334 lines
13 KiB
C++
334 lines
13 KiB
C++
/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
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/*
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* This file is part of the LibreOffice project.
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*
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* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/.
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*
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*/
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#include <oox/crypto/Standard2007Engine.hxx>
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#include <oox/helper/binaryinputstream.hxx>
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#include <oox/helper/binaryoutputstream.hxx>
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#include <rtl/random.h>
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#include <comphelper/crypto/Crypto.hxx>
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#include <comphelper/hash.hxx>
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namespace oox::crypto {
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/* =========================================================================== */
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/* Kudos to Caolan McNamara who provided the core decryption implementations. */
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/* =========================================================================== */
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namespace
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{
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void lclRandomGenerateValues(sal_uInt8* aArray, sal_uInt32 aSize)
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{
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if (rtl_random_getBytes(nullptr, aArray, aSize) != rtl_Random_E_None)
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{
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throw css::uno::RuntimeException(u"rtl_random_getBytes failed"_ustr);
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}
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}
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constexpr OUString lclCspName = u"Microsoft Enhanced RSA and AES Cryptographic Provider"_ustr;
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constexpr const sal_uInt32 AES128Size = 16;
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} // end anonymous namespace
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bool Standard2007Engine::generateVerifier()
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{
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// only support key of size 128 bit (16 byte)
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if (mKey.size() != 16)
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return false;
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std::vector<sal_uInt8> verifier(msfilter::ENCRYPTED_VERIFIER_LENGTH);
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std::vector<sal_uInt8> encryptedVerifier(msfilter::ENCRYPTED_VERIFIER_LENGTH);
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lclRandomGenerateValues(verifier.data(), verifier.size());
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std::vector<sal_uInt8> iv;
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comphelper::Encrypt aEncryptorVerifier(mKey, iv, comphelper::CryptoType::AES_128_ECB);
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if (aEncryptorVerifier.update(encryptedVerifier, verifier) != msfilter::ENCRYPTED_VERIFIER_LENGTH)
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return false;
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std::copy(encryptedVerifier.begin(), encryptedVerifier.end(), mInfo.verifier.encryptedVerifier);
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mInfo.verifier.encryptedVerifierHashSize = comphelper::SHA1_HASH_LENGTH;
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std::vector<sal_uInt8> hash = comphelper::Hash::calculateHash(verifier.data(), verifier.size(), comphelper::HashType::SHA1);
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hash.resize(comphelper::SHA256_HASH_LENGTH, 0);
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std::vector<sal_uInt8> encryptedHash(comphelper::SHA256_HASH_LENGTH, 0);
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comphelper::Encrypt aEncryptorHash(mKey, iv, comphelper::CryptoType::AES_128_ECB);
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aEncryptorHash.update(encryptedHash, hash, hash.size());
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std::copy(encryptedHash.begin(), encryptedHash.end(), mInfo.verifier.encryptedVerifierHash);
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return true;
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}
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bool Standard2007Engine::calculateEncryptionKey(std::u16string_view rPassword)
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{
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sal_uInt32 saltSize = mInfo.verifier.saltSize;
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size_t passwordByteLength = rPassword.size() * 2;
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const sal_uInt8* saltArray = mInfo.verifier.salt;
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// Prepare initial data -> salt + password (in 16-bit chars)
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std::vector<sal_uInt8> initialData(saltSize + passwordByteLength);
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std::copy(saltArray, saltArray + saltSize, initialData.begin());
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auto p = initialData.begin() + saltSize;
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for (size_t i = 0; i != rPassword.size(); ++i) {
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auto c = rPassword[i];
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*p++ = c & 0xFF;
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*p++ = c >> 8;
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}
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// use "hash" vector for result of sha1 hashing
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// calculate SHA1 hash of initialData
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std::vector<sal_uInt8> hash = comphelper::Hash::calculateHash(initialData.data(), initialData.size(), comphelper::HashType::SHA1);
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// data = iterator (4bytes) + hash
