anchor.diff:  
   bulk_cipher_algorithm(null) ->
       ?NULL;
  -%% Not supported yet
  -%% bulk_cipher_algorithm(idea_cbc) ->
  -%%     ?IDEA;
   bulk_cipher_algorithm(rc4_128) ->
       ?RC4;
   bulk_cipher_algorithm(des_cbc) ->
  
positive.code: iv_size(Cipher) ->
      block_size(Cipher).
  
  block_size(Cipher) when Cipher == idea_cbc;
  			Cipher == des_cbc;
  			Cipher == '3des_ede_cbc' -> 
      8;
  
  
negative.code: 
  key_material(null) ->
      0;
  key_material(rc4_128) ->
      16;
  key_material(des_cbc) ->
      8;
  