RFC 1851 (rfc1851) - Page 3 of 11

The ESP Triple DES Transform

RFC 1851                        ESP 3DES                  September 1995


      Other implementations exhibit unpredictability, usually through a
      pseudo-random number generator.  Care should be taken that the
      periodicity of the number generator is long enough to prevent
      repetition during the lifetime of the session key.



1.3.  Data Size

   The 3DES algorithm operates on blocks of eight octets.  This often
   requires padding after the end of the unencrypted payload data.

   Both input and output result in the same number of octets, which
   facilitates in-place encryption and decryption.

   On receipt, if the length of the data to be decrypted is not an
   integral multiple of eight octets, then an error is indicated, as
   described in [RFC-1825].



1.4.  Performance

   Three DES-CBC implementations may be pipelined in series to provide
   parallel computation.  At the time of writing, at least one hardware
   implementation can encrypt or decrypt at about 1 Gbps [Schneier94, p.
   231].
























Karn, et al                   Experimental