cyberchef
Version:
The Cyber Swiss Army Knife for encryption, encoding, compression and data analysis.
174 lines (154 loc) • 7.6 kB
JavaScript
/**
* @author n1474335 [n1474335@gmail.com]
* @copyright Crown Copyright 2016
* @license Apache-2.0
*/
import Operation from "../Operation.mjs";
import Utils from "../Utils.mjs";
import {fromBase64, toBase64} from "../lib/Base64.mjs";
import OperationError from "../errors/OperationError.mjs";
/**
* Show Base64 offsets operation
*/
class ShowBase64Offsets extends Operation {
/**
* ShowBase64Offsets constructor
*/
constructor() {
super();
this.name = "Show Base64 offsets";
this.module = "Default";
this.description = "When a string is within a block of data and the whole block is Base64'd, the string itself could be represented in Base64 in three distinct ways depending on its offset within the block.<br><br>This operation shows all possible offsets for a given string so that each possible encoding can be considered.";
this.infoURL = "https://wikipedia.org/wiki/Base64#Output_padding";
this.inputType = "byteArray";
this.outputType = "html";
this.args = [
{
name: "Alphabet",
type: "binaryString",
value: "A-Za-z0-9+/="
},
{
name: "Show variable chars and padding",
type: "boolean",
value: true
},
{
name: "Input format",
type: "option",
value: ["Raw", "Base64"]
}
];
}
/**
* @param {byteArray} input
* @param {Object[]} args
* @returns {html}
*/
run(input, args) {
const [alphabet, showVariable, format] = args;
if (format === "Base64") {
input = fromBase64(Utils.byteArrayToUtf8(input), null, "byteArray");
}
let offset0 = toBase64(input, alphabet),
offset1 = toBase64([0].concat(input), alphabet),
offset2 = toBase64([0, 0].concat(input), alphabet),
staticSection = "",
padding = "";
const len0 = offset0.indexOf("="),
len1 = offset1.indexOf("="),
len2 = offset2.indexOf("="),
script = "<script type='application/javascript'>$('[data-toggle=\"tooltip\"]').tooltip()</script>";
if (input.length < 1) {
throw new OperationError("Please enter a string.");
}
// Highlight offset 0
if (len0 % 4 === 2) {
staticSection = offset0.slice(0, -3);
offset0 = "<span data-toggle='tooltip' data-placement='top' title='" +
Utils.escapeHtml(fromBase64(staticSection, alphabet).slice(0, -2)) + "'>" +
staticSection + "</span>" +
"<span class='hl5'>" + offset0.substr(offset0.length - 3, 1) + "</span>" +
"<span class='hl3'>" + offset0.substr(offset0.length - 2) + "</span>";
} else if (len0 % 4 === 3) {
staticSection = offset0.slice(0, -2);
offset0 = "<span data-toggle='tooltip' data-placement='top' title='" +
Utils.escapeHtml(fromBase64(staticSection, alphabet).slice(0, -1)) + "'>" +
staticSection + "</span>" +
"<span class='hl5'>" + offset0.substr(offset0.length - 2, 1) + "</span>" +
"<span class='hl3'>" + offset0.substr(offset0.length - 1) + "</span>";
} else {
staticSection = offset0;
offset0 = "<span data-toggle='tooltip' data-placement='top' title='" +
Utils.escapeHtml(fromBase64(staticSection, alphabet)) + "'>" +
staticSection + "</span>";
}
if (!showVariable) {
offset0 = staticSection;
}
// Highlight offset 1
padding = "<span class='hl3'>" + offset1.substr(0, 1) + "</span>" +
"<span class='hl5'>" + offset1.substr(1, 1) + "</span>";
offset1 = offset1.substr(2);
if (len1 % 4 === 2) {
staticSection = offset1.slice(0, -3);
offset1 = padding + "<span data-toggle='tooltip' data-placement='top' title='" +
Utils.escapeHtml(fromBase64("AA" + staticSection, alphabet).slice(1, -2)) + "'>" +
staticSection + "</span>" +
"<span class='hl5'>" + offset1.substr(offset1.length - 3, 1) + "</span>" +
"<span class='hl3'>" + offset1.substr(offset1.length - 2) + "</span>";
} else if (len1 % 4 === 3) {
staticSection = offset1.slice(0, -2);
offset1 = padding + "<span data-toggle='tooltip' data-placement='top' title='" +
Utils.escapeHtml(fromBase64("AA" + staticSection, alphabet).slice(1, -1)) + "'>" +
staticSection + "</span>" +
"<span class='hl5'>" + offset1.substr(offset1.length - 2, 1) + "</span>" +
"<span class='hl3'>" + offset1.substr(offset1.length - 1) + "</span>";
} else {
staticSection = offset1;
offset1 = padding + "<span data-toggle='tooltip' data-placement='top' title='" +
Utils.escapeHtml(fromBase64("AA" + staticSection, alphabet).slice(1)) + "'>" +
staticSection + "</span>";
}
if (!showVariable) {
offset1 = staticSection;
}
// Highlight offset 2
padding = "<span class='hl3'>" + offset2.substr(0, 2) + "</span>" +
"<span class='hl5'>" + offset2.substr(2, 1) + "</span>";
offset2 = offset2.substr(3);
if (len2 % 4 === 2) {
staticSection = offset2.slice(0, -3);
offset2 = padding + "<span data-toggle='tooltip' data-placement='top' title='" +
Utils.escapeHtml(fromBase64("AAA" + staticSection, alphabet).slice(2, -2)) + "'>" +
staticSection + "</span>" +
"<span class='hl5'>" + offset2.substr(offset2.length - 3, 1) + "</span>" +
"<span class='hl3'>" + offset2.substr(offset2.length - 2) + "</span>";
} else if (len2 % 4 === 3) {
staticSection = offset2.slice(0, -2);
offset2 = padding + "<span data-toggle='tooltip' data-placement='top' title='" +
Utils.escapeHtml(fromBase64("AAA" + staticSection, alphabet).slice(2, -2)) + "'>" +
staticSection + "</span>" +
"<span class='hl5'>" + offset2.substr(offset2.length - 2, 1) + "</span>" +
"<span class='hl3'>" + offset2.substr(offset2.length - 1) + "</span>";
} else {
staticSection = offset2;
offset2 = padding + "<span data-toggle='tooltip' data-placement='top' title='" +
Utils.escapeHtml(fromBase64("AAA" + staticSection, alphabet).slice(2)) + "'>" +
staticSection + "</span>";
}
if (!showVariable) {
offset2 = staticSection;
}
return (showVariable ? "Characters highlighted in <span class='hl5'>green</span> could change if the input is surrounded by more data." +
"\nCharacters highlighted in <span class='hl3'>red</span> are for padding purposes only." +
"\nUnhighlighted characters are <span data-toggle='tooltip' data-placement='top' title='Tooltip on left'>static</span>." +
"\nHover over the static sections to see what they decode to on their own.\n" +
"\nOffset 0: " + offset0 +
"\nOffset 1: " + offset1 +
"\nOffset 2: " + offset2 +
script :
offset0 + "\n" + offset1 + "\n" + offset2);
}
}
export default ShowBase64Offsets;