Man-in-the-Middle Secure Authentication Schemes from LPN and Weak PRFs.

We show how to construct, from any weak pseudorandom function, a 3-round symmetric-key authentication protocol that is secure against man-in-the-middle attacks. The construction is very efficient, requiring both the secret key and communication size to be only 3n bits long and involving only one call to the weak-PRF. Our techniques also extend to certain classes of randomized weak-PRFs, chiefly among which are those based on the classical LPN problem and its more efficient variants such as Toeplitz-LPN and Ring-LPN. Building an efficient manin- the-middle secure authentication scheme from any weak-PRF resolves a problem left open by Dodis et al. (Eurocrypt 2012), while building a man-in-the-middle secure scheme based on any variant of the LPN problem solves the main open question in a long line of research aimed at constructing a practical light-weight authentication scheme based on learning problems, which began with the work of Hopper and Blum (Asiacrypt 2001).