Paper 1999/014 Original: eprint.iacr.org/1999/014 ↗

Concurrent Zero-Knowledge is Easy in Practice

Abstract

We show that if any one-way function exists, then 3-round concurrent zero-knowledge arguments for all NP problems can be built in a model where a short auxiliary string with a prescribed distribution is available to the players. We also show that all known efficient identification schemes using specialized assumptions can be modified to work in this model with no essential loss of efficiency. We argue that the assumptions of the model will be satisfied in most practical scenarios where public key cryptography is used, in particular our construction works given any secure public key infrastructure. Finally, we point out that in a model with preprocessing (and no auxiliary string) proposed earlier, concurrent zero-knowledge for NP can be based on any one-way function.