Add Base64url encoder and decoder

src/util/base64/__tests__/decode-base64url.spec.ts

@@ -0,0 +1,20 @@
+import {toBase64} from '../toBase64';
+import {fromBase64Url} from '../fromBase64Url';
+
+const generateBlob = (): Uint8Array => {
+  const length = Math.floor(Math.random() * 100);
+  const uint8 = new Uint8Array(length);
+  for (let i = 0; i < length; i++) {
+    uint8[i] = Math.floor(Math.random() * 256);
+  }
+  return uint8;
+};
+
+test('works', () => {
+  for (let i = 0; i < 100; i++) {
+    const blob = generateBlob();
+    const encoded = toBase64(blob).replace(/\+/g, '-').replace(/\//g, '_').replace(/=+$/, '');
+    const decoded2 = fromBase64Url(encoded);
+    expect(decoded2).toEqual(blob);
+  }
+});

src/util/base64/__tests__/encode-base64url.spec.ts

@@ -0,0 +1,23 @@
+import {toBase64Url} from '../toBase64Url';
+
+const generateBlob = (): Uint8Array => {
+  const length = Math.floor(Math.random() * 100) + 1;
+  const uint8 = new Uint8Array(length);
+  for (let i = 0; i < length; i++) {
+    uint8[i] = Math.floor(Math.random() * 256);
+  }
+  return uint8;
+};
+
+test('works', () => {
+  for (let i = 0; i < 100; i++) {
+    const blob = generateBlob();
+    const expected = Buffer.from(blob).toString('base64');
+    const base64url = toBase64Url(blob, blob.length);
+    let encoded = base64url.replace(/-/g, '+').replace(/_/g, '/');
+    const mod = encoded.length % 4;
+    if (mod === 2) encoded += '==';
+    else if (mod === 3) encoded += '=';
+    expect(encoded).toEqual(expected);
+  }
+});

src/util/base64/createFromBase64.ts

@@ -2,7 +2,7 @@ import {alphabet} from './constants';
 
 const E = '=';
 
-export const createFromBase64 = (chars: string = alphabet) => {
+export const createFromBase64 = (chars: string = alphabet, noPadding: boolean = false) => {
   if (chars.length !== 64) throw new Error('chars must be 64 characters long');
   let max = 0;
   for (let i = 0; i < chars.length; i++) max = Math.max(max, chars.charCodeAt(i));
@@ -12,7 +12,17 @@ export const createFromBase64 = (chars: string = alphabet) => {
 
   return (encoded: string): Uint8Array => {
     if (!encoded) return new Uint8Array(0);
-    const length = encoded.length;
+    let length = encoded.length;
+    if (noPadding) {
+      const mod = length % 4;
+      if (mod === 2) {
+        encoded += '==';
+        length += 2;
+      } else if (mod === 3) {
+        encoded += '=';
+        length += 1;
+      }
+    }
     if (length % 4 !== 0) throw new Error('Base64 string length must be a multiple of 4');
     const mainLength = encoded[length - 1] !== E ? length : length - 4;
     let bufferLength = (length >> 2) * 3;

src/util/base64/createToBase64.ts

@@ -1,9 +1,6 @@
 import {alphabet} from './constants';
 
-const E = '=';
-const EE = '==';
-
-export const createToBase64 = (chars: string = alphabet) => {
+export const createToBase64 = (chars: string = alphabet, E: string = '=', EE: string = '==') => {
   if (chars.length !== 64) throw new Error('chars must be 64 characters long');
 
   const table = chars.split('');

src/util/base64/fromBase64Url.ts

@@ -0,0 +1,3 @@
+import {createFromBase64} from './createFromBase64';
+
+export const fromBase64Url = createFromBase64('ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_', true);

src/util/base64/toBase64Url.ts

@@ -0,0 +1,3 @@
+import {createToBase64} from './createToBase64';
+
+export const toBase64Url = createToBase64('ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_', '', '');