tilde-oauth/base64url.js

31 lines
1.1 KiB
JavaScript

// adapted from https://tools.ietf.org/html/draft-ietf-jose-json-web-signature-08#appendix-C
function base64urlEncode(arg) {
const step1 = window.btoa(arg); // Regular base64 encoder
const step2 = step1.split("=")[0]; // Remove any trailing '='s
const step3 = step2.replace(/\+/g, "-"); // 62nd char of encoding
const step4 = step3.replace(/\//g, "_"); // 63rd char of encoding
return step4;
}
function base64urlDecode(s) {
const step1 = s.replace(/-/g, "+"); // 62nd char of encoding
const step2 = step1.replace(/_/g, "/"); // 63rd char of encoding
let step3 = step2;
switch (step2.length % 4) { // Pad with trailing '='s
case 0: // No pad chars in this case
break;
case 2: // Two pad chars
step3 += "==";
break;
case 3: // One pad char
step3 += "=";
break;
default:
throw new Error("Illegal base64url string!");
}
return window.atob(step3); // Regular base64 decoder
}
const module = window.module || {};
module.exports = { base64urlDecode, base64urlEncode };