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/*
Copyright (C) 2019-2025 Selwin van Dijk
This file is part of signalbackup-tools.
signalbackup-tools is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
signalbackup-tools is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with signalbackup-tools. If not, see <https://www.gnu.org/licenses/>.
*/
#include "filedecryptor.ih"
std::unique_ptr<BackupFrame> FileDecryptor::getFrame(std::ifstream &file)
{
if (d_backupfileversion == 0) [[unlikely]]
return getFrameOld(file);
unsigned long long int filepos = file.tellg();
if (d_verbose) [[unlikely]]
Logger::message("Getting frame at filepos: ", filepos, " (COUNTER: ", d_counter, ")");
if (static_cast<uint64_t>(filepos) == d_filesize) [[unlikely]]
{
if (d_verbose) [[unlikely]]
Logger::message("Read entire backup file...");
return std::unique_ptr<BackupFrame>(nullptr);
}
if (d_headerframe)
{
file.seekg(4 + d_headerframe->dataSize());
return std::unique_ptr<BackupFrame>(d_headerframe.release());
}
uint32_t encrypted_encryptedframelength = 0;
if (!file.read(reinterpret_cast<char *>(&encrypted_encryptedframelength), sizeof(decltype(encrypted_encryptedframelength)))) [[unlikely]]
{
Logger::error("Failed to read ", sizeof(decltype(encrypted_encryptedframelength)),
" bytes from file to get next frame size... (", file.tellg(),
" / ", d_filesize, ")");
return std::unique_ptr<BackupFrame>(nullptr);
}
// set up context for caclulating MAC
#if OPENSSL_VERSION_NUMBER >= 0x30000000L
std::unique_ptr<EVP_MAC, decltype(&::EVP_MAC_free)> mac(EVP_MAC_fetch(nullptr, "hmac", nullptr), &::EVP_MAC_free);
std::unique_ptr<EVP_MAC_CTX, decltype(&::EVP_MAC_CTX_free)> hctx(EVP_MAC_CTX_new(mac.get()), &::EVP_MAC_CTX_free);
char digest[] = "SHA256";
OSSL_PARAM params[] = {OSSL_PARAM_construct_utf8_string("digest", digest, 0), OSSL_PARAM_construct_end()};
#else
std::unique_ptr<HMAC_CTX, decltype(&::HMAC_CTX_free)> hctx(HMAC_CTX_new(), &::HMAC_CTX_free);
#endif
#if OPENSSL_VERSION_NUMBER >= 0x30000000L
if (EVP_MAC_init(hctx.get(), d_mackey, d_mackey_size, params) != 1) [[unlikely]]
#else
if (HMAC_Init_ex(hctx.get(), d_mackey, d_mackey_size, EVP_sha256(), nullptr) != 1) [[unlikely]]
#endif
{
Logger::error("Failed to initialize HMAC context");
return std::unique_ptr<BackupFrame>(nullptr);
}
// update MAC with frame length
#if OPENSSL_VERSION_NUMBER >= 0x30000000L
if (EVP_MAC_update(hctx.get(), reinterpret_cast<unsigned char *>(&encrypted_encryptedframelength), sizeof(decltype(encrypted_encryptedframelength))) != 1) [[unlikely]]
#else
if (HMAC_Update(hctx.get(), reinterpret_cast<unsigned char *>(&encrypted_encryptedframelength), sizeof(decltype(encrypted_encryptedframelength))) != 1) [[unlikely]]
#endif
{
Logger::error("Failed to update HMAC");
return std::unique_ptr<BackupFrame>(nullptr);
}
// decrypt encrypted_encryptedframelength
uintToFourBytes(d_iv, d_counter++);
// create context
std::unique_ptr<EVP_CIPHER_CTX, decltype(&::EVP_CIPHER_CTX_free)> ctx(EVP_CIPHER_CTX_new(), &::EVP_CIPHER_CTX_free);
// disable padding
EVP_CIPHER_CTX_set_padding(ctx.get(), 0);
if (EVP_DecryptInit_ex(ctx.get(), EVP_aes_256_ctr(), nullptr, d_cipherkey, d_iv) != 1) [[unlikely]]
{
Logger::error("CTX INIT FAILED");
return nullptr;
}
uint32_t encryptedframelength = 0;
int encryptedframelength_size = sizeof(decltype(encryptedframelength));
