def testPRF(self):
logging.debug('Running testPRF method.')
output1 = ccrypto.PRF(_KEY1, _PLAINTEXT1, hashfunc='sha256')
output1_again = ccrypto.PRF(_KEY1, _PLAINTEXT1, hashfunc='sha256')
output2 = ccrypto.PRF(_KEY1, _PLAINTEXT2, hashfunc='sha256')
self.assertEqual(16, len(output1))
self.assertEqual(output1, output1_again)
self.assertNotEqual(output1, output2)
self.assertEqual(
'\xa7\x15\xd9\xbbyO@\xad\xfc\x9f\x02\xcb\x9cD\xb7\x29', output1)
output3 = ccrypto.PRF(_KEY1,
_PLAINTEXT1,
output_len=37,
hashfunc='sha256')
self.assertEqual(37, len(output3))
self.assertTrue(output1 in output3)
self.assertFalse(output1
in output3[16:]) # check prefix is not repeated.
# test using default hash function sha1
output4 = ccrypto.PRF(_KEY1, _PLAINTEXT1)
self.assertEqual(16, len(output4))
self.assertNotEqual(output1, output4)
def GetStringKeyHash(self,
field_name,
data,
output_len=None,
hashfunc=None):
"""Calculates a keyed hash of a string.
Args:
field_name: unicode string that is used as part of hash calculation - i.e.
an 8 byte length of field_name and field_name is prepended to data
before hashing.
data: unicode string.
output_len: in bytes, if not set then use value from constructor.
hashfunc: if not set then use value from constructor.
Returns:
base64 encoding of keyed hash of utf8 encoded data.
Raises:
ValueError: when data or fieldname is not a unicode string or when
fieldname is an empty string.
"""
if not isinstance(data, unicode):
raise ValueError('SubstringHash methods only works with data '
'input type unicode, given: %s' % type(data))
if not isinstance(field_name, unicode):
raise ValueError(
'fieldname input type should be unicode, given: %s' %
type(field_name))
if not field_name:
raise ValueError('field_name cannot be empty.')
output_digest_len = output_len or self._output_len
digest_hashfunc = hashfunc or self._hashfunc
# data --> len, field_name, data
extended_data = ccrypto.IntToFixedSizeString(len(field_name))
extended_data += field_name + data
utf8_data = extended_data.encode('utf-8')
raw_hash = ccrypto.PRF(self._key, utf8_data, output_digest_len,
digest_hashfunc)
return base64.b64encode(raw_hash)
def GenerateStringHashKey(key, identifier):
return ccrypto.PRF(key, 'stringhash_' + str(identifier))
def GenerateHomomorphicCipherKey(key, identifier):
return ccrypto.PRF(key, 'homomorphic_' + str(identifier))
def GenerateProbabilisticCipherKey(key, identifier):
return ccrypto.PRF(key, 'probabilistic_' + str(identifier))
def GeneratePseudonymCipherKey(key, identifier):
return ccrypto.PRF(key, 'pseudonym_' + str(identifier))