 Fido Pascal Conference  PASCAL 
Msg  : 362 of 362                                                               
From : Steve P.                            1:141/410.0          31 May 93  23:38 
To   : Justin Broste                                                             
Subj : Encryption Alg.                                                        

This method of encryption is called RSA Encryption, it's a form of public key
encryption.  The encryption algorithm is..

                     C = M to the power of e MOD n

   C is the encrypted byte(s)
   M is the original byte(s)
   e is a prime number
   n is the product of 2 prime numbers ( p and q )

This will only work if gcd(e, (p-1)(q-1)) = 1..

 Some #'s to use are...
             e = 13
             p = 43
             q = 59

 with these value the algorithm is   C = M to the power of 13 MOD 2537...


To decrypt you must get the inverse of  e MOD (p-1)(q-1)

  When the values mentioned the inverse of  e MOD (p-1)(q-1) is 937...

The decryption key is
 
           P = C to the power of 937 MOD 2537

    P is the original byte(s)
    C is the encrypted byte(s)
    937 is the inverse of  13 MOD (p-1)(q-1)
    2537 is  p * q

  It's not an easy form of encryption, but it's secure....  You can give
someone the encryption key, but the would need to know the prime #'s p and q
to decrypt it ( which if you use big enough numbers, it would take quit some
time to figure them out)..

--- Maximus 2.00
 * Origin: Ho-Bo's House of Ill Repute (1:141/410)

