The script seems to be for demonstrating the algorithm, not to fulfil security standards. Why are u taking input from user it should be randomly generated Look at Wikipedia's articles about this and the Extended Euclidean algorithm, but you can use existing algorithms like I did (and also probably). Your confusion comes from the function name: Actually, the modular multiplicative inverse is calculated here, which is far more complicated than the 'normal' inverse you described. I haven't seen a None return in my calculations yet. If all previous numbers are correct, it should give a number as output. The multiplicative_inverse() can return None right? How do you deal with that?Īlso, please can you explain that function? Isn't a multiplicative inverse of a number p/q supposed to be q/p so that it's product is 1? Print 'Decrypting message with public key ', public, '. join( map( lambda x: str( x), encrypted_msg)) Message = raw_input( 'Enter a message to encrypt with your private key: ')Įncrypted_msg = encrypt( private, message) Print 'Your public key is ', public, ' and your private key is ', private Public, private = generate_keypair( p, q) Print 'Generating your public/private keypairs now. Q = int( raw_input( 'Enter another prime number (Not one you entered above): '))

P = int( raw_input( 'Enter a prime number (17, 19, 23, etc): '))

Plain = ĭetect if the script is being run directly by the user #Generate the plaintext based on the ciphertext and key using a^b mod m #Convert each letter in the plaintext to numbers based on the character using a^b mod mĬipher = #Public key is (e, n) and private key is (d, n) #Use Extended Euclid's Algorithm to generate the private key #Use Euclid's Algorithm to verify that e and phi(n) are comprime #Choose an integer e such that e and phi(n) are coprime

Raise ValueError( 'p and q cannot be equal') Raise ValueError( 'Both numbers must be prime.') Use iteration to make it faster for larger integersĮuclid's extended algorithm for finding the multiplicative inverse of two numbersįor n in xrange( 3, int( num ** 0.5) + 2, 2): Euclid's algorithm for determining the greatest common divisor

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