fix bug with n % 8 length wrapping on AESKWP (#4160)
* fix bug with n % 8 length wrapping on AESKWP
* review feedback
diff --git a/src/cryptography/hazmat/primitives/keywrap.py b/src/cryptography/hazmat/primitives/keywrap.py
index 3b53131..2b7955f 100644
--- a/src/cryptography/hazmat/primitives/keywrap.py
+++ b/src/cryptography/hazmat/primitives/keywrap.py
@@ -118,11 +118,16 @@
b = (8 * n) - mli
if (
not bytes_eq(a[:4], b"\xa6\x59\x59\xa6") or not
- 8 * (n - 1) < mli <= 8 * n or not bytes_eq(data[-b:], b"\x00" * b)
+ 8 * (n - 1) < mli <= 8 * n or (
+ b != 0 and not bytes_eq(data[-b:], b"\x00" * b)
+ )
):
raise InvalidUnwrap()
- return data[:-b]
+ if b == 0:
+ return data
+ else:
+ return data[:-b]
def aes_key_unwrap(wrapping_key, wrapped_key, backend):
diff --git a/tests/hazmat/primitives/test_keywrap.py b/tests/hazmat/primitives/test_keywrap.py
index 8311c2a..9b1e43e 100644
--- a/tests/hazmat/primitives/test_keywrap.py
+++ b/tests/hazmat/primitives/test_keywrap.py
@@ -143,6 +143,18 @@
@pytest.mark.parametrize(
"params",
+ _load_all_params("keywrap", ["kwp_botan.txt"], load_nist_vectors)
+ )
+ def test_wrap_additional_vectors(self, backend, params):
+ wrapping_key = binascii.unhexlify(params["key"])
+ key_to_wrap = binascii.unhexlify(params["input"])
+ wrapped_key = keywrap.aes_key_wrap_with_padding(
+ wrapping_key, key_to_wrap, backend
+ )
+ assert wrapped_key == binascii.unhexlify(params["output"])
+
+ @pytest.mark.parametrize(
+ "params",
_load_all_params(
os.path.join("keywrap", "kwtestvectors"),
["KWP_AD_128.txt", "KWP_AD_192.txt", "KWP_AD_256.txt"],
@@ -163,6 +175,18 @@
)
assert params["p"] == binascii.hexlify(unwrapped_key)
+ @pytest.mark.parametrize(
+ "params",
+ _load_all_params("keywrap", ["kwp_botan.txt"], load_nist_vectors)
+ )
+ def test_unwrap_additional_vectors(self, backend, params):
+ wrapping_key = binascii.unhexlify(params["key"])
+ wrapped_key = binascii.unhexlify(params["output"])
+ unwrapped_key = keywrap.aes_key_unwrap_with_padding(
+ wrapping_key, wrapped_key, backend
+ )
+ assert unwrapped_key == binascii.unhexlify(params["input"])
+
def test_unwrap_invalid_wrapped_key_length(self, backend):
# Keys to unwrap must be at least 16 bytes
with pytest.raises(ValueError, match='Must be at least 16 bytes'):