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// SPDX-FileCopyrightText: 2021 Carl Schwan <carlschwan@kde.org>
//
// SPDX-License-Identifier: LGPL-2.1-or-later
#include "encryptedfile.h"
#include "logging.h"
#include <openssl/evp.h>
#include <QtCore/QCryptographicHash>
using namespace Quotient;
QByteArray EncryptedFile::decryptFile(const QByteArray &ciphertext) const
{
QString _key = key.k;
_key = QByteArray::fromBase64(_key.replace(QLatin1Char('_'), QLatin1Char('/')).replace(QLatin1Char('-'), QLatin1Char('+')).toLatin1());
const auto sha256 = QByteArray::fromBase64(hashes["sha256"].toLatin1());
if(sha256 != QCryptographicHash::hash(ciphertext, QCryptographicHash::Sha256)) {
qCWarning(E2EE) << "Hash verification failed for file";
return QByteArray();
}
QByteArray plaintext(ciphertext.size(), 0);
EVP_CIPHER_CTX *ctx;
int length;
ctx = EVP_CIPHER_CTX_new();
EVP_DecryptInit_ex(ctx, EVP_aes_256_ctr(), NULL, (const unsigned char *)_key.data(), (const unsigned char *)iv.toLatin1().data());
EVP_DecryptUpdate(ctx, (unsigned char *)plaintext.data(), &length, (const unsigned char *)ciphertext.data(), ciphertext.size());
EVP_DecryptFinal_ex(ctx, (unsigned char *)plaintext.data() + length, &length);
EVP_CIPHER_CTX_free(ctx);
return plaintext;
}
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