---
_id: '7411'
abstract:
- lang: eng
text: "Proofs of sequential work (PoSW) are proof systems where a prover, upon receiving
a statement χ and a time parameter T computes a proof ϕ(χ,T) which is efficiently
and publicly verifiable. The proof can be computed in T sequential steps, but
not much less, even by a malicious party having large parallelism. A PoSW thus
serves as a proof that T units of time have passed since χ\r\n\r\nwas received.\r\n\r\nPoSW
were introduced by Mahmoody, Moran and Vadhan [MMV11], a simple and practical
construction was only recently proposed by Cohen and Pietrzak [CP18].\r\n\r\nIn
this work we construct a new simple PoSW in the random permutation model which
is almost as simple and efficient as [CP18] but conceptually very different. Whereas
the structure underlying [CP18] is a hash tree, our construction is based on skip
lists and has the interesting property that computing the PoSW is a reversible
computation.\r\nThe fact that the construction is reversible can potentially be
used for new applications like constructing proofs of replication. We also show
how to “embed” the sloth function of Lenstra and Weselowski [LW17] into our PoSW
to get a PoSW where one additionally can verify correctness of the output much
more efficiently than recomputing it (though recent constructions of “verifiable
delay functions” subsume most of the applications this construction was aiming
at)."
alternative_title:
- LNCS
article_processing_charge: No
author:
- first_name: Hamza M
full_name: Abusalah, Hamza M
id: 40297222-F248-11E8-B48F-1D18A9856A87
last_name: Abusalah
- 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: Krzysztof Z
full_name: Pietrzak, Krzysztof Z
id: 3E04A7AA-F248-11E8-B48F-1D18A9856A87
last_name: Pietrzak
orcid: 0000-0002-9139-1654
- first_name: Michael
full_name: Walter, Michael
id: 488F98B0-F248-11E8-B48F-1D18A9856A87
last_name: Walter
orcid: 0000-0003-3186-2482
citation:
ama: 'Abusalah HM, Kamath Hosdurg C, Klein K, Pietrzak KZ, Walter M. Reversible
proofs of sequential work. In: Advances in Cryptology – EUROCRYPT 2019.
Vol 11477. Springer International Publishing; 2019:277-291. doi:10.1007/978-3-030-17656-3_10'
apa: 'Abusalah, H. M., Kamath Hosdurg, C., Klein, K., Pietrzak, K. Z., & Walter,
M. (2019). Reversible proofs of sequential work. In Advances in Cryptology
– EUROCRYPT 2019 (Vol. 11477, pp. 277–291). Darmstadt, Germany: Springer International
Publishing. https://doi.org/10.1007/978-3-030-17656-3_10'
chicago: Abusalah, Hamza M, Chethan Kamath Hosdurg, Karen Klein, Krzysztof Z Pietrzak,
and Michael Walter. “Reversible Proofs of Sequential Work.” In Advances in
Cryptology – EUROCRYPT 2019, 11477:277–91. Springer International Publishing,
2019. https://doi.org/10.1007/978-3-030-17656-3_10.
ieee: H. M. Abusalah, C. Kamath Hosdurg, K. Klein, K. Z. Pietrzak, and M. Walter,
“Reversible proofs of sequential work,” in Advances in Cryptology – EUROCRYPT
2019, Darmstadt, Germany, 2019, vol. 11477, pp. 277–291.
ista: Abusalah HM, Kamath Hosdurg C, Klein K, Pietrzak KZ, Walter M. 2019. Reversible
proofs of sequential work. Advances in Cryptology – EUROCRYPT 2019. International
Conference on the Theory and Applications of Cryptographic Techniques, LNCS, vol.
