented
at the EUROCRYPT: Theory and Applications of Cryptographic Techniques, Vienna,
Austria, 2016, vol. 9665, pp. 87–116.'
ista: 'Gazi P, Tessaro S. 2016. Provably robust sponge-based PRNGs and KDFs. EUROCRYPT:
Theory and Applications of Cryptographic Techniques, LNCS, vol. 9665, 87–116.'
mla: Gazi, Peter, and Stefano Tessaro. Provably Robust Sponge-Based PRNGs and
KDFs. Vol. 9665, Springer, 2016, pp. 87–116, doi:10.1007/978-3-662-49890-3_4.
short: P. Gazi, S. Tessaro, in:, Springer, 2016, pp. 87–116.
conference:
end_date: 2016-05-12
location: Vienna, Austria
name: 'EUROCRYPT: Theory and Applications of Cryptographic Techniques'
start_date: 2016-05-08
date_created: 2018-12-11T11:51:36Z
date_published: 2016-05-01T00:00:00Z
date_updated: 2021-01-12T06:50:11Z
day: '01'
department:
- _id: KrPi
doi: 10.1007/978-3-662-49890-3_4
ec_funded: 1
intvolume: ' 9665'
language:
- iso: eng
main_file_link:
- open_access: '1'
url: https://eprint.iacr.org/2016/169/20160219:201940
month: '05'
oa: 1
oa_version: Preprint
page: 87 - 116
project:
- _id: 258C570E-B435-11E9-9278-68D0E5697425
call_identifier: FP7
grant_number: '259668'
name: Provable Security for Physical Cryptography
publication_status: published
publisher: Springer
publist_id: '5872'
quality_controlled: '1'
scopus_import: 1
status: public
title: Provably robust sponge-based PRNGs and KDFs
type: conference
user_id: 3E5EF7F0-F248-11E8-B48F-1D18A9856A87
volume: 9665
year: '2016'
...
---
_id: '1225'
abstract:
- lang: eng
text: At Crypto 2015 Fuchsbauer, Hanser and Slamanig (FHS) presented the first standard-model
construction of efficient roundoptimal blind signatures that does not require
complexity leveraging. It is conceptually simple and builds on the primitive of
structure-preserving signatures on equivalence classes (SPS-EQ). FHS prove the
unforgeability of their scheme assuming EUF-CMA security of the SPS-EQ scheme
and hardness of a version of the DH inversion problem. Blindness under adversarially
chosen keys is proven under an interactive variant of the DDH assumption. We propose
a variant of their scheme whose blindness can be proven under a non-interactive
assumption, namely a variant of the bilinear DDH assumption. We moreover prove
its unforgeability assuming only unforgeability of the underlying SPS-EQ but no
additional assumptions as needed for the FHS scheme.
alternative_title:
- LNCS
author:
- first_name: Georg
full_name: Fuchsbauer, Georg
id: 46B4C3EE-F248-11E8-B48F-1D18A9856A87
last_name: Fuchsbauer
- first_name: Christian
full_name: Hanser, Christian
last_name: Hanser
- first_name: Chethan
full_name: Kamath Hosdurg, Chethan
id: 4BD3F30E-F248-11E8-B48F-1D18A9856A87
last_name: Kamath Hosdurg
- first_name: Daniel
full_name: Slamanig, Daniel
last_name: Slamanig
citation:
ama: 'Fuchsbauer G, Hanser C, Kamath Hosdurg C, Slamanig D. Practical round-optimal
blind signatures in the standard model from weaker assumptions. In: Vol 9841.
Springer; 2016:391-408. doi:10.1007/978-3-319-44618-9_21'
apa: 'Fuchsbauer, G., Hanser, C., Kamath Hosdurg, C., & Slamanig, D. (2016).