if (EVP_DecryptUpdate(ctx.get(), reinterpret_cast<unsigned char *>(&encryptedframelength), &encryptedframelength_size,
reinterpret_cast<unsigned char *>(&encrypted_encryptedframelength),
sizeof(decltype(encrypted_encryptedframelength))) != 1) [[unlikely]]
{
Logger::error("Failed to decrypt data");
return nullptr;
}
encryptedframelength = bepaald::swap_endian<uint32_t>(encryptedframelength);
if (d_verbose) [[unlikely]]
Logger::message("Framelength: ", encryptedframelength);
if (encryptedframelength > 115343360 /*110MB*/ || encryptedframelength < 11)
{
Logger::error("Failed to read next frame (", encryptedframelength, " bytes at filepos ", filepos, ")");
if (d_framecount == 1)
Logger::message(Logger::Control::BOLD, " *** NOTE : IT IS LIKELY AN INCORRECT PASSPHRASE WAS PROVIDED ***", Logger::Control::NORMAL);
return std::unique_ptr<BackupFrame>(nullptr);
}
// read in the encrypted frame data
std::unique_ptr<unsigned char[]> encryptedframe(new unsigned char[encryptedframelength]);
if (!getNextFrameBlock(file, encryptedframe.get(), encryptedframelength)) [[unlikely]]
{
Logger::error("Failed to read next frame (", encryptedframelength, " bytes at filepos ", filepos, ")");
return std::unique_ptr<BackupFrame>(nullptr);
}
// update MAC with read data
#if OPENSSL_VERSION_NUMBER >= 0x30000000L
if (EVP_MAC_update(hctx.get(), encryptedframe.get(), encryptedframelength - MACSIZE) != 1)
#else
if (HMAC_Update(hctx.get(), encryptedframe.get(), encryptedframelength - MACSIZE) != 1)
#endif
{
Logger::error("Failed to update HMAC");
return std::unique_ptr<BackupFrame>(nullptr);
}
// finalize MAC
#if OPENSSL_VERSION_NUMBER >= 0x30000000L
unsigned long int digest_size = SHA256_DIGEST_LENGTH;
unsigned char hash[SHA256_DIGEST_LENGTH];
if (EVP_MAC_final(hctx.get(), hash, nullptr, digest_size) != 1)
#else
unsigned int digest_size = SHA256_DIGEST_LENGTH;
unsigned char hash[SHA256_DIGEST_LENGTH];
if (HMAC_Final(hctx.get(), hash, &digest_size) != 1)
#endif
{
Logger::error("Failed to finalize MAC");
return std::unique_ptr<BackupFrame>(nullptr);
}
// check MAC
if (std::memcmp(encryptedframe.get() + (encryptedframelength - MACSIZE), hash, 10) != 0) [[unlikely]]
{
Logger::message("\n");
Logger::warning("Bad MAC in frame: theirMac: ", bepaald::bytesToHexString(encryptedframe.get() + (encryptedframelength - MACSIZE), MACSIZE),
"\n ourMac: ", bepaald::bytesToHexString(hash, SHA256_DIGEST_LENGTH));
if (d_framecount == 1) [[unlikely]]
Logger::message(Logger::Control::BOLD, " *** NOTE : IT IS LIKELY AN INCORRECT PASSPHRASE WAS PROVIDED ***", Logger::Control::NORMAL);
d_badmac = true;
return std::unique_ptr<BackupFrame>(nullptr);
}
else
{
d_badmac = false;
if (d_verbose) [[unlikely]]
{
Logger::message("Calculated mac: ", bepaald::bytesToHexString(hash, SHA256_DIGEST_LENGTH));
Logger::message("Mac in file : ", bepaald::bytesToHexString(encryptedframe.get() + (encryptedframelength - MACSIZE), MACSIZE));
}
}
// decode frame data
int decodedframelength = encryptedframelength - MACSIZE;
unsigned char *decodedframe = new unsigned char[decodedframelength];
if (EVP_DecryptUpdate(ctx.get(), decodedframe, &decodedframelength, encryptedframe.get(), encryptedframelength - MACSIZE) != 1) [[unlikely]]
{
Logger::error("Failed to decrypt data");
delete[] decodedframe;
return std::unique_ptr<BackupFrame>(nullptr);
}
delete[] encryptedframe.release(); // free up already....
