#pragma once
#include <stdint.h>
#include <stddef.h>
#include <string.h>
#include "mbedtls/md.h"
#include "config.h"

// Returns a 4-byte truncated HMAC-SHA256 over `data` of `len` bytes.
inline uint32_t hmac_sig(const uint8_t *data, size_t len)
{
  static const char *key = HMAC_KEY;
  uint8_t out[32];
  mbedtls_md_hmac(
    mbedtls_md_info_from_type(MBEDTLS_MD_SHA256),
    reinterpret_cast<const uint8_t *>(key), strlen(key),
    data, len, out);
  uint32_t sig;
  memcpy(&sig, out, 4);
  return sig;
}