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- // 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 <windows.h>
- #include "base/base64.h"
- #include "base/logging.h"
- #include "base/memory/singleton.h"
- #include "base/metrics/histogram_functions.h"
- #include "base/metrics/histogram_macros.h"
- #include "base/strings/string_util.h"
- #include "base/strings/utf_string_conversions.h"
- #include "base/win/wincrypt_shim.h"
- #include "components/os_crypt/os_crypt.h"
- #include "components/prefs/pref_registry_simple.h"
- #include "components/prefs/pref_service.h"
- #include "crypto/aead.h"
- #include "crypto/hkdf.h"
- #include "crypto/random.h"
- namespace {
- // Contains base64 random key encrypted with DPAPI.
- constexpr char kOsCryptEncryptedKeyPrefName[] = "os_crypt.encrypted_key";
- // AEAD key length in bytes.
- constexpr size_t kKeyLength = 256 / 8;
- // AEAD nonce length in bytes.
- constexpr size_t kNonceLength = 96 / 8;
- // Version prefix for data encrypted with profile bound key.
- constexpr char kEncryptionVersionPrefix[] = "v10";
- // Key prefix for a key encrypted with DPAPI.
- constexpr char kDPAPIKeyPrefix[] = "DPAPI";
- bool EncryptStringWithDPAPI(const std::string& plaintext,
- std::string* ciphertext) {
- DATA_BLOB input;
- input.pbData =
- const_cast<BYTE*>(reinterpret_cast<const BYTE*>(plaintext.data()));
- input.cbData = static_cast<DWORD>(plaintext.length());
- BOOL result = FALSE;
- DATA_BLOB output;
- {
- SCOPED_UMA_HISTOGRAM_TIMER("OSCrypt.Win.Encrypt.Time");
- result =
- CryptProtectData(&input, L"", nullptr, nullptr, nullptr, 0, &output);
- }
- base::UmaHistogramBoolean("OSCrypt.Win.Encrypt.Result", result);
- if (!result) {
- PLOG(ERROR) << "Failed to encrypt";
- return false;
- }
- // this does a copy
- ciphertext->assign(reinterpret_cast<std::string::value_type*>(output.pbData),
- output.cbData);
- LocalFree(output.pbData);
- return true;
- }
- bool DecryptStringWithDPAPI(const std::string& ciphertext,
- std::string* plaintext) {
- DATA_BLOB input;
- input.pbData =
- const_cast<BYTE*>(reinterpret_cast<const BYTE*>(ciphertext.data()));
- input.cbData = static_cast<DWORD>(ciphertext.length());
- BOOL result = FALSE;
- DATA_BLOB output;
- {
- SCOPED_UMA_HISTOGRAM_TIMER("OSCrypt.Win.Decrypt.Time");
- result = CryptUnprotectData(&input, nullptr, nullptr, nullptr, nullptr, 0,
- &output);
- }
- base::UmaHistogramBoolean("OSCrypt.Win.Decrypt.Result", result);
- if (!result) {
- PLOG(ERROR) << "Failed to decrypt";
- return false;
- }
- plaintext->assign(reinterpret_cast<char*>(output.pbData), output.cbData);
- LocalFree(output.pbData);
- return true;
- }
- } // namespace
- namespace OSCrypt {
- bool EncryptString16(const std::u16string& plaintext, std::string* ciphertext) {
- return OSCryptImpl::GetInstance()->EncryptString16(plaintext, ciphertext);
- }
- bool DecryptString16(const std::string& ciphertext, std::u16string* plaintext) {
- return OSCryptImpl::GetInstance()->DecryptString16(ciphertext, plaintext);
- }
- bool EncryptString(const std::string& plaintext, std::string* ciphertext) {
- return OSCryptImpl::GetInstance()->EncryptString(plaintext, ciphertext);
- }
- bool DecryptString(const std::string& ciphertext, std::string* plaintext) {
- return OSCryptImpl::GetInstance()->DecryptString(ciphertext, plaintext);