Practical round-optimal blind signatures in the standard model from weaker assumptions
(Vol. 9841, pp. 391–408). Presented at the SCN: Security and Cryptography for
Networks, Amalfi, Italy: Springer. https://doi.org/10.1007/978-3-319-44618-9_21'
chicago: Fuchsbauer, Georg, Christian Hanser, Chethan Kamath Hosdurg, and Daniel
Slamanig. “Practical Round-Optimal Blind Signatures in the Standard Model from
Weaker Assumptions,” 9841:391–408. Springer, 2016. https://doi.org/10.1007/978-3-319-44618-9_21.
ieee: 'G. Fuchsbauer, C. Hanser, C. Kamath Hosdurg, and D. Slamanig, “Practical
round-optimal blind signatures in the standard model from weaker assumptions,”
presented at the SCN: Security and Cryptography for Networks, Amalfi, Italy, 2016,
vol. 9841, pp. 391–408.'
ista: 'Fuchsbauer G, Hanser C, Kamath Hosdurg C, Slamanig D. 2016. Practical round-optimal
blind signatures in the standard model from weaker assumptions. SCN: Security
and Cryptography for Networks, LNCS, vol. 9841, 391–408.'
mla: Fuchsbauer, Georg, et al. Practical Round-Optimal Blind Signatures in the
Standard Model from Weaker Assumptions. Vol. 9841, Springer, 2016, pp. 391–408,
doi:10.1007/978-3-319-44618-9_21.
short: G. Fuchsbauer, C. Hanser, C. Kamath Hosdurg, D. Slamanig, in:, Springer,
2016, pp. 391–408.
conference:
end_date: 2016-09-02
location: Amalfi, Italy
name: 'SCN: Security and Cryptography for Networks'
start_date: 2016-08-31
date_created: 2018-12-11T11:50:49Z
date_published: 2016-08-11T00:00:00Z
date_updated: 2023-02-23T10:08:16Z
day: '11'
department:
- _id: KrPi
doi: 10.1007/978-3-319-44618-9_21
ec_funded: 1
intvolume: ' 9841'
language:
- iso: eng
main_file_link:
- open_access: '1'
url: https://eprint.iacr.org/2016/662
month: '08'
oa: 1
oa_version: Submitted Version
page: 391 - 408
project:
- _id: 258C570E-B435-11E9-9278-68D0E5697425
call_identifier: FP7
grant_number: '259668'
name: Provable Security for Physical Cryptography
- _id: 258AA5B2-B435-11E9-9278-68D0E5697425
call_identifier: H2020
grant_number: '682815'
name: Teaching Old Crypto New Tricks
publication_status: published
publisher: Springer
publist_id: '6109'
quality_controlled: '1'
related_material:
record:
- id: '1647'
relation: earlier_version
status: public
scopus_import: 1
status: public
title: Practical round-optimal blind signatures in the standard model from weaker
assumptions
type: conference
user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87
volume: 9841
year: '2016'
...
---
_id: '1229'
abstract:
- lang: eng
text: Witness encryption (WE) was introduced by Garg et al. [GGSW13]. A WE scheme
is defined for some NP language L and lets a sender encrypt messages relative
to instances x. A ciphertext for x can be decrypted using w witnessing x ∈ L,
but hides the message if x ∈ L. Garg et al. construct WE from multilinear maps
and give another construction [GGH+13b] using indistinguishability obfuscation
(iO) for circuits. Due to the reliance on such heavy tools, WE can cur- rently
hardly be implemented on powerful hardware and will unlikely be realizable on
constrained devices like smart cards any time soon. We construct a WE scheme where
encryption is done by simply computing a Naor-Yung ciphertext (two CPA encryptions
and a NIZK proof). To achieve this, our scheme has a setup phase, which outputs
public parameters containing an obfuscated circuit (only required for decryption),
two encryption keys and a common reference string (used for encryption). This
setup need only be run once, and the parame- ters can be used for arbitrary many
encryptions. Our scheme can also be turned into a functional WE scheme, where
a message is encrypted w.r.t. a statement and a function f, and decryption with
a witness w yields f (m, w). Our construction is inspired by the functional encryption
scheme by Garg et al. and we prove (selective) security assuming iO and statistically
simulation-sound NIZK. We give a construction of the latter in bilinear groups
and combining it with ElGamal encryption, our ciphertexts are of size 1.3 kB at
a 128-bit security level and can be computed on a smart card.
