def derive(self, key_material):
utils._check_byteslike("key_material", key_material)
if self._used:
raise AlreadyFinalized
self._used = True
return self._expand(key_material)
def derive(self, key_material):
if self._used:
raise AlreadyFinalized
utils._check_byteslike("key_material", key_material)
self._used = True
# inverse floor division (equivalent to ceiling)
rounds = -(-self._length // self._algorithm.digest_size)
output = [b""]
# For counter mode, the number of iterations shall not be
# larger than 2^r-1, where r <= 32 is the binary length of the counter
# This ensures that the counter values used as an input to the
# PRF will not repeat during a particular call to the KDF function.
r_bin = utils.int_to_bytes(1, self._rlen)
if rounds > pow(2, len(r_bin) * 8) - 1:
raise ValueError("There are too many iterations.")
for i in range(1, rounds + 1):
h = hmac.HMAC(key_material, self._algorithm, backend=self._backend)
counter = utils.int_to_bytes(i, self._rlen)
if self._location == CounterLocation.BeforeFixed:
h.update(counter)
h.update(self._generate_fixed_input())
if self._location == CounterLocation.AfterFixed:
h.update(counter)
output.append(h.finalize())
return b"".join(output)[:self._length]
def __init__(self, tweak):
utils._check_byteslike("tweak", tweak)
if len(tweak) != 16:
raise ValueError("tweak must be 128-bits (16 bytes)")
self._tweak = tweak
def __init__(self, key, nonce):
self.key = _verify_key_size(self, key)
utils._check_byteslike("nonce", nonce)
if len(nonce) != 16:
raise ValueError("nonce must be 128-bits (16 bytes)")
self._nonce = nonce
def _verify_key_size(algorithm, key):
# Verify that the key is instance of bytes
utils._check_byteslike("key", key)
# Verify that the key size matches the expected key size
if len(key) * 8 not in algorithm.key_sizes:
raise ValueError("Invalid key size ({}) for {}.".format(
len(key) * 8, algorithm.name))
return key
def derive(self, key_material):
if self._used:
raise AlreadyFinalized("Scrypt instances can only be used once.")
self._used = True
utils._check_byteslike("key_material", key_material)
return self._backend.derive_scrypt(key_material, self._salt,
self._length, self._n, self._r,
self._p)
def __init__(self, key):
if not backend.aead_cipher_supported(self):
raise exceptions.UnsupportedAlgorithm(
"ChaCha20Poly1305 is not supported by this version of OpenSSL",
exceptions._Reasons.UNSUPPORTED_CIPHER,
)
utils._check_byteslike("key", key)
if len(key) != 32:
raise ValueError("ChaCha20Poly1305 key must be 32 bytes.")
self._key = key
def __init__(self, key, tag_length=16):
utils._check_byteslike("key", key)
if len(key) not in (16, 24, 32):
raise ValueError("AESCCM key must be 128, 192, or 256 bits.")
self._key = key
if not isinstance(tag_length, int):
raise TypeError("tag_length must be an integer")
if tag_length not in (4, 6, 8, 10, 12, 14, 16):
raise ValueError("Invalid tag_length")
self._tag_length = tag_length
def derive(self, key_material):
if self._used:
raise AlreadyFinalized("PBKDF2 instances can only be used once.")
self._used = True
utils._check_byteslike("key_material", key_material)
return self._backend.derive_pbkdf2_hmac(
self._algorithm,
self._length,
self._salt,
self._iterations,
key_material,
)
def _byte_unpadding_update(buffer_, data, block_size):
if buffer_ is None:
raise AlreadyFinalized("Context was already finalized.")
utils._check_byteslike("data", data)
buffer_ += bytes(data)
finished_blocks = max(len(buffer_) // (block_size // 8) - 1, 0)
result = buffer_[:finished_blocks * (block_size // 8)]
buffer_ = buffer_[finished_blocks * (block_size // 8):]
return buffer_, result
def _concatkdf_derive(key_material, length, auxfn, otherinfo):
utils._check_byteslike("key_material", key_material)
output = [b""]
outlen = 0
counter = 1
while length > outlen:
h = auxfn()
h.update(_int_to_u32be(counter))
h.update(key_material)
h.update(otherinfo)
output.append(h.finalize())
outlen += len(output[-1])
counter += 1
return b"".join(output)[:length]
def __init__(self, initialization_vector, tag=None, min_tag_length=16):
# len(initialization_vector) must in [1, 2 ** 64), but it's impossible
# to actually construct a bytes object that large, so we don't check
# for it
utils._check_byteslike("initialization_vector", initialization_vector)
if len(initialization_vector) == 0:
raise ValueError("initialization_vector must be at least 1 byte")
self._initialization_vector = initialization_vector
if tag is not None:
utils._check_bytes("tag", tag)
if min_tag_length < 4:
raise ValueError("min_tag_length must be >= 4")
if len(tag) < min_tag_length:
raise ValueError(
"Authentication tag must be {} bytes or longer.".format(
min_tag_length))
self._tag = tag
self._min_tag_length = min_tag_length
def derive(self, key_material):
if self._used:
raise AlreadyFinalized
self._used = True
utils._check_byteslike("key_material", key_material)
output = [b""]
outlen = 0
counter = 1
while self._length > outlen:
h = hashes.Hash(self._algorithm, self._backend)
h.update(key_material)
h.update(_int_to_u32be(counter))
if self._sharedinfo is not None:
h.update(self._sharedinfo)
output.append(h.finalize())
outlen += len(output[-1])
counter += 1
return b"".join(output)[:self._length]
def __init__(self, key):
utils._check_byteslike("key", key)
if len(key) not in (16, 24, 32):
raise ValueError("AESGCM key must be 128, 192, or 256 bits.")
self._key = key
def _check_params(self, nonce, data, associated_data):
utils._check_byteslike("nonce", nonce)
utils._check_bytes("data", data)
utils._check_bytes("associated_data", associated_data)
if not 7 <= len(nonce) <= 13:
raise ValueError("Nonce must be between 7 and 13 bytes")
def derive(self, key_material):
utils._check_byteslike("key_material", key_material)
return self._hkdf_expand.derive(self._extract(key_material))
def __init__(self, nonce):
utils._check_byteslike("nonce", nonce)
self._nonce = nonce
def _check_params(self, nonce, data, associated_data):
utils._check_byteslike("nonce", nonce)
utils._check_bytes("data", data)
utils._check_bytes("associated_data", associated_data)
if len(nonce) != 12:
raise ValueError("Nonce must be 12 bytes")
def __init__(self, initialization_vector):
utils._check_byteslike("initialization_vector", initialization_vector)
self._initialization_vector = initialization_vector
def update(self, data):
if self._ctx is None:
raise AlreadyFinalized("Context was already finalized.")
utils._check_byteslike("data", data)
self._ctx.update(data)
def set_data(self, data):
_check_byteslike("data", data)
if self._data is not None:
raise ValueError("data may only be set once")
return PKCS7SignatureBuilder(data, self._signers)
