RSA encryption. The encryption key is: C = M to the power of e MOD n where C is the encrypted byte(s) M is the byte(s) to be encrypted n is the product of p and q p is a prime number ( theoretically 100 digits long ) q is a prime number ( theoretically 100 digits long ) e is a number that gcd(e,(p-1),(q-1)) = 1 The decryption key is: M = C to the power of d MOD n Where C is the encrypted byte(s) M is the original byte(s) n is the product of p and q p is a prime number ( must be the same as the encrypting one ) q is a prime number ( " " " " ) d is the inverse of the modulo e MOD (p-1)(q-1) As you can see in order to crack the encrypted byte(s) you would need to know the original prime #'s, Even with the encryption key it would take a long time to genetate the correct prime #'s needed.... an Example... C = M to the power of 13 MOD 2537 2537 is the product of 43 and 59. the decryption key is M = C to the power of 937 MOD 2537 937 is the inverse of 13 MOD (43 - 1)(59 - 1).