Lockpick/source/Key.cpp
2019-03-07 11:06:32 -05:00

163 lines
4.5 KiB
C++

/*
* Copyright (c) 2018 shchmue
*
* This program is free software; you can redistribute it and/or modify it
* under the terms and conditions of the GNU General Public License,
* version 2, as published by the Free Software Foundation.
*
* This program is distributed in the hope 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 this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include "Key.hpp"
#include <algorithm>
#include <vector>
#include <mbedtls/aes.h>
#include <mbedtls/cmac.h>
#include "Common.hpp"
#include "xxhash64.h"
size_t Key::saved_key_count = 0;
Key::Key(std::string name, u64 xx_hash, byte_vector hash, u8 length, byte_vector key) :
key(key),
name(name),
xx_hash(xx_hash),
hash(hash),
length(length)
{
}
// init with hash only
Key::Key(std::string name, u64 xx_hash, byte_vector hash, u8 length) :
Key(name, xx_hash, hash, length, {})
{
}
// init with key only
Key::Key(std::string name, u8 length, byte_vector key) :
Key(name, {}, {}, length, key)
{
is_found = true;
}
// nameless key
Key::Key(byte_vector key, u8 length) :
Key({}, {}, {}, length, key)
{
is_found = true;
}
// key to be assigned later
Key::Key(std::string name, u8 length) :
Key(name, {}, {}, length, {})
{
}
// declare only
Key::Key() :
Key({}, {}, {}, {}, {})
{
}
void Key::save_key(FILE *file) {
if (!found())
return;
// format: <keyname> = <hex key> for hactool and similar tools
fprintf(file, "%s = ", name.c_str());
for (auto n : key)
fprintf(file, "%02x", n);
fprintf(file, "\n");
saved_key_count++;
}
byte_vector Key::aes_decrypt_ctr(const byte_vector &data, byte_vector iv) {
byte_vector dest(data.size());
if (!found())
return dest;
// used internally
size_t nc_off = 0;
u8 stream_block[0x10];
mbedtls_aes_context dec;
mbedtls_aes_init(&dec);
mbedtls_aes_setkey_enc(&dec, key.data(), length * 8);
mbedtls_aes_crypt_ctr(&dec, data.size(), &nc_off, iv.data(), stream_block, data.data(), dest.data());
mbedtls_aes_free(&dec);
return dest;
}
byte_vector Key::aes_decrypt_ecb(const byte_vector &data) {
byte_vector dest(data.size());
if (!found())
return dest;
mbedtls_aes_context dec;
mbedtls_aes_init(&dec);
mbedtls_aes_setkey_dec(&dec, key.data(), length * 8);
for (size_t offset = 0; offset < data.size(); offset += 0x10)
mbedtls_aes_crypt_ecb(&dec, MBEDTLS_AES_DECRYPT, data.data() + offset, dest.data() + offset);
mbedtls_aes_free(&dec);
return dest;
}
byte_vector Key::cmac(byte_vector data) {
byte_vector dest(data.size());
if (!found())
return dest;
mbedtls_cipher_cmac(mbedtls_cipher_info_from_type(MBEDTLS_CIPHER_AES_128_ECB), key.data(), length * 8, data.data(), data.size(), dest.data());
return dest;
}
void Key::find_key(const byte_vector &buffer, size_t start) {
if ((buffer.size() == 0) || (found()))
return;
u8 temp_hash[0x20];
if (buffer.size() == length) {
Common::sha256(buffer.data(), temp_hash, length);
if (!std::equal(hash.begin(), hash.end(), temp_hash))
return;
std::copy(buffer.begin(), buffer.begin() + length, std::back_inserter(key));
is_found = true;
return;
}
// hash every length-sized byte chunk in buffer until it matches member hash
for (size_t i = start; i < buffer.size() - length; i++) {
if (xx_hash == XXHash64::hash(buffer.data() + i, length, 0)) {
// double-check sha256 since xxhash64 isn't as collision-safe
Common::sha256(buffer.data() + i, temp_hash, length);
if (!std::equal(hash.begin(), hash.end(), temp_hash))
continue;
std::copy(buffer.begin() + i, buffer.begin() + i + length, std::back_inserter(key));
is_found = true;
break;
}
}
}
byte_vector Key::generate_kek(Key &master_key, const Key &kek_seed, const Key &key_seed) {
Key kek(master_key.aes_decrypt_ecb(kek_seed.key), 0x10);
Key srcKek(kek.aes_decrypt_ecb(key), 0x10);
if (key_seed.found())
return srcKek.aes_decrypt_ecb(key_seed.key);
else
return srcKek.key;
}