Algoritmo RSA

rsa.py

from sys import argv
from primos import rprime, pickone, inverse
from potmod import potmod
from gcd import gcdr

def e(m,(e,n)):
	return potmod(m, e, n)

def d(c,(d,n)):
	return potmod(c, d, n)

def cifrar(m):
    cyphertxt = 0
    for c in m:
        cyphertxt <<= 8
        cyphertxt += ord(c)
    return cyphertxt

def decifrar(c):
	mensaje = []
   	while c > 0:
   		mensaje.insert(0, chr(c & 255))
   		c >>= 8
   	return ''.join(mensaje)

def public(d):
	p = rprime(d)
	q = rprime(d)
	n = p * q
	phin = (p - 1) * (q - 1)
	while True:
		e = pickone(phin)
		if gcdr(phin, e) == 1:
			break
	d = inverse(e, phin)
	return ((e, n),(d, n))

def main():
	(publica,privada) = public(randint(1,5))
	#(publica,privada) = public(int(argv[1]))
	print 'Publica = ',publica
	print 'Privada = ',privada

	plantxt = argv[2]

	cifrado = cifrar(plantxt)
	print 'Cifrado = ', cifrado
	c = e(cifrado, publica)
	print 'C = ',c

	decifrado = decifrar(cifrado)
	print 'Decifrado = ',decifrado
	m = d(decifrado,privada)
	print 'M = ',m

#main()