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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 "components/os_crypt/os_crypt.h"
#include "base/logging.h"
#include "base/memory/scoped_ptr.h"
#include "base/strings/utf_string_conversions.h"
#include "crypto/encryptor.h"
#include "crypto/symmetric_key.h"
namespace {
// Salt for Symmetric key derivation.
const char kSalt[] = "saltysalt";
// Key size required for 128 bit AES.
const size_t kDerivedKeySizeInBits = 128;
// Constant for Symmetic key derivation.
const size_t kEncryptionIterations = 1;
// Size of initialization vector for AES 128-bit.
const size_t kIVBlockSizeAES128 = 16;
// Prefix for cypher text returned by obfuscation version. We prefix the
// cyphertext with this string so that future data migration can detect
// this and migrate to full encryption without data loss.
const char kObfuscationPrefix[] = "v10";
// Generates a newly allocated SymmetricKey object based a hard-coded password.
// Ownership of the key is passed to the caller. Returns NULL key if a key
// generation error occurs.
crypto::SymmetricKey* GetEncryptionKey() {
// We currently "obfuscate" by encrypting and decrypting with hard-coded
// password. We need to improve this password situation by moving a secure
// password into a system-level key store.
// http://crbug.com/25404 and http://crbug.com/49115
std::string password = "peanuts";
std::string salt(kSalt);
// Create an encryption key from our password and salt.
scoped_ptr<crypto::SymmetricKey> encryption_key(
crypto::SymmetricKey::DeriveKeyFromPassword(crypto::SymmetricKey::AES,
password,
salt,
kEncryptionIterations,
kDerivedKeySizeInBits));
DCHECK(encryption_key.get());
return encryption_key.release();
}
} // namespace
bool OSCrypt::EncryptString16(const base::string16& plaintext,
std::string* ciphertext) {
return EncryptString(base::UTF16ToUTF8(plaintext), ciphertext);
}
bool OSCrypt::DecryptString16(const std::string& ciphertext,
base::string16* plaintext) {
std::string utf8;
if (!DecryptString(ciphertext, &utf8))
return false;
*plaintext = base::UTF8ToUTF16(utf8);
return true;
}
bool OSCrypt::EncryptString(const std::string& plaintext,
std::string* ciphertext) {
// This currently "obfuscates" by encrypting with hard-coded password.
// We need to improve this password situation by moving a secure password
// into a system-level key store.
// http://crbug.com/25404 and http://crbug.com/49115
if (plaintext.empty()) {
*ciphertext = std::string();
return true;
}
scoped_ptr<crypto::SymmetricKey> encryption_key(GetEncryptionKey());
if (!encryption_key.get())
return false;
std::string iv(kIVBlockSizeAES128, ' ');
crypto::Encryptor encryptor;
if (!encryptor.Init(encryption_key.get(), crypto::Encryptor::CBC, iv))
return false;
if (!encryptor.Encrypt(plaintext, ciphertext))
return false;
// Prefix the cypher text with version information.
ciphertext->insert(0, kObfuscationPrefix);
return true;
}
bool OSCrypt::DecryptString(const std::string& ciphertext,
std::string* plaintext) {
// This currently "obfuscates" by encrypting with hard-coded password.
// We need to improve this password situation by moving a secure password
// into a system-level key store.
// http://crbug.com/25404 and http://crbug.com/49115
if (ciphertext.empty()) {
*plaintext = std::string();
return true;
}
// Check that the incoming cyphertext was indeed encrypted with the expected
// version. If the prefix is not found then we'll assume we're dealing with
// old data saved as clear text and we'll return it directly.
// Credit card numbers are current legacy data, so false match with prefix
// won't happen.
if (ciphertext.find(kObfuscationPrefix) != 0) {
*plaintext = ciphertext;
return true;
}
// Strip off the versioning prefix before decrypting.
std::string raw_ciphertext = ciphertext.substr(strlen(kObfuscationPrefix));
scoped_ptr<crypto::SymmetricKey> encryption_key(GetEncryptionKey());
if (!encryption_key.get())
return false;
std::string iv(kIVBlockSizeAES128, ' ');
crypto::Encryptor encryptor;
if (!encryptor.Init(encryption_key.get(), crypto::Encryptor::CBC, iv))
return false;
if (!encryptor.Decrypt(raw_ciphertext, plaintext))
return false;
return true;
}
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