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Encrypt(Alice) -> re-encrypt(Ursula) -> decrypt(Bob). With tests

pull/66/head^2
Michael Egorov 2017-09-30 15:41:03 -07:00
parent 7062c6b186
commit 1ec8a788c4
2 changed files with 25 additions and 10 deletions
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21
nkms/crypto/encrypting_keypair.py
View File

@ -66,7 +66,7 @@ class EncryptingKeypair(object):
key, ekey = self.pre.encapsulate(pubkey) key, ekey = self.pre.encapsulate(pubkey)
cipher = SecretBox(key) cipher = SecretBox(key)
return (ec.serialize(ekey.ekey), return ((ec.serialize(ekey.ekey), None),
cipher.encrypt(data)) cipher.encrypt(data))
def decrypt(self, def decrypt(self,
@ -82,11 +82,11 @@ class EncryptingKeypair(object):
""" """
if isinstance(edata[0], tuple) and isinstance(edata[1], tuple): if isinstance(edata[0], tuple) and isinstance(edata[1], tuple):
# In case it was re-encrypted data # In case it was re-encrypted data
return self.decrypt_reencrypted(edata, privkey=privkey) return self.decrypt_reencrypted(edata)
ekey, edata = edata ekey, edata = edata
ekey = umbral.EncryptedKey( ekey = umbral.EncryptedKey(
ekey=ec.deserialize(self.pre.ecgroup, ekey), re_id=None) ekey=ec.deserialize(self.pre.ecgroup, ekey[0]), re_id=ekey[1])
if privkey is None: if privkey is None:
privkey = self._priv_key privkey = self._priv_key
else: else:
@ -111,7 +111,7 @@ class EncryptingKeypair(object):
return self.decrypt(edata_by_eph, privkey=priv_eph) return self.decrypt(edata_by_eph, privkey=priv_eph)
def rekey(self, def rekey(self,
pubkey: bytes) -> Tuple[bytes, Tuple[bytes, bytes]]: pubkey: bytes) -> Tuple[tuple, Tuple[bytes, bytes]]:
""" """
Create re-encryption key from private key which we have to public key Create re-encryption key from private key which we have to public key
pubkey. pubkey.
@ -121,11 +121,11 @@ class EncryptingKeypair(object):
""" """
priv_eph = self.pre.gen_priv() priv_eph = self.pre.gen_priv()
rk = self.pre.rekey(self._priv_key, priv_eph) rk = self.pre.rekey(self._priv_key, priv_eph)
encrypted_eph = self.encrypt(ec.serialize(priv_eph)) encrypted_eph = self.encrypt(ec.serialize(priv_eph), pubkey=pubkey)
return (ec.serialize(rk), encrypted_eph) return ((rk.id, ec.serialize(rk.key)), encrypted_eph)
def reencrypt(self, def reencrypt(self,
rekey: Tuple[bytes, Tuple[bytes, bytes]], rekey: Tuple[tuple, Tuple[bytes, bytes]],
ciphertext: Tuple[bytes, bytes] ciphertext: Tuple[bytes, bytes]
) -> Tuple[Tuple[bytes, bytes], Tuple[bytes, bytes]]: ) -> Tuple[Tuple[bytes, bytes], Tuple[bytes, bytes]]:
""" """
@ -137,13 +137,14 @@ class EncryptingKeypair(object):
and the ephemeral private key encrypted for recepient (Bob) and the ephemeral private key encrypted for recepient (Bob)
""" """
rk, encrypted_eph = rekey rk, encrypted_eph = rekey
rk = ec.deserialize(self.pre.ecgroup, rekey) rk = umbral.RekeyFrag(rk[0], ec.deserialize(self.pre.ecgroup, rk[1]))
ekey, edata = ciphertext ekey, edata = ciphertext
ekey = ec.deserialize(self.pre.ecgroup, ekey) ekey = umbral.EncryptedKey(
ekey=ec.deserialize(self.pre.ecgroup, ekey[0]), re_id=ekey[1])
ekey = self.pre.reencrypt(rk, ekey) ekey = self.pre.reencrypt(rk, ekey)
ekey = ec.serialize(ekey) ekey = (ec.serialize(ekey.ekey), ekey.re_id)
return (ekey, edata), encrypted_eph return (ekey, edata), encrypted_eph
def combine(): def combine():

14
tests/crypto/test_encrypting_keypair.py
View File

@ -10,3 +10,17 @@ def test_encrypt_decrypt():
bob = EncryptingKeypair() bob = EncryptingKeypair()
e = bob.encrypt(data, pubkey=alice.pub_key) e = bob.encrypt(data, pubkey=alice.pub_key)
assert alice.decrypt(e) == data assert alice.decrypt(e) == data
def test_reencrypt():
data = b'Hello Bob'
alice = EncryptingKeypair()
bob = EncryptingKeypair()
ursula = EncryptingKeypair()
e = alice.encrypt(data)
re_ab = alice.rekey(bob.pub_key)
e_b = ursula.reencrypt(re_ab, e)
assert bob.decrypt(e_b) == data