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/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
/*
* This file is part of the LibreOffice project.
*
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/.
*
*/
#include "oox/crypto/Standard2007Engine.hxx"
#include <oox/crypto/CryptTools.hxx>
#include <oox/helper/binaryinputstream.hxx>
#include <oox/helper/binaryoutputstream.hxx>
#include <osl/time.h>
#include <rtl/digest.h>
#include <rtl/random.h>
namespace oox {
namespace core {
/* =========================================================================== */
/* Kudos to Caolan McNamara who provided the core decryption implementations. */
/* =========================================================================== */
namespace
{
void lclRandomGenerateValues(sal_uInt8* aArray, sal_uInt32 aSize)
{
TimeValue aTime;
osl_getSystemTime(&aTime);
rtlRandomPool aRandomPool = rtl_random_createPool();
rtl_random_addBytes(aRandomPool, &aTime, 8);
rtl_random_getBytes(aRandomPool, aArray, aSize);
rtl_random_destroyPool(aRandomPool);
}
static const OUString lclCspName = "Microsoft Enhanced RSA and AES Cryptographic Provider";
} // end anonymous namespace
bool Standard2007Engine::generateVerifier()
{
// only support key of size 128 bit (16 byte)
if (mKey.size() != 16)
return false;
std::vector<sal_uInt8> verifier(msfilter::ENCRYPTED_VERIFIER_LENGTH);
std::vector<sal_uInt8> encryptedVerifier(msfilter::ENCRYPTED_VERIFIER_LENGTH);
lclRandomGenerateValues(verifier.data(), verifier.size());
std::vector<sal_uInt8> iv;
Encrypt aEncryptorVerifier(mKey, iv, Crypto::AES_128_ECB);
if (aEncryptorVerifier.update(encryptedVerifier, verifier) != msfilter::ENCRYPTED_VERIFIER_LENGTH)
return false;
std::copy(encryptedVerifier.begin(), encryptedVerifier.end(), mInfo.verifier.encryptedVerifier);
std::vector<sal_uInt8> hash(msfilter::SHA1_HASH_LENGTH, 0);
mInfo.verifier.encryptedVerifierHashSize = msfilter::SHA1_HASH_LENGTH;
Digest::sha1(hash, verifier);
hash.resize(msfilter::SHA256_HASH_LENGTH, 0);
std::vector<sal_uInt8> encryptedHash(msfilter::SHA256_HASH_LENGTH, 0);
Encrypt aEncryptorHash(mKey, iv, Crypto::AES_128_ECB);
aEncryptorHash.update(encryptedHash, hash, hash.size());
std::copy(encryptedHash.begin(), encryptedHash.end(), mInfo.verifier.encryptedVerifierHash);
return true;
}
bool Standard2007Engine::calculateEncryptionKey(const OUString& rPassword)
{
sal_uInt32 saltSize = mInfo.verifier.saltSize;
sal_uInt32 passwordByteLength = rPassword.getLength() * 2;
const sal_uInt8* saltArray = mInfo.verifier.salt;
// Prepare initial data -> salt + password (in 16-bit chars)
std::vector<sal_uInt8> initialData(saltSize + passwordByteLength);
std::copy(saltArray, saltArray + saltSize, initialData.begin());
const sal_uInt8* passwordByteArray = reinterpret_cast<const sal_uInt8*>(rPassword.getStr());
std::copy(
passwordByteArray,
passwordByteArray + passwordByteLength,
initialData.begin() + saltSize);
// use "hash" vector for result of sha1 hashing
std::vector<sal_uInt8> hash(msfilter::SHA1_HASH_LENGTH, 0);
// calculate SHA1 hash of initialData
Digest::sha1(hash, initialData);
// data = iterator (4bytes) + hash
std::vector<sal_uInt8> data(msfilter::SHA1_HASH_LENGTH + 4, 0);
for (sal_Int32 i = 0; i < 50000; ++i)
{
ByteOrderConverter::writeLittleEndian(data.data(), i);
std::copy(hash.begin(), hash.end(), data.begin() + 4);
Digest::sha1(hash, data);
}
std::copy(hash.begin(), hash.end(), data.begin() );
std::fill(data.begin() + msfilter::SHA1_HASH_LENGTH, data.end(), 0 );
Digest::sha1(hash, data);
// derive key
std::vector<sal_uInt8> buffer(64, 0x36);
for (size_t i = 0; i < hash.size(); ++i)
buffer[i] ^= hash[i];
Digest::sha1(hash, buffer);
std::copy(hash.begin(), hash.begin() + mKey.size(), mKey.begin());
