rsa.js

const gcd = (a, b) => b ? gcd(b, a % b) : a

const p = 61n
const q = 53n

const n = p * q

const r = (p - 1n) * (q - 1n)

let e = 1n
for (let i = 2n; i < r; i++) {
  if (gcd(i, r) === 1n) {
    e = i
    break
  }
}

let d
for (let i = e + 1n; i < r; i++) {
  if ((i * e) % r === 1n) {
    d = i
    break
  }
}

const pubKeyN = n
const pubKeyE = e
const priKeyN = n
const priKeyD = d

const m = 100n
const encrypted = m ** pubKeyE % pubKeyN
const decrypted = encrypted ** priKeyD % n

console.log('p', p)
console.log('q', q)
console.log('r', r)
console.log('pubKeyN', pubKeyN)
console.log('pubKeyE', pubKeyE)
console.log('priKeyN', priKeyN)
console.log('priKeyD', priKeyD)
console.log('m', m)
console.log('encrypted', encrypted)
console.log('decrypted', decrypted)