components/os_crypt/keychain_password_mac.mm

// 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.

#include "components/os_crypt/keychain_password_mac.h"

#import <Security/Security.h>

#include "base/base64.h"
#include "base/mac/mac_logging.h"
#include "base/rand_util.h"
#include "crypto/apple_keychain.h"

using crypto::AppleKeychain;

namespace {

// Generates a random password and adds it to the Keychain.  The added password
// is returned from the function.  If an error occurs, an empty password is
// returned.
std::string AddRandomPasswordToKeychain(const AppleKeychain& keychain,
                                        const std::string& service_name,
                                        const std::string& account_name) {
  // Generate a password with 128 bits of randomness.
  const int kBytes = 128 / 8;
  std::string password;
  base::Base64Encode(base::RandBytesAsString(kBytes), &password);
  void* password_data =
      const_cast<void*>(static_cast<const void*>(password.data()));

  OSStatus error = keychain.AddGenericPassword(NULL,
                                               service_name.size(),
                                               service_name.data(),
                                               account_name.size(),
                                               account_name.data(),
                                               password.size(),
                                               password_data,
                                               NULL);

  if (error != noErr) {
    OSSTATUS_DLOG(ERROR, error) << "Keychain add failed";
    return std::string();
  }

  return password;
}

}  // namespace

std::string KeychainPassword::GetPassword() const {
  // These two strings ARE indeed user facing.  But they are used to access
  // the encryption keyword.  So as to not lose encrypted data when system
  // locale changes we DO NOT LOCALIZE.
#if defined(OFFICIAL_BUILD)
  const std::string service_name = "Chrome Safe Storage";
  const std::string account_name = "Chrome";
#else
  const std::string service_name = "Chromium Safe Storage";
  const std::string account_name = "Chromium";
#endif

  UInt32 password_length = 0;
  void* password_data = NULL;
  OSStatus error = keychain_.FindGenericPassword(NULL,
                                                 service_name.size(),
                                                 service_name.data(),
                                                 account_name.size(),
                                                 account_name.data(),
                                                 &password_length,
                                                 &password_data,
                                                 NULL);

  if (error == noErr) {
    std::string password =
        std::string(static_cast<char*>(password_data), password_length);
    keychain_.ItemFreeContent(NULL, password_data);
    return password;
  } else if (error == errSecItemNotFound) {
    return AddRandomPasswordToKeychain(keychain_, service_name, account_name);
  } else {
    OSSTATUS_DLOG(ERROR, error) << "Keychain lookup failed";
    return std::string();
  }
}