TY - GEN
T1 - A CCA secure hybrid Damgård's ElGamal encryption
AU - Desmedt, Yvo
AU - Phan, Duong Hieu
PY - 2008/1/1
Y1 - 2008/1/1
N2 - ElGamal encryption, by its efficiency, is one of the most used schemes in cryptographic applications. However, the original ElGamal scheme is only provably secure against passive attacks. Damgård proposed a slight modification of ElGamal encryption scheme (named Damgård's ElGamal scheme) that provides security against non-adaptive chosen ciphertext attacks under a knowledge-of-exponent assumption. Recently, the CCA1-security of Damgård's ElGamal scheme has been proven under more standard assumptions. In this paper, we study the open problem of CCA2-security of Damgård's ElGamal. By employing a data encapsulation mechanism, we prove that the resulted hybrid Damgård's ElGamal Encryption is secure against adaptive chosen ciphertext attacks. The down side is that the proof of security is based on a knowledge-of-exponent assumption. In terms of efficiency, this scheme is more efficient (e.g. one exponentiation less in encryption) than Kurosawa-Desmedt scheme, the most efficient scheme in the standard model so far.
AB - ElGamal encryption, by its efficiency, is one of the most used schemes in cryptographic applications. However, the original ElGamal scheme is only provably secure against passive attacks. Damgård proposed a slight modification of ElGamal encryption scheme (named Damgård's ElGamal scheme) that provides security against non-adaptive chosen ciphertext attacks under a knowledge-of-exponent assumption. Recently, the CCA1-security of Damgård's ElGamal scheme has been proven under more standard assumptions. In this paper, we study the open problem of CCA2-security of Damgård's ElGamal. By employing a data encapsulation mechanism, we prove that the resulted hybrid Damgård's ElGamal Encryption is secure against adaptive chosen ciphertext attacks. The down side is that the proof of security is based on a knowledge-of-exponent assumption. In terms of efficiency, this scheme is more efficient (e.g. one exponentiation less in encryption) than Kurosawa-Desmedt scheme, the most efficient scheme in the standard model so far.
UR - https://www.scopus.com/pages/publications/57049084040
U2 - 10.1007/978-3-540-88733-1_5
DO - 10.1007/978-3-540-88733-1_5
M3 - Conference contribution
AN - SCOPUS:57049084040
SN - 3540887326
SN - 9783540887324
T3 - Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)
SP - 68
EP - 82
BT - Provable Security - Second International Conference, ProvSec 2008, Proceedings
PB - Springer Verlag
T2 - 2nd International Conference on Provable Security, ProvSec 2008
Y2 - 30 October 2008 through 1 November 2008
ER -