Excerpt from the README:  
  SRP stands for the Secure Remote Password protocol, which is a secure
  password-based authentication and key-exchange mechanism that can be
  used to establish session security and mutual authentication over
  untrusted networks without requiring an external public-key infrastructure
  or trusted third parties.  The SRP distribution consists of a fully-
  featured, portable library that implements SRP-based secure password
  authentication as well as implementations of popular applications and
  services like Telnet and FTP with support for transport security and
  SRP.  These password-based applications leverage the strength of the
  SRP authentication mechanism to offer fairly good protection against
  both passive and active network attacks, which is an improvement over
  most existing password-only techniques.

WWW: http://srp.stanford.edu/