- }
- void RegisterLocalPrefs(PrefRegistrySimple* registry) {
- OSCryptImpl::RegisterLocalPrefs(registry);
- }
- InitResult InitWithExistingKey(PrefService* local_state) {
- return OSCryptImpl::GetInstance()->InitWithExistingKey(local_state);
- }
- bool Init(PrefService* local_state) {
- return OSCryptImpl::GetInstance()->Init(local_state);
- }
- std::string GetRawEncryptionKey() {
- return OSCryptImpl::GetInstance()->GetRawEncryptionKey();
- }
- void SetRawEncryptionKey(const std::string& key) {
- OSCryptImpl::GetInstance()->SetRawEncryptionKey(key);
- }
- bool IsEncryptionAvailable() {
- return OSCryptImpl::GetInstance()->IsEncryptionAvailable();
- }
- void UseMockKeyForTesting(bool use_mock) {
- OSCryptImpl::GetInstance()->UseMockKeyForTesting(use_mock);
- }
- void SetLegacyEncryptionForTesting(bool legacy) {
- OSCryptImpl::GetInstance()->SetLegacyEncryptionForTesting(legacy);
- }
- void ResetStateForTesting() {
- OSCryptImpl::GetInstance()->ResetStateForTesting();
- }
- } // namespace OSCrypt
- OSCryptImpl::OSCryptImpl() = default;
- OSCryptImpl::~OSCryptImpl() = default;
- OSCryptImpl* OSCryptImpl::GetInstance() {
- return base::Singleton<OSCryptImpl,
- base::LeakySingletonTraits<OSCryptImpl>>::get();
- }
- bool OSCryptImpl::EncryptString16(const std::u16string& plaintext,
- std::string* ciphertext) {
- return EncryptString(base::UTF16ToUTF8(plaintext), ciphertext);
- }
- bool OSCryptImpl::DecryptString16(const std::string& ciphertext,
- std::u16string* plaintext) {
- std::string utf8;
- if (!DecryptString(ciphertext, &utf8))
- return false;
- *plaintext = base::UTF8ToUTF16(utf8);
- return true;
- }
- bool OSCryptImpl::EncryptString(const std::string& plaintext,
- std::string* ciphertext) {
- if (use_legacy_)
- return EncryptStringWithDPAPI(plaintext, ciphertext);
- crypto::Aead aead(crypto::Aead::AES_256_GCM);
- const auto key = GetRawEncryptionKey();
- aead.Init(&key);
- // Note: can only check these once AEAD is initialized.
- DCHECK_EQ(kKeyLength, aead.KeyLength());
- DCHECK_EQ(kNonceLength, aead.NonceLength());
- std::string nonce;
- crypto::RandBytes(base::WriteInto(&nonce, kNonceLength + 1), kNonceLength);
- if (!aead.Seal(plaintext, nonce, std::string(), ciphertext))
- return false;
- ciphertext->insert(0, nonce);
- ciphertext->insert(0, kEncryptionVersionPrefix);
- return true;
- }
- bool OSCryptImpl::DecryptString(const std::string& ciphertext,
- std::string* plaintext) {
- if (!base::StartsWith(ciphertext, kEncryptionVersionPrefix,
- base::CompareCase::SENSITIVE))
- return DecryptStringWithDPAPI(ciphertext, plaintext);
- crypto::Aead aead(crypto::Aead::AES_256_GCM);
- const auto key = GetRawEncryptionKey();
- aead.Init(&key);
- // Obtain the nonce.
- const std::string nonce =
- ciphertext.substr(sizeof(kEncryptionVersionPrefix) - 1, kNonceLength);
- // Strip off the versioning prefix before decrypting.
- const std::string raw_ciphertext =
- ciphertext.substr(kNonceLength + (sizeof(kEncryptionVersionPrefix) - 1));
- return aead.Open(raw_ciphertext, nonce, std::string(), plaintext);
- }
- // static
- void OSCryptImpl::RegisterLocalPrefs(PrefRegistrySimple* registry) {
- registry->RegisterStringPref(kOsCryptEncryptedKeyPrefName, "");
- }
- bool OSCryptImpl::Init(PrefService* local_state) {
- // Try to pull the key from the local state.
