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Replaces KDF

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Uses H(txid) for locator and H(txid|txid) for master_key now
This commit is contained in:
Sergi Delgado Segura
2019-06-20 18:26:34 +01:00
parent c7ba4fb423
commit dd3dee5b7a
2 changed files with 15 additions and 35 deletions
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25
pisa-btc/apps/blob.py
View File

@@ -1,9 +1,7 @@
from binascii import hexlify, unhexlify from binascii import hexlify, unhexlify
from hashlib import sha256
from cryptography.hazmat.primitives.ciphers.aead import AESGCM from cryptography.hazmat.primitives.ciphers.aead import AESGCM
from cryptography.hazmat.primitives.kdf.hkdf import HKDF from conf import SUPPORTED_HASH_FUNCTIONS, SUPPORTED_CIPHERS
from cryptography.hazmat.primitives import hashes
from cryptography.hazmat.backends import default_backend
from conf import SALT, SUPPORTED_HASH_FUNCTIONS, SUPPORTED_CIPHERS
class Blob: class Blob:
@@ -31,19 +29,12 @@ class Blob:
# Extend the key using HKDF # Extend the key using HKDF
tx_id = unhexlify(tx_id) tx_id = unhexlify(tx_id)
hkdf = HKDF( # master_key = H(tx_id | tx_id)
algorithm=hashes.SHA256(), master_key = sha256(tx_id + tx_id).digest()
length=32,
salt=SALT.encode(),
info=None,
backend=default_backend()
)
extended_key = hkdf.derive(tx_id[16:]) # 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]
# The 16 MSB of the extended key will serve as the AES GCM 128 secret key. The 16 LSB will serve as the IV. nonce = master_key[16:]
sk = extended_key[:16]
nonce = extended_key[16:]
# Encrypt the data # Encrypt the data
aesgcm = AESGCM(sk) aesgcm = AESGCM(sk)
@@ -52,7 +43,7 @@ class Blob:
if debug: if debug:
logging.info("[Client] creating new blob") logging.info("[Client] creating new blob")
logging.info("[Client] master key: {}".format(hexlify(tx_id[16:]).decode())) logging.info("[Client] master key: {}".format(hexlify(master_key).decode()))
logging.info("[Client] sk: {}".format(hexlify(sk).decode())) logging.info("[Client] sk: {}".format(hexlify(sk).decode()))
logging.info("[Client] nonce: {}".format(hexlify(nonce).decode())) logging.info("[Client] nonce: {}".format(hexlify(nonce).decode()))
logging.info("[Client] encrypted_blob: {}".format(encrypted_blob)) logging.info("[Client] encrypted_blob: {}".format(encrypted_blob))

25
pisa-btc/pisa/encrypted_blob.py
View File

@@ -1,9 +1,6 @@
from binascii import unhexlify, hexlify from binascii import unhexlify, hexlify
from hashlib import sha256
from cryptography.hazmat.primitives.ciphers.aead import AESGCM from cryptography.hazmat.primitives.ciphers.aead import AESGCM
from cryptography.hazmat.primitives.kdf.hkdf import HKDF
from cryptography.hazmat.primitives import hashes
from cryptography.hazmat.backends import default_backend
from conf import SALT
class EncryptedBlob: class EncryptedBlob:
@@ -11,24 +8,16 @@ class EncryptedBlob:
self.data = data self.data = data
def decrypt(self, key, debug, logging): def decrypt(self, key, debug, logging):
# Extend the key using HKDF # master_key = H(tx_id | tx_id)
hkdf = HKDF( master_key = sha256(key + key).digest()
algorithm=hashes.SHA256(),
length=32,
salt=SALT.encode(),
info=None,
backend=default_backend()
)
extended_key = hkdf.derive(key) # 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]
# The 16 MSB of the extended key will serve as the AES GCM 128 secret key. The 16 LSB will serve as the IV. nonce = master_key[16:]
sk = extended_key[:16]
nonce = extended_key[16:]
if debug: if debug:
logging.info("[Watcher] creating new blob") logging.info("[Watcher] creating new blob")
logging.info("[Watcher] master key: {}".format(hexlify(key).decode())) logging.info("[Watcher] master key: {}".format(hexlify(master_key).decode()))
logging.info("[Watcher] sk: {}".format(hexlify(sk).decode())) logging.info("[Watcher] sk: {}".format(hexlify(sk).decode()))
logging.info("[Watcher] nonce: {}".format(hexlify(nonce).decode())) logging.info("[Watcher] nonce: {}".format(hexlify(nonce).decode()))
logging.info("[Watcher] encrypted_blob: {}".format(self.data)) logging.info("[Watcher] encrypted_blob: {}".format(self.data))