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/*
* Copyright (c) 2023 Simone 'evilsocket' Margaritelli - evilsocket@gmail.com.
*
* This program 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, version 3.
*
* This program 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 this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <openssl/conf.h>
#include <openssl/evp.h>
#include <openssl/err.h>
#include <string.h>
#include <stdio.h>
// as seen in /usr/lib/libzc.so / SetupKeys
static unsigned char KEY_MATERIAL[] = {
0x13, 0x27, 0x3f, 0x42,
0xa5, 0xb6, 0x79, 0xe8,
0x20, 0x31, 0xc4, 0xf5,
0x16, 0x17, 0x88, 0x2f,
0x43, 0xa4, 0x55, 0x69,
0x77, 0xb8, 0xe2, 0x83,
0x04, 0x05, 0x60, 0x70,
0x80, 0x02, 0x03, 0x04,
0x50, 0x6a, 0x7c, 0x8a,
0x02, 0x30, 0x40, 0x51,
0x6a, 0x7d, 0x8d, 0x22,
0x33, 0x44, 0x59, 0x66,
0x71, 0x08, 0x02, 0x03,
0x43, 0x05, 0x67, 0x7a,
0x8f};
int main(int argc, char **argv)
{
if (argc != 3)
{
printf("Usage: %s <serial number> <encrypted file>\n", argv[0]);
return 1;
}
char *serialNumber = argv[1],
*inputFileName = argv[2];
printf("Input file name: %s\n", inputFileName);
// Split into the path and the file name
char *path = strrchr(inputFileName, '/');
if (path == NULL)
{
printf("No path found in %s\n", inputFileName);
return 1;
}
unsigned long serialSize = strlen(serialNumber);
if (serialSize != 9 && serialSize != 0)
{
printf("the serial number must be empty or 9 characters long.\n");
return 1;
}
// concatenate the hardcoded key material with the serial number from /etc/qc_sn
unsigned long key_material_size = sizeof(KEY_MATERIAL) / sizeof(KEY_MATERIAL[0]);
unsigned char *key_material = (unsigned char *)malloc(key_material_size + serialSize);
memcpy(key_material, KEY_MATERIAL, key_material_size);
memcpy(key_material + key_material_size, serialNumber, serialSize);
key_material_size += serialSize;
// derive the actual key and iv from it
unsigned char key[32] = {0};
unsigned char iv[32] = {0};
int iterations = 10;
const EVP_CIPHER *pCipher = EVP_aes_128_ctr();
const EVP_MD *pDigest = EVP_sha1();
int derivedKeySize = EVP_BytesToKey(
pCipher,
pDigest,
NULL, // no salt
key_material,
key_material_size,
iterations,
key,
iv);
if (derivedKeySize != 16)
{
printf("wrong derived key size: %d\n", derivedKeySize);
return 1;
}
// read the encrypted file
FILE *fp = fopen(inputFileName, "rb");
if (!fp)
{
printf("can't open %s\n", inputFileName);
return 1;
}
fseek(fp, 0, SEEK_END);
long input_size = ftell(fp);
fseek(fp, 0, SEEK_SET);
int ret, final_size, outlen;
unsigned char *input = (unsigned char *)malloc(input_size),
*plaintext = (unsigned char *)malloc(input_size);
long read = fread(input, 1, input_size, fp);
fclose(fp);
// decrypt it
EVP_CIPHER_CTX *ctx = EVP_CIPHER_CTX_new();
ret = EVP_DecryptInit_ex(ctx, pCipher, NULL, key, iv);
if (ret != 1)
{
printf("EVP_DecryptInit_ex failed: %d\n", ret);
return 1;
}
ret = EVP_DecryptUpdate(ctx, plaintext, &outlen, input, input_size);
if (ret != 1)
{
printf("EVP_DecryptUpdate failed: %d\n", ret);
return 1;
}
ret = EVP_DecryptFinal(ctx, &plaintext[outlen], &final_size);
if (ret != 1)
{
printf("EVP_DecryptFinal failed: %d\n", ret);
return 1;
}
// Print and save the decrypted file
for (int i = 0; i < outlen; i++)
{
printf("%c", plaintext[i]);
}
printf("\n");
// Save the decrypted file to disk
// It should be saved to the same directory as the encrypted file with the extension .dec
char *outputFileName = (char *)malloc(strlen(inputFileName) + 5);
strcpy(outputFileName, inputFileName);
strcat(outputFileName, ".dec");
fp = fopen(outputFileName, "wb");
if (!fp)
{
printf("can't open %s\n", outputFileName);
return 1;
}
fwrite(plaintext, 1, outlen, fp);
fclose(fp);
free(key_material);
free(input);
free(plaintext);
free(outputFileName);
EVP_CIPHER_CTX_free(ctx);
return 0;
}
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