- switch (InitWithExistingKey(local_state)) {
- case OSCrypt::kSuccess:
- return true;
- case OSCrypt::kKeyDoesNotExist:
- break;
- case OSCrypt::kInvalidKeyFormat:
- return false;
- case OSCrypt::kDecryptionFailed:
- break;
- }
- // If there is no key in the local state, or if DPAPI decryption fails,
- // generate a new key.
- std::string key;
- crypto::RandBytes(base::WriteInto(&key, kKeyLength + 1), kKeyLength);
- std::string encrypted_key;
- if (!EncryptStringWithDPAPI(key, &encrypted_key))
- return false;
- // Add header indicating this key is encrypted with DPAPI.
- encrypted_key.insert(0, kDPAPIKeyPrefix);
- std::string base64_key;
- base::Base64Encode(encrypted_key, &base64_key);
- local_state->SetString(kOsCryptEncryptedKeyPrefName, base64_key);
- encryption_key_.assign(key);
- return true;
- }
- OSCrypt::InitResult OSCryptImpl::InitWithExistingKey(PrefService* local_state) {
- DCHECK(encryption_key_.empty()) << "Key already exists.";
- // Try and pull the key from the local state.
- if (!local_state->HasPrefPath(kOsCryptEncryptedKeyPrefName))
- return OSCrypt::kKeyDoesNotExist;
- const std::string base64_encrypted_key =
- local_state->GetString(kOsCryptEncryptedKeyPrefName);
- std::string encrypted_key_with_header;
- base::Base64Decode(base64_encrypted_key, &encrypted_key_with_header);
- if (!base::StartsWith(encrypted_key_with_header, kDPAPIKeyPrefix,
- base::CompareCase::SENSITIVE)) {
- NOTREACHED() << "Invalid key format.";
- return OSCrypt::kInvalidKeyFormat;
- }
- const std::string encrypted_key =
- encrypted_key_with_header.substr(sizeof(kDPAPIKeyPrefix) - 1);
- std::string key;
- // This DPAPI decryption can fail if the user's password has been reset
- // by an Administrator.
- if (!DecryptStringWithDPAPI(encrypted_key, &key)) {
- base::UmaHistogramSparse("OSCrypt.Win.KeyDecryptionError",
- ::GetLastError());
- return OSCrypt::kDecryptionFailed;
- }
- encryption_key_.assign(key);
- return OSCrypt::kSuccess;
- }
- void OSCryptImpl::SetRawEncryptionKey(const std::string& raw_key) {
- DCHECK(!use_mock_key_) << "Mock key in use.";
- DCHECK(!raw_key.empty()) << "Bad key.";
- DCHECK(encryption_key_.empty()) << "Key already set.";
- encryption_key_.assign(raw_key);
- }
- std::string OSCryptImpl::GetRawEncryptionKey() {
- if (use_mock_key_) {
- if (mock_encryption_key_.empty())
- mock_encryption_key_.assign(
- crypto::HkdfSha256("peanuts", "salt", "info", kKeyLength));
- DCHECK(!mock_encryption_key_.empty()) << "Failed to initialize mock key.";
- return mock_encryption_key_;
- }
- DCHECK(!encryption_key_.empty()) << "No key.";
- return encryption_key_;
- }
- bool OSCryptImpl::IsEncryptionAvailable() {
- return !encryption_key_.empty();
- }
- void OSCryptImpl::UseMockKeyForTesting(bool use_mock) {
- use_mock_key_ = use_mock;
- }
- void OSCryptImpl::SetLegacyEncryptionForTesting(bool legacy) {
- use_legacy_ = legacy;
- }
- void OSCryptImpl::ResetStateForTesting() {
- use_legacy_ = false;
- use_mock_key_ = false;
- encryption_key_.clear();
- mock_encryption_key_.clear();
- }
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