## CryptoDB

### Yuliang Zheng

#### Publications

Year
Venue
Title
2018
ASIACRYPT
The consensus protocol underlying Bitcoin (the blockchain) works remarkably well in practice. However proving its security in a formal setting has been an elusive goal. A recent analytical result by Pass, Seeman and shelat indicates that an idealized blockchain is indeed secure against attacks in an asynchronous network where messages are maliciously delayed by at most $\varDelta \ll 1/np$, with n being the number of miners and p the mining hardness. This paper improves upon the result by showing that if appropriate inconsistency tolerance is allowed the blockchain can withstand even more powerful external attacks in the honest miner setting. Specifically we prove that the blockchain is secure against long delay attacks with $\varDelta \ge 1/np$ in an asynchronous network.
2010
EPRINT
In this paper, we consider the Frobenius endomorphism on twisted Edwards curve and give the characteristic polynomial of the map. Applying the Frobenius endomorphism on twisted Edwards curve, we construct a skew-Frobenius map defined on the quadratic twist of an twisted Edwards curve. Our results show that the Frobenius endomorphism on twisted Edwards curve and the skew-Frobenius endomorphism on quadratic twist of an twisted Edwards curve can be exploited to devise fast point multiplication algorithm that do not use any point doubling. As an application, the GLV method can be used for speeding up point multiplication on twisted Edwards curve.
2007
JOFC
2005
EPRINT
One-way hash algorithms are an indispensable tool in data security. Over the last decade or so a number of one-way hash algorithms have been designed and many of them have been used in numerous applications. Recent progress in cryptanalytic attacks on one-way hash algorithms by Wang and co-workers, however, has brought up the urgency of research into new and more secure algorithms. The goal of this paper is two-folded. On one hand we propose a simple technique to affix authentication tags to messages prior to being hashed by an iterative one-way hash algorithm with the aim of increasing the overall security of the algorithm against cryptanalytic attacks. One the other hand we advocate the importance of a system oriented approach towards the design and deployment of new families of one-way hash algorithms that support greater scalability and facilitate migration to newer member algorithms upon the compromise of deployed ones. We base our observations on a common sense premise that there is no specific one-way hash algorithm can remain secure forever and it will eventually be broken by a cryptanalytic attack faster than exhaustive research.
2004
PKC
2003
EPRINT
In this paper, we examine issues related to the construction of identity-based threshold decryption schemes and argue that it is important in practice to design an identity-based threshold decryption scheme in which a private key associated with an identity is shared. A major contribution of this paper is to construct the first identity-based threshold decryption scheme secure against chosen ciphertext attack. A formal proof of security of the scheme is provided in the random oracle model, assuming the Bilinear Diffie-Hellman problem is computationally hard. Another contribution of this paper is, by extending the proposed identity-based threshold decryption scheme, to construct a mediated identity-based encryption scheme secure against more powerful attacks than those considered previously.
2002
EUROCRYPT
2002
PKC
2002
PKC
2002
EPRINT
Motivated by emerging needs in online interactions, we define a new type of digital signature called a Content Extraction Signature' (CES). A CES allows the owner, Bob, of a document signed by Alice, to produce an extracted signature' on selected extracted portions of the original document, which can be verified to originate from Alice by any third party Cathy, while hiding the unextracted (removed) document portions. The new signature therefore achieves verifiable content extraction with minimal multi-party interaction. We specify desirable functional and security requirements for a CES (including an efficiency requirement: a CES should be more efficient in either computation or communication than the simple multiple signature solution). We propose and analyze four CES constructions which are provably secure with respect to known cryptographic assumptions and compare their performance characteristics.
2001
PKC
2000
ASIACRYPT
2000
ASIACRYPT
1999
ASIACRYPT
1999
ASIACRYPT
1999
PKC
1998
PKC
1997
CRYPTO
1996
EUROCRYPT
1995
EUROCRYPT
1994
ASIACRYPT
1994
CRYPTO
1994
EUROCRYPT
1994
EUROCRYPT
1994
EUROCRYPT
1993
CRYPTO
1993
EUROCRYPT
1992
AUSCRYPT
1992
AUSCRYPT
1992
CRYPTO
1992
AUSCRYPT
1991
ASIACRYPT
1991
ASIACRYPT
1990
CRYPTO
1989
CRYPTO
1989
EUROCRYPT

#### Program Committees

PKC 2012
Asiacrypt 2008
PKC 2007
PKC 2005
Asiacrypt 2004
PKC 2004
PKC 2003
Asiacrypt 2002 (Program chair)
PKC 2001
Asiacrypt 2001
Asiacrypt 2000
PKC 2000 (Program chair)
Eurocrypt 1999
PKC 1999 (Program chair)
PKC 1999
Asiacrypt 1999
Asiacrypt 1998
PKC 1998 (Program chair)
Crypto 1997
Asiacrypt 1996
Asiacrypt 1994