This module implements the United States Data Encryption Standard (DES) for IPsec. encrdes uses cipher-block
chaining (CBC), as per RFC 2405
and has the following properties:
Key Size
64 bits. 56 bit key, plus
8 parity bits. 7 bits of key are followed by one bit of odd parity. For example,
the 56-bit key FF FF FF FF FF FF FF would be encoded as FE FE FE FE FE FE FE FE. encrdes supports weak-key
checking and parity-fixing to aid pf_key(7P).