mima-kit/dist/cipher/streamCipher/arc4.js

mima-kit is a cryptographic suite implemented in TypeScript. The goal is to provide an easy-to-use cryptographic library. mima-kit 是一个使用 TypeScript 实现的密码学套件。目标是提供一个简单易用的密码学库。

import { createCipher } from '../../core/cipher';
import { KitError, U8 } from '../../core/utils';
// * Functions
function KSA(K) {
    const SBox = new Uint8Array(256);
    SBox.forEach((_, i) => SBox[i] = i);
    let j = 0;
    for (let i = 0; i < 256; i++) {
        j = (j + SBox[i] + K[i % K.byteLength]) % 256;
        [SBox[i], SBox[j]] = [SBox[j], SBox[i]];
    }
    return SBox;
}
// * RC4 Algorithm
function cipher(M, SBox) {
    SBox = SBox.slice(0);
    const result = new U8(M.byteLength);
    let i = 0;
    let j = 0;
    M.forEach((_, k) => {
        i = (i + 1) % 256;
        j = (j + SBox[i]) % 256;
        [SBox[i], SBox[j]] = [SBox[j], SBox[i]];
        result[k] = M[k] ^ SBox[(SBox[i] + SBox[j]) % 256];
    });
    return result;
}
function _arc4(K) {
    if (K.byteLength < 5 || K.byteLength > 256) {
        throw new KitError(`RC4 key must be between 5 and 256 byte`);
    }
    const SBox = KSA(K);
    return {
        encrypt: (M) => cipher(M, SBox),
        decrypt: (M) => cipher(M, SBox),
    };
}
/**
 * ARC4 流密码 / stream cipher
 */
export const arc4 = createCipher(_arc4, {
    ALGORITHM: `ARC4`,
    KEY_SIZE: 16,
    MIN_KEY_SIZE: 5,
    MAX_KEY_SIZE: 256,
});