funciones Matematicas

#!/usr/bin/env python

from random import randint
from gcd import egcd
from math import sqrt

def prime(n):
    if n <=1:
        return False
    if n % 2 == 0:
        if n == 2:
            return True
        else:
            return False
    i = 3
    while i <= sqrt(n):
        if n % i == 0:
            return False
        i += 2
    return True


def inversa(e, n):
    (gcd,tmp,d) = egcd(e, n)
    if not gcd == 1:
        return None
    else:
        return (tmp+n) %n

def rprime(digits):
    minimum = 10**(digits-1)
    maximum = minimum * 10 - 1
    while True:
        r = randint(minimum,maximum)
        if prime(r):
            return r

def checkgen(n,mod):
    t = 1
    c = 0
    while not t == 1 or c == 0:
        t = (t*n) % mod
        c+=1
        if c == mod:
            break
    if c == mod - 1:
        return True
    else:
        return False

def findgen(mod):
    while True:
        cand = randint(2,mod -1)
        if checkgen(cand,mod):
            return cand

def pickone(mod):
    return randint(2,mod-1)

def potmod(x, pot, mod):
    bits = pot
    pot
    res = 1
    temp = x
    while bits > 0:
        if bits %2 == 1:
            res = (res * temp  % mod)
        temp = (temp * temp) % mod
        bits = bits >> 1
    return res