Results 1  10
of
12
Generating ElGamal signatures without knowing the secret key
, 1996
"... . We present a new method to forge ElGamal signatures if the public parameters of the system are not chosen properly. Since the secret key is hereby not found this attack shows that forging ElGamal signatures is sometimes easier than the underlying discrete logarithm problem. 1 Introduction ElGamal ..."
Abstract

Cited by 42 (0 self)
 Add to MetaCart
. We present a new method to forge ElGamal signatures if the public parameters of the system are not chosen properly. Since the secret key is hereby not found this attack shows that forging ElGamal signatures is sometimes easier than the underlying discrete logarithm problem. 1 Introduction ElGamal's digital signature scheme [4] relies on the difficulty of computing discrete logarithms in the multiplicative group IF p and can therefore be broken if the computation of discrete logarithms is feasible. However, the converse has never been proved. In this paper we show that it is sometimes possible to forge signatures without breaking the underlying discrete logarithm problem. This shows that the ElGamal signature scheme and some variants of the scheme must be used very carefully. The paper is organized as follows. Section 2 describes the ElGamal signature scheme. In Section 3 we present a method to forge signatures if some additional information on the generator is known. We show that...
Generalized ElGamal signatures for one message block
, 1994
"... There have been many approaches in the past to generalize the ElGamal signature scheme. In this paper we integrate all these approaches in a generalized ElGamal signature scheme. We also investigate some new types of variations, that haven't been considered before. By this method we obtain nume ..."
Abstract

Cited by 10 (0 self)
 Add to MetaCart
There have been many approaches in the past to generalize the ElGamal signature scheme. In this paper we integrate all these approaches in a generalized ElGamal signature scheme. We also investigate some new types of variations, that haven't been considered before. By this method we obtain numerous variants of the ElGamal scheme. From these variants, we can extract new, highly efficient signature schemes, which haven't been proposed before. 1. Introduction There have been many approaches to generalize the ElGamal signature scheme [ElGa84, Schn89, AgMV90, NIST91, Schn91, BrMc91, YeLa93, Knob93, NyR293, Har194, NyRu94, HoP194, HoP294, HoP394, Har294]. In this paper we try to integrate all these approaches in a generalized ElGamal signature scheme. We also investigate some new types of variation, that haven't been considered before. By this method we obtain various variants of the ElGamal scheme. The advantage of this proceeding is that we can extract highly efficient schemes out of thes...
MetaElGamal signature schemes using a composite module
, 1994
"... In 1984 ElGamal published the first signature scheme based on the discrete logarithm problem. Since then a lot of work was done to modify and generalize this signature scheme. Very important steps of recent research were the discovery of efficient signature schemes with appendix , e.g. by Schnorr, N ..."
Abstract

Cited by 2 (0 self)
 Add to MetaCart
In 1984 ElGamal published the first signature scheme based on the discrete logarithm problem. Since then a lot of work was done to modify and generalize this signature scheme. Very important steps of recent research were the discovery of efficient signature schemes with appendix , e.g. by Schnorr, Nyberg/Rueppel or Harn. All these variants can be embedded into a MetaElGamal signature scheme. Until now all schemes except one have in common that the verification is done over a finite field. In this paper we focus on those schemes where a composite modul n = pq instead of a primemodul p is used in the MetaElGamal signature scheme. An unmodified scheme is cryptoanalysed in this composite mode, further we introduce some new refined modes and give a security and performance analysis of the various schemes. As a result, some schemes can be used in these modes with slight modifications. Although the security of these schemes can't be proven, the advantages are that ffl even existential for...
Digital Signature Scheme Based on Two Hard
 Problems,” IJCSNS International Journal of Computer Science and Network Security, December 2007, vol.7 No.12
"... In 1998, Shao Proposed two digital signature schemes based on factoring and discrete logarithms. At the same year, Li and Xiao showed that Shao’s schemes are insecure are not based on any hard problem. This paper modifies Shao’s schemes. Two new schemes whose security is based on both factorization ..."
Abstract

