[refactor] Extract the CertVerifyResult assignment of has_md2, has_md4,

net/cert/x509_certificate_nss.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <cert.h>
 #include <cryptohi.h>
 #include <keyhi.h>
 #include <nss.h>
 #include <pk11pub.h>
 #include <prtime.h>
@@ skipping 245 matching lines @@
 }
 
 // static
 void X509Certificate::GetPublicKeyInfo(OSCertHandle cert_handle,
                                        size_t* size_bits,
                                        PublicKeyType* type) {
   x509_util::GetPublicKeyInfo(cert_handle, size_bits, type);
 }
 
 // static
+X509Certificate::SignatureHashAlgorithm
+X509Certificate::GetSignatureHashAlgorithm(OSCertHandle cert_handle) {
+  SECAlgorithmID& signature = cert_handle->signature;
+  SECOidTag oid_tag = SECOID_FindOIDTag(&signature.algorithm);
+  switch (oid_tag) {
+    case SEC_OID_PKCS1_MD5_WITH_RSA_ENCRYPTION:
+      return kSignatureHashAlgorithmMd5;
+    case SEC_OID_PKCS1_MD2_WITH_RSA_ENCRYPTION:
+      return kSignatureHashAlgorithmMd2;
+    case SEC_OID_PKCS1_MD4_WITH_RSA_ENCRYPTION:
+      return kSignatureHashAlgorithmMd4;
+    case SEC_OID_PKCS1_SHA1_WITH_RSA_ENCRYPTION:
+    case SEC_OID_ISO_SHA1_WITH_RSA_SIGNATURE:
+    case SEC_OID_ANSIX9_DSA_SIGNATURE_WITH_SHA1_DIGEST:
+    case SEC_OID_ANSIX962_ECDSA_SHA1_SIGNATURE:
+      return kSignatureHashAlgorithmSha1;
+    default:
+      return kSignatureHashAlgorithmOther;
+  }
+}
+
+// static
 bool X509Certificate::IsSelfSigned(OSCertHandle cert_handle) {
   crypto::ScopedSECKEYPublicKey public_key(CERT_ExtractPublicKey(cert_handle));
   if (!public_key.get())
     return false;
   if (SECSuccess != CERT_VerifySignedDataWithPublicKey(
                         &cert_handle->signatureWrap, public_key.get(), NULL)) {
     return false;
   }
   return CERT_CompareName(&cert_handle->subject, &cert_handle->issuer) ==
          SECEqual;
 }
 
 }  // namespace net