SPAKE2, a Password-Authenticated Key Exchange

This document describes SPAKE2, which is a protocol for two parties that share a password to derive a strong shared key without disclosing the password. This method is compatible with any group, is computationally efficient, and has a security proof. This document predated the Crypto Forum Research Group (CFRG) password-authenticated key exchange (PAKE) competition, and it was not selected; however, given existing use of variants in Kerberos and other applications, it was felt that publication was beneficial. Applications that need a symmetric PAKE, but are unable to hash onto an elliptic curve at execution time, can use SPAKE2. This document is a product of the Crypto Forum Research Group in the Internet Research Task Force (IRTF).