////////////////////////////////////////////////////////////////////////////////
// Copyright 2016 Google LLC.
//
// This software is licensed under the terms defined in the Widevine Master
// License Agreement. For a copy of this agreement, please contact
// widevine-licensing@google.com.
////////////////////////////////////////////////////////////////////////////////

#include "common/sha_util.h"

#include <cstdint>
#include "openssl/sha.h"

namespace widevine {

std::string Sha1_Hash(const std::string& message) {
  std::string digest;
  digest.resize(SHA_DIGEST_LENGTH);
  SHA1(reinterpret_cast<const uint8_t*>(message.data()), message.size(),
       reinterpret_cast<uint8_t*>(&digest[0]));
  return digest;
}

std::string Sha256_Hash(const std::string& message) {
  std::string digest;
  digest.resize(SHA256_DIGEST_LENGTH);
  SHA256(reinterpret_cast<const uint8_t*>(message.data()), message.size(),
         reinterpret_cast<uint8_t*>(&digest[0]));
  return digest;
}

std::string GenerateSha1Uuid(const std::string& name_space, const std::string& name) {
  // X.667 14 Setting the fields of a name-based UUID.
  // - Allocate a UUID to use as a "name space identifier" for all UUIDs
  // generated from names in that name space.
  // - Compute the 16-octet hash value of the name space identifier concatenated
  // with the name.
  SHA_CTX ctx;
  SHA1_Init(&ctx);
  SHA1_Update(&ctx, name_space.data(), name_space.length());
  SHA1_Update(&ctx, name.data(), name.length());
  unsigned char hash[SHA_DIGEST_LENGTH];
  SHA1_Final(hash, &ctx);
  std::string hash_str =
      std::string(reinterpret_cast<const char*>(hash), SHA_DIGEST_LENGTH);

  // - For a SHA-1 hash function, the "hash value" referenced in 14.1 shall be
  // octets zero to 15.
  std::string uuid = hash_str.substr(0, 16);

  // - Overwrite the four most significant bits (bits 15 through 12) of the
  // "VersionAndTimeHigh" field with the four-bit version number from Table 3
  // of 12.2 for the hash function that was used. [Name-based SHA-1 is 5]
  (uuid[6] &= 0xF) |= 0x50;

  // - Overwrite the two most significant bits (bits 7 and 6) of the
  // "VariantAndClockSeqHigh" field with 1 and 0, respectively.
  (uuid[8] &= 0x3F) |= 0x80;

  return uuid;
}

}  // namespace widevine