text: /*
   *  Copyright 2011 The WebRTC Project Authors. All rights reserved.
   *
   *  Use of this source code is governed by a BSD-style license
   *  that can be found in the LICENSE file in the root of the source
   *  tree. An additional intellectual property rights grant can be found
   *  in the file PATENTS.  All contributing project authors may
   *  be found in the AUTHORS file in the root of the source tree.
   */
  
  #include "rtc_base/messagedigest.h"
  
  #include <string.h>
  #include <cstdint>
  #include <memory>
  
  #include "rtc_base/openssldigest.h"
  #include "rtc_base/stringencode.h"
  
  namespace rtc {
  
  // From RFC 4572.
  const char DIGEST_MD5[] = "md5";
  const char DIGEST_SHA_1[] = "sha-1";
  const char DIGEST_SHA_224[] = "sha-224";
  const char DIGEST_SHA_256[] = "sha-256";
  const char DIGEST_SHA_384[] = "sha-384";
  const char DIGEST_SHA_512[] = "sha-512";
  
  static const size_t kBlockSize = 64;  // valid for SHA-256 and down
  
  MessageDigest* MessageDigestFactory::Create(const std::string& alg) {
    MessageDigest* digest = new OpenSSLDigest(alg);
    if (digest->Size() == 0) {  // invalid algorithm
      delete digest;
      digest = nullptr;
    }
    return digest;
  }
  
  bool IsFips180DigestAlgorithm(const std::string& alg) {
    // These are the FIPS 180 algorithms.  According to RFC 4572 Section 5,
    // "Self-signed certificates (for which legacy certificates are not a
    // consideration) MUST use one of the FIPS 180 algorithms (SHA-1,
    // SHA-224, SHA-256, SHA-384, or SHA-512) as their signature algorithm,
    // and thus also MUST use it to calculate certificate fingerprints."
    return alg == DIGEST_SHA_1 || alg == DIGEST_SHA_224 ||
           alg == DIGEST_SHA_256 || alg == DIGEST_SHA_384 ||
           alg == DIGEST_SHA_512;
  }
  
  size_t ComputeDigest(MessageDigest* digest,
                       const void* input,
                       size_t in_len,
                       void* output,
                       size_t out_len) {
    digest->Update(input, in_len);
    return digest->Finish(output, out_len);
  }
  
  size_t ComputeDigest(const std::string& alg,
                       const void* input,
                       size_t in_len,
                       void* output,
                       size_t out_len) {
    std::unique_ptr<MessageDigest> digest(MessageDigestFactory::Create(alg));
    return (digest) ? ComputeDigest(digest.get(), input, in_len, output, out_len)
                    : 0;
  }
  
  std::string ComputeDigest(MessageDigest* digest, const std::string& input) {
    std::unique_ptr<char[]> output(new char[digest->Size()]);
    ComputeDigest(digest, input.data(), input.size(), output.get(),
                  digest->Size());
    return hex_encode(output.get(), digest->Size());
  }
  
  bool ComputeDigest(const std::string& alg,
                     const std::string& input,
                     std::string* output) {
    std::unique_ptr<MessageDigest> digest(MessageDigestFactory::Create(alg));
    if (!digest) {
      return false;
    }
    *output = ComputeDigest(digest.get(), input);
    return true;
  }
  
  std::string ComputeDigest(const std::string& alg, const std::string& input) {
    std::string output;
    ComputeDigest(alg, input, &output);
    return output;
  }
  
  // Compute a RFC 2104 HMAC: H(K XOR opad, H(K XOR ipad, text))
  size_t ComputeHmac(MessageDigest* digest,
                     const void* key,
                     size_t key_len,
                     const void* input,
                     size_t in_len,
                     void* output,
                     size_t out_len) {
    // We only handle algorithms with a 64-byte blocksize.
    // TODO: Add BlockSize() method to MessageDigest.
    size_t block_len = kBlockSize;
    if (digest->Size() > 32) {
      return 0;
    }
    // Copy the key to a block-sized buffer to simplify padding.
    // If the key is longer than a block, hash it and use the result instead.
    std::unique_ptr<uint8_t[]> new_key(new uint8_t[block_len]);
    if (key_len > block_len) {
      ComputeDigest(digest, key, key_len, new_key.get(), block_len);
      memset(new_key.get() + digest->Size(), 0, block_len - digest->Size());
    } else {
      memcpy(new_key.get(), key, key_len);
      memset(new_key.get() + key_len, 0, block_len - key_len);
    }
    // Set up the padding from the key, salting appropriately for each padding.
    std::unique_ptr<uint8_t[]> o_pad(new uint8_t[block_len]);
    std::unique_ptr<uint8_t[]> i_pad(new uint8_t[block_len]);
    for (size_t i = 0; i < block_len; ++i) {
      o_pad[i] = 0x5c ^ new_key[i];
      i_pad[i] = 0x36 ^ new_key[i];
    }
    // Inner hash; hash the inner padding, and then the input buffer.
    std::unique_ptr<uint8_t[]> inner(new uint8_t[digest->Size()]);
    digest->Update(i_pad.get(), block_len);
    digest->Update(input, in_len);
    digest->Finish(inner.get(), digest->Size());
    // Outer hash; hash the outer padding, and then the result of the inner hash.
    digest->Update(o_pad.get(), block_len);
    digest->Update(inner.get(), digest->Size());
    return digest->Finish(output, out_len);
  }
  
  size_t ComputeHmac(const std::string& alg,
                     const void* key,
                     size_t key_len,
                     const void* input,
                     size_t in_len,
                     void* output,
                     size_t out_len) {
    std::unique_ptr<MessageDigest> digest(MessageDigestFactory::Create(alg));
    if (!digest) {
      return 0;
    }
    return ComputeHmac(digest.get(), key, key_len, input, in_len, output,
                       out_len);
  }
  
  std::string ComputeHmac(MessageDigest* digest,
                          const std::string& key,
                          const std::string& input) {
    std::unique_ptr<char[]> output(new char[digest->Size()]);
    ComputeHmac(digest, key.data(), key.size(), input.data(), input.size(),
                output.get(), digest->Size());
    return hex_encode(output.get(), digest->Size());
  }
  
  bool ComputeHmac(const std::string& alg,
                   const std::string& key,
                   const std::string& input,
                   std::string* output) {
    std::unique_ptr<MessageDigest> digest(MessageDigestFactory::Create(alg));
    if (!digest) {
      return false;
    }
    *output = ComputeHmac(digest.get(), key, input);
    return true;
  }
  
  std::string ComputeHmac(const std::string& alg,
                          const std::string& key,
                          const std::string& input) {
    std::string output;
    ComputeHmac(alg, key, input, &output);
    return output;
  }
  
  }  // namespace rtc
  