1 files changed, 79 insertions, 8 deletions

diff --git a/src/openvpn/cryptoapi.c b/src/openvpn/cryptoapi.c
index 89d253c..720fce0 100644
--- a/src/openvpn/cryptoapi.c
+++ b/src/openvpn/cryptoapi.c
@@ -217,22 +217,21 @@ rsa_pub_dec(int flen, const unsigned char *from, unsigned char *to, RSA *rsa, in
  * Sign the hash in 'from' using NCryptSignHash(). This requires an NCRYPT
  * key handle in cd->crypt_prov. On return the signature is in 'to'. Returns
  * the length of the signature or 0 on error.
+ * If the hash_algo is not NULL, PKCS #1 DigestInfo header gets added
+ * to 'from', else it is signed as is.
  * For now we support only RSA and the padding is assumed to be PKCS1 v1.5
  */
 static int
-priv_enc_CNG(const CAPI_DATA *cd, const unsigned char *from, int flen,
-              unsigned char *to, int tlen, int padding)
+priv_enc_CNG(const CAPI_DATA *cd, const wchar_t *hash_algo, const unsigned char *from,
+             int flen, unsigned char *to, int tlen, int padding)
 {
     NCRYPT_KEY_HANDLE hkey = cd->crypt_prov;
-    DWORD len;
+    DWORD len = 0;
     ASSERT(cd->key_spec == CERT_NCRYPT_KEY_SPEC);
 
     msg(D_LOW, "Signing hash using CNG: data size = %d", flen);
 
-    /* The hash OID is already in 'from'.  So set the hash algorithm
-     * in the padding info struct to NULL.
-     */
-    BCRYPT_PKCS1_PADDING_INFO padinfo = {NULL};
+    BCRYPT_PKCS1_PADDING_INFO padinfo = {hash_algo};
     DWORD status;
 
     status = NCryptSignHash(hkey, padding? &padinfo : NULL, (BYTE*) from, flen,
@@ -270,7 +269,7 @@ rsa_priv_enc(int flen, const unsigned char *from, unsigned char *to, RSA *rsa, i
     }
     if (cd->key_spec == CERT_NCRYPT_KEY_SPEC)
     {
-        return priv_enc_CNG(cd, from, flen, to, RSA_size(rsa), padding);
+        return priv_enc_CNG(cd, NULL, from, flen, to, RSA_size(rsa), padding);
     }
 
     /* Unfortunately, there is no "CryptSign()" function in CryptoAPI, that would
@@ -334,6 +333,69 @@ rsa_priv_enc(int flen, const unsigned char *from, unsigned char *to, RSA *rsa, i
     return len;
 }
 
+/*
+ * Sign the hash in |m| and return the signature in |sig|.
+ * Returns 1 on success, 0 on error.
+ * NCryptSignHash() is used to sign and it is instructed to add the
+ * the PKCS #1 DigestInfo header to |m| unless the hash algorithm is
+ * the MD5/SHA1 combination used in TLS 1.1 and earlier versions.
+ */
+static int
+rsa_sign_CNG(int type, const unsigned char *m, unsigned int m_len,
+              unsigned char *sig, unsigned int *siglen, const RSA *rsa)
+{
+    CAPI_DATA *cd = (CAPI_DATA *) RSA_meth_get0_app_data(RSA_get_method(rsa));
+    const wchar_t *alg = NULL;
+    int padding = RSA_PKCS1_PADDING;
+
+    *siglen = 0;
+    if (cd == NULL)
+    {
+        RSAerr(RSA_F_RSA_OSSL_PRIVATE_ENCRYPT, ERR_R_PASSED_NULL_PARAMETER);
+        return 0;
+    }
+
+    switch (type)
+    {
+        case NID_md5:
+            alg = BCRYPT_MD5_ALGORITHM;
+            break;
+
+        case NID_sha1:
+            alg = BCRYPT_SHA1_ALGORITHM;
+            break;
+
+        case NID_sha256:
+            alg = BCRYPT_SHA256_ALGORITHM;
+            break;
+
+        case NID_sha384:
+            alg = BCRYPT_SHA384_ALGORITHM;
+            break;
+
+        case NID_sha512:
+            alg = BCRYPT_SHA512_ALGORITHM;
+            break;
+
+        case NID_md5_sha1:
+            if (m_len != SSL_SIG_LENGTH)
+            {
+                RSAerr(RSA_F_RSA_SIGN, RSA_R_INVALID_MESSAGE_LENGTH);
+                return 0;
+            }
+            /* No DigestInfo header is required -- set alg-name to NULL */
+            alg = NULL;
+            break;
+        default:
+            msg(M_WARN, "cryptoapicert: Unknown hash type NID=0x%x", type);
+            RSAerr(RSA_F_RSA_SIGN, RSA_R_UNKNOWN_ALGORITHM_TYPE);
+            return 0;
+    }
+
+    *siglen = priv_enc_CNG(cd, alg, m, (int)m_len, sig, RSA_size(rsa), padding);
+    return (siglen == 0) ? 0 : 1;
+}
+
 /* decrypt */
 static int
 rsa_priv_dec(int flen, const unsigned char *from, unsigned char *to, RSA *rsa, int padding)
@@ -555,6 +617,15 @@ SSL_CTX_use_CryptoAPI_certificate(SSL_CTX *ssl_ctx, const char *cert_prop)
     RSA_meth_set_finish(my_rsa_method, finish);
     RSA_meth_set0_app_data(my_rsa_method, cd);
 
+    /* For CNG, set the RSA_sign method which gets priority over priv_enc().
+     * This method is called with the raw hash without the digestinfo
+     * header and works better when using NCryptSignHash() with some tokens.
+     */
+    if (cd->key_spec == CERT_NCRYPT_KEY_SPEC)
+    {
+        RSA_meth_set_sign(my_rsa_method, rsa_sign_CNG);
+    }
+
     rsa = RSA_new();
     if (rsa == NULL)
     {