std::unique_ptr<BackupFrame> frame(initBackupFrame(decodedframe, decodedframelength, d_framecount++));
if (!d_editattachments.empty() && frame && frame->frameType() == BackupFrame::FRAMETYPE::ATTACHMENT) [[unlikely]]
for (unsigned int i = 0; i < d_editattachments.size(); i += 2)
if (frame->frameNumber() == static_cast<uint64_t>(d_editattachments[i]))
{
auto oldlength = reinterpret_cast<AttachmentFrame *>(frame.get())->length();
// set new length
reinterpret_cast<AttachmentFrame *>(frame.get())->setLengthField(d_editattachments[i + 1]);
Logger::message("Editing attachment data size in AttachmentFrame ", oldlength, " -> ",
reinterpret_cast<AttachmentFrame *>(frame.get())->length(),
"\nFrame has _id = ", reinterpret_cast<AttachmentFrame *>(frame.get())->rowId(),
", unique_id = ", reinterpret_cast<AttachmentFrame *>(frame.get())->attachmentId());
break;
}
if (!frame) [[unlikely]]
{
Logger::error("Failed to get valid frame from decoded data...");
if (d_badmac)
{
Logger::error_indent("Encrypted data had failed verification (Bad MAC)");
delete[] decodedframe;
return std::make_unique<InvalidFrame>();
}
else
{
Logger::error_indent("Data was verified ok, but does not represent a valid frame... Don't know what happened, but it's bad... :(");
Logger::error_indent("Decrypted frame data: ", bepaald::bytesToHexString(decodedframe, decodedframelength));
delete[] decodedframe;
return std::make_unique<InvalidFrame>();
}
delete[] decodedframe;
return std::unique_ptr<BackupFrame>(nullptr);
}
delete[] decodedframe;
// if (!frame->validate(d_filesize - file.tellg()))
// {
// std::cout << std::endl << " ************** FRAME NOT VALIDATED ****************" << std::endl;
// frame->printInfo();
// std::cout << "TOTAL SIZE: " << d_filesize << std::endl;
// std::cout << "POSITION : " << file.tellg() << std::endl;
// std::cout << "AVAILABLE : " << (d_filesize - file.tellg()) << std::endl;
// }
uint32_t attsize = frame->attachmentSize();
if (!d_badmac && attsize > 0 &&
(frame->frameType() == BackupFrame::FRAMETYPE::ATTACHMENT ||
frame->frameType() == BackupFrame::FRAMETYPE::AVATAR ||
frame->frameType() == BackupFrame::FRAMETYPE::STICKER))
{
if ((file.tellg() < 0 && file.eof()) || (attsize + static_cast<uint64_t>(file.tellg()) > d_filesize)) [[unlikely]]
if (!d_assumebadframesize)
{
Logger::error("Unexpectedly hit end of file while reading attachment!");
return std::unique_ptr<BackupFrame>(nullptr);
}
uintToFourBytes(d_iv, d_counter++);
reinterpret_cast<FrameWithAttachment *>(frame.get())->setReader(new AndroidAttachmentReader(d_iv, d_iv_size, d_mackey, d_mackey_size, d_cipherkey, d_cipherkey_size, attsize, d_filename, file.tellg()));
file.seekg(attsize + MACSIZE, std::ios_base::cur);
}
//std::cout << "FILEPOS: " << file.tellg() << std::endl;
return frame;
}
// old style, where frame length was not encrypted
std::unique_ptr<BackupFrame> FileDecryptor::getFrameOld(std::ifstream &file)
{
unsigned long long int filepos = file.tellg();
if (d_verbose) [[unlikely]]
Logger::message("Getting frame at filepos: ", filepos, " (COUNTER: ", d_counter, ")");
if (static_cast<uint64_t>(filepos) == d_filesize) [[unlikely]]
{
Logger::message("Read entire backup file...");
return std::unique_ptr<BackupFrame>(nullptr);
}
if (d_headerframe)
{
file.seekg(4 + d_headerframe->dataSize());
return std::unique_ptr<BackupFrame>(d_headerframe.release());
}
uint32_t encryptedframelength = getNextFrameBlockSize(file);
//if (encryptedframelength > 3145728/*= 3MB*/ /*115343360 / * =110MB*/ || encryptedframelength < 11)
//{
// std::cout << "Suspicious framelength" << std::endl;
// bruteForceFrom(filepos)???
