ES6 DES implementation (with PKCS7 padding)

DES.js

export default class DES {

    _initial_permutation = [
        58, 50, 42, 34, 26, 18, 10, 2,
        60, 52, 44, 36, 28, 20, 12, 4,
        62, 54, 46, 38, 30, 22, 14, 6,
        64, 56, 48, 40, 32, 24, 16, 8,
        57, 49, 41, 33, 25, 17, 9, 1,
        59, 51, 43, 35, 27, 19, 11, 3,
        61, 53, 45, 37, 29, 21, 13, 5,
        63, 55, 47, 39, 31, 23, 15, 7
    ]

    _final_permutation = [
        40, 8, 48, 16, 56, 24, 64, 32,
        39, 7, 47, 15, 55, 23, 63, 31,
        38, 6, 46, 14, 54, 22, 62, 30,
        37, 5, 45, 13, 53, 21, 61, 29,
        36, 4, 44, 12, 52, 20, 60, 28,
        35, 3, 43, 11, 51, 19, 59, 27,
        34, 2, 42, 10, 50, 18, 58, 26,
        33, 1, 41, 9, 49, 17, 57, 25
    ]

    _expansion_function = [
        32, 1, 2, 3, 4, 5,
        4, 5, 6, 7, 8, 9,
        8, 9, 10, 11, 12, 13,
        12, 13, 14, 15, 16, 17,
        16, 17, 18, 19, 20, 21,
        20, 21, 22, 23, 24, 25,
        24, 25, 26, 27, 28, 29,
        28, 29, 30, 31, 32, 1
    ]

    _permutation = [
        16, 7, 20, 21, 29, 12, 28, 17,
        1, 15, 23, 26, 5, 18, 31, 10,
        2, 8, 24, 14, 32, 27, 3, 9,
        19, 13, 30, 6, 22, 11, 4, 25
    ]

    _pc1 = [
        57, 49, 41, 33, 25, 17, 9,
        1, 58, 50, 42, 34, 26, 18,
        10, 2, 59, 51, 43, 35, 27,
        19, 11, 3, 60, 52, 44, 36,
        63, 55, 47, 39, 31, 23, 15,
        7, 62, 54, 46, 38, 30, 22,
        14, 6, 61, 53, 45, 37, 29,
        21, 13, 5, 28, 20, 12, 4
    ]

    _pc2 = [
        14, 17, 11, 24, 1, 5,
        3, 28, 15, 6, 21, 10,
        23, 19, 12, 4, 26, 8,
        16, 7, 27, 20, 13, 2,
        41, 52, 31, 37, 47, 55,
        30, 40, 51, 45, 33, 48,
        44, 49, 39, 56, 34, 53,
        46, 42, 50, 36, 29, 32
    ]

    _left_rotations = [
        1, 1, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 1
    ]

    _sbox = [
        // S1
        [
            [14, 4, 13, 1, 2, 15, 11, 8, 3, 10, 6, 12, 5, 9, 0, 7],
            [0, 15, 7, 4, 14, 2, 13, 1, 10, 6, 12, 11, 9, 5, 3, 8],
            [4, 1, 14, 8, 13, 6, 2, 11, 15, 12, 9, 7, 3, 10, 5, 0],
            [15, 12, 8, 2, 4, 9, 1, 7, 5, 11, 3, 14, 10, 0, 6, 13]
        ],

        // S2
        [
            [15, 1, 8, 14, 6, 11, 3, 4, 9, 7, 2, 13, 12, 0, 5, 10],
            [3, 13, 4, 7, 15, 2, 8, 14, 12, 0, 1, 10, 6, 9, 11, 5],
            [0, 14, 7, 11, 10, 4, 13, 1, 5, 8, 12, 6, 9, 3, 2, 15],
            [13, 8, 10, 1, 3, 15, 4, 2, 11, 6, 7, 12, 0, 5, 14, 9]
        ],

