
1.  p  q
2. n = p * q
3.  d ---  ⮥  (p-1)*(q-1)
4.  e --- (e * d) mod ((p-1)*(q-1)) = 1.
5. {e,n} - , {d,n} - ᥪ
6. encrypt: encr = (text ^ e) mod n
   decrypt: text = (encr ^ d) mod n