//}
if (encryptedframelength == 0 && file.eof()) [[unlikely]]
{
Logger::error("Unexpectedly hit end of file!");
return std::unique_ptr<BackupFrame>(nullptr);
}
DEBUGOUT("Framelength: ", encryptedframelength);
if (d_verbose) [[unlikely]]
Logger::message("Framelength: ", encryptedframelength);
if (encryptedframelength > 115343360 /*110MB*/ || encryptedframelength < 11)
{
Logger::error("Failed to read next frame (", encryptedframelength, " bytes at filepos ", filepos, ")");
if (d_stoponerror || d_backupfileversion > 0)
return std::unique_ptr<BackupFrame>(nullptr);
return bruteForceFrom(file, filepos, encryptedframelength);
}
std::unique_ptr<unsigned char[]> encryptedframe(new unsigned char[encryptedframelength]);
if (!getNextFrameBlock(file, encryptedframe.get(), encryptedframelength)) [[unlikely]]
{
Logger::error("Failed to read next frame (", encryptedframelength, " bytes at filepos ", filepos, ")");
if (d_stoponerror || d_backupfileversion > 0)
return std::unique_ptr<BackupFrame>(nullptr);
return bruteForceFrom(file, filepos, encryptedframelength);
}
// check hash
unsigned int digest_size = SHA256_DIGEST_LENGTH;
unsigned char hash[SHA256_DIGEST_LENGTH];
HMAC(EVP_sha256(), d_mackey, d_mackey_size, encryptedframe.get(), encryptedframelength - MACSIZE, hash, &digest_size);
if (std::memcmp(encryptedframe.get() + (encryptedframelength - MACSIZE), hash, 10) != 0) [[unlikely]]
{
Logger::message("\n");
Logger::warning("Bad MAC in frame: theirMac: ", bepaald::bytesToHexString(encryptedframe.get() + (encryptedframelength - MACSIZE), MACSIZE),
"\n ourMac: ", bepaald::bytesToHexString(hash, SHA256_DIGEST_LENGTH));
// std::cout << "" << std::endl;
// std::cout << bepaald::bold_on << "WARNING" << bepaald::bold_off << " : Bad MAC in frame: theirMac: "
// << bepaald::bytesToHexString(encryptedframe.get() + (encryptedframelength - MACSIZE), MACSIZE) << std::endl;
// std::cout << " ourMac: " << bepaald::bytesToHexString(hash, SHA256_DIGEST_LENGTH) << std::endl;
if (d_framecount == 1) [[unlikely]]
Logger::message(Logger::Control::BOLD, " *** NOTE : IT IS LIKELY AN INCORRECT PASSPHRASE WAS PROVIDED ***", Logger::Control::NORMAL);
//std::cout << bepaald::bold_on << " *** NOTE : IT IS LIKELY AN INCORRECT PASSPHRASE WAS PROVIDED ***" << bepaald::bold_off << std::endl;
d_badmac = true;
if (d_stoponerror)
{
Logger::message("Stop reading backup. Next frame would be read at offset ", filepos + encryptedframelength);
return std::unique_ptr<BackupFrame>(nullptr);
}
}
else
{
d_badmac = false;
if (d_verbose) [[unlikely]]
{
Logger::message("Calculated mac: ", bepaald::bytesToHexString(hash, SHA256_DIGEST_LENGTH));
Logger::message("Mac in file : ", bepaald::bytesToHexString(encryptedframe.get() + (encryptedframelength - MACSIZE), MACSIZE));
}
}
uintToFourBytes(d_iv, d_counter++);
// create context
std::unique_ptr<EVP_CIPHER_CTX, decltype(&::EVP_CIPHER_CTX_free)> ctx(EVP_CIPHER_CTX_new(), &::EVP_CIPHER_CTX_free);
// disable padding
EVP_CIPHER_CTX_set_padding(ctx.get(), 0);
if (EVP_DecryptInit_ex(ctx.get(), EVP_aes_256_ctr(), nullptr, d_cipherkey, d_iv) != 1) [[unlikely]]
{
Logger::error("CTX INIT FAILED");
return std::unique_ptr<BackupFrame>(nullptr);
}
int decodedframelength = encryptedframelength - MACSIZE;
unsigned char *decodedframe = new unsigned char[decodedframelength];
if (EVP_DecryptUpdate(ctx.get(), decodedframe, &decodedframelength, encryptedframe.get(), encryptedframelength - MACSIZE) != 1) [[unlikely]]
{
Logger::error("Failed to decrypt data");
delete[] decodedframe;
return std::unique_ptr<BackupFrame>(nullptr);
}
delete[] encryptedframe.release(); // free up already....
