Implemented compatibility handling for AES-256 migration

This commit is contained in:
Mark Qvist 2025-05-06 12:08:17 +02:00
parent 5dc8cdc6dc
commit d7791c60e2
4 changed files with 64 additions and 26 deletions

View file

@ -37,6 +37,8 @@ from RNS.Cryptography import AES
from RNS.Cryptography.AES import AES_128_CBC
from RNS.Cryptography.AES import AES_256_CBC
# import RNS # TODO: Remove
class Token():
"""
This class provides a slightly modified implementation of the Fernet spec
@ -64,11 +66,23 @@ class Token():
self._signing_key = key[:16]
self._encryption_key = key[16:]
####################################################################
self.mode_legacy = AES_128_CBC # TODO: Remove after migration
self._signing_key_128 = key[:16] # TODO: Remove after migration
self._encryption_key_128 = key[16:] # TODO: Remove after migration
####################################################################
elif len(key) == 64:
self.mode = AES_256_CBC
self._signing_key = key[:32]
self._encryption_key = key[32:]
####################################################################
self.mode_legacy = AES_128_CBC # TODO: Remove after migration
self._signing_key_128 = key[:16] # TODO: Remove after migration
self._encryption_key_128 = key[16:32] # TODO: Remove after migration
####################################################################
else: raise ValueError("Token key must be 128 or 256 bits, not "+str(len(key)*8))
else: raise TypeError(f"Invalid token mode: {mode}")
@ -79,16 +93,17 @@ class Token():
else:
received_hmac = token[-32:]
expected_hmac = HMAC.new(self._signing_key, token[:-32]).digest()
expected_hmac_128 = HMAC.new(self._signing_key_128, token[:-32]).digest() # TODO: Remove after migration
if received_hmac == expected_hmac: return True
# TODO: Reset after migration
# if received_hmac == expected_hmac: return True
if received_hmac == expected_hmac or received_hmac == expected_hmac_128: return True
else: return False
def encrypt(self, data = None):
iv = os.urandom(16)
current_time = int(time.time())
if not isinstance(data, bytes): raise TypeError("Token plaintext input must be bytes")
iv = os.urandom(16)
ciphertext = self.mode.encrypt(
plaintext = PKCS7.pad(data),
@ -108,12 +123,31 @@ class Token():
ciphertext = token[16:-32]
try:
try:
# RNS.log(f"Trying decryption with {self.mode}", RNS.LOG_DEBUG) # TODO: Remove
plaintext = PKCS7.unpad(
self.mode.decrypt(
ciphertext = ciphertext,
key = self._encryption_key,
iv = iv))
# RNS.log(f"Decrypted packet with {self.mode}", RNS.LOG_DEBUG) # TODO: Remove
return plaintext
except Exception as e: raise ValueError("Could not decrypt token")
# TODO: Remove after migration ############################
except Exception as e:
# RNS.log(f"{self.mode} decryption failed", RNS.LOG_DEBUG) # TODO: Remove
# RNS.log(f"Trying decryption with {self.mode_legacy}", RNS.LOG_DEBUG) # TODO: Remove
plaintext = PKCS7.unpad(
self.mode_legacy.decrypt(
ciphertext = ciphertext,
key = self._encryption_key_128,
iv = iv))
# RNS.log(f"Decrypted packet with {self.mode_legacy}", RNS.LOG_DEBUG) # TODO: Remove
return plaintext
###########################################################
except Exception as e:
RNS.trace_exception(e) # TODO: Remove after migration
raise ValueError("Could not decrypt token")

View file

@ -418,7 +418,8 @@ class Destination:
else:
plaintext = self.decrypt(packet.data)
packet.ratchet_id = self.latest_ratchet_id
if plaintext != None:
if plaintext == None: return False
else:
if packet.packet_type == RNS.Packet.DATA:
if self.callbacks.packet != None:
try:
@ -426,6 +427,8 @@ class Destination:
except Exception as e:
RNS.log("Error while executing receive callback from "+str(self)+". The contained exception was: "+str(e), RNS.LOG_ERROR)
return True
def incoming_link_request(self, data, packet):
if self.accept_link_requests:
link = RNS.Link.validate_request(self, data, packet)

View file

@ -544,6 +544,8 @@ class Identity:
RNS.log("The contained exception was: "+str(e))
def __init__(self,create_keys=True):
self.derived_key_length = 64
# Initialize keys to none
self.prv = None
self.prv_bytes = None
@ -677,7 +679,7 @@ class Identity:
shared_key = ephemeral_key.exchange(target_public_key)
derived_key = RNS.Cryptography.hkdf(
length=32,
length=self.derived_key_length,
derive_from=shared_key,
salt=self.get_salt(),
context=self.get_context(),
@ -715,7 +717,7 @@ class Identity:
ratchet_id = Identity._get_ratchet_id(ratchet_prv.public_key().public_bytes())
shared_key = ratchet_prv.exchange(peer_pub)
derived_key = RNS.Cryptography.hkdf(
length=32,
length=self.derived_key_length,
derive_from=shared_key,
salt=self.get_salt(),
context=self.get_context(),
@ -740,7 +742,7 @@ class Identity:
if plaintext == None:
shared_key = self.prv.exchange(peer_pub)
derived_key = RNS.Cryptography.hkdf(
length=32,
length=self.derived_key_length,
derive_from=shared_key,
salt=self.get_salt(),
context=self.get_context(),

View file

@ -1879,8 +1879,7 @@ class Transport:
for destination in Transport.destinations:
if destination.hash == packet.destination_hash and destination.type == packet.destination_type:
packet.destination = destination
destination.receive(packet)
if destination.receive(packet):
if destination.proof_strategy == RNS.Destination.PROVE_ALL:
packet.prove()