11477, 277–291.
mla: Abusalah, Hamza M., et al. “Reversible Proofs of Sequential Work.” Advances
in Cryptology – EUROCRYPT 2019, vol. 11477, Springer International Publishing,
2019, pp. 277–91, doi:10.1007/978-3-030-17656-3_10.
short: H.M. Abusalah, C. Kamath Hosdurg, K. Klein, K.Z. Pietrzak, M. Walter, in:,
Advances in Cryptology – EUROCRYPT 2019, Springer International Publishing, 2019,
pp. 277–291.
conference:
end_date: 2019-05-23
location: Darmstadt, Germany
name: International Conference on the Theory and Applications of Cryptographic Techniques
start_date: 2019-05-19
date_created: 2020-01-30T09:26:14Z
date_published: 2019-04-24T00:00:00Z
date_updated: 2023-09-06T15:26:06Z
day: '24'
department:
- _id: KrPi
doi: 10.1007/978-3-030-17656-3_10
ec_funded: 1
external_id:
isi:
- '000483516200010'
intvolume: ' 11477'
isi: 1
language:
- iso: eng
main_file_link:
- open_access: '1'
url: https://eprint.iacr.org/2019/252
month: '04'
oa: 1
oa_version: Submitted Version
page: 277-291
project:
- _id: 258AA5B2-B435-11E9-9278-68D0E5697425
call_identifier: H2020
grant_number: '682815'
name: Teaching Old Crypto New Tricks
publication: Advances in Cryptology – EUROCRYPT 2019
publication_identifier:
eissn:
- 1611-3349
isbn:
- '9783030176556'
- '9783030176563'
issn:
- 0302-9743
publication_status: published
publisher: Springer International Publishing
quality_controlled: '1'
scopus_import: '1'
status: public
title: Reversible proofs of sequential work
type: conference
user_id: c635000d-4b10-11ee-a964-aac5a93f6ac1
volume: 11477
year: '2019'
...
---
_id: '83'
abstract:
- lang: eng
text: "A proof system is a protocol between a prover and a verifier over a common
input in which an honest prover convinces the verifier of the validity of true
statements. Motivated by the success of decentralized cryptocurrencies, exemplified
by Bitcoin, the focus of this thesis will be on proof systems which found applications
in some sustainable alternatives to Bitcoin, such as the Spacemint and Chia cryptocurrencies.
In particular, we focus on proofs of space and proofs of sequential work.\r\nProofs
of space (PoSpace) were suggested as more ecological, economical, and egalitarian
alternative to the energy-wasteful proof-of-work mining of Bitcoin. However, the
state-of-the-art constructions of PoSpace are based on sophisticated graph pebbling
lower bounds, and are therefore complex. Moreover, when these PoSpace are used
in cryptocurrencies like Spacemint, miners can only start mining after ensuring
that a commitment to their space is already added in a special transaction to
the blockchain. Proofs of sequential work (PoSW) are proof systems in which a
prover, upon receiving a statement x and a time parameter T, computes a proof
which convinces the verifier that T time units had passed since x was received.
Whereas Spacemint assumes synchrony to retain some interesting Bitcoin dynamics,
Chia requires PoSW with unique proofs, i.e., PoSW in which it is hard to come
up with more than one accepting proof for any true statement. In this thesis we
construct simple and practically-efficient PoSpace and PoSW. When using our PoSpace
in cryptocurrencies, miners can start mining on the fly, like in Bitcoin, and
unlike current constructions of PoSW, which either achieve efficient verification
of sequential work, or faster-than-recomputing verification of correctness of
proofs, but not both at the same time, ours achieve the best of these two worlds."
alternative_title:
- ISTA Thesis
article_processing_charge: No
author:
- first_name: Hamza M
full_name: Abusalah, Hamza M
id: 40297222-F248-11E8-B48F-1D18A9856A87
last_name: Abusalah
citation:
ama: Abusalah HM. Proof systems for sustainable decentralized cryptocurrencies.
2018. doi:10.15479/AT:ISTA:TH_1046
apa: Abusalah, H. M. (2018). Proof systems for sustainable decentralized cryptocurrencies.
Institute of Science and Technology Austria. https://doi.org/10.15479/AT:ISTA:TH_1046
chicago: Abusalah, Hamza M. “Proof Systems for Sustainable Decentralized Cryptocurrencies.”