        // S3
        [
            [10, 0, 9, 14, 6, 3, 15, 5, 1, 13, 12, 7, 11, 4, 2, 8],
            [13, 7, 0, 9, 3, 4, 6, 10, 2, 8, 5, 14, 12, 11, 15, 1],
            [13, 6, 4, 9, 8, 15, 3, 0, 11, 1, 2, 12, 5, 10, 14, 7],
            [1, 10, 13, 0, 6, 9, 8, 7, 4, 15, 14, 3, 11, 5, 2, 12]
        ],

        // S4
        [
            [7, 13, 14, 3, 0, 6, 9, 10, 1, 2, 8, 5, 11, 12, 4, 15],
            [13, 8, 11, 5, 6, 15, 0, 3, 4, 7, 2, 12, 1, 10, 14, 9],
            [10, 6, 9, 0, 12, 11, 7, 13, 15, 1, 3, 14, 5, 2, 8, 4],
            [3, 15, 0, 6, 10, 1, 13, 8, 9, 4, 5, 11, 12, 7, 2, 14]
        ],

        // S5
        [
            [2, 12, 4, 1, 7, 10, 11, 6, 8, 5, 3, 15, 13, 0, 14, 9],
            [14, 11, 2, 12, 4, 7, 13, 1, 5, 0, 15, 10, 3, 9, 8, 6],
            [4, 2, 1, 11, 10, 13, 7, 8, 15, 9, 12, 5, 6, 3, 0, 14],
            [11, 8, 12, 7, 1, 14, 2, 13, 6, 15, 0, 9, 10, 4, 5, 3]
        ],

        // S6
        [
            [12, 1, 10, 15, 9, 2, 6, 8, 0, 13, 3, 4, 14, 7, 5, 11],
            [10, 15, 4, 2, 7, 12, 9, 5, 6, 1, 13, 14, 0, 11, 3, 8],
            [9, 14, 15, 5, 2, 8, 12, 3, 7, 0, 4, 10, 1, 13, 11, 6],
            [4, 3, 2, 12, 9, 5, 15, 10, 11, 14, 1, 7, 6, 0, 8, 13]
        ],

        // S7
        [
            [4, 11, 2, 14, 15, 0, 8, 13, 3, 12, 9, 7, 5, 10, 6, 1],
            [13, 0, 11, 7, 4, 9, 1, 10, 14, 3, 5, 12, 2, 15, 8, 6],
            [1, 4, 11, 13, 12, 3, 7, 14, 10, 15, 6, 8, 0, 5, 9, 2],
            [6, 11, 13, 8, 1, 4, 10, 7, 9, 5, 0, 15, 14, 2, 3, 12]
        ],

        // S8
        [
            [13, 2, 8, 4, 6, 15, 11, 1, 10, 9, 3, 14, 5, 0, 12, 7],
            [1, 15, 13, 8, 10, 3, 7, 4, 12, 5, 6, 11, 0, 14, 9, 2],
            [7, 11, 4, 1, 9, 12, 14, 2, 0, 6, 10, 13, 15, 3, 5, 8],
            [2, 1, 14, 7, 4, 10, 8, 13, 15, 12, 9, 0, 3, 5, 6, 11]
        ]
    ]

    constructor(key) {
        this.key = key;
    }

    encrypt(message) {
        let padded = this.pkcs7Padding(message),
            result = [];

        for (let block of padded) {
            result = result.concat(this.encrypt64bit(block.join('')));
        }

        return result;
    }

    decrypt(message, msgInBits=false) {
        let bitsArrayMsg;

        if (msgInBits) {
            bitsArrayMsg = message;
        } else {
            bitsArrayMsg = this._stringToBitsArray(message);
        }

        if (bitsArrayMsg.length % 64 !== 0) {
            throw new Error('Ciphered code can only be a multiple of 64');
        }

        let blocksLst = this._chunkify(bitsArrayMsg, 64, true, 64);

        let result = [];

