pqcrypto/crypto_kem/test.c

#include "api.h"
#include "randombytes.h"
#include <stdio.h>
#include <string.h>

#define NTESTS 10

/* allocate a bit more for all keys and messages and
 * make sure it is not touched by the implementations.
 */
static void write_canary(unsigned char *d) {
  *((uint64_t *)d) = 0x0123456789ABCDEF;
}

static int check_canary(unsigned char *d) {
  if (*(uint64_t *)d != 0x0123456789ABCDEF)
    return -1;
  else
    return 0;
}

static int test_keys(void) {
  unsigned char key_a[CRYPTO_BYTES + 16], key_b[CRYPTO_BYTES + 16];
  unsigned char pk[CRYPTO_PUBLICKEYBYTES + 16];
  unsigned char sendb[CRYPTO_CIPHERTEXTBYTES + 16];
  unsigned char sk_a[CRYPTO_SECRETKEYBYTES + 16];

  write_canary(key_a);
  write_canary(key_a + sizeof(key_a) - 8);
  write_canary(key_b);
  write_canary(key_b + sizeof(key_b) - 8);
  write_canary(pk);
  write_canary(pk + sizeof(pk) - 8);
  write_canary(sendb);
  write_canary(sendb + sizeof(sendb) - 8);
  write_canary(sk_a);
  write_canary(sk_a + sizeof(sk_a) - 8);

  int i;

  for (i = 0; i < NTESTS; i++) {
    // Alice generates a public key
    crypto_kem_keypair(pk + 8, sk_a + 8);

    // Bob derives a secret key and creates a response
    crypto_kem_enc(sendb + 8, key_b + 8, pk + 8);

    // Alice uses Bobs response to get her secret key
    crypto_kem_dec(key_a + 8, sendb + 8, sk_a + 8);

    if (memcmp(key_a + 8, key_b + 8, CRYPTO_BYTES)) {
      printf("ERROR KEYS\n");
    } else if (check_canary(key_a) || check_canary(key_a + sizeof(key_a) - 8) ||
               check_canary(key_b) || check_canary(key_b + sizeof(key_b) - 8) ||
               check_canary(pk) || check_canary(pk + sizeof(pk) - 8) ||
               check_canary(sendb) || check_canary(sendb + sizeof(sendb) - 8) ||
               check_canary(sk_a) || check_canary(sk_a + sizeof(sk_a) - 8)) {
      printf("ERROR canary overwritten\n");
    }
  }

  return 0;
}

static int test_invalid_sk_a(void) {
  unsigned char sk_a[CRYPTO_SECRETKEYBYTES];
  unsigned char key_a[CRYPTO_BYTES], key_b[CRYPTO_BYTES];
  unsigned char pk[CRYPTO_PUBLICKEYBYTES];
  unsigned char sendb[CRYPTO_CIPHERTEXTBYTES];
  int i;

  for (i = 0; i < NTESTS; i++) {
    // Alice generates a public key
    crypto_kem_keypair(pk, sk_a);

    // Bob derives a secret key and creates a response
    crypto_kem_enc(sendb, key_b, pk);

    // Replace secret key with random values
    randombytes(sk_a, CRYPTO_SECRETKEYBYTES);

    // Alice uses Bobs response to get her secret key
    crypto_kem_dec(key_a, sendb, sk_a);

    if (!memcmp(key_a, key_b, CRYPTO_BYTES)) {
      printf("ERROR invalid sk_a\n");
    }
  }

  return 0;
}

static int test_invalid_ciphertext(void) {
  unsigned char sk_a[CRYPTO_SECRETKEYBYTES];
  unsigned char key_a[CRYPTO_BYTES], key_b[CRYPTO_BYTES];
  unsigned char pk[CRYPTO_PUBLICKEYBYTES];
  unsigned char sendb[CRYPTO_CIPHERTEXTBYTES];
  int i;
  size_t pos;

  for (i = 0; i < NTESTS; i++) {
    randombytes((unsigned char *)&pos, sizeof(size_t));

    // Alice generates a public key
    crypto_kem_keypair(pk, sk_a);

    // Bob derives a secret key and creates a response
    crypto_kem_enc(sendb, key_b, pk);

    // Change some byte in the ciphertext (i.e., encapsulated key)
    sendb[pos % CRYPTO_CIPHERTEXTBYTES] ^= 23;

    // Alice uses Bobs response to get her secret key
    crypto_kem_dec(key_a, sendb, sk_a);

    if (!memcmp(key_a, key_b, CRYPTO_BYTES)) {
      printf("ERROR invalid ciphertext\n");
    }
  }

  return 0;
}

int main(void) {
  test_keys();
  test_invalid_sk_a();
  test_invalid_ciphertext();

  return 0;
}