The output file for all the algorithms (except unix crypt) when not used in
bare mode is:

3 bytes as: NULL + "m" + NULL
1 byte the algorithm
1 byte the algorithm's mode
1 byte the key mode
blocksize bytes the crc32 of the plaintext(encrypted)
x bytes encrypted data (x=k*blocksize, k=1,2...)
1 byte the number of bytes that didn't fit to the algorithm and were
  padded.

blocksize is 8 bytes for DES, 3DES, Blowfish, GOST, Safer and 12 bytes for
3-way.