        for (let block of blocksLst) {
            let decrypted = this.decrypt64bit(block, true),
                bl = this._bitsArrayToCharArray(decrypted);
            result = result.concat(this._unpad(bl));
        }

        return result.join('');
    }

    encrypt64bit(message) {
        return this.crypt(message, true, false);
    }

    decrypt64bit(message, msgInBits=false) {
        return this.crypt(message, false, msgInBits);
    }

    crypt(message, encrypt=true, msgInBits=false) {
        let bitsArrayMsg;

        if (msgInBits) {
            bitsArrayMsg = message;
        } else {
            bitsArrayMsg = this._stringToBitsArray(message);
        }

        let bitsArrayKey = this._stringToBitsArray(this.key);

        if (bitsArrayMsg.length != 64) {
            throw new Error('Message must be 64 bit!');
        }

        if (bitsArrayKey.length != 64) {
            throw new Error('Key must be 64 bit!');
        }

        // Compute 16 48-bit subkeys
        let subkeys = this.getSubkeys(bitsArrayKey);

        // Convert the message using the initial permutation block
        let msg = [];
        for (let i of this._initial_permutation) {
            msg.push(bitsArrayMsg[i - 1]);
        }

        let L = msg.slice(0, 32),
            R = msg.slice(32);

        if (encrypt) {
            for (let i = 0; i < 16; ++i) {
                let prevR = R;
                let rFeistel = this.feistelFunction(R, subkeys[i]);
                R = [];
                for (let j = 0; j < 32; ++j) {
                    R.push(L[j] ^ rFeistel[j]);
                }
                L = prevR;
            }
        } else {
            for (let i = 15; i >= 0; --i) {
                let prevL = L;
                let lFeistel = this.feistelFunction(L, subkeys[i]);
                L = [];
                for (let j = 0; j < 32; ++j) {
                    L.push(R[j] ^ lFeistel[j]);
                }
                R = prevL;
            }
        }

        let beforeFinalPermute = L.concat(R);

        // compute final permutation
        let finalPermute = [];
        for (let i of this._final_permutation) {
            finalPermute.push(beforeFinalPermute[i - 1]);
        }

        return finalPermute;
    }

    pkcs7Padding(message, blockSize = 8, pad=true) {
        let msg = message.split(''),
            blocksLst = this._chunkify(msg, blockSize, true, blockSize);

        if (pad) {
            let s = blockSize;
            return blocksLst
                    .map(b => b.length < s ? this._pad(b, s) : b);
        } else {
            return blocksLst;
        }
    }

    feistelFunction(r32bit, subkey48bit) {
        let r48bit = [];
        for (let i of this._expansion_function) {
            r48bit.push(r32bit[i - 1]);
        }

        let subkeyXorR = [];
        for (let i = 0; i < 48; ++i) {
            subkeyXorR.push(r48bit[i] ^ subkey48bit[i]);
        }

        // Divide subkeyXorR into 8 6-bit blocks for computing s-boxes
        let b6bitBlocks = this._chunkify(subkeyXorR, 8);

        let afterSboxes32bit = [];
        for (let i = 0; i < 8; ++i) {
            afterSboxes32bit = afterSboxes32bit.concat(
                this.computeSBox(this._sbox[i], b6bitBlocks[i])
            );
        }

        // Compute the permutation and return the 32-bit block
        let res32bit = [];
        for (let i of this._permutation) {
            res32bit.push(afterSboxes32bit[i - 1]);
        }

        return res32bit;
    }

    computeSBox(sbox, b6bit) {
        let row = parseInt(b6bit[0] + '' + b6bit[5], 2),
            col = parseInt(b6bit.slice(1, 5).join(''), 2);
        const sboxRes = sbox[row][col];

        return this._createBinaryString(sboxRes)
                .substr(28).split('')
                .map(i => parseInt(i));
    }

    getSubkeys(bitsArrayKey) {
        // Compute Permuted Choice 1 on the key
        let key56bit = []

        for (let i of this._pc1) {
            key56bit.push(bitsArrayKey[i-1]);
        }