Institute of Science and Technology Austria, 2018. https://doi.org/10.15479/AT:ISTA:TH_1046.
ieee: H. M. Abusalah, “Proof systems for sustainable decentralized cryptocurrencies,”
Institute of Science and Technology Austria, 2018.
ista: Abusalah HM. 2018. Proof systems for sustainable decentralized cryptocurrencies.
Institute of Science and Technology Austria.
mla: Abusalah, Hamza M. Proof Systems for Sustainable Decentralized Cryptocurrencies.
Institute of Science and Technology Austria, 2018, doi:10.15479/AT:ISTA:TH_1046.
short: H.M. Abusalah, Proof Systems for Sustainable Decentralized Cryptocurrencies,
Institute of Science and Technology Austria, 2018.
date_created: 2018-12-11T11:44:32Z
date_published: 2018-09-05T00:00:00Z
date_updated: 2023-09-07T12:30:23Z
day: '05'
ddc:
- '004'
degree_awarded: PhD
department:
- _id: KrPi
doi: 10.15479/AT:ISTA:TH_1046
ec_funded: 1
file:
- access_level: open_access
checksum: c4b5f7d111755d1396787f41886fc674
content_type: application/pdf
creator: dernst
date_created: 2019-04-09T06:43:41Z
date_updated: 2020-07-14T12:48:11Z
file_id: '6245'
file_name: 2018_Thesis_Abusalah.pdf
file_size: 876241
relation: main_file
- access_level: closed
checksum: 0f382ac56b471c48fd907d63eb87dafe
content_type: application/x-gzip
creator: dernst
date_created: 2019-04-09T06:43:41Z
date_updated: 2020-07-14T12:48:11Z
file_id: '6246'
file_name: 2018_Thesis_Abusalah_source.tar.gz
file_size: 2029190
relation: source_file
file_date_updated: 2020-07-14T12:48:11Z
has_accepted_license: '1'
language:
- iso: eng
month: '09'
oa: 1
oa_version: Published Version
page: '59'
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_identifier:
issn:
- 2663-337X
publication_status: published
publisher: Institute of Science and Technology Austria
publist_id: '7971'
pubrep_id: '1046'
related_material:
record:
- id: '1229'
relation: part_of_dissertation
status: public
- id: '1235'
relation: part_of_dissertation
status: public
- id: '1236'
relation: part_of_dissertation
status: public
- id: '559'
relation: part_of_dissertation
status: public
status: public
supervisor:
- first_name: Krzysztof Z
full_name: Pietrzak, Krzysztof Z
id: 3E04A7AA-F248-11E8-B48F-1D18A9856A87
last_name: Pietrzak
orcid: 0000-0002-9139-1654
title: Proof systems for sustainable decentralized cryptocurrencies
type: dissertation
user_id: c635000d-4b10-11ee-a964-aac5a93f6ac1
year: '2018'
...
---
_id: '559'
abstract:
- lang: eng
text: 'Proofs of space (PoS) were suggested as more ecological and economical alternative
to proofs of work, which are currently used in blockchain designs like Bitcoin.
The existing PoS are based on rather sophisticated graph pebbling lower bounds.
Much simpler and in several aspects more efficient schemes based on inverting
random functions have been suggested, but they don’t give meaningful security
guarantees due to existing time-memory trade-offs. In particular, Hellman showed
that any permutation over a domain of size N can be inverted in time T by an algorithm
that is given S bits of auxiliary information whenever (Formula presented). For
functions Hellman gives a weaker attack with S2· T≈ N2 (e.g., S= T≈ N2/3). To
prove lower bounds, one considers an adversary who has access to an oracle f:
[ N] → [N] and can make T oracle queries. The best known lower bound is S· T∈
Ω(N) and holds for random functions and permutations. We construct functions that
provably require more time and/or space to invert. Specifically, for any constant
k we construct a function [N] → [N] that cannot be inverted unless Sk· T∈ Ω(Nk)
(in particular, S= T≈ (Formula presented). Our construction does not contradict
Hellman’s time-memory trade-off, because it cannot be efficiently evaluated in
forward direction. However, its entire function table can be computed in time
quasilinear in N, which is sufficient for the PoS application. Our simplest construction
is built from a random function oracle g: [N] × [N] → [ N] and a random permutation
oracle f: [N] → N] and is defined as h(x) = g(x, x′) where f(x) = π(f(x′)) with
π being any involution without a fixed point, e.g. flipping all the bits. For
this function we prove that any adversary who gets S bits of auxiliary information,
makes at most T oracle queries, and inverts h on an ϵ fraction of outputs must
satisfy S2· T∈ Ω(ϵ2N2).'
