Merge pull request #1651 from reaperhulk/x509-signature-algorithm

X509 certificate signature algorithm support

3 files changed, 73 insertions, 8 deletions

diff --git a/src/cryptography/hazmat/backends/openssl/x509.py b/src/cryptography/hazmat/backends/openssl/x509.py
index 76dcf32f..b712f1f9 100644
--- a/src/cryptography/hazmat/backends/openssl/x509.py
+++ b/src/cryptography/hazmat/backends/openssl/x509.py
@@ -16,6 +16,7 @@ from __future__ import absolute_import, division, print_function
 import datetime
 
 from cryptography import utils, x509
+from cryptography.exceptions import UnsupportedAlgorithm
 from cryptography.hazmat.primitives import hashes
 
 
@@ -121,14 +122,7 @@ class _Certificate(object):
                 buf, lambda buf: self._backend._lib.OPENSSL_free(buf[0])
             )
             value = self._backend._ffi.buffer(buf[0], res)[:].decode('utf8')
-            # Set to 80 on the recommendation of
-            # https://www.openssl.org/docs/crypto/OBJ_nid2ln.html
-            buf_len = 80
-            buf = self._backend._ffi.new("char[]", buf_len)
-            res = self._backend._lib.OBJ_obj2txt(buf, buf_len, obj, 1)
-            assert res > 0
-            oid = self._backend._ffi.buffer(buf, res)[:].decode()
-
+            oid = self._obj2txt(obj)
             attributes.append(
                 x509.NameAttribute(
                     x509.ObjectIdentifier(oid), value
@@ -136,3 +130,22 @@ class _Certificate(object):
             )
 
         return x509.Name(attributes)
+
+    def _obj2txt(self, obj):
+        # Set to 80 on the recommendation of
+        # https://www.openssl.org/docs/crypto/OBJ_nid2ln.html#return_values
+        buf_len = 80
+        buf = self._backend._ffi.new("char[]", buf_len)
+        res = self._backend._lib.OBJ_obj2txt(buf, buf_len, obj, 1)
+        assert res > 0
+        return self._backend._ffi.buffer(buf, res)[:].decode()
+
+    @property
+    def signature_hash_algorithm(self):
+        oid = self._obj2txt(self._x509.sig_alg.algorithm)
+        try:
+            return x509._SIG_OIDS_TO_HASH[oid]
+        except KeyError:
+            raise UnsupportedAlgorithm(
+                "Signature algorithm OID:{0} not recognized".format(oid)
+            )
diff --git a/src/cryptography/hazmat/bindings/openssl/x509.py b/src/cryptography/hazmat/bindings/openssl/x509.py
index e30d23b7..bf689e33 100644
--- a/src/cryptography/hazmat/bindings/openssl/x509.py
+++ b/src/cryptography/hazmat/bindings/openssl/x509.py
@@ -65,6 +65,7 @@ typedef struct {
 } X509_CRL;
 
 typedef struct {
+    X509_ALGOR *sig_alg;
     X509_CINF *cert_info;
     ...;
 } X509;
diff --git a/src/cryptography/x509.py b/src/cryptography/x509.py
index 8a6ecc8d..ad7ebbe0 100644
--- a/src/cryptography/x509.py
+++ b/src/cryptography/x509.py
@@ -10,6 +10,7 @@ from enum import Enum
 import six
 
 from cryptography import utils
+from cryptography.hazmat.primitives import hashes
 
 
 _OID_NAMES = {
@@ -28,6 +29,19 @@ _OID_NAMES = {
     "2.5.4.65": "pseudonym",
     "0.9.2342.19200300.100.1.25": "domainComponent",
     "1.2.840.113549.1.9.1": "emailAddress",
+    "1.2.840.113549.1.1.4": "md5WithRSAEncryption",
+    "1.2.840.113549.1.1.5": "sha1WithRSAEncryption",
+    "1.2.840.113549.1.1.14": "sha224WithRSAEncryption",
+    "1.2.840.113549.1.1.11": "sha256WithRSAEncryption",
+    "1.2.840.113549.1.1.12": "sha384WithRSAEncryption",
+    "1.2.840.113549.1.1.13": "sha512WithRSAEncryption",
+    "1.2.840.10045.4.3.1": "ecdsa-with-SHA224",
+    "1.2.840.10045.4.3.2": "ecdsa-with-SHA256",
+    "1.2.840.10045.4.3.3": "ecdsa-with-SHA384",
+    "1.2.840.10045.4.3.4": "ecdsa-with-SHA512",
+    "1.2.840.10040.4.3": "dsa-with-sha1",
+    "2.16.840.1.101.3.4.3.1": "dsa-with-sha224",
+    "2.16.840.1.101.3.4.3.2": "dsa-with-sha256",
 }
 
