JavaScript: Decrypt content of GnuPG encrypted files using openpgp.js
Question
I'm trying to write a sample decryptor for GnuPG encrypted files in JavaScript using openpgp.js .
So I tried it naively without even asking if it is even possible. I made the following page.
popup.html
<!doctype html>
<!--
-->
<html>
<head>
<title>Popup</title>
<script src="openpgp.js"></script>
<script src="popup.js"></script>
</head>
<body>
<p>Upload message: </p><input id="message" type="file"/><br>
<p>Upload secret key: </p><input id="secret" type="file"/><br>
<p>Secret key password: </p><input id="password" type="password"/><br><br>
<button id="decrypt">Decrypt</button>
<p id="output"></p>
<div id="loadingDiv"></div>
</body>
</html>
popup.js
var message = "";
var secret = "";
function readMessage (e) {
var file = e.target.files[0];
if (!file) {
message = "";
}
var reader = new FileReader();
reader.onload = function (e) {
message = e.target.result;
};
reader.readAsText (file);
}
function readSecret (e) {
var file = e.target.files[0];
if (!file) {
secret = "";
}
var reader = new FileReader();
reader.onload = function (e) {
secret = e.target.result;
};
reader.readAsText (file);
}
function loadScript(url, callback)
{
var head = document.getElementsByTagName ("head")[0];
var script = document.createElement ("script");
script.type = "text/javascript";
script.src = url;
script.onreadystatechange = callback;
script.onload = callback;
head.appendChild(script);
}
document.addEventListener ("DOMContentLoaded", function() {
document.getElementById ("message").addEventListener("change", readMessage, false);
document.getElementById ("secret").addEventListener("change", readSecret, false);
var gen = function() {
document.getElementById ("decrypt").addEventListener ("click", function() {
var output = document.getElementById ("output");
output.style.color = "black";
if (document.getElementById ("message").value == "") {
output.innerHTML = "No message provided";
output.style.color = "red";
}
else if (document.getElementById ("secret").value == "") {
output.innerHTML = "No secret key provided";
output.style.color = "red";
}
else if (document.getElementById ("password").value == "") {
output.innerHTML = "No password for secret key provided";
output.style.color = "red";
}
else {
var privateKey = openpgp.key.readArmored (secret).keys[0];
var isCorrect = privateKey.decrypt (document.getElementById ("password").value);
if (isCorrect) {
output.innerHTML = "";
output.style.color = "black";
var img = document.createElement ("img");
img.src = "loading.gif";
img.id = "loading";
document.getElementById ("loadingDiv").appendChild (img);
message = openpgp.message.readArmored (message);
openpgp.decryptMessage (privateKey, message).then (function (plaintext) {
output.innerHTML = plaintext;
}).catch (function(error) {
output.innerHTML = "Error while decrypting";
output.style.color = "red";
});
}
else {
output.innerHTML = "Incorrect password";
output.style.color = "red";
}
}
});
}
loadScript ("openpgp.js", gen);
});
openpgp.js gives an Unknown ASCII armor type error on message = openpgp.message.readArmored (message); .
So is it possible? If it is, should I do something different?
2 answers
solution1
2 2015-11-13 10:24:32
OpenPGP knows to encodings of messages,
- binary messages , which are more space-efficient and
- ASCII-armored messages encoded in a format similar to base64, providing higher reliability when transmitted through different channels as being plain text.
openpgp.message.readArmored (message) only understands ASCII-armored information. use openpgp.message.fromBinary (message) instead. As an alternative, encode the message through GnuPG using the --armor option while encrypting, or gpg --enarmor an already encrypted binary message.
solution2
0 2018-05-09 00:25:32
With Openpgpjs version 3.x, I found that a private key object has to be created and used with the publicKey and message in the options variable. The private key object is created with the private key. First create the private key object, then decrypt it with your "secret" phrase, and then decrypt the message.
Here's an example using your variables.
privKeyObj.decrypt(secret).then(function(oBoolean) {
//Name oBoolean anything you want.
//It will be true or false indicating
//whether the secret phrase is right.
if(!oBoolean) {
output.innerHTML = "Incorrect password.";
output.style.color = "red";
}
else {
var privateKey = "your openpgpjs private key created with your secret phrase";
var privKeyObj = openpgp.key.readArmored(privateKey).keys[0];
var options = {
message: openpgp.message.readArmored(message),
publicKeys: openpgp.key.readArmored(publickey).keys,
privateKeys: [privKeyObj]
};
openpgp.decrypt(options).then(function(plaintext) {
output.innerHTML = plaintext.data;
}, function(error) {
output.innerHTML = "Error while decrypting";
output.style.color = "red";
});
}
});
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