661 research outputs found
Practical IBC Using Hybrid-Mode Problems: Factoring and Discrete Logarithm
Shamir proposed the concept of the ID-based cryptosystem (IBC) in 1984. Instead of generating and publishing a public key for each user, the ID-based scheme permits each user to choose his name or network address as his public key. This is advantageous to public-key cryptosystems because the public-key verification is so easy and direct. In such a way, a large public key file is not required. Since new cryptographic schemes always face security challenges and many integer factorization problem and discrete logarithm based cryptographic systems have been deployed, therefore, the purpose of this paper is to design practical IBC using hybrid mode problems factoring and discrete logarithm. We consider the security against a conspiracy of some entities in the proposed system and show the possibility of establishing a more secure system
Practical IBC using Hybrid-Mode Problems: Factoring and Discrete Logarithm
Shamir proposed the concept of the ID-based cryptosystem (IBC) in 1984. Instead of generating and publishing a public key for each user, the ID-based scheme permits each user to choose his name or network address as his public key. This is advantageous to public-key cryptosystems because the public-key verification is so easy and direct. In such a way, a large public key file is not required. Since new cryptographic schemes always face security challenges and many integer factorization problem and discrete logarithm based cryptographic systems have been deployed, therefore, the purpose of this paper is to design practical IBC using hybrid mode problems factoring and discrete logarithm. We consider the security against a conspiracy of some entities in the proposed system and show the possibility of establishing a more secure system
A New PVSS Scheme with a Simple Encryption Function
A Publicly Verifiable Secret Sharing (PVSS) scheme allows anyone to verify
the validity of the shares computed and distributed by a dealer. The idea of
PVSS was introduced by Stadler in [18] where he presented a PVSS scheme based
on Discrete Logarithm. Later, several PVSS schemes were proposed. In [2],
Behnad and Eghlidos present an interesting PVSS scheme with explicit membership
and disputation processes. In this paper, we present a new PVSS having the
advantage of being simpler while offering the same features.Comment: In Proceedings SCSS 2012, arXiv:1307.8029. This PVSS scheme was
proposed to be used to provide a distributed Timestamping schem
Pairing-based identification schemes
We propose four different identification schemes that make use of bilinear
pairings, and prove their security under certain computational assumptions.
Each of the schemes is more efficient and/or more secure than any known
pairing-based identification scheme
Some Facets of Complexity Theory and Cryptography: A Five-Lectures Tutorial
In this tutorial, selected topics of cryptology and of computational
complexity theory are presented. We give a brief overview of the history and
the foundations of classical cryptography, and then move on to modern
public-key cryptography. Particular attention is paid to cryptographic
protocols and the problem of constructing the key components of such protocols
such as one-way functions. A function is one-way if it is easy to compute, but
hard to invert. We discuss the notion of one-way functions both in a
cryptographic and in a complexity-theoretic setting. We also consider
interactive proof systems and present some interesting zero-knowledge
protocols. In a zero-knowledge protocol one party can convince the other party
of knowing some secret information without disclosing any bit of this
information. Motivated by these protocols, we survey some complexity-theoretic
results on interactive proof systems and related complexity classes.Comment: 57 pages, 17 figures, Lecture Notes for the 11th Jyvaskyla Summer
Schoo
Lattice-based Blind Signatures
Motivated by the need to have secure blind signatures even in the presence of quantum computers, we present two efficient blind signature schemes based on hard worst-case lattice problems. Both schemes are provably secure in the random oracle model and unconditionally blind. The first scheme is based on preimage samplable functions that were introduced at STOC 2008 by Gentry, Peikert, and Vaikuntanathan. The scheme is stateful and runs in 3 moves. The second scheme builds upon the PKC 2008 identification scheme of Lyubashevsky. It is stateless, has 4 moves, and its security is based on the hardness of worst-case problems in ideal lattices
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Privacy-Preserving, Taxable Bank Accounts
Current banking systems do not aim to protect user privacy. Purchases made from a single bank account can be linked to each other by many parties. This could be addressed in a straight-forward way by generating unlinkable credentials from a single master credential using Camenisch and Lysyanskaya's algorithm; however, if bank accounts are taxable, some report must be made to the tax authority about each account. Using unlinkable credentials, digital cash, and zero knowledge proofs of knowledge, we present a solution that prevents anyone, even the tax authority, from knowing which accounts belong to which users, or from being able to link any account to another or to purchases or deposits
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