alternative_title:
- LNCS
author:
- first_name: Hamza M
full_name: Abusalah, Hamza M
id: 40297222-F248-11E8-B48F-1D18A9856A87
last_name: Abusalah
- first_name: Joel F
full_name: Alwen, Joel F
id: 2A8DFA8C-F248-11E8-B48F-1D18A9856A87
last_name: Alwen
- first_name: Bram
full_name: Cohen, Bram
last_name: Cohen
- first_name: Danylo
full_name: Khilko, Danylo
last_name: Khilko
- 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
citation:
ama: 'Abusalah HM, Alwen JF, Cohen B, Khilko D, Pietrzak KZ, Reyzin L. Beyond Hellman’s
time-memory trade-offs with applications to proofs of space. In: Vol 10625. Springer;
2017:357-379. doi:10.1007/978-3-319-70697-9_13'
apa: 'Abusalah, H. M., Alwen, J. F., Cohen, B., Khilko, D., Pietrzak, K. Z., &
Reyzin, L. (2017). Beyond Hellman’s time-memory trade-offs with applications to
proofs of space (Vol. 10625, pp. 357–379). Presented at the ASIACRYPT: Theory
and Applications of Cryptology and Information Security, Hong Kong, China: Springer.
https://doi.org/10.1007/978-3-319-70697-9_13'
chicago: Abusalah, Hamza M, Joel F Alwen, Bram Cohen, Danylo Khilko, Krzysztof Z
Pietrzak, and Leonid Reyzin. “Beyond Hellman’s Time-Memory Trade-Offs with Applications
to Proofs of Space,” 10625:357–79. Springer, 2017. https://doi.org/10.1007/978-3-319-70697-9_13.
ieee: 'H. M. Abusalah, J. F. Alwen, B. Cohen, D. Khilko, K. Z. Pietrzak, and L.
Reyzin, “Beyond Hellman’s time-memory trade-offs with applications to proofs of
space,” presented at the ASIACRYPT: Theory and Applications of Cryptology and
Information Security, Hong Kong, China, 2017, vol. 10625, pp. 357–379.'
ista: 'Abusalah HM, Alwen JF, Cohen B, Khilko D, Pietrzak KZ, Reyzin L. 2017. Beyond
Hellman’s time-memory trade-offs with applications to proofs of space. ASIACRYPT:
Theory and Applications of Cryptology and Information Security, LNCS, vol. 10625,
357–379.'
mla: Abusalah, Hamza M., et al. Beyond Hellman’s Time-Memory Trade-Offs with
Applications to Proofs of Space. Vol. 10625, Springer, 2017, pp. 357–79, doi:10.1007/978-3-319-70697-9_13.
short: H.M. Abusalah, J.F. Alwen, B. Cohen, D. Khilko, K.Z. Pietrzak, L. Reyzin,
in:, Springer, 2017, pp. 357–379.