std::unique_ptr<BackupFrame> frame(initBackupFrame(decodedframe, decodedframelength, d_framecount++));
if (!d_editattachments.empty() && frame && frame->frameType() == BackupFrame::FRAMETYPE::ATTACHMENT) [[unlikely]]
for (unsigned int i = 0; i < d_editattachments.size(); i += 2)
if (frame->frameNumber() == static_cast<uint64_t>(d_editattachments[i]))
{
auto oldlength = reinterpret_cast<AttachmentFrame *>(frame.get())->length();
// set new length
reinterpret_cast<AttachmentFrame *>(frame.get())->setLengthField(d_editattachments[i + 1]);
Logger::message("Editing attachment data size in AttachmentFrame ", oldlength, " -> ",
reinterpret_cast<AttachmentFrame *>(frame.get())->length(),
"\nFrame has _id = ", reinterpret_cast<AttachmentFrame *>(frame.get())->rowId(),
", unique_id = ", reinterpret_cast<AttachmentFrame *>(frame.get())->attachmentId());
// std::cout << "Editing attachment data size in AttachmentFrame "
// << reinterpret_cast<AttachmentFrame *>(frame.get())->length() << " -> ";
// reinterpret_cast<AttachmentFrame *>(frame.get())->setLengthField(d_editattachments[i + 1]);
// std::cout << reinterpret_cast<AttachmentFrame *>(frame.get())->length() << std::endl;
// std::cout << "Frame has _id = " << reinterpret_cast<AttachmentFrame *>(frame.get())->rowId()
// << ", unique_id = " << reinterpret_cast<AttachmentFrame *>(frame.get())->attachmentId() << std::endl;
break;
}
if (!frame) [[unlikely]]
{
Logger::error("Failed to get valid frame from decoded data...");
if (d_badmac)
{
Logger::error_indent("Encrypted data had failed verification (Bad MAC)");
delete[] decodedframe;
return bruteForceFrom(file, filepos, encryptedframelength);
}
else
{
Logger::error_indent("Data was verified ok, but does not represent a valid frame... Don't know what happened, but it's bad... :(");
Logger::error_indent("Decrypted frame data: ", bepaald::bytesToHexString(decodedframe, decodedframelength));
delete[] decodedframe;
return std::make_unique<InvalidFrame>();
}
delete[] decodedframe;
return std::unique_ptr<BackupFrame>(nullptr);
}
delete[] decodedframe;
// if (!frame->validate(d_filesize - file.tellg()))
// {
// std::cout << std::endl << " ************** FRAME NOT VALIDATED ****************" << std::endl;
// frame->printInfo();
// std::cout << "TOTAL SIZE: " << d_filesize << std::endl;
// std::cout << "POSITION : " << file.tellg() << std::endl;
// std::cout << "AVAILABLE : " << (d_filesize - file.tellg()) << std::endl;
// }
uint32_t attsize = frame->attachmentSize();
if (!d_badmac && attsize > 0 &&
(frame->frameType() == BackupFrame::FRAMETYPE::ATTACHMENT ||
frame->frameType() == BackupFrame::FRAMETYPE::AVATAR ||
frame->frameType() == BackupFrame::FRAMETYPE::STICKER))
{
if ((file.tellg() < 0 && file.eof()) || (attsize + static_cast<uint64_t>(file.tellg()) > d_filesize)) [[unlikely]]
if (!d_assumebadframesize)
{
Logger::error("Unexpectedly hit end of file while reading attachment!");
return std::unique_ptr<BackupFrame>(nullptr);
}
uintToFourBytes(d_iv, d_counter++);
//reinterpret_cast<FrameWithAttachment *>(frame.get())->setLazyData(d_iv, d_iv_size, d_mackey, d_mackey_size, d_cipherkey, d_cipherkey_size, attsize, d_filename, file.tellg());
reinterpret_cast<FrameWithAttachment *>(frame.get())->setReader(new AndroidAttachmentReader(d_iv, d_iv_size, d_mackey, d_mackey_size, d_cipherkey, d_cipherkey_size, attsize, d_filename, file.tellg()));
file.seekg(attsize + MACSIZE, std::ios_base::cur);
}
//std::cout << "FILEPOS: " << file.tellg() << std::endl;
//delete frame;
return frame;
}
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