'Returns the name of the symmetric encryption cipher to use. The key
length can be retrieved via the .key_length property to disabiguate
between different variations of TripleDES, AES, and the RC* ciphers.
:return:
A unicode string from one of the following: "rc2", "rc5", "des",
"tripledes", "aes"'

@property
def encryption_cipher(self):

    encryption_algo = self[u'algorithm'].native
    if (encryption_algo[0:7] in set([u'aes128_', u'aes192_', u'aes256_'])):
        return u'aes'
    if (encryption_algo in set([u'des', u'rc2', u'rc5'])):
        return encryption_algo
    if (encryption_algo == u'tripledes_3key'):
        return u'tripledes'
    if (encryption_algo == u'pbes2'):
        return self[u'parameters'][u'encryption_scheme'].encryption_cipher
    if (encryption_algo.find(u'.') == (-1)):
        return {u'pbes1_md2_des': u'des', u'pbes1_md5_des': u'des', u'pbes1_md2_rc2': u'rc2', u'pbes1_md5_rc2': u'rc2', u'pbes1_sha1_des': u'des', u'pbes1_sha1_rc2': u'rc2', u'pkcs12_sha1_rc4_128': u'rc4', u'pkcs12_sha1_rc4_40': u'rc4', u'pkcs12_sha1_tripledes_3key': u'tripledes', u'pkcs12_sha1_tripledes_2key': u'tripledes', u'pkcs12_sha1_rc2_128': u'rc2', u'pkcs12_sha1_rc2_40': u'rc2'}[encryption_algo]
    raise ValueError(unwrap(u'\n                                                Unrecognized    encryption    algorithm    "%s"\n                                                ', encryption_algo))