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std::vector<sal_uInt8> data(comphelper::SHA1_HASH_LENGTH + 4, 0);
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for (sal_Int32 i = 0; i < 50000; ++i)
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{
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ByteOrderConverter::writeLittleEndian(data.data(), i);
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std::copy(hash.begin(), hash.end(), data.begin() + 4);
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hash = comphelper::Hash::calculateHash(data.data(), data.size(), comphelper::HashType::SHA1);
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}
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std::copy(hash.begin(), hash.end(), data.begin() );
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std::fill(data.begin() + comphelper::SHA1_HASH_LENGTH, data.end(), 0 );
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hash = comphelper::Hash::calculateHash(data.data(), data.size(), comphelper::HashType::SHA1);
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// derive key
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std::vector<sal_uInt8> buffer(64, 0x36);
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for (size_t i = 0; i < hash.size(); ++i)
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buffer[i] ^= hash[i];
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hash = comphelper::Hash::calculateHash(buffer.data(), buffer.size(), comphelper::HashType::SHA1);
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if (mKey.size() > hash.size())
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return false;
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std::copy(hash.begin(), hash.begin() + mKey.size(), mKey.begin());
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return true;
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}
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bool Standard2007Engine::generateEncryptionKey(const OUString& password)
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{
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mKey.clear();
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/*
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KeySize (4 bytes): An unsigned integer that specifies the number of bits in the encryption key.
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MUST be a multiple of 8. MUST be one of the values in the following table:
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Algorithm Value Comment
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Any 0x00000000 Determined by Flags
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RC4 0x00000028 – 0x00000080 (inclusive) 8-bit increments.
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AES 0x00000080, 0x000000C0, 0x00000100 128, 192 or 256-bit
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*/
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if (mInfo.header.keyBits > 8192) // should we strictly enforce the above 256 bit limit ?
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return false;
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mKey.resize(mInfo.header.keyBits / 8, 0);
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if (mKey.empty())
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return false;
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calculateEncryptionKey(password);
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std::vector<sal_uInt8> encryptedVerifier(msfilter::ENCRYPTED_VERIFIER_LENGTH);
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std::copy(
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mInfo.verifier.encryptedVerifier,
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mInfo.verifier.encryptedVerifier + msfilter::ENCRYPTED_VERIFIER_LENGTH,
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encryptedVerifier.begin());
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std::vector<sal_uInt8> encryptedHash(comphelper::SHA256_HASH_LENGTH);
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std::copy(
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mInfo.verifier.encryptedVerifierHash,
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mInfo.verifier.encryptedVerifierHash + comphelper::SHA256_HASH_LENGTH,
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encryptedHash.begin());
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std::vector<sal_uInt8> verifier(encryptedVerifier.size(), 0);
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comphelper::Decrypt::aes128ecb(verifier, encryptedVerifier, mKey);
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std::vector<sal_uInt8> verifierHash(encryptedHash.size(), 0);
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comphelper::Decrypt::aes128ecb(verifierHash, encryptedHash, mKey);
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std::vector<sal_uInt8> hash = comphelper::Hash::calculateHash(verifier.data(), verifier.size(), comphelper::HashType::SHA1);
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return std::equal(hash.begin(), hash.end(), verifierHash.begin());
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}
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bool Standard2007Engine::decrypt(BinaryXInputStream& aInputStream,
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BinaryXOutputStream& aOutputStream)
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{
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sal_uInt32 totalSize = aInputStream.readuInt32(); // Document unencrypted size - 4 bytes
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aInputStream.skip(4); // Reserved 4 Bytes
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std::vector<sal_uInt8> iv;
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comphelper::Decrypt aDecryptor(mKey, iv, comphelper::CryptoType::AES_128_ECB);
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std::vector<sal_uInt8> inputBuffer (4096);
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std::vector<sal_uInt8> outputBuffer(4096);
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sal_uInt32 inputLength;
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sal_uInt32 outputLength;
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sal_uInt32 remaining = totalSize;
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while ((inputLength = aInputStream.readMemory(inputBuffer.data(), inputBuffer.size())) > 0)
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{
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outputLength = aDecryptor.update(outputBuffer, inputBuffer, inputLength);
