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Fix bugs in secio implementation

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This commit is contained in:
Alex Stokes
2019-08-24 19:57:56 +02:00
parent 228032805a
commit b8c0ef9ebb
3 changed files with 29 additions and 23 deletions
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30
libp2p/crypto/authenticated_encryption.py
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@ -3,6 +3,7 @@ import hmac
from typing import Tuple
from Crypto.Cipher import AES
import Crypto.Util.Counter as Counter
class InvalidMACException(Exception):
@ -23,8 +24,14 @@ class MacAndCipher:
self.authenticator = hmac.new(
parameters.mac_key, digestmod=parameters.hash_type
)
iv_bit_size = 8 * len(parameters.iv)
cipher = AES.new(
parameters.cipher_key, AES.MODE_CTR, initial_value=parameters.iv
parameters.cipher_key,
AES.MODE_CTR,
counter=Counter.new(
iv_bit_size,
initial_value=int.from_bytes(parameters.iv, byteorder="big"),
),
)
self.cipher = cipher
@ -70,14 +77,16 @@ def initialize_pair(
hmac_key_size = 20
seed = "key expansion".encode()
result = bytearray(2 * (iv_size + cipher_key_size + hmac_key_size))
params_size = iv_size + cipher_key_size + hmac_key_size
result = bytearray(2 * params_size)
authenticator = hmac.new(secret, digestmod=hash_type)
authenticator.update(seed)
tag = authenticator.digest()
i = 0
while i < len(result):
len_result = 2 * params_size
while i < len_result:
authenticator = hmac.new(secret, digestmod=hash_type)
authenticator.update(tag)
@ -87,10 +96,10 @@ def initialize_pair(
remaining_bytes = len(another_tag)
if i + remaining_bytes > len(result):
remaining_bytes = len(result) - i
if i + remaining_bytes > len_result:
remaining_bytes = len_result - i
result[i : i + remaining_bytes] = another_tag
result[i : i + remaining_bytes] = another_tag[0:remaining_bytes]
i += remaining_bytes
@ -98,23 +107,22 @@ def initialize_pair(
authenticator.update(tag)
tag = authenticator.digest()
half = int(len(result) / 2)
first_half = result[:half]
second_half = result[half:]
first_half = result[:params_size]
second_half = result[params_size:]
return (
EncryptionParameters(
cipher_type,
hash_type,
first_half[0:iv_size],
first_half[iv_size : iv_size + cipher_key_size],
first_half[iv_size + cipher_key_size :],
first_half[iv_size : iv_size + cipher_key_size],
),
EncryptionParameters(
cipher_type,
hash_type,
second_half[0:iv_size],
second_half[iv_size : iv_size + cipher_key_size],
second_half[iv_size + cipher_key_size :],
second_half[iv_size : iv_size + cipher_key_size],
),
)