ES</h1>

<pre><code>#include &lt;stdlib.h&gt;
#include &lt;stdio.h&gt;
#include &lt;string.h&gt;
#include &lt;stdarg.h&gt;
#include &lt;unistd.h&gt;

#include &lt;openssl/evp.h&gt;
#include &lt;openssl/err.h&gt;
#include &lt;openssl/params.h&gt;

int main() {
    EVP_MAC *mac = EVP_MAC_fetch(NULL, getenv(&quot;MY_MAC&quot;), NULL);
    const char *cipher = getenv(&quot;MY_MAC_CIPHER&quot;);
    const char *digest = getenv(&quot;MY_MAC_DIGEST&quot;);
    const char *key = getenv(&quot;MY_KEY&quot;);
    EVP_