add hmac_supported method to backend.
Previously we were implicitly assuming that if a hash was supported then
its hmac equivalent was as well.
diff --git a/cryptography/hazmat/backends/openssl/backend.py b/cryptography/hazmat/backends/openssl/backend.py
index f11ddf2..7b67fb0 100644
--- a/cryptography/hazmat/backends/openssl/backend.py
+++ b/cryptography/hazmat/backends/openssl/backend.py
@@ -184,6 +184,9 @@
digest = self.lib.EVP_get_digestbyname(algorithm.name.encode("ascii"))
return digest != self.ffi.NULL
+ def hmac_supported(self, algorithm):
+ return self.hash_supported(algorithm)
+
def create_hash_ctx(self, algorithm):
return _HashContext(self, algorithm)
diff --git a/docs/hazmat/backends/interfaces.rst b/docs/hazmat/backends/interfaces.rst
index b524943..45fbaf0 100644
--- a/docs/hazmat/backends/interfaces.rst
+++ b/docs/hazmat/backends/interfaces.rst
@@ -126,12 +126,23 @@
A backend with methods for using cryptographic hash functions as message
authentication codes.
+ .. method:: hmac_supported(algorithm)
+
+ Check if the specified ``algorithm`` is supported by this backend.
+
+ :param algorithm: An instance of a
+ :class:`~cryptography.hazmat.primitives.interfaces.HashAlgorithm`
+ provider.
+
+ :returns: ``True`` if the specified ``algorithm`` is supported for HMAC
+ by this backend, otherwise ``False``.
+
.. method:: create_hmac_ctx(algorithm)
Create a
:class:`~cryptogrpahy.hazmat.primitives.interfaces.HashContext` that
- uses the specified ``algorithm`` to calculate a hash-based message
- authentication code.
+ uses the specified ``algorithm`` to calculate a hash-based message
+ authentication code.
:param algorithm: An instance of a
:class:`~cryptography.hazmat.primitives.interfaces.HashAlgorithm`
diff --git a/tests/hazmat/primitives/test_hmac.py b/tests/hazmat/primitives/test_hmac.py
index 124c437..1e776c9 100644
--- a/tests/hazmat/primitives/test_hmac.py
+++ b/tests/hazmat/primitives/test_hmac.py
@@ -34,7 +34,7 @@
class TestHMAC(object):
test_copy = generate_base_hmac_test(
hashes.MD5(),
- only_if=lambda backend: backend.hash_supported(hashes.MD5),
+ only_if=lambda backend: backend.hmac_supported(hashes.MD5),
skip_message="Does not support MD5",
)
diff --git a/tests/hazmat/primitives/test_hmac_vectors.py b/tests/hazmat/primitives/test_hmac_vectors.py
index 7d0f156..f884d85 100644
--- a/tests/hazmat/primitives/test_hmac_vectors.py
+++ b/tests/hazmat/primitives/test_hmac_vectors.py
@@ -27,7 +27,7 @@
"rfc-2202-md5.txt",
],
hashes.MD5(),
- only_if=lambda backend: backend.hash_supported(hashes.MD5),
+ only_if=lambda backend: backend.hmac_supported(hashes.MD5),
skip_message="Does not support MD5",
)
@@ -40,7 +40,7 @@
"rfc-2202-sha1.txt",
],
hashes.SHA1(),
- only_if=lambda backend: backend.hash_supported(hashes.SHA1),
+ only_if=lambda backend: backend.hmac_supported(hashes.SHA1),
skip_message="Does not support SHA1",
)
@@ -53,7 +53,7 @@
"rfc-4231-sha224.txt",
],
hashes.SHA224(),
- only_if=lambda backend: backend.hash_supported(hashes.SHA224),
+ only_if=lambda backend: backend.hmac_supported(hashes.SHA224),
skip_message="Does not support SHA224",
)
@@ -66,7 +66,7 @@
"rfc-4231-sha256.txt",
],
hashes.SHA256(),
- only_if=lambda backend: backend.hash_supported(hashes.SHA256),
+ only_if=lambda backend: backend.hmac_supported(hashes.SHA256),
skip_message="Does not support SHA256",
)
@@ -79,7 +79,7 @@
"rfc-4231-sha384.txt",
],
hashes.SHA384(),
- only_if=lambda backend: backend.hash_supported(hashes.SHA384),
+ only_if=lambda backend: backend.hmac_supported(hashes.SHA384),
skip_message="Does not support SHA384",
)
@@ -92,7 +92,7 @@
"rfc-4231-sha512.txt",
],
hashes.SHA512(),
- only_if=lambda backend: backend.hash_supported(hashes.SHA512),
+ only_if=lambda backend: backend.hmac_supported(hashes.SHA512),
skip_message="Does not support SHA512",
)
@@ -105,6 +105,6 @@
"rfc-2286-ripemd160.txt",
],
hashes.RIPEMD160(),
- only_if=lambda backend: backend.hash_supported(hashes.RIPEMD160),
+ only_if=lambda backend: backend.hmac_supported(hashes.RIPEMD160),
skip_message="Does not support RIPEMD160",
)