|
|
@@ -161,6 +161,20 @@ class PlaintextKey(KeyBase):
|
|
|
return Chunk(data)
|
|
|
|
|
|
|
|
|
+def random_blake2b_256_key():
|
|
|
+ # This might look a bit curious, but is the same construction used in the keyed mode of BLAKE2b.
|
|
|
+ # Why limit the key to 64 bytes and pad it with 64 nulls nonetheless? The answer is that BLAKE2b
|
|
|
+ # has a 128 byte block size, but only 64 bytes of internal state (this is also referred to as a
|
|
|
+ # "local wide pipe" design, because the compression function transforms (block, state) => state,
|
|
|
+ # and len(block) >= len(state), hence wide.)
|
|
|
+ # In other words, a key longer than 64 bytes would have simply no advantage, since the function
|
|
|
+ # has no way of propagating more than 64 bytes of entropy internally.
|
|
|
+ # It's padded to a full block so that the key is never buffered internally by blake2b_update, ie.
|
|
|
+ # it remains in a single memory location that can be tracked and could be erased securely, if we
|
|
|
+ # wanted to.
|
|
|
+ return os.urandom(64) + bytes(64)
|
|
|
+
|
|
|
+
|
|
|
class ID_BLAKE2b_256:
|
|
|
"""
|
|
|
Key mix-in class for using BLAKE2b-256 for the id key.
|
|
|
@@ -171,6 +185,12 @@ class ID_BLAKE2b_256:
|
|
|
def id_hash(self, data):
|
|
|
return blake2b_256(self.id_key, data)
|
|
|
|
|
|
+ def init_from_random_data(self, data=None):
|
|
|
+ assert data is None # PassphraseKey is the only caller using *data*
|
|
|
+ super().init_from_random_data()
|
|
|
+ self.enc_hmac_key = random_blake2b_256_key()
|
|
|
+ self.id_key = random_blake2b_256_key()
|
|
|
+
|
|
|
|
|
|
class ID_HMAC_SHA_256:
|
|
|
"""
|
|
|
@@ -198,12 +218,14 @@ class AESKeyBase(KeyBase):
|
|
|
|
|
|
PAYLOAD_OVERHEAD = 1 + 32 + 8 # TYPE + HMAC + NONCE
|
|
|
|
|
|
+ MAC = hmac_sha256
|
|
|
+
|
|
|
def encrypt(self, chunk):
|
|
|
chunk = self.compress(chunk)
|
|
|
self.nonce_manager.ensure_reservation(num_aes_blocks(len(chunk.data)))
|
|
|
self.enc_cipher.reset()
|
|
|
data = b''.join((self.enc_cipher.iv[8:], self.enc_cipher.encrypt(chunk.data)))
|
|
|
- hmac = hmac_sha256(self.enc_hmac_key, data)
|
|
|
+ hmac = self.MAC(self.enc_hmac_key, data)
|
|
|
return b''.join((self.TYPE_STR, hmac, data))
|
|
|
|
|
|
def decrypt(self, id, data, decompress=True):
|
|
|
@@ -212,7 +234,7 @@ class AESKeyBase(KeyBase):
|
|
|
raise IntegrityError('Chunk %s: Invalid encryption envelope' % bin_to_hex(id))
|
|
|
data_view = memoryview(data)
|
|
|
hmac_given = data_view[1:33]
|
|
|
- hmac_computed = memoryview(hmac_sha256(self.enc_hmac_key, data_view[33:]))
|
|
|
+ hmac_computed = memoryview(self.MAC(self.enc_hmac_key, data_view[33:]))
|
|
|
if not compare_digest(hmac_computed, hmac_given):
|
|
|
raise IntegrityError('Chunk %s: Encryption envelope checksum mismatch' % bin_to_hex(id))
|
|
|
self.dec_cipher.reset(iv=PREFIX + data[33:41])
|
|
|
@@ -230,7 +252,9 @@ class AESKeyBase(KeyBase):
|
|
|
nonce = bytes_to_long(payload[33:41])
|
|
|
return nonce
|
|
|
|
|
|
- def init_from_random_data(self, data):
|
|
|
+ def init_from_random_data(self, data=None):
|
|
|
+ if data is None:
|
|
|
+ data = os.urandom(100)
|
|
|
self.enc_key = data[0:32]
|
|
|
self.enc_hmac_key = data[32:64]
|
|
|
self.id_key = data[64:96]
|
|
|
@@ -457,7 +481,7 @@ class KeyfileKeyBase(AESKeyBase):
|
|
|
passphrase = Passphrase.new(allow_empty=True)
|
|
|
key = cls(repository)
|
|
|
key.repository_id = repository.id
|
|
|
- key.init_from_random_data(os.urandom(100))
|
|
|
+ key.init_from_random_data()
|
|
|
key.init_ciphers()
|
|
|
target = key.get_new_target(args)
|
|
|
key.save(target, passphrase)
|
|
|
@@ -568,11 +592,13 @@ class Blake2KeyfileKey(ID_BLAKE2b_256, KeyfileKey):
|
|
|
TYPE = 0x04
|
|
|
NAME = 'key file BLAKE2b'
|
|
|
FILE_ID = 'BORG_KEY'
|
|
|
+ MAC = blake2b_256
|
|
|
|
|
|
|
|
|
class Blake2RepoKey(ID_BLAKE2b_256, RepoKey):
|
|
|
TYPE = 0x05
|
|
|
NAME = 'repokey BLAKE2b'
|
|
|
+ MAC = blake2b_256
|
|
|
|
|
|
|
|
|
class AuthenticatedKey(ID_BLAKE2b_256, RepoKey):
|
Marian Beermann