[cli] encrypt, decrypt via aes-256-ctr

cipher.js

#!/usr/bin/env node
const crypto = require('crypto');
const alg    = 'aes-256-ctr';
const usage  = _ => {
    console.log('[usage]');
    ['c', 'd'].map(opt => console.log(`   ${exe} -${opt} secret payload`));
    process.exit();
};
const [_, exe, opt = '-h', secret, payload] = process.argv;

if (opt === '-h' || !opt.startsWith('-') || process.argv.length !== 5) {
    usage();
} else if (opt === '-c') {
    const cipher = crypto.createCipher(alg, secret);
    const crypted = cipher.update(payload, 'utf8', 'hex');
    console.log(crypted + cipher.final('hex'));
} else if (opt === '-d') {
    const decipher = crypto.createDecipher(alg, secret);
    const crypted = decipher.update(payload, 'hex', 'utf8');
    console.log(crypted + decipher.final('utf8'));
}