des.js

const
    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
    ],
    IP = [
        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
    ],
    E = [
        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
    ],
    S = [
        [
            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
        ],
        [
            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
        ],
        [
            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
        ],
        [
            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
        ],
        [
            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
        ],
        [
            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
        ],
        [
            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
        ],
        [
            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
        ]
    ],
    P = [
        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
    ],
    FINAL_IP = [
        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
    ],
    NUM_OF_LEFT_SHIFTS = [1, 1, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 1];

const chunkString = (str, len) => str.match(new RegExp('.{1,' + len + '}', 'g'));
const hexToBin = (hex) => ("00000000" + (parseInt(hex, 16)).toString(2)).substr(-8);
const decToBin = (dec) => ("0000" + (parseInt(dec, 10)).toString(2)).substr(-4);
const binToHex = (bin) => parseInt(bin, 2).toString(16);
const bin = key => chunkString(key, 2).map(hex => hexToBin(hex)).join("");
const shiftString = (str, shift) => str.slice(shift, str.length) + str.slice(0, shift);

const keySchedule = (key) => {
  let subkeys = [];
  let perm = PC1.map(index => key[index - 1]).join("");
  let C0 = perm.substr(0, perm.length / 2);
  let D0 = perm.substr(perm.length / 2);
  let prevC0 = C0, prevD0 = D0;
  NUM_OF_LEFT_SHIFTS.forEach((shift, i) => {
    C0 = shiftString(prevC0, shift);
    D0 = shiftString(prevD0, shift);
    prevC0 = C0;
    prevD0 = D0;
    let pair = C0 + D0;
    subkeys.push(PC2.map(index => pair[index - 1]).join(""));
  });

  return subkeys;
};

const expandBlock = block => E.map(index => block[index - 1]).join("");

const stringXOR = (str1, str2, len) => {
  let xor = Array(len);
  for (let i = 0; i < len; i++) {
    xor[i] = (str1[i] === str2[i] ? 0 : 1);
  }
  return xor.join("");
}

const sBoxOutput = bits => {
  return chunkString(bits, 6).map((group, sBox) => {
    let row = parseInt(group[0] + group[5], 2);
    let col = parseInt(group.slice(1, 5), 2);
    return decToBin(S[sBox][16 * row + col]);
  }).join("");
};

const des = (msg, key, subkeys) => {
  let perm = IP.map(index => msg[index - 1]).join(""); // init permute (IP)
  let L0 = perm.substr(0, perm.length / 2);
  let R0 = perm.substr(perm.length / 2);

  let prevL0 = L0, prevR0 = R0;
  for (let i = 0; i < 16; i++) {
    L0 = prevR0;
    let sBoxOut = sBoxOutput(stringXOR(subkeys[i], expandBlock(R0), 48));
    let finalPerm = P.map(index => sBoxOut[index - 1]).join("");
    R0 = stringXOR(prevL0, finalPerm, 32);
    prevL0 = L0;
    prevR0 = R0;
  }
  let pair = R0 + L0;
  let enc = FINAL_IP.map(index => pair[index - 1]).join("");
  return chunkString(enc, 4).map(binToHex).join("").toUpperCase();
}

const encode = (msg, key) => des(msg, key, keySchedule(key));
const decode = (msg, key) => des(msg, key, keySchedule(key).reverse());

let key = bin("133457799BBCDFF1"); // hex
let msg = bin("0123456789ABCDEF"); // hex
let enc = encode(msg, key);

console.log(enc); // => 85E813540F0AB405
console.log(decode(bin(enc), key)); // => 0123456789ABCDEF

// Triple DES (3DES) Example
// Variant 2: Two keys (K1 = K3)

let key2 = bin("0DAE3BF4ECCAD161");

let tripleEnc = encode(msg, key);
tripleEnc = decode(bin(tripleEnc), key2);
tripleEnc = encode(bin(tripleEnc), key);
console.log(tripleEnc); // => DDF3FFA6F0FC22DC

let tripleDec = decode(bin(tripleEnc), key);
tripleDec = encode(bin(tripleDec), key2);
tripleDec = decode(bin(tripleDec), key);
console.log(tripleDec); // => 0123456789ABCDEF