website-theme/layouts/shortcodes/pgpform.html

{{- $openPGP := resources.Get "js/openpgp.min.js" -}}
<script src="{{ $openPGP.Permalink }}"></script>
<textarea id="pgpcleartext" class="pgpform" style="width: 100%; min-height: 10rem;"></textarea>
<button class="pgpbutton" onclick="encrypt()">Encrypt</button>
<br/>
Encrypted Result:
<pre id="pgpresult" class="pgpform"></pre>
<script>
function encrypt() {
    let textarea = document.querySelector("#pgpcleartext");
    let resultarea = document.querySelector('#pgpresult');
    let pubKeyURL = "{{ .Get 0 }}";
    resultarea.textContent = "";
    fetch(pubKeyURL).then(function(response) {
        return response.text().then(function(text) {
            const pubKey = openpgp.readKey({ armoredKey: text });
            const message = openpgp.createMessage({ text: textarea.value })
            return Promise.all([message, pubKey]).then(function(mp) {
                const encryptionParameters = {
                    message: mp[0],
                    encryptionKeys: mp[1]
                };
                return openpgp.encrypt(encryptionParameters).then(function(encryptedMessage) {
                    resultarea.textContent = encryptedMessage;
                });
            });
        });    
    });
}

function genEmail() {
    let resultarea = document.querySelector('#pgpresult');
    let contents = resultarea.textContent;
    let encodedContents = encodeURIComponent(contents);
    let encodedSubject = encodeURIComponent("Contact Form");
    window.location.href = "mailto:{{ .Site.Params.email }}?subject=" +
        encodedSubject + "&body=" + encodedContents;
}
</script>
<button class="pgpbutton" onclick="genEmail()">Generate Email</button>