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// Copyright 2021 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "components/sync/test/fake_cryptographer.h"
#include <algorithm>
#include <iterator>
#include "base/strings/strcat.h"
#include "base/strings/string_util.h"
#include "components/sync/protocol/encryption.pb.h"
namespace syncer {
namespace {
const char kSeparator[] = "@@";
} // namespace
// static
std::unique_ptr<FakeCryptographer> FakeCryptographer::FromSingleDefaultKey(
const std::string& key_name) {
auto cryptographer = std::make_unique<FakeCryptographer>();
cryptographer->AddEncryptionKey(key_name);
cryptographer->SelectDefaultEncryptionKey(key_name);
return cryptographer;
}
FakeCryptographer::FakeCryptographer() = default;
FakeCryptographer::~FakeCryptographer() = default;
void FakeCryptographer::AddEncryptionKey(const std::string& key_name) {
DCHECK(!key_name.empty());
known_key_names_.insert(key_name);
}
void FakeCryptographer::SelectDefaultEncryptionKey(
const std::string& key_name) {
DCHECK(known_key_names_.contains(key_name));
default_key_name_ = key_name;
}
void FakeCryptographer::ClearDefaultEncryptionKey() {
default_key_name_.clear();
}
bool FakeCryptographer::CanEncrypt() const {
return !default_key_name_.empty();
}
bool FakeCryptographer::CanDecrypt(
const sync_pb::EncryptedData& encrypted) const {
return known_key_names_.contains(encrypted.key_name());
}
std::string FakeCryptographer::GetDefaultEncryptionKeyName() const {
return default_key_name_;
}
bool FakeCryptographer::EncryptString(const std::string& decrypted,
sync_pb::EncryptedData* encrypted) const {
if (default_key_name_.empty()) {
return false;
}
*encrypted->mutable_key_name() = default_key_name_;
*encrypted->mutable_blob() =
base::StrCat({default_key_name_, kSeparator, decrypted});
return true;
}
bool FakeCryptographer::DecryptToString(const sync_pb::EncryptedData& encrypted,
std::string* decrypted) const {
auto key_iter = std::ranges::find(known_key_names_, encrypted.key_name());
if (key_iter == known_key_names_.end()) {
return false;
}
std::string key_name_and_separator = base::StrCat({*key_iter, kSeparator});
if (!base::StartsWith(encrypted.blob(), key_name_and_separator)) {
// Corrupted blob.
return false;
}
*decrypted =
std::string(encrypted.blob().begin() + key_name_and_separator.size(),
encrypted.blob().end());
return true;
}
const CrossUserSharingPublicPrivateKeyPair&
FakeCryptographer::GetCrossUserSharingKeyPair(uint32_t version) const {
return cross_user_sharing_key_pair_;
}
std::optional<std::vector<uint8_t>>
FakeCryptographer::AuthEncryptForCrossUserSharing(
base::span<const uint8_t> plaintext,
base::span<const uint8_t> recipient_public_key) const {
// Just join two parts of the data. Note that sender's private key is omitted
// here for simplicity.
std::vector<uint8_t> result;
result.reserve(plaintext.size() + recipient_public_key.size());
std::ranges::copy(recipient_public_key, std::back_inserter(result));
std::ranges::copy(plaintext, std::back_inserter(result));
return result;
}
std::optional<std::vector<uint8_t>>
FakeCryptographer::AuthDecryptForCrossUserSharing(
base::span<const uint8_t> encrypted_data,
base::span<const uint8_t> sender_public_key,
const uint32_t recipient_key_version) const {
// `encrypted_data` is expected to contain receiver's public key as a prefix,
// and the actual data. `sender_public_key` is not used for simplicity. In
// real case, sender's private key is used during encryption and sender's
// public key during decryption.
if (encrypted_data.size() <
cross_user_sharing_key_pair_.GetRawPublicKey().size()) {
return std::nullopt;
}
// Verify that the prefix contains an expected public key.
if (std::ranges::equal(
cross_user_sharing_key_pair_.GetRawPublicKey().begin(),
cross_user_sharing_key_pair_.GetRawPublicKey().end(),
encrypted_data.begin(),
encrypted_data.begin() +
cross_user_sharing_key_pair_.GetRawPublicKey().size())) {
return std::nullopt;
}
return std::vector<uint8_t>(
encrypted_data.begin() +
cross_user_sharing_key_pair_.GetRawPublicKey().size(),
encrypted_data.end());
}
} // namespace syncer
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