AaronFiore/electrum
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channel backups: add MAC

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This commit is contained in:
ThomasV
2020-06-16 11:52:08 +02:00
parent 6922d81a1e
commit f9788a5d90
2 changed files with 16 additions and 9 deletions
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16
electrum/crypto.py
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@@ -229,21 +229,29 @@ def pw_decode_bytes(data: str, password: Union[bytes, str], *, version:int) -> b
return pw_decode_raw(data_bytes, password, version=version)
def pw_encode_b64_with_version(data: bytes, password: Union[bytes, str]) -> str:
def pw_encode_with_version_and_mac(data: bytes, password: Union[bytes, str]) -> str:
"""plaintext bytes -> base64 ciphertext"""
# https://crypto.stackexchange.com/questions/202/should-we-mac-then-encrypt-or-encrypt-then-mac
# Encrypt-and-MAC. The MAC will be used to detect invalid passwords
version = PW_HASH_VERSION_LATEST
mac = sha256(data)[0:4]
ciphertext = pw_encode_raw(data, password, version=version)
ciphertext_b64 = base64.b64encode(bytes([version]) + ciphertext)
ciphertext_b64 = base64.b64encode(bytes([version]) + ciphertext + mac)
return ciphertext_b64.decode('utf8')
def pw_decode_b64_with_version(data: str, password: Union[bytes, str]) -> bytes:
def pw_decode_with_version_and_mac(data: str, password: Union[bytes, str]) -> bytes:
"""base64 ciphertext -> plaintext bytes"""
data_bytes = bytes(base64.b64decode(data))
version = int(data_bytes[0])
encrypted = data_bytes[1:-4]
mac = data_bytes[-4:]
if version not in KNOWN_PW_HASH_VERSIONS:
raise UnexpectedPasswordHashVersion(version)
return pw_decode_raw(data_bytes[1:], password, version=version)
decrypted = pw_decode_raw(encrypted, password, version=version)
if sha256(decrypted)[0:4] != mac:
raise InvalidPassword()
return decrypted
def pw_encode(data: str, password: Union[bytes, str, None], *, version: int) -> str: