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89 lines
2.5 KiB
TypeScript
89 lines
2.5 KiB
TypeScript
// Copyright 2018-2024 the Deno authors. All rights reserved. MIT license.
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// This module is browser compatible.
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/**
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* Utilities for
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* {@link https://www.rfc-editor.org/rfc/rfc4648.html#section-5 | base64url}
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* encoding and decoding.
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*
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* @module
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*/
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import * as base64 from "./base64.ts";
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/**
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* Some variants allow or require omitting the padding '=' signs:
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* https://en.wikipedia.org/wiki/Base64#The_URL_applications
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*
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* @param base64url
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*/
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function addPaddingToBase64url(base64url: string): string {
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if (base64url.length % 4 === 2) return base64url + "==";
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if (base64url.length % 4 === 3) return base64url + "=";
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if (base64url.length % 4 === 1) {
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throw new TypeError("Illegal base64url string");
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}
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return base64url;
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}
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function convertBase64urlToBase64(b64url: string): string {
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if (!/^[-_A-Z0-9]*?={0,2}$/i.test(b64url)) {
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// Contains characters not part of base64url spec.
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throw new TypeError("Failed to decode base64url: invalid character");
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}
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return addPaddingToBase64url(b64url).replace(/\-/g, "+").replace(/_/g, "/");
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}
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function convertBase64ToBase64url(b64: string) {
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return b64.endsWith("=")
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? b64.endsWith("==")
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? b64.replace(/\+/g, "-").replace(/\//g, "_").slice(0, -2)
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: b64.replace(/\+/g, "-").replace(/\//g, "_").slice(0, -1)
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: b64.replace(/\+/g, "-").replace(/\//g, "_");
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}
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/**
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* Convert data into a base64url-encoded string.
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*
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* @see {@link https://www.rfc-editor.org/rfc/rfc4648.html#section-5}
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*
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* @param data The data to encode.
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* @returns The base64url-encoded string.
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*
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* @example Usage
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* ```ts
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* import { encodeBase64Url } from "@std/encoding/base64url";
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* import { assertEquals } from "@std/assert";
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*
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* assertEquals(encodeBase64Url("foobar"), "Zm9vYmFy");
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* ```
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*/
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export function encodeBase64Url(
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data: ArrayBuffer | Uint8Array | string,
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): string {
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return convertBase64ToBase64url(base64.encodeBase64(data));
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}
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/**
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* Decodes a given base64url-encoded string.
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*
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* @see {@link https://www.rfc-editor.org/rfc/rfc4648.html#section-5}
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*
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* @param b64url The base64url-encoded string to decode.
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* @returns The decoded data.
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*
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* @example Usage
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* ```ts
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* import { decodeBase64Url } from "@std/encoding/base64url";
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* import { assertEquals } from "@std/assert";
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*
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* assertEquals(
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* decodeBase64Url("Zm9vYmFy"),
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* new TextEncoder().encode("foobar")
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* );
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* ```
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*/
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export function decodeBase64Url(b64url: string): Uint8Array {
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return base64.decodeBase64(convertBase64urlToBase64(b64url));
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}
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