conference:
end_date: 2017-12-07
location: Hong Kong, China
name: 'ASIACRYPT: Theory and Applications of Cryptology and Information Security'
start_date: 2017-12-03
date_created: 2018-12-11T11:47:10Z
date_published: 2017-11-18T00:00:00Z
date_updated: 2023-09-07T12:30:22Z
day: '18'
department:
- _id: KrPi
doi: 10.1007/978-3-319-70697-9_13
ec_funded: 1
intvolume: ' 10625'
language:
- iso: eng
main_file_link:
- open_access: '1'
url: https://eprint.iacr.org/2017/893.pdf
month: '11'
oa: 1
oa_version: Submitted Version
page: 357 - 379
project:
- _id: 258AA5B2-B435-11E9-9278-68D0E5697425
call_identifier: H2020
grant_number: '682815'
name: Teaching Old Crypto New Tricks
publication_identifier:
isbn:
- 978-331970696-2
publication_status: published
publisher: Springer
publist_id: '7257'
quality_controlled: '1'
related_material:
record:
- id: '83'
relation: dissertation_contains
status: public
scopus_import: 1
status: public
title: Beyond Hellman’s time-memory trade-offs with applications to proofs of space
type: conference
user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87
volume: 10625
year: '2017'
...
---
_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'
...
---
_id: '1235'
abstract:
- lang: eng
text: 'A constrained pseudorandom function (CPRF) F: K×X → Y for a family T of subsets
of χ is a function where for any key k ∈ K and set S ∈ T one can efficiently compute
a short constrained key kS, which allows to evaluate F(k, ·) on all inputs x ∈
S, while the outputs on all inputs x /∈ S look random even given kS. Abusalah
et al. recently constructed the first constrained PRF for inputs of arbitrary
length whose sets S are decided by Turing machines. They use their CPRF to build
broadcast encryption and the first ID-based non-interactive key exchange for an
unbounded number of users. Their constrained keys are obfuscated circuits and
are therefore large. In this work we drastically reduce the key size and define
a constrained key for a Turing machine M as a short signature on M. For this,
we introduce a new signature primitive with constrained signing keys that let
one only sign certain messages, while forging a signature on others is hard even
when knowing the coins for key generation.'
acknowledgement: H. Abusalah—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
citation:
ama: 'Abusalah HM, Fuchsbauer G. Constrained PRFs for unbounded inputs with short
keys. In: Vol 9696. Springer; 2016:445-463. doi:10.1007/978-3-319-39555-5_24'
apa: 'Abusalah, H. M., & Fuchsbauer, G. (2016). Constrained PRFs for unbounded
inputs with short keys (Vol. 9696, pp. 445–463). Presented at the ACNS: Applied
Cryptography and Network Security, Guildford, UK: Springer. https://doi.org/10.1007/978-3-319-39555-5_24'
chicago: Abusalah, Hamza M, and Georg Fuchsbauer. “Constrained PRFs for Unbounded
Inputs with Short Keys,” 9696:445–63. Springer, 2016. https://doi.org/10.1007/978-3-319-39555-5_24.
ieee: 'H. M. Abusalah and G. Fuchsbauer, “Constrained PRFs for unbounded inputs
with short keys,” presented at the ACNS: Applied Cryptography and Network Security,
Guildford, UK, 2016, vol. 9696, pp. 445–463.'
ista: 'Abusalah HM, Fuchsbauer G. 2016. Constrained PRFs for unbounded inputs with
short keys. ACNS: Applied Cryptography and Network Security, LNCS, vol. 9696,
445–463.'
mla: Abusalah, Hamza M., and Georg Fuchsbauer. Constrained PRFs for Unbounded
Inputs with Short Keys. Vol. 9696, Springer, 2016, pp. 445–63, doi:10.1007/978-3-319-39555-5_24.
short: H.M. Abusalah, G. Fuchsbauer, in:, Springer, 2016, pp. 445–463.
conference:
end_date: 2016-06-22
location: Guildford, UK
name: 'ACNS: Applied Cryptography and Network Security'
start_date: 2016-06-19
date_created: 2018-12-11T11:50:52Z
date_published: 2016-01-01T00:00:00Z
date_updated: 2023-09-07T12:30:22Z
day: '01'
department:
- _id: KrPi
doi: 10.1007/978-3-319-39555-5_24
ec_funded: 1
intvolume: ' 9696'
language:
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main_file_link:
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month: '01'
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oa_version: Submitted Version
page: 445 - 463
project:
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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
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record:
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relation: dissertation_contains
status: public
scopus_import: 1
status: public
title: Constrained PRFs for unbounded inputs with short keys
type: conference
user_id: 3E5EF7F0-F248-11E8-B48F-1D18A9856A87
volume: 9696
year: '2016'
...