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sal_uInt32 writeLength = std::min(outputLength, remaining);
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aOutputStream.writeMemory(outputBuffer.data(), writeLength);
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remaining -= outputLength;
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}
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return true;
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}
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bool Standard2007Engine::checkDataIntegrity()
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{
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return true;
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}
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bool Standard2007Engine::setupEncryption(OUString const & password)
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{
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mInfo.header.flags = msfilter::ENCRYPTINFO_AES | msfilter::ENCRYPTINFO_CRYPTOAPI;
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mInfo.header.algId = msfilter::ENCRYPT_ALGO_AES128;
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mInfo.header.algIdHash = msfilter::ENCRYPT_HASH_SHA1;
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mInfo.header.keyBits = msfilter::ENCRYPT_KEY_SIZE_AES_128;
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mInfo.header.providedType = msfilter::ENCRYPT_PROVIDER_TYPE_AES;
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lclRandomGenerateValues(mInfo.verifier.salt, mInfo.verifier.saltSize);
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const sal_Int32 keyLength = mInfo.header.keyBits / 8;
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mKey.clear();
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mKey.resize(keyLength, 0);
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if (!calculateEncryptionKey(password))
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return false;
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if (!generateVerifier())
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return false;
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return true;
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}
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void Standard2007Engine::writeEncryptionInfo(BinaryXOutputStream& rStream)
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{
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rStream.WriteUInt32(msfilter::VERSION_INFO_2007_FORMAT);
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sal_uInt32 cspNameSize = (lclCspName.getLength() * 2) + 2;
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sal_uInt32 encryptionHeaderSize = static_cast<sal_uInt32>(sizeof(msfilter::EncryptionStandardHeader));
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rStream.WriteUInt32(mInfo.header.flags);
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sal_uInt32 headerSize = encryptionHeaderSize + cspNameSize;
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rStream.WriteUInt32(headerSize);
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rStream.WriteUInt32(mInfo.header.flags);
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rStream.WriteUInt32(mInfo.header.sizeExtra);
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rStream.WriteUInt32(mInfo.header.algId);
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rStream.WriteUInt32(mInfo.header.algIdHash);
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rStream.WriteUInt32(mInfo.header.keyBits);
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rStream.WriteUInt32(mInfo.header.providedType);
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rStream.WriteUInt32(mInfo.header.reserved1);
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rStream.WriteUInt32(mInfo.header.reserved2);
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rStream.writeUnicodeArray(lclCspName);
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rStream.WriteUInt16(0);
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rStream.WriteUInt32(mInfo.verifier.saltSize);
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rStream.writeMemory(&mInfo.verifier.salt, sizeof mInfo.verifier.salt);
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rStream.writeMemory(&mInfo.verifier.encryptedVerifier, sizeof mInfo.verifier.encryptedVerifier);
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rStream.WriteUInt32(mInfo.verifier.encryptedVerifierHashSize);
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rStream.writeMemory(
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&mInfo.verifier.encryptedVerifierHash, sizeof mInfo.verifier.encryptedVerifierHash);
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}
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void Standard2007Engine::encrypt(const css::uno::Reference<css::io::XInputStream> & rxInputStream,
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css::uno::Reference<css::io::XOutputStream> & rxOutputStream,
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sal_uInt32 nSize)
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{
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if (mKey.empty())
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return;
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BinaryXOutputStream aBinaryOutputStream(rxOutputStream, false);
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BinaryXInputStream aBinaryInputStream(rxInputStream, false);
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aBinaryOutputStream.WriteUInt32(nSize); // size
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aBinaryOutputStream.WriteUInt32(0U); // reserved
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std::vector<sal_uInt8> inputBuffer(1024);
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std::vector<sal_uInt8> outputBuffer(1024);
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sal_uInt32 inputLength;
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sal_uInt32 outputLength;
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std::vector<sal_uInt8> iv;
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comphelper::Encrypt aEncryptor(mKey, iv, comphelper::CryptoType::AES_128_ECB);
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while ((inputLength = aBinaryInputStream.readMemory(inputBuffer.data(), inputBuffer.size())) > 0)
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{
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// increase size to multiple of 16 (size of mKey) if necessary
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inputLength = inputLength % AES128Size == 0 ?
