text: // Copyright 2015 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.
  
  #include "components/proximity_auth/cryptauth/cryptauth_enrollment_utils.h"
  
  #include <math.h>
  #include <stddef.h>
  
  #include "base/base64url.h"
  #include "base/md5.h"
  #include "base/sha1.h"
  
  namespace proximity_auth {
  
  int64_t HashStringToInt64(const std::string& string) {
    base::MD5Context context;
    base::MD5Init(&context);
    base::MD5Update(&context, string);
  
    base::MD5Digest digest;
    base::MD5Final(&digest, &context);
  
    // Fold the digest into an int64_t value. |digest.a| is a 16-byte array, so we
    // sum the two 8-byte halves of the digest to create the hash.
    int64_t hash = 0;
    for (size_t i = 0; i < sizeof(digest.a); ++i) {
      uint8_t byte = digest.a[i];
      hash += static_cast<int64_t>(byte) << (i % sizeof(int64_t));
    }
  
    return hash;
  }
  
  std::string CalculateDeviceUserId(const std::string& device_id,
                                    const std::string& user_id) {
    std::string device_user_id;
    base::Base64UrlEncode(base::SHA1HashString(device_id + "|" + user_id),
                          base::Base64UrlEncodePolicy::INCLUDE_PADDING,
                          &device_user_id);
    return device_user_id;
  }
  
  }  // namespace proximity_auth
  