Hey All, Just a newbie asking silly questions. I was trying to decrypt initial payload for quic . I tried using libgcrypt , but failed to decrypt another payload using a sample code.
include <gcrypt.h>
include <string.h>
void main() { #define GCRY_CIPHER GCRY_CIPHER_SHA256 // Pick the cipher here #define GCRY_C_MODE GCRY_CIPHER_MODE_OCB // Pick the cipher mode here
gcry_error_t gcryError;
gcry_cipher_hd_t gcryCipherHd;
size_t index;
size_t keyLength = gcry_cipher_get_algo_keylen(GCRY_CIPHER);
size_t blkLength = gcry_cipher_get_algo_blklen(GCRY_CIPHER);
char * txtBuffer = "123456789 abcdefghijklmnopqrstuvwzyz ABCDEFGHIJKLMNOPQRSTUVWZYZ";
size_t txtLength = strlen(txtBuffer)+1; // string plus termination
char * encBuffer = malloc(txtLength);
char * outBuffer = malloc(txtLength);
char * aesSymKey = "one test AES key"; // 16 bytes
char * iniVector = "a test ini value"; // 16 bytes
gcryError = gcry_cipher_open(
&gcryCipherHd, // gcry_cipher_hd_t *
GCRY_CIPHER, // int
GCRY_C_MODE, // int
0); // unsigned int
if (gcryError)
{
printf("gcry_cipher_open failed: %s/%s\n",
gcry_strsource(gcryError),
gcry_strerror(gcryError));
return;
}
printf("gcry_cipher_open worked\n");
gcryError = gcry_cipher_setkey(gcryCipherHd, aesSymKey, keyLength);
if (gcryError)
{
printf("gcry_cipher_setkey failed: %s/%s\n",
gcry_strsource(gcryError),
gcry_strerror(gcryError));
return;
}
printf("gcry_cipher_setkey worked\n");
gcryError = gcry_cipher_setiv(gcryCipherHd, iniVector, blkLength);
if (gcryError)
{
printf("gcry_cipher_setiv failed: %s/%s\n",
gcry_strsource(gcryError),
gcry_strerror(gcryError));
return;
}
printf("gcry_cipher_setiv worked\n");
gcryError = gcry_cipher_encrypt(gcryCipherHd, // gcry_cipher_hd_t
encBuffer, // void *
txtLength, // size_t
txtBuffer, // const void *
txtLength ); // size_t
if (gcryError)
{
printf("gcry_cipher_encrypt failed: %s/%s\n",
gcry_strsource(gcryError),
gcry_strerror(gcryError));
return;
}
printf("gcry_cipher_encrypt worked\n");
gcryError = gcry_cipher_setiv(gcryCipherHd, iniVector, blkLength);
if (gcryError)
{
printf("gcry_cipher_setiv failed: %s/%s\n",
gcry_strsource(gcryError),
gcry_strerror(gcryError));
return;
}
printf("gcry_cipher_setiv worked\n");
gcryError = gcry_cipher_decrypt(
gcryCipherHd, // gcry_cipher_hd_t
outBuffer, // void *
txtLength, // size_t
encBuffer, // const void *
txtLength); // size_t
if (gcryError)
{
printf("gcry_cipher_decrypt failed: %s/%s\n",
gcry_strsource(gcryError),
gcry_strerror(gcryError));
return;
}
printf("gcry_cipher_decrypt worked\n");
printf("keyLength = %zu\n", keyLength);
printf("blkLength = %zu\n", blkLength);
printf("txtLength = %zu\n", txtLength);
printf("aesSymKey = %s\n", aesSymKey);
printf("iniVector = %s\n", iniVector);
printf("txtBuffer = %s\n", txtBuffer);
printf("encBuffer = ");
for (index = 0; index<(strlen(txtBuffer)+1) index++)
printf("%02X", (unsigned char)encBuffer[index]);
printf("\n");
printf("outBuffer = %s\n", outBuffer);
// clean up after ourselves
gcry_cipher_close(gcryCipherHd);
free(encBuffer);
free(outBuffer);
}
This ample code works. but i would really like to know which cipher and cipher mode is used by QUIC version 0xfaceb00 and what are these aesSymKey , iniVector.
Kindly ignore my limited knowledge .
