[webcrypto] Implement RSA-PSS using BoringSSL.

content/child/webcrypto/openssl/rsa_sign_openssl.h

 // Copyright 2014 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.
 
 #ifndef CONTENT_CHILD_WEBCRYPTO_OPENSSL_RSA_SIGN_OPENSSL_H_
 #define CONTENT_CHILD_WEBCRYPTO_OPENSSL_RSA_SIGN_OPENSSL_H_
 
 #include <stdint.h>
 
 #include <vector>
 
 namespace blink {
 class WebCryptoKey;
 }
 
 namespace content {
 
 namespace webcrypto {
 
 class CryptoData;
 class Status;
 
-// Helper functions for doing RSA-SSA signing and verification.
+// Helper functions for doing RSA-SSA signing and verification
+// (both PKCS1-v1_5 and PSS flavor).
+//
+// The salt length parameter is only relevant when the key is for RSA-PSS. In
+// other cases it should be set to zero.
 
 Status RsaSign(const blink::WebCryptoKey& key,
+               unsigned int pss_salt_length_bytes,
                const CryptoData& data,
                std::vector<uint8_t>* buffer);
 
 Status RsaVerify(const blink::WebCryptoKey& key,
+                 unsigned int pss_salt_length_bytes,
                  const CryptoData& signature,
                  const CryptoData& data,
                  bool* signature_match);
 
 }  // namespace webcrypto
 
 }  // namespace content
 
 #endif  // CONTENT_CHILD_WEBCRYPTO_OPENSSL_RSA_SIGN_OPENSSL_H_