def test_paillier_key_generation(self):
key = paillier.generate_keys(bits = 128)
public = key.public()
ptxt_original = 521
ctxt = paillier.encrypt(public, ptxt_original)
ptxt = paillier.decrypt(key, ctxt)
self.assertEqual(ptxt_original, ptxt)
# test homomorphism
ptxt1 = 14
ptxt2 = 19
ctxt1 = paillier.encrypt(public, ptxt1)
ctxt2 = paillier.encrypt(public, ptxt2)
final_ptxt = paillier.decrypt(key, ctxt1 * ctxt2)
self.assertEqual(final_ptxt, ptxt1 + ptxt2)
# test average
ptxt3 = 12
ctxt3 = paillier.encrypt(public, ptxt3)
ciphertext = [ctxt1, ctxt2, ctxt3]
numerator, denominator = paillier.average(public, ciphertext)
numerator = paillier.decrypt(key, numerator)
denominator = paillier.decrypt(key, denominator)
average = numerator/denominator
self.assertAlmostEqual(average, 15)
def generate_keyinfo(keyschema):
"""Return a dict of secure randomly-generated keys.
The provided parameter `keyschema` should be a dict mapping key names to
descriptions. For example:
{
'encrypt': {'type': 'block', 'bits': 256},
'hmac': {'type': 'block', 'bits': 256},
'homomorphic': {'type': 'paillier', 'bits': 512}
}
Supported types include "block" (random string of bit size) and "paillier"
(key for the paillier cryptosystem). The default type is "block" if
unspecified. The default number of bits is 256.
Example return value:
{
'encrypt': b'\xb5c\x1d...',
'hmac': b'\x7f\xa7\xcd...',
'homomorphic': paillier.Key(modulus=..., ...)
}
"""
keyinfo = {}
for name, attrs in keyschema.items():
bad_attrs = set(attrs.keys()) - set(['type', 'bits'])
if bad_attrs:
raise EDBError("invalid schema: unexpected attrs: "
"{}".format(bad_attrs))
keytype = attrs.get('type', 'block')
try:
keybits = int(attrs.get('bits', 256))
except ValueError:
raise EDBError("invalid schema: {}/bits is not int".format(name))
if keytype == 'block':
key = get_random_bytes(keybits // 8)
elif keytype == 'paillier':
key = paillier.generate_keys(keybits)
else:
raise EDBError("invalid schema: bad type: ".format(keytype))
keyinfo[name] = key
return keyinfo
def generate_keyinfo(keyschema):
"""Return a dict of secure randomly-generated keys.
The provided parameter `keyschema` should be a dict mapping key names to
descriptions. For example:
{
'encrypt': {'type': 'block', 'bits': 256},
'hmac': {'type': 'block', 'bits': 256},
'homomorphic': {'type': 'paillier', 'bits': 512}
}
Supported types include "block" (random string of bit size) and "paillier"
(key for the paillier cryptosystem). The default type is "block" if
unspecified. The default number of bits is 256.
Example return value:
{
'encrypt': b'\xb5c\x1d...',
'hmac': b'\x7f\xa7\xcd...',
'homomorphic': paillier.Key(modulus=..., ...)
}
"""
keyinfo = {}
for name, attrs in keyschema.items():
bad_attrs = set(attrs.keys()) - set(['type', 'bits'])
if bad_attrs:
raise EDBError("invalid schema: unexpected attrs: "
"{}".format(bad_attrs))
keytype = attrs.get('type', 'block')
try:
keybits = int(attrs.get('bits', 256))
except ValueError:
raise EDBError("invalid schema: {}/bits is not int".format(name))
if keytype == 'block':
key = get_random_bytes(keybits // 8)
elif keytype == 'paillier':
key = paillier.generate_keys(keybits)
else:
raise EDBError("invalid schema: bad type: ".format(keytype))
keyinfo[name] = key
return keyinfo