---
_id: '1236'
abstract:
- lang: eng
text: 'A constrained pseudorandom function F: K × X → Y for a family T ⊆ 2X of subsets
of X is a function where for any key k ∈ K and set S ∈ T one can efficiently compute
a constrained key kS which allows to evaluate F (k, ·) on all inputs x ∈ S, while
even given this key, the outputs on all inputs x ∉ S look random. At Asiacrypt’13
Boneh and Waters gave a construction which supports the most general set family
so far. Its keys kc are defined for sets decided by boolean circuits C and enable
evaluation of the PRF on any x ∈ X where C(x) = 1. In their construction the PRF
input length and the size of the circuits C for which constrained keys can be
computed must be fixed beforehand during key generation. We construct a constrained
PRF that has an unbounded input length and whose constrained keys can be defined
for any set recognized by a Turing machine. The only a priori bound we make is
on the description size of the machines. We prove our construction secure assuming
publiccoin differing-input obfuscation. As applications of our constrained PRF
we build a broadcast encryption scheme where the number of potential receivers
need not be fixed at setup (in particular, the length of the keys is independent
of the number of parties) and the first identity-based non-interactive key exchange
protocol with no bound on the number of parties that can agree on a shared key.'
acknowledgement: Supported by the European Research Council, ERC Starting Grant (259668-PSPC).
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. Constrained PRFs for unbounded inputs.
In: Vol 9610. Springer; 2016:413-428. doi:10.1007/978-3-319-29485-8_24'
apa: 'Abusalah, H. M., Fuchsbauer, G., & Pietrzak, K. Z. (2016). Constrained
PRFs for unbounded inputs (Vol. 9610, pp. 413–428). Presented at the CT-RSA: Topics
in Cryptology, San Francisco, CA, USA: Springer. https://doi.org/10.1007/978-3-319-29485-8_24'
chicago: Abusalah, Hamza M, Georg Fuchsbauer, and Krzysztof Z Pietrzak. “Constrained
PRFs for Unbounded Inputs,” 9610:413–28. Springer, 2016. https://doi.org/10.1007/978-3-319-29485-8_24.
ieee: 'H. M. Abusalah, G. Fuchsbauer, and K. Z. Pietrzak, “Constrained PRFs for
unbounded inputs,” presented at the CT-RSA: Topics in Cryptology, San Francisco,
CA, USA, 2016, vol. 9610, pp. 413–428.'
ista: 'Abusalah HM, Fuchsbauer G, Pietrzak KZ. 2016. Constrained PRFs for unbounded
inputs. CT-RSA: Topics in Cryptology, LNCS, vol. 9610, 413–428.'
mla: Abusalah, Hamza M., et al. Constrained PRFs for Unbounded Inputs. Vol.
9610, Springer, 2016, pp. 413–28, doi:10.1007/978-3-319-29485-8_24.
short: H.M. Abusalah, G. Fuchsbauer, K.Z. Pietrzak, in:, Springer, 2016, pp. 413–428.
conference:
end_date: 2016-03-04
location: San Francisco, CA, USA
name: 'CT-RSA: Topics in Cryptology'
start_date: 2016-02-29
date_created: 2018-12-11T11:50:52Z
date_published: 2016-02-02T00:00:00Z
date_updated: 2023-09-07T12:30:22Z
day: '02'
ddc:
- '005'
- '600'
department:
- _id: KrPi
doi: 10.1007/978-3-319-29485-8_24
ec_funded: 1
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date_updated: 2020-07-14T12:44:41Z
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language:
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month: '02'
oa: 1
oa_version: Submitted Version
page: 413 - 428
project:
- _id: 258C570E-B435-11E9-9278-68D0E5697425
call_identifier: FP7
grant_number: '259668'
name: Provable Security for Physical Cryptography
publication_status: published
publisher: Springer
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quality_controlled: '1'
related_material:
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scopus_import: 1
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type: conference
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