<!DOCTYPE html>
<title>HMAC Generator</title>
<style>body { font-size: 1.2em; }</style>
<form method="post" action="/sign">
Professional ID: <input type="text" name="userid" /> <br/>
Patient ID: <input type="text" name="clientid" /> <br/>
<input type="submit" value="Generate URL" />
</form>