of the Dissertation Studies in Non-Malleable Commitment

We present new constructions of non-malleable commitment schemes, in the public parameter model (where a trusted party makes parameters available to all parties), based on the discrete logarithm or RSA assumptions. The main features of our schemes are: they achieve near-optimal communication for arbitrarily-large messages and are non-interactive. Previous schemes either required (several rounds...

In this work, we significantly improve the efficiency of non-malleable codes in the split state model, by constructing a code with codeword length |s|+O(k), where |s| is the length of the message, and k is the security parameter. This is a substantial improvement over previous constructions, both asymptotically and concretely. Our construction relies on a new primitive which we define and study...

In this paper, we discuss end user requirements that we elicited for the use of malleable signatures in a Cloud-based eHealth scenario. The concept of a malleable signature, which is a privacy enhancing cryptographic scheme that enables the redaction of personal information from signed documents while preserving the validity of the signature, might be counterintuitive to end users as its functi...

Depending on the application, malleability in cryptography can be viewed as either a flaw or — especially if sufficiently understood and restricted — a feature. In this vein, Chase, Kohlweiss, Lysyanskaya, and Meiklejohn recently defined malleable zero-knowledge proofs, and showed how to control the set of allowable transformations on proofs. As an application, they construct the first compact ...

We explore a new man-in-the-middle adversarial model for multi-prover interactive proofs (MIPs), and construct round-optimal, unconditionally secure, non-malleable MIPs. We compile from a large sub-class of Σ-protocols to a non-malleable MIP, avoiding the use of expensive NP-reductions to Graph Hamiltonicity or other NP-complete problems. Our compiler makes novel use of non-malleable codes – in...

Nowadays, achieving cryptosystems secure in an asynchronous network like the Internet is demanded to be necessary, where concurrent non-malleable proof-of-knowledge and universal composability are among the most powerful and fundamental security properties. But, when achieving more and more complex cryptosystems secure in an open network like the Internet, it is often the case that generic solu...

PURPOSE Today, we find that the implant of malleable prostheses still plays a leading role in the surgical treatment of erectile dysfunction. These may involve patients for which the cosmetic advantages of inflatable devices are not as important as low cost, the easier use and less incidence of mechanical complications in the malleable implants. This paper demonstrates infrapubic approach as a ...

Recently, non-black-box techniques have enjoyed great success in cryptography. In particular, they have led to the construction of constant round protocols for two basic cryptographic tasks (in the plain model): non-malleable zero-knowledge (nmzk) arguments for np, and non-malleable commitments. Earlier protocols, whose security proofs relied only on black-box techniques, required non-constant ...

A non-malleable encoding scheme is a keyless encoding scheme which is resilient to tampering attacks. Such a scheme is said to be continuously secure if the scheme is resilient to attacks containing more than one tampering procedure. Also, such a scheme is said to have tamper-detection property if any kind of tampering attack is detected. In [S. Faust, et al., Continuous nonmalleable codes, TCC...