        // Split the key into two 28-bit subkeys
        let key56left = key56bit.slice(0, 28),
            key56right = key56bit.slice(28);

        // Compute 16 48-bit keys using left rotations and permuted choice 2
        let subkeys48bit = [];
        let C = key56left, D = key56right;

        for (let i = 0; i < 16; ++i) {
            C = this._arrayLeftRotate(C, this._left_rotations[i]);
            D = this._arrayLeftRotate(D, this._left_rotations[i]);
            let CD = C.concat(D);

            let CDres = []
            for (let j of this._pc2) {
                CDres.push(CD[j-1]);
            }
            subkeys48bit.push(CDres);
        }

        return subkeys48bit;
    }

    _stringToBitsArray(str) {
        return this._stringToByteArray(str)
                .map(i => this._createBinaryString(i).substr(24))
                .map(i => i.split(''))
                .reduce((i1, i2) => i1.concat(i2))
                .map(i => parseInt(i));
    }

    _bitsArrayToCharArray(arr) {
        return this._chunkify(arr, 8, true, 8)
                   .map(b => parseInt(b.join(''), 2))
                   .map(c => String.fromCharCode(c));
    }

    _stringToByteArray(str) {
        let byteArray = [],
            len = str.length,
            i = 0;

        for (i; i < len; ++i) {
            byteArray.push(str.charCodeAt(i));
        }

        return byteArray;
    }

    _createBinaryString(nMask) {
        for (var nFlag = 0, nShifted = nMask, sMask = ''; nFlag < 32;
             nFlag++, sMask += String(nShifted >>> 31), nShifted <<= 1);
        return sMask;
    }

    _arrayLeftRotate(arr, rotations=1) {
        for (let i = 0; i < rotations; ++i) {
            arr = this._arrayLeftShift(arr);
        }
        return arr;
    }

    _arrayLeftShift(arr) {
        let temp = new Array(),
            len = arr.length - 1,
            i = 1;

        for (i; i <= len; ++i) {
            temp.push(arr[i]);
        }
        temp.push(arr[0]);

        return temp;
    }

    _chunkify(a, n, balanced, chunkSize) {

        if (!isNaN(chunkSize)) {
            return a.map(
                (e, i) => i % chunkSize === 0 ? a.slice(i, i + chunkSize) : null
            ).filter(e => e);
        }

        if (n < 2) {
            return [a];
        }
        let len = a.length,
            out = [],
            i = 0,
            size;
        if (len % n === 0) {
            size = Math.floor(len / n);
            while (i < len) {
                out.push(a.slice(i, i += size));
            }
        }
        else if (balanced) {
            while (i < len) {
                size = Math.ceil((len - i) / n--);
                out.push(a.slice(i, i += size));
            }
        }
        else {
            n--;
            size = Math.floor(len / n);
            if (len % size === 0)
                size--;
            while (i < size * n) {
                out.push(a.slice(i, i += size));
            }
            out.push(a.slice(size * n));
        }
        return out;
    }

    _pad(arr, blockSize) {
        let z = blockSize - arr.length;
        return arr.concat(Array(z).fill(z));
    }

    _unpad(arr) {
        let last = arr[arr.length - 1];

        if (!isNaN(last)) {
            let arrStr = arr.join('');
            let i = +last, j = i;

            while (arrStr[arrStr.length - 1] === j.toString() && i > 0) {
                arrStr = arrStr.slice(0, -1);
                i--;
            }

            return arrStr.split('');
        } else {
            return arr;
        }
    }
}

DES_test.js

import DES from './DES';


let d = new DES('qwertyui');

// let cipher = d.encrypt64bit('heleo we')

// console.log(cipher);

// let decipheredBits = d.decrypt64bit(cipher, true);

// console.log(decipheredBits.length);

// console.log(decipheredBits);

let cipher = d.encrypt('hello world!');

// console.log(cipher);

let deciphered = d.decrypt(cipher, true);

console.log(deciphered);