Node JS version

node_modules/adm-zip/methods/zipcrypto.js

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+"use strict";
+
+// node crypt, we use it for generate salt
+// eslint-disable-next-line node/no-unsupported-features/node-builtins
+const { randomFillSync } = require("crypto");
+
+// generate CRC32 lookup table
+const crctable = new Uint32Array(256).map((t, crc) => {
+    for (let j = 0; j < 8; j++) {
+        if (0 !== (crc & 1)) {
+            crc = (crc >>> 1) ^ 0xedb88320;
+        } else {
+            crc >>>= 1;
+        }
+    }
+    return crc >>> 0;
+});
+
+// C-style uInt32 Multiply (discards higher bits, when JS multiply discards lower bits)
+const uMul = (a, b) => Math.imul(a, b) >>> 0;
+
+// crc32 byte single update (actually same function is part of utils.crc32 function :) )
+const crc32update = (pCrc32, bval) => {
+    return crctable[(pCrc32 ^ bval) & 0xff] ^ (pCrc32 >>> 8);
+};
+
+// function for generating salt for encrytion header
+const genSalt = () => {
+    if ("function" === typeof randomFillSync) {
+        return randomFillSync(Buffer.alloc(12));
+    } else {
+        // fallback if function is not defined
+        return genSalt.node();
+    }
+};
+
+// salt generation with node random function (mainly as fallback)
+genSalt.node = () => {
+    const salt = Buffer.alloc(12);
+    const len = salt.length;
+    for (let i = 0; i < len; i++) salt[i] = (Math.random() * 256) & 0xff;
+    return salt;
+};
+
+// general config
+const config = {
+    genSalt
+};
+
+// Class Initkeys handles same basic ops with keys
+function Initkeys(pw) {
+    const pass = Buffer.isBuffer(pw) ? pw : Buffer.from(pw);
+    this.keys = new Uint32Array([0x12345678, 0x23456789, 0x34567890]);
+    for (let i = 0; i < pass.length; i++) {
+        this.updateKeys(pass[i]);
+    }
+}
+
+Initkeys.prototype.updateKeys = function (byteValue) {
+    const keys = this.keys;
+    keys[0] = crc32update(keys[0], byteValue);
+    keys[1] += keys[0] & 0xff;
+    keys[1] = uMul(keys[1], 134775813) + 1;
+    keys[2] = crc32update(keys[2], keys[1] >>> 24);
+    return byteValue;
+};
+
+Initkeys.prototype.next = function () {
+    const k = (this.keys[2] | 2) >>> 0; // key
+    return (uMul(k, k ^ 1) >> 8) & 0xff; // decode
+};
+
+function make_decrypter(/*Buffer*/ pwd) {
+    // 1. Stage initialize key
+    const keys = new Initkeys(pwd);
+
+    // return decrypter function
+    return function (/*Buffer*/ data) {
+        // result - we create new Buffer for results
+        const result = Buffer.alloc(data.length);
+        let pos = 0;
+        // process input data
+        for (let c of data) {
+            //c ^= keys.next();
+            //result[pos++] = c; // decode & Save Value
+            result[pos++] = keys.updateKeys(c ^ keys.next()); // update keys with decoded byte
+        }
+        return result;
+    };
+}
+
+function make_encrypter(/*Buffer*/ pwd) {
+    // 1. Stage initialize key
+    const keys = new Initkeys(pwd);
+
+    // return encrypting function, result and pos is here so we dont have to merge buffers later
+    return function (/*Buffer*/ data, /*Buffer*/ result, /* Number */ pos = 0) {
+        // result - we create new Buffer for results
+        if (!result) result = Buffer.alloc(data.length);
+        // process input data
+        for (let c of data) {
+            const k = keys.next(); // save key byte
+            result[pos++] = c ^ k; // save val
+            keys.updateKeys(c); // update keys with decoded byte
+        }
+        return result;
+    };
+}
+
+function decrypt(/*Buffer*/ data, /*Object*/ header, /*String, Buffer*/ pwd) {
+    if (!data || !Buffer.isBuffer(data) || data.length < 12) {
+        return Buffer.alloc(0);
+    }
+
+    // 1. We Initialize and generate decrypting function
+    const decrypter = make_decrypter(pwd);
+
+    // 2. decrypt salt what is always 12 bytes and is a part of file content
+    const salt = decrypter(data.slice(0, 12));
+
+    // 3. does password meet expectations
+    if (salt[11] !== header.crc >>> 24) {
+        throw "ADM-ZIP: Wrong Password";
+    }
+
+    // 4. decode content
+    return decrypter(data.slice(12));
+}
+
+// lets add way to populate salt, NOT RECOMMENDED for production but maybe useful for testing general functionality
+function _salter(data) {
+    if (Buffer.isBuffer(data) && data.length >= 12) {
+        // be aware - currently salting buffer data is modified
+        config.genSalt = function () {
+            return data.slice(0, 12);
+        };
+    } else if (data === "node") {
+        // test salt generation with node random function
+        config.genSalt = genSalt.node;
+    } else {
+        // if value is not acceptable config gets reset.
+        config.genSalt = genSalt;
+    }
+}
+
+function encrypt(/*Buffer*/ data, /*Object*/ header, /*String, Buffer*/ pwd, /*Boolean*/ oldlike = false) {
+    // 1. test data if data is not Buffer we make buffer from it
+    if (data == null) data = Buffer.alloc(0);
+    // if data is not buffer be make buffer from it
+    if (!Buffer.isBuffer(data)) data = Buffer.from(data.toString());
+
+    // 2. We Initialize and generate encrypting function
+    const encrypter = make_encrypter(pwd);
+
+    // 3. generate salt (12-bytes of random data)
+    const salt = config.genSalt();
+    salt[11] = (header.crc >>> 24) & 0xff;
+
+    // old implementations (before PKZip 2.04g) used two byte check
+    if (oldlike) salt[10] = (header.crc >>> 16) & 0xff;
+
+    // 4. create output
+    const result = Buffer.alloc(data.length + 12);
+    encrypter(salt, result);
+
+    // finally encode content
+    return encrypter(data, result, 12);
+}
+
+module.exports = { decrypt, encrypt, _salter };