Concrete Security Characterizations of PRFs and PRPs: Reductions and Applications

Abstract. We investigate several alternate characterizations of pseudorandom functions (PRFs) and pseudorandom permutations (PRPs) in a concrete security setting. By analyzing the concrete complexity of the reductions between the standard notions and the alternate ones, we show that the latter, while equivalent under polynomial-time reductions, are weaker in the concrete security sense. With these alternate notions, we argue that it is possible to get better concrete security bounds for certain PRF/PRP-based schemes. As an example, we show how using an alternate characterization of a PRF could result in tighter security bounds for some types of message authentication codes. We also use this method to give a simple concrete security analysis of the counter mode of encryption. In addition, our results provide some insight into how injectivity impacts pseudorandomness.

• Type: Conference
• Year: 2000
• Where: ASIACRYPT
• Authors: Anand Desai, Sara K. Miner
• Keywords: Alternate Characterization, ASIACRYPT 2000, Concrete Security, Cryptology, Security Bounds