return true;
}
bool Standard2007Engine::generateEncryptionKey(const OUString& password)
{
mKey.clear();
mKey.resize(mInfo.header.keyBits / 8, 0);
calculateEncryptionKey(password);
std::vector<sal_uInt8> encryptedVerifier(msfilter::ENCRYPTED_VERIFIER_LENGTH);
std::copy(
mInfo.verifier.encryptedVerifier,
mInfo.verifier.encryptedVerifier + msfilter::ENCRYPTED_VERIFIER_LENGTH,
encryptedVerifier.begin());
std::vector<sal_uInt8> encryptedHash(msfilter::SHA256_HASH_LENGTH);
std::copy(
mInfo.verifier.encryptedVerifierHash,
mInfo.verifier.encryptedVerifierHash + msfilter::SHA256_HASH_LENGTH,
encryptedHash.begin());
std::vector<sal_uInt8> verifier(encryptedVerifier.size(), 0);
Decrypt::aes128ecb(verifier, encryptedVerifier, mKey);
std::vector<sal_uInt8> verifierHash(encryptedHash.size(), 0);
Decrypt::aes128ecb(verifierHash, encryptedHash, mKey);
std::vector<sal_uInt8> hash(msfilter::SHA1_HASH_LENGTH, 0);
Digest::sha1(hash, verifier);
return std::equal(hash.begin(), hash.end(), verifierHash.begin());
}
bool Standard2007Engine::decrypt(BinaryXInputStream& aInputStream,
BinaryXOutputStream& aOutputStream)
{
aInputStream.skip(4); // Document unencrypted size - 4 bytes
aInputStream.skip(4); // Reserved 4 Bytes
std::vector<sal_uInt8> iv;
Decrypt aDecryptor(mKey, iv, Crypto::AES_128_ECB);
std::vector<sal_uInt8> inputBuffer (4096);
std::vector<sal_uInt8> outputBuffer(4096);
sal_uInt32 inputLength;
sal_uInt32 outputLength;
while ((inputLength = aInputStream.readMemory(inputBuffer.data(), inputBuffer.size())) > 0)
{
outputLength = aDecryptor.update(outputBuffer, inputBuffer, inputLength);
aOutputStream.writeMemory(outputBuffer.data(), outputLength);
}
return true;
}
void Standard2007Engine::writeEncryptionInfo(const OUString& password, BinaryXOutputStream& rStream)
{
mInfo.header.flags = msfilter::ENCRYPTINFO_AES | msfilter::ENCRYPTINFO_CRYPTOAPI;
mInfo.header.algId = msfilter::ENCRYPT_ALGO_AES128;
mInfo.header.algIdHash = msfilter::ENCRYPT_HASH_SHA1;
mInfo.header.keyBits = msfilter::ENCRYPT_KEY_SIZE_AES_128;
mInfo.header.providedType = msfilter::ENCRYPT_PROVIDER_TYPE_AES;
lclRandomGenerateValues(mInfo.verifier.salt, mInfo.verifier.saltSize);
const sal_Int32 keyLength = mInfo.header.keyBits / 8;
mKey.clear();
mKey.resize(keyLength, 0);
if (!calculateEncryptionKey(password))
return;
if (!generateVerifier())
return;
rStream.WriteUInt32(msfilter::VERSION_INFO_2007_FORMAT);
sal_uInt32 cspNameSize = (lclCspName.getLength() * 2) + 2;
sal_uInt32 encryptionHeaderSize = static_cast<sal_uInt32>(sizeof(msfilter::EncryptionStandardHeader));
rStream.WriteUInt32(mInfo.header.flags);
sal_uInt32 headerSize = encryptionHeaderSize + cspNameSize;
rStream.WriteUInt32(headerSize);
rStream.writeMemory(&mInfo.header, encryptionHeaderSize);
rStream.writeUnicodeArray(lclCspName);
rStream.WriteUInt16(0);
sal_uInt32 encryptionVerifierSize = static_cast<sal_uInt32>(sizeof(msfilter::EncryptionVerifierAES));
rStream.writeMemory(&mInfo.verifier, encryptionVerifierSize);
}
void Standard2007Engine::encrypt(BinaryXInputStream& aInputStream,
BinaryXOutputStream& aOutputStream)
{
std::vector<sal_uInt8> inputBuffer(1024);
std::vector<sal_uInt8> outputBuffer(1024);
sal_uInt32 inputLength;
sal_uInt32 outputLength;
std::vector<sal_uInt8> iv;
Encrypt aEncryptor(mKey, iv, Crypto::AES_128_ECB);
while ((inputLength = aInputStream.readMemory(inputBuffer.data(), inputBuffer.size())) > 0)
{
inputLength = inputLength % 16 == 0 ? inputLength : ((inputLength / 16) * 16) + 16;
outputLength = aEncryptor.update(outputBuffer, inputBuffer, inputLength);
aOutputStream.writeMemory(outputBuffer.data(), outputLength);
}
}
} // namespace core
} // namespace oox
/* vim:set shiftwidth=4 softtabstop=4 expandtab: */
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