#!/usr/bin/python

sig = """
-----BEGIN PGP SIGNED MESSAGE-----

"""

from number import *
import sys

# number.py is part of the Python Cryptography Toolkit

#
# 2003/8/20
# calculates a P- strong prime X based on prime P
# checking i*P+1 for primality with Rabin-Miller test
#

max = 1000

################################################################
def Line (S) :
     while S[-1:] == "\r"  or  S[-1:] == "\n" :
          S = S[:-1]
     return S

################################################################
def toLong (S) :
     while ord(S[:1]) < 48 or ord (S[:1]) > 57 :
          S = S[1:]
     while ord(S[-1:]) < 48 or ord (S[-1:]) > 57 :
          S = S[:-1]
     return long(S)

################################################################
def toString (L) :
     # returns only decimal digits
     S = str(L)
     if S[-1:] == "L" :
          S = S[:-1]
     return S

################################################################
def bits(N) :
     I = 0
     while N > 0 :
           N = N / 2
           I = I + 1
     return I
################################################################

EOL = "\n"
P = Q = 1L

if len(sys.argv) != 2 :
     print "usage: strongprimes primefile"
else:
     try:
          FILE = open(sys.argv[1], "r")
          Content = FILE.readlines()
          FILE.close()
          try:
               P = toLong(Content[0])
               Q = toLong(Content[1])
          except:
               print EOL + "File does not contain two primes " + EOL
               sys.exit(3)

     except IOError :
          print "Input file is unavailable."
          sys.exit(1)

# check if both numbers are really prime.
if not isPrime(P) :
      print "First number is not prime."
      sys.exit(4)

if not isPrime(Q) :
      print "Second number is not prime."
      sys.exit(4)

FirstP = FirstQ = 0L

for i in range(max):
    X = i*P+1
    if isPrime(X) :
         print "#####"
         print "Strong prime found in round ", i
         print " P  = ", X, toString(bits(X)), " bits"
         print " P- = ", P, toString(bits(P)), " bits"
         Prime1 = X
         if FirstP == 0L :
              FirstP = Prime1

for i in range(max):
    X = i*Q+1
    if isPrime(X) :
         print "#####"
         print "Strong prime found in round ", i
         print " Q  = ", X, toString(bits(X)), " bits"
         print " Q- = ", Q, toString(bits(Q)), " bits"
         Prime2 = X
         if FirstQ == 0L :
              FirstQ = Prime2


print "***********************************"
print "First primes"
print "P = " , FirstP
print "Q = ",  FirstQ
print
print "Hashmodulus =", toString(FirstP*FirstQ)
print toString(bits(FirstP*FirstQ)), " bits"

D = FirstQ - FirstP
print "Distance ", D, toString(bits(D)), " bits"


print "***********************************"
print "Last primes"
print "P = " , Prime1
print "Q = ",  Prime2
print
print "Hashmodulus =", toString(Prime1*Prime2)
print toString(bits(Prime1*Prime2)), " bits"

D = Prime2 - Prime1
print "Distance ", D, toString(bits(D)), " bits"
print "***********************************"

sys.exit(0)

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