1 /*
2  *  Copyright 2004 The WebRTC Project Authors. All rights reserved.
3  *
4  *  Use of this source code is governed by a BSD-style license
5  *  that can be found in the LICENSE file in the root of the source
6  *  tree. An additional intellectual property rights grant can be found
7  *  in the file PATENTS.  All contributing project authors may
8  *  be found in the AUTHORS file in the root of the source tree.
9  */
10 
11 #ifndef WEBRTC_BASE_OPENSSLDIGEST_H_
12 #define WEBRTC_BASE_OPENSSLDIGEST_H_
13 
14 #include <openssl/evp.h>
15 
16 #include "webrtc/base/messagedigest.h"
17 
18 namespace rtc {
19 
20 // An implementation of the digest class that uses OpenSSL.
21 class OpenSSLDigest : public MessageDigest {
22  public:
23   // Creates an OpenSSLDigest with |algorithm| as the hash algorithm.
24   explicit OpenSSLDigest(const std::string& algorithm);
25   ~OpenSSLDigest() override;
26   // Returns the digest output size (e.g. 16 bytes for MD5).
27   size_t Size() const override;
28   // Updates the digest with |len| bytes from |buf|.
29   void Update(const void* buf, size_t len) override;
30   // Outputs the digest value to |buf| with length |len|.
31   size_t Finish(void* buf, size_t len) override;
32 
33   // Helper function to look up a digest's EVP by name.
34   static bool GetDigestEVP(const std::string &algorithm,
35                            const EVP_MD** md);
36   // Helper function to look up a digest's name by EVP.
37   static bool GetDigestName(const EVP_MD* md,
38                             std::string* algorithm);
39   // Helper function to get the length of a digest.
40   static bool GetDigestSize(const std::string &algorithm,
41                             size_t* len);
42 
43  private:
44   EVP_MD_CTX ctx_;
45   const EVP_MD* md_;
46 };
47 
48 }  // namespace rtc
49 
50 #endif  // WEBRTC_BASE_OPENSSLDIGEST_H_
51