+.TP
+.BR sha256 ", " sha384 " and " sha512
+Designed by the US National Security Agency to provide security
+commensurate with the Advanced Encryption Standard, these hash functions
+provide long outputs. SHA-256 is fairly quick, though the longer
+variants are slower on 32-bit hardware since they require 64-bit
+arithmetic. They're all very new at the moment, and should be
+approached with an open-minded caution.