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inputLength : comphelper::roundUp(inputLength, AES128Size);
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outputLength = aEncryptor.update(outputBuffer, inputBuffer, inputLength);
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aBinaryOutputStream.writeMemory(outputBuffer.data(), outputLength);
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}
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}
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bool Standard2007Engine::readEncryptionInfo(css::uno::Reference<css::io::XInputStream> & rxInputStream)
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{
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BinaryXInputStream aBinaryStream(rxInputStream, false);
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mInfo.header.flags = aBinaryStream.readuInt32();
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if (getFlag(mInfo.header.flags, msfilter::ENCRYPTINFO_EXTERNAL))
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return false;
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sal_uInt32 nHeaderSize = aBinaryStream.readuInt32();
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sal_uInt32 actualHeaderSize = sizeof(mInfo.header);
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if (nHeaderSize < actualHeaderSize)
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return false;
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mInfo.header.flags = aBinaryStream.readuInt32();
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mInfo.header.sizeExtra = aBinaryStream.readuInt32();
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mInfo.header.algId = aBinaryStream.readuInt32();
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mInfo.header.algIdHash = aBinaryStream.readuInt32();
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mInfo.header.keyBits = aBinaryStream.readuInt32();
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mInfo.header.providedType = aBinaryStream.readuInt32();
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mInfo.header.reserved1 = aBinaryStream.readuInt32();
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mInfo.header.reserved2 = aBinaryStream.readuInt32();
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aBinaryStream.skip(nHeaderSize - actualHeaderSize);
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mInfo.verifier.saltSize = aBinaryStream.readuInt32();
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aBinaryStream.readArray(mInfo.verifier.salt, SAL_N_ELEMENTS(mInfo.verifier.salt));
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aBinaryStream.readArray(mInfo.verifier.encryptedVerifier, SAL_N_ELEMENTS(mInfo.verifier.encryptedVerifier));
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mInfo.verifier.encryptedVerifierHashSize = aBinaryStream.readuInt32();
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aBinaryStream.readArray(mInfo.verifier.encryptedVerifierHash, SAL_N_ELEMENTS(mInfo.verifier.encryptedVerifierHash));
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if (mInfo.verifier.saltSize != 16)
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return false;
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// check flags and algorithm IDs, required are AES128 and SHA-1
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if (!getFlag(mInfo.header.flags, msfilter::ENCRYPTINFO_CRYPTOAPI))
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return false;
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if (!getFlag(mInfo.header.flags, msfilter::ENCRYPTINFO_AES))
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return false;
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// algorithm ID 0 defaults to AES128 too, if ENCRYPTINFO_AES flag is set
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if (mInfo.header.algId != 0 && mInfo.header.algId != msfilter::ENCRYPT_ALGO_AES128)
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return false;
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// hash algorithm ID 0 defaults to SHA-1 too
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if (mInfo.header.algIdHash != 0 && mInfo.header.algIdHash != msfilter::ENCRYPT_HASH_SHA1)
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return false;
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if (mInfo.verifier.encryptedVerifierHashSize != 20)
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return false;
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return !aBinaryStream.isEof();
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}
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} // namespace oox::crypto
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/* vim:set shiftwidth=4 softtabstop=4 expandtab: */
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