acknowledgement: Research supported by the European Research Council, ERC starting grant
(259668-PSPC) and ERC consolidator grant (682815 - TOCNeT).
alternative_title:
- LNCS
author:
- first_name: Hamza M
full_name: Abusalah, Hamza M
id: 40297222-F248-11E8-B48F-1D18A9856A87
last_name: Abusalah
- first_name: Georg
full_name: Fuchsbauer, Georg
id: 46B4C3EE-F248-11E8-B48F-1D18A9856A87
last_name: Fuchsbauer
- first_name: Krzysztof Z
full_name: Pietrzak, Krzysztof Z
id: 3E04A7AA-F248-11E8-B48F-1D18A9856A87
last_name: Pietrzak
orcid: 0000-0002-9139-1654
citation:
ama: 'Abusalah HM, Fuchsbauer G, Pietrzak KZ. Offline witness encryption. In: Vol
9696. Springer; 2016:285-303. doi:10.1007/978-3-319-39555-5_16'
apa: 'Abusalah, H. M., Fuchsbauer, G., & Pietrzak, K. Z. (2016). Offline witness
encryption (Vol. 9696, pp. 285–303). Presented at the ACNS: Applied Cryptography
and Network Security, Guildford, UK: Springer. https://doi.org/10.1007/978-3-319-39555-5_16'
chicago: Abusalah, Hamza M, Georg Fuchsbauer, and Krzysztof Z Pietrzak. “Offline
Witness Encryption,” 9696:285–303. Springer, 2016. https://doi.org/10.1007/978-3-319-39555-5_16.
ieee: 'H. M. Abusalah, G. Fuchsbauer, and K. Z. Pietrzak, “Offline witness encryption,”
presented at the ACNS: Applied Cryptography and Network Security, Guildford, UK,
2016, vol. 9696, pp. 285–303.'
ista: 'Abusalah HM, Fuchsbauer G, Pietrzak KZ. 2016. Offline witness encryption.
ACNS: Applied Cryptography and Network Security, LNCS, vol. 9696, 285–303.'
mla: Abusalah, Hamza M., et al. Offline Witness Encryption. Vol. 9696, Springer,
2016, pp. 285–303, doi:10.1007/978-3-319-39555-5_16.
short: H.M. Abusalah, G. Fuchsbauer, K.Z. Pietrzak, in:, Springer, 2016, pp. 285–303.
conference:
end_date: 2016-06-22
location: Guildford, UK
name: 'ACNS: Applied Cryptography and Network Security'
start_date: 2016-06-19
date_created: 2018-12-11T11:50:50Z
date_published: 2016-06-09T00:00:00Z
date_updated: 2023-09-07T12:30:22Z
day: '09'
ddc:
- '005'
- '600'
department:
- _id: KrPi
doi: 10.1007/978-3-319-39555-5_16
ec_funded: 1
file:
- access_level: open_access
checksum: 34fa9ce681da845a1ba945ba3dc57867
content_type: application/pdf
creator: system
date_created: 2018-12-12T10:17:20Z
date_updated: 2020-07-14T12:44:39Z
file_id: '5273'
file_name: IST-2017-765-v1+1_838.pdf
file_size: 515000
relation: main_file
file_date_updated: 2020-07-14T12:44:39Z
has_accepted_license: '1'
intvolume: ' 9696'
language:
- iso: eng
month: '06'
oa: 1
oa_version: Submitted Version
page: 285 - 303
project:
- _id: 258C570E-B435-11E9-9278-68D0E5697425
call_identifier: FP7
grant_number: '259668'
name: Provable Security for Physical Cryptography
- _id: 258AA5B2-B435-11E9-9278-68D0E5697425
call_identifier: H2020
grant_number: '682815'
name: Teaching Old Crypto New Tricks
publication_status: published
publisher: Springer
publist_id: '6105'
pubrep_id: '765'
quality_controlled: '1'
related_material:
record:
- id: '83'
relation: dissertation_contains
status: public
scopus_import: 1
status: public
title: Offline witness encryption
type: conference
user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87
volume: 9696
year: '2016'
...