 
@@ -143,6 +157,36 @@ OID_PSEUDONYM = ObjectIdentifier("2.5.4.65")
 OID_DOMAIN_COMPONENT = ObjectIdentifier("0.9.2342.19200300.100.1.25")
 OID_EMAIL_ADDRESS = ObjectIdentifier("1.2.840.113549.1.9.1")
 
+OID_RSA_WITH_MD5 = ObjectIdentifier("1.2.840.113549.1.1.4")
+OID_RSA_WITH_SHA1 = ObjectIdentifier("1.2.840.113549.1.1.5")
+OID_RSA_WITH_SHA224 = ObjectIdentifier("1.2.840.113549.1.1.14")
+OID_RSA_WITH_SHA256 = ObjectIdentifier("1.2.840.113549.1.1.11")
+OID_RSA_WITH_SHA384 = ObjectIdentifier("1.2.840.113549.1.1.12")
+OID_RSA_WITH_SHA512 = ObjectIdentifier("1.2.840.113549.1.1.13")
+OID_ECDSA_WITH_SHA224 = ObjectIdentifier("1.2.840.10045.4.3.1")
+OID_ECDSA_WITH_SHA256 = ObjectIdentifier("1.2.840.10045.4.3.2")
+OID_ECDSA_WITH_SHA384 = ObjectIdentifier("1.2.840.10045.4.3.3")
+OID_ECDSA_WITH_SHA512 = ObjectIdentifier("1.2.840.10045.4.3.4")
+OID_DSA_WITH_SHA1 = ObjectIdentifier("1.2.840.10040.4.3")
+OID_DSA_WITH_SHA224 = ObjectIdentifier("2.16.840.1.101.3.4.3.1")
+OID_DSA_WITH_SHA256 = ObjectIdentifier("2.16.840.1.101.3.4.3.2")
+
+_SIG_OIDS_TO_HASH = {
+    OID_RSA_WITH_MD5.dotted_string: hashes.MD5(),
+    OID_RSA_WITH_SHA1.dotted_string: hashes.SHA1(),
+    OID_RSA_WITH_SHA224.dotted_string: hashes.SHA224(),
+    OID_RSA_WITH_SHA256.dotted_string: hashes.SHA256(),
+    OID_RSA_WITH_SHA384.dotted_string: hashes.SHA384(),
+    OID_RSA_WITH_SHA512.dotted_string: hashes.SHA512(),
+    OID_ECDSA_WITH_SHA224.dotted_string: hashes.SHA224(),
+    OID_ECDSA_WITH_SHA256.dotted_string: hashes.SHA256(),
+    OID_ECDSA_WITH_SHA384.dotted_string: hashes.SHA384(),
+    OID_ECDSA_WITH_SHA512.dotted_string: hashes.SHA512(),
+    OID_DSA_WITH_SHA1.dotted_string: hashes.SHA1(),
+    OID_DSA_WITH_SHA224.dotted_string: hashes.SHA224(),
+    OID_DSA_WITH_SHA256.dotted_string: hashes.SHA256()
+}
+
 
 @six.add_metaclass(abc.ABCMeta)
 class Certificate(object):
@@ -193,3 +237,10 @@ class Certificate(object):
         """
         Returns the subject name object.
         """
+
+    @abc.abstractproperty
+    def signature_hash_algorithm(self):
+        """
+        Returns a HashAlgorithm corresponding to the type of the digest signed
+        in the certificate.
+        """