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/**
* Base64 Encodes an arraybuffer
* @param {ArrayBuffer} arraybuffer
* @returns {string}
*/
export function encode64(arraybuffer) {
const dv = new DataView(arraybuffer);
let binaryString = "";
for (let i = 0; i < arraybuffer.byteLength; i++) {
binaryString += String.fromCharCode(dv.getUint8(i));
}
return binaryToAscii(binaryString);
}
/**
* Decodes a base64 string into an arraybuffer
* @param {string} string
* @returns {ArrayBuffer}
*/
export function decode64(string) {
const binaryString = asciiToBinary(string);
const arraybuffer = new ArrayBuffer(binaryString.length);
const dv = new DataView(arraybuffer);
for (let i = 0; i < arraybuffer.byteLength; i++) {
dv.setUint8(i, binaryString.charCodeAt(i));
}
return arraybuffer;
}
const KEY_STRING =
"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
/**
* Substitute for atob since it's deprecated in node.
* Does not do any input validation.
*
* @see https://github.com/jsdom/abab/blob/master/lib/atob.js
*
* @param {string} data
* @returns {string}
*/
function asciiToBinary(data) {
if (data.length % 4 === 0) {
data = data.replace(/==?$/, "");
}
let output = "";
let buffer = 0;
let accumulatedBits = 0;
for (let i = 0; i < data.length; i++) {
buffer <<= 6;
buffer |= KEY_STRING.indexOf(data[i]);
accumulatedBits += 6;
if (accumulatedBits === 24) {
output += String.fromCharCode((buffer & 0xff0000) >> 16);
output += String.fromCharCode((buffer & 0xff00) >> 8);
output += String.fromCharCode(buffer & 0xff);
buffer = accumulatedBits = 0;
}
}
if (accumulatedBits === 12) {
buffer >>= 4;
output += String.fromCharCode(buffer);
} else if (accumulatedBits === 18) {
buffer >>= 2;
output += String.fromCharCode((buffer & 0xff00) >> 8);
output += String.fromCharCode(buffer & 0xff);
}
return output;
}
/**
* Substitute for btoa since it's deprecated in node.
* Does not do any input validation.
*
* @see https://github.com/jsdom/abab/blob/master/lib/btoa.js
*
* @param {string} str
* @returns {string}
*/
function binaryToAscii(str) {
let out = "";
for (let i = 0; i < str.length; i += 3) {
/** @type {[number, number, number, number]} */
const groupsOfSix = [undefined, undefined, undefined, undefined];
groupsOfSix[0] = str.charCodeAt(i) >> 2;
groupsOfSix[1] = (str.charCodeAt(i) & 0x03) << 4;
if (str.length > i + 1) {
groupsOfSix[1] |= str.charCodeAt(i + 1) >> 4;
groupsOfSix[2] = (str.charCodeAt(i + 1) & 0x0f) << 2;
}
if (str.length > i + 2) {
groupsOfSix[2] |= str.charCodeAt(i + 2) >> 6;
groupsOfSix[3] = str.charCodeAt(i + 2) & 0x3f;
}
for (let j = 0; j < groupsOfSix.length; j++) {
if (typeof groupsOfSix[j] === "undefined") {
out += "=";
} else {
out += KEY_STRING[groupsOfSix[j]];
}
}
}
return out;
}
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