ripem -- {Riordan's | RSAREF-based} Internet Privacy Enhanced Mail, v.
Encrypts/decrypts mail messages using RSA and DES, and generates keys.
ripem is in the public domain, but requires agreeing to the RSAREF license 
from RSA Data Security; contact rsaref-info@rsa.com.  It's free but limited.
ripem was written by Mark Riordan (mrr@scss3.cl.msu.edu).  See doc for credits.  
Usage:  ripem {-e | -d | -g | -c}     <in >out
  [-r recipient] [-m {encrypted | mic-only | mic-clear}]
  [-u myusername]  [-h head] [-b #_of_bits_in_gen_key]
  [-p publickey_infile(s)] [-s privatekey_infile] [-k key_to_private_key or -]
  [-P publickey_outfile] [-S privatekey_outfile] [-A enc_alg]
  [-y pub_key_server_name] [-Y key_sources] [-T recip_opts]
  [-i infile] [-o outfile] [-D debug_level] [-Z debug_out_file]          
  [-R random_sources] [-F random_input_file] [-C random_string]         
where:
  enc_alg is the encryption algorithm:  des-cbc (default) or des-ede-cbc.
  key_sources is a string of one or more of "fgs", which tell ripem to look
    for public keys from a File, finGer, or Server, in the order specified.
  head is one or more of "ipr", for Include headers in msg; Prepend headers
    to output; get Recipients from headers.  
  random_sources is one or more of "cefkms", specifying "random" input from
    Command line, Entire command, File, Keyboard, Message, or running System.
  recip_opts is one or more of "amn", for Abort if can't find keys for
    all users; include Me as a recipient if encrypting; None of the above.
Relevant environment variables:
  RIPEM_PUBLIC_KEY_FILE, RIPEM_PRIVATE_KEY_FILE, RIPEM_KEY_TO_PRIVATE_KEY,
  RIPEM_USER_NAME, RIPEM_RANDOM_FILE, RIPEM_SERVER_NAME, RIPEM_ARGS
