Probably from NIST Special Publication 800-63. Level 3 authentication requires cryptographic keys with an entropy of at least 80 bits. http://csrc.nist.gov/publ

Probably from NIST Special Publication 800-63. Level 3 authentication requires cryptographic keys with an entropy of at least 80 bits. http://csrc.nist.gov/publications/nistpubs/800-63/SP800-63V1_0_2.pdf http://csrc.nist.gov/publications/nistpubs/800-63/SP800-63V1...