title: free memory after using HMAC() function?
body: <p>I have the following function:</p>
  
  <pre><code>static int my_hmac(unsigned char *data, int len, char *password, unsigned char *hmac)
  {
      unsigned char* digest;
  
      digest = HMAC(EVP_sha1(), password, strlen(password), data, len, NULL, NULL);
      memcpy(hmac, digest, 20);
      return 0;
  }
  </code></pre>
  
  <p>I call it in the <code>main()</code> in this way</p>
  
  <pre><code>unsigned char buffer[20]
  my_hmac(str, strlen(str), "password", buffer)
  </code></pre>
  
  <p>Should I call some free memory api of libcrypto/libopenssl after using the <code>HMAC()</code> function ?</p>