8chan signed messages, r1

// Replace this comment with the content of https://tweetnacl.js.org/nacl.min.js
// Replace this comment with the content of https://tweetnacl.js.org/nacl-util.min.js
+function() {
function traverseHtml(node, v) {
  if (node.nodeType == 3) {
    v.ontext(node.textContent);
  } else {
    var tagName = node.tagName.toLowerCase();
    v.onopentag(tagName, node);
    for (var i = 0; i < node.childNodes.length; ++i) {
      traverseHtml(node.childNodes[i], v);
    }
    v.onclosetag(tagName);
  }
}
function reverseFormatNode(node) {
  let chunks = [];
  function append(str) {
    chunks.push(str);
  }
  let eolStack = [];
  let spanStack = [];
  traverseHtml(node, {
    onopentag: function(tagName, node) {
      if (tagName === 'span' && node.className === 'heading') {
        append("==");
        eolStack.unshift("==");
      } else if (tagName === 'span' && node.className === 'spoiler') {
        append("**");
        spanStack.push("**")
      } else if (tagName === 'em') {
        append("''");
      } else if (tagName === 'strong') {
        append("'''");
      } else if (tagName === 'u') {
        append("__");
      } else if (tagName === 's') {
        append("~~");
      }
    },
    onclosetag: function(tagName) {
      if (tagName === 'p') {
        for (var i = 0; i < eolStack.length; ++i) {
          append(eolStack[i]);
        }
        eolStack = [];
        append("\n");
      } else if (tagName === 'span') {
        append(spanStack.pop());
      } else if (tagName === 'em') {
        append("''");
      } else if (tagName === 'strong') {
        append("'''");
      } else if (tagName === 'u') {
        append("__");
      } else if (tagName === 's') {
        append("~~");
      }
    },
    ontext: function (text) {
      text = text.replace(/—/g, '---');
      text = text.replace(/–/g, '--');
      append(text);
    },
  });
  return chunks.join('');
}
function getThread() {
  var ps = document.location.pathname.split('/');
  var opNode = document.querySelector('.post .body');
  var opHash = nacl.util.encodeBase64(nacl.hash(nacl.util.decodeUTF8(reverseFormatNode(opNode))));
  var board = ps[1];
  var threadId = ps[3].split('.')[0];
  return {board: board, id: threadId, opHash: opHash};
}
function encodeMessage(thread, ts, msg) {
  var text = [
    "Board: " + thread.board,
    "ThreadId: " + thread.id,
    "OP: " + thread.opHash,
    "TS: " + ts,
    msg
  ].join('\n');
  console.log(text);
  return nacl.util.decodeUTF8(text);
}
function checkPost(thread, node) {
  var ranges = [], range, msg;
  var cs = node.childNodes;
  for (var i = 0; i < cs.length; ++i) {
    var line = reverseFormatNode(cs[i]);
    if (range) {
      md = /^\*\*END SIG ([0-9A-Za-z+/]+=*)\*\*/.exec(line);
      if (md) {
        range.last = i;
        range.sig = md[1];
        range.msg = msg;
        ranges.push(range);
        range = undefined;
      } else {
        msg.push(line);
      }
    } else {
      md = /^\*\*BEGIN SIG ([0-9]+) ([0-9A-Za-z+/]+=*)\*\*/.exec(line);
      if (md) {
        range = {first: i, ts: md[1], pub: md[2]};
        msg = [];
      }
    }
  }
  for (var i = ranges.length - 1; i >= 0; i--) {
    var range = ranges[i];
    var text = encodeMessage(thread, range.ts, range.msg.join(''));
    var sigOk = nacl.sign.detached.verify(
      text,
      nacl.util.decodeBase64(range.sig),
      nacl.util.decodeBase64(range.pub));
    // Remove the END line
    node.removeChild(cs[range.last]);
    // Replace the BEGIN line with a DIV
    var div = document.createElement("div");
    if (sigOk) {
      div.className = "signed-message signature-good";
      $(div).append("<p class='body-line ltr'>Good signature by <span class='public-key'>"
        + range.pub + "</span></p>");
    } else {
      div.className = "signed-message signature-bad";
      $(div).append("<p class='body-line ltr'>Signature could not be verified.</p>");
    }
    node.replaceChild(div, cs[range.first]);
    // Move the message lines into the DIV
    for (var j = range.first + 1; j < range.last; j++) {
      div.appendChild(cs[range.first + 1]);
    }
  }
}
function checkSignatures() {
  var thread = getThread();
  $('.post .body').each(function (i, el) { checkPost(thread, el); });
}
function signPostBody() {
  var ts = new Date().getTime().toString();
  var msg = $('#body').val() + "\n";
  var text = encodeMessage(getThread(), ts, msg);
  var sig = nacl.util.encodeBase64(nacl.sign.detached(text, nacl.util.decodeBase64(window.localStorage.secretKey)));
  $('#body').val(`**BEGIN SIG ${ts} ${window.localStorage.publicKey}**\n${msg}**END SIG ${sig}**\n`);
}
$(function(){
  if (!window.localStorage.secretKey) {
    var keys = nacl.sign.keyPair();
    window.localStorage.secretKey = nacl.util.encodeBase64(keys.secretKey);
    window.localStorage.publicKey = nacl.util.encodeBase64(keys.publicKey);
  }
  $(document.head).append(`<style>
    .signed-message { padding: 2px; }
    .signed-message.signature-good { border: 2px solid green; }
    .signed-message.signature-bad { border: 2px solid red; }
    span.public-key { font-family: monospace; font-size: 80%; color: #181; }
  </style>`);
  $('#post-form-inner tr:nth(2) td').append('<input id="sign-button" accesskey="i" style="margin-left:2px;" type="button" name="sign" value="Sign">');
  $('#sign-button').on('click', signPostBody);
  $(document).on('new_post', checkSignatures);
  checkSignatures();
});
}();