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Removes hash/cipher configuration and changes AESGCM128 for CHACHA20POLY1305

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Updates tests accordingly
This commit is contained in:
Sergi Delgado Segura
2019-12-04 17:46:07 +01:00
parent c679d59451
commit f0150ce585
22 changed files with 78 additions and 351 deletions
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41
apps/cli/blob.py
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@@ -1,34 +1,17 @@
import re
from hashlib import sha256
from binascii import hexlify, unhexlify
from cryptography.hazmat.primitives.ciphers.aead import AESGCM
from cryptography.hazmat.primitives.ciphers.aead import ChaCha20Poly1305
from apps.cli import SUPPORTED_HASH_FUNCTIONS, SUPPORTED_CIPHERS
from apps.cli import logger
class Blob:
def __init__(self, data, cipher, hash_function):
def __init__(self, data):
if type(data) is not str or re.search(r"^[0-9A-Fa-f]+$", data) is None:
raise ValueError("Non-Hex character found in txid.")
self.data = data
self.cipher = cipher
self.hash_function = hash_function
# FIXME: We only support SHA256 for now
if self.hash_function.upper() not in SUPPORTED_HASH_FUNCTIONS:
raise ValueError(
"Hash function not supported ({}). Supported Hash functions: {}".format(
self.hash_function, SUPPORTED_HASH_FUNCTIONS
)
)
# FIXME: We only support AES-GCM-128 for now
if self.cipher.upper() not in SUPPORTED_CIPHERS:
raise ValueError(
"Cipher not supported ({}). Supported ciphers: {}".format(self.hash_function, SUPPORTED_CIPHERS)
)
def encrypt(self, tx_id):
if len(tx_id) != 64:
@@ -40,26 +23,18 @@ class Blob:
# Transaction to be encrypted
# FIXME: The blob data should contain more things that just the transaction. Leaving like this for now.
tx = unhexlify(self.data)
tx_id = unhexlify(tx_id)
# master_key = H(tx_id | tx_id)
master_key = sha256(tx_id + tx_id).digest()
# The 16 MSB of the master key will serve as the AES GCM 128 secret key. The 16 LSB will serve as the IV.
sk = master_key[:16]
nonce = master_key[16:]
# sk is the H(txid) (32-byte) and nonce is set to 0 (12-byte)
sk = sha256(unhexlify(tx_id)).digest()
nonce = bytearray(12)
# Encrypt the data
aesgcm = AESGCM(sk)
encrypted_blob = aesgcm.encrypt(nonce=nonce, data=tx, associated_data=None)
cipher = ChaCha20Poly1305(sk)
encrypted_blob = cipher.encrypt(nonce=nonce, data=tx, associated_data=None)
encrypted_blob = hexlify(encrypted_blob).decode()
logger.info(
"Creating new blob",
master_key=hexlify(master_key).decode(),
sk=hexlify(sk).decode(),
nonce=hexlify(nonce).decode(),
encrypted_blob=encrypted_blob,
"Creating new blob", sk=hexlify(sk).decode(), nonce=hexlify(nonce).decode(), encrypted_blob=encrypted_blob
)
return encrypted_blob