Non-malleable codes, introduced by Dziembowski, Pietrzak and Wichs [DPW10], provide a useful message integrity guarantee in situations where traditional error-correction (and even error-detection) is impossible; for example, when the attacker can completely overwrite the encoded message. Informally, a code is non-malleable if the message contained in a modified codeword is either the original m...

We present a constant-round non-malleable commitment scheme based on the existence of sub-exponential one-way functions and using a blackbox proof of security. As far as we know, this is the first construction of a constant-round non-malleable protocol based on only one-wayness, or to admit a black-box proof of security under any standard-type assumption.

We show the existence of concurrent non-malleable commitments based on the existence one-way functions. Our proof of security only requires the use of black-box techniques, and additionally provides an arguably simplified proof of the existence of even stand-alone secure non-malleable commitments. Cornell University, E-Mail: [email protected] Cornell University, E-Mail: [email protected]...

Dodis and Wichs [DW09] introduced the notion of a non-malleable extractor to study the problem of privacy amplification with an active adversary. A non-malleable extractor is a much stronger version of a strong extractor. Given a weakly-random string x and a uniformly random seed y as the inputs, the non-malleable extractor nmExt has the property that nmExt(x, y) appears uniform even given y as...

We show the existence of concurrent non-malleable commitments based on the existence of one-way functions. Our proof of security only requires the use of black-box techniques, and additionally provides an arguably simplified proof of the existence of even stand-alone secure non-malleable commitments.

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 ...

One approach towards basing public-key encryption (PKE) schemes on weak and credible assumptions is to build “stronger” or more general schemes generically from “weaker” or more restricted ones. One particular line of work in this context was initiated by Myers and shelat (FOCS ’09) and continued by Hohenberger, Lewko, and Waters (Eurocrypt ’12), who provide constructions of multi-bit CCA-secur...