Port X509.get_signature_algorithm
diff --git a/OpenSSL/crypto.py b/OpenSSL/crypto.py
index 2f3d68a..e42dca9 100644
--- a/OpenSSL/crypto.py
+++ b/OpenSSL/crypto.py
@@ -197,6 +197,21 @@
_raise_current_error()
+ def get_signature_algorithm(self):
+ """
+ Retrieve the signature algorithm used in the certificate
+
+ :return: A byte string giving the name of the signature algorithm used in
+ the certificate.
+ :raise ValueError: If the signature algorithm is undefined.
+ """
+ alg = self._x509.cert_info.signature.algorithm
+ nid = _api.OBJ_obj2nid(alg)
+ if nid == _api.NID_undef:
+ raise ValueError("Undefined signature algorithm")
+ return _api.string(_api.OBJ_nid2ln(nid))
+
+
def digest(self, digest_name):
"""
Return the digest of the X509 object.