Language: C
Label: vulnerable
CWE: CWE-190 \u2014 Integer Overflow or Wraparound
The product performs a calculation that can produce an integer overflow or wraparound, when the logic assumes that the resulting value will always be larger than the original value. This can introduce other weaknesses when the calculation is used for resource management or execution control.

Code:
static int benaloh(void) {
	int code = RLC_ERR;
	bdpe_t pub, prv;
	bn_t a, b;
	dig_t in, out;
	uint8_t buf[RLC_BN_BITS / 8 + 1];
	size_t len;
	int result;

	bn_null(a);
	bn_null(b);
	bdpe_null(pub);
	bdpe_null(prv);

	RLC_TRY {
		bn_new(a);
		bn_new(b);
		bdpe_new(pub);
		bdpe_new(prv);

		result = cp_bdpe_gen(pub, prv, bn_get_prime(47), RLC_BN_BITS);

		TEST_CASE("benaloh encryption/decryption is correct") {
			TEST_ASSERT(result == RLC_OK, end);
			len = RLC_BN_BITS / 8 + 1;
			rand_bytes(buf, 1);
			in = buf[0] % bn_get_prime(47);
			TEST_ASSERT(cp_bdpe_enc(buf, &len, in, pub) == RLC_OK, end);
			TEST_ASSERT(cp_bdpe_dec(&out, buf, len, prv) == RLC_OK, end);
			TEST_ASSERT(in == out, end);
		} TEST_END;

		TEST_CASE("benaloh encryption/decryption is homomorphic") {
			TEST_ASSERT(result == RLC_OK, end);
			len = RLC_BN_BITS / 8 + 1;
			rand_bytes(buf, 1);
			in = buf[0] % bn_get_prime(47);
			TEST_ASSERT(cp_bdpe_enc(buf, &len, in, pub) == RLC_OK, end);
			bn_read_bin(a, buf, len);
			rand_bytes(buf, 1);
			out = (buf[0] % bn_get_prime(47));
			in = (in + out) % bn_get_prime(47);
			TEST_ASSERT(cp_bdpe_enc(buf, &len, out, pub) == RLC_OK, end);
			bn_read_bin(b, buf, len);
			bn_mul(a, a, b);
			bn_mod(a, a, pub->n);
			len = bn_size_bin(pub->n);
			bn_write_bin(buf, len, a);
			TEST_ASSERT(cp_bdpe_dec(&out, buf, len, prv) == RLC_OK, end);
			TEST_ASSERT(in == out, end);
		} TEST_END;
	} RLC_CATCH_ANY {
		RLC_ERROR(end);
	}
	code = RLC_OK;

  end:
	bn_free(a);
	bn_free(b);
	bdpe_free(pub);
	bdpe_free(prv);
	return code;
}