Refuse to accept certificate chains containing any RSA public key smaller

net/base/x509_certificate_win.cc

Index: net/base/x509_certificate_win.cc
===================================================================
--- net/base/x509_certificate_win.cc	(revision 110129)
+++ net/base/x509_certificate_win.cc	(working copy)
@@ -1153,4 +1153,35 @@
                            length);
 }
 
+//static
+void X509Certificate::GetPublicKeyInfo(OSCertHandle cert_handle,
+                                       size_t* size_bits,
+                                       PublicKeyType* type) {
+  *size_bits = CertGetPublicKeyLength(
+      X509_ASN_ENCODING | PKCS_7_ASN_ENCODING,
+      cert_handle->pCertInfo->SubjectPublicKeyInfo);
+
+  PCCRYPT_OID_INFO oid_info = CryptFindOIDInfo(
+      CRYPT_OID_INFO_OID_KEY,
+      cert_handle->pCertInfo->SubjectPublicKeyInfo->Algorithm->pszObjId,
+      CRYPT_SIGN_ALG_OID_GROUP_ID);
+  CHECK(CRYPT_OID_INFO.dwGroupId == CRYPT_SIGN_ALG_OID_GROUP_ID);

[Ryan Sleevi, 2011/11/16 03:46:11]

nit: oid_info->dwGroupId (and the next two lines)

+  CHECK(CRYPT_OID_INFO.ExtraInfo.cbData >= sizeof(DWORD));
+  DWORD id = *reinterpret_cast<DWORD*>(CRYPT_OID_INFO.ExtraInfo.pbData);
+
+  switch (id) {
+    case CALG_RSA_SIGN:
+      *type = PublicKeyType::RSA;
+      break;
+    case CALG_DSS_SIGN:
+      *type = PublicKeyType::DSA;
+      break;
+    case CALG_ECDSA:
+      *type = PublicKeyType::ECDSA;
+      break;
+    default:
+      *type = PublicKeyType::None;
+  }
+}
+
 }  // namespace net