Cited by 1 (0 self)
 Add to MetaCart
(Show Context)
In 1998, Shao Proposed two digital signature schemes based on factoring and discrete logarithms. At the same year, Li and Xiao showed that Shao’s schemes are insecure are not based on any hard problem. This paper modifies Shao’s schemes. Two new schemes whose security is based on both factorization and discrete logarithms are proposed. Key words:
Implementing Swati Verma’s Digital Signature Schemes based on Integer Factorization and
"... A digital signature is a cryptographic method for verifying the identity of an individual. It can be a process, computer system, or any other entity, in much the same way as a handwritten signature verifies the identity of a person. Digital signatures use the properties of publickey cryptography to ..."
Abstract
 Add to MetaCart
A digital signature is a cryptographic method for verifying the identity of an individual. It can be a process, computer system, or any other entity, in much the same way as a handwritten signature verifies the identity of a person. Digital signatures use the properties of publickey cryptography to produce pieces of information that verify the origin of the data. Several digital schemes have been proposed as on date based on factorization, discrete logarithm and elliptical curve. However, the Swati Verma and Birendra Kumar Sharma [8] digital signature scheme which combines factorization and discrete logarithm together making it difficult for solving two hard problems from the hackers point of view. This paper presents the implementation of same, with the help of different tools and further analyzes them from different perceptions.
A Provably Secure Signature Scheme based on Factoring and Discrete Logarithms
, 2014
"... Abstract: To make users put much confidence in digital signatures, this paper proposes the first provably secure signature scheme based on both factoring and discrete logarithms. The new scheme incorporates both the Schnorr signature scheme and the PSSRabin signature scheme. Unless both the two cry ..."
Abstract
 Add to MetaCart
(Show Context)
Abstract: To make users put much confidence in digital signatures, this paper proposes the first provably secure signature scheme based on both factoring and discrete logarithms. The new scheme incorporates both the Schnorr signature scheme and the PSSRabin signature scheme. Unless both the two cryptographic assumptions could be become solved simultaneously, anyone would not forge any signature. The proposed scheme is efficient since the computation requirement and the storage requirement are slightly larger than those for the Schnorr signature scheme and the PSSRabin signature scheme.
A New Digital Signature Scheme Based on Two Hard Problems
"... Abstract: In this paper, we propose a new signature scheme based on factoring and discrete logarithm. This scheme is based on two hard problems and provides higher level security as compare to a single hard problem. Most of the designated signature schemes are based on a single hard problem. Althoug ..."
Abstract
 Add to MetaCart
(Show Context)
Abstract: In this paper, we propose a new signature scheme based on factoring and discrete logarithm. This scheme is based on two hard problems and provides higher level security as compare to a single hard problem. Most of the designated signature schemes are based on a single hard problem. Although these schemes secure but in a future if an enemy manages to solve this problem, are then he can recover all secret information including secret keys and parameters of the scheme. Our scheme is protected from such four attacks which are most common attacks for signature schemes.
Generating ElGamal signatures without knowing the secret key
, 1996
"... . We present a new method to forge ElGamal signatures if the public parameters of the system are not chosen properly. Since the secret key is hereby not found this attack shows that forging ElGamal signatures is sometimes easier than the underlying discrete logarithm problem. 1 Introduction El ..."
Abstract
 Add to MetaCart
. We present a new method to forge ElGamal signatures if the public parameters of the system are not chosen properly. Since the secret key is hereby not found this attack shows that forging ElGamal signatures is sometimes easier than the underlying discrete logarithm problem. 1 Introduction ElGamal's digital signature scheme [4] relies on the difficulty of computing discrete logarithms in the multiplicative group IF p and can therefore be broken if the computation of discrete logarithms is feasible. However, the converse has never been proved. In this paper we show that it is sometimes possible to forge signatures without breaking the underlying discrete logarithm problem. This shows that the ElGamal signature scheme and some variants of the scheme must be used very carefully. The paper is organized as follows. Section 2 describes the ElGamal signature scheme. In Section 3 we present a method to forge signatures if some additional information on the generator is known. We show ...
Improved Shao’s Signature Scheme
"... In 1998, Shao proposed two digital signature schemes and claimed that the security of which is based on the difficulties of computing both integer factorization and discrete logarithm. However, in 1999, Lee demonstrated that Shao’s signature schemes can be broken if the factorization problem can be ..."
Abstract
 Add to MetaCart
(Show Context)
In 1998, Shao proposed two digital signature schemes and claimed that the security of which is based on the difficulties of computing both integer factorization and discrete logarithm. However, in 1999, Lee demonstrated that Shao’s signature schemes can be broken if the factorization problem can be solved. This paper presents an improvement of Shao’s signature schemes and shows that it can resist Lee’s attack. This makes our proposed scheme based on two hard problems. Some possible common attacks are considered. We show that the problem of recovering the signer’s secret key from his/her public key is equivalent to solve both the discrete logarithm problem and the factorization problem; the problem of forging a valid signature for a message is at least equivalent to solve the discrete logarithm problem or the factorization problem. In addition, our proposed scheme is immune from substitution and homomorphism attacks.
Comments on Wei’s Digital Signature Scheme Based on Two Hard Problems
, 2009
"... In 1998, Shao proposed two digital signature schemes and claimed that the security of which is based on the difficulties of computing both integer factorization and discrete logarithm. However, at the same year, Li and Xiao demonstrated that Shao’s schemes are insecure are not based on any hard prob ..."
Abstract
 Add to MetaCart
In 1998, Shao proposed two digital signature schemes and claimed that the security of which is based on the difficulties of computing both integer factorization and discrete logarithm. However, at the same year, Li and Xiao demonstrated that Shao’s schemes are insecure are not based on any hard problem. Recently, Wei proposed two “Digital Signature Schemes Based on Two Hard Problems ” to improve Shao’s schemes, and showed that it can resist Li and Xiao’s attack. We show that neither scheme is as secure as the author claim. One can forge a valid signature of an arbitrary message by using Pollard and Schnorr’s method without solving the discrete logarithm problem or the factorization hard problem. Key words: digital signature, factorization problem, discrete logarithm problem, two hard problems 1.