Extraction of RSA keys

rsa-keys.py

#Extract RSA keys in separate files

"""
Example of usage: 
1. Generate your RSA keys
# openssl genrsa 2048 > mykeys.key 
2. Read keys in human way and save it to a new .txt file 
# openssl rsa -in mykeys.key -noout -text 
3. Exclude keys in separate files with rsa-keys.py script
"""

def readN(file):
    key = open(file, 'r')
    counterN = 0
    N = ''
    for line in key:
        if line[:8] == "modulus:": counterN = 1
        if line[:15] == "publicExponent:": counterN = 0
        if counterN: N += line
    N = N[9:]
    N = N.replace(' ', '')
    N = N.replace('\n', '')
    N = N.replace(':','')
    return int(N, 16)

def readE(file):
    key = open(file, 'r')
    E = ''
    for line in key:
        if line[:15] == "publicExponent:": E = line[16:21]
    return int(E,10)

def readPrime1(file):
    key = open(file, 'r')
    counterPrime1 = 0
    prime1 = ''
    for line in key:
        if line[:7] == "prime1:": counterPrime1 = 1
        if line[:7] == "prime2:": counterPrime1 = 0
        if counterPrime1: prime1 += line
    prime1 = prime1[8:]
    prime1 = prime1.replace(' ', '')
    prime1 = prime1.replace('\n', '')
    prime1 = prime1.replace(':','')
    return int(prime1, 16)

def readPrime2(file):
    key = open(file, 'r')
    counterPrime2 = 0
    prime2 = ''
    for line in key:
        if line[:7] == "prime2:": counterPrime2 = 1
        if line[:10] == "exponent1:": counterPrime2 = 0
        if counterPrime2: prime2 += line
    prime2 = prime2[8:]
    prime2 = prime2.replace(' ', '')
    prime2 = prime2.replace('\n', '')
    prime2 = prime2.replace(':','')
    return int(prime2, 16)


# Greatest common divisor
def gcd(a,b):
    v,v1 = 0,1
    u,u1 = 1,0
    while b:
        q = a // b
        u,u1 = u1, u-q * u1
        v,v1 = v1, v-q * v1
        a,b = b, a-q * b
    return a, u, v

def multiInverse(b, m):
   n,u,v = gcd(b, m)
   
   if n == 1:
       return u%m
   else:
       return None
 

if __name__ == "__main__":
    file = raw_input("Type name of a keys file(Must be in .txt): ")

    N = readN(file)
    E = readE(file)
    D = multiInverse(E, (readPrime1(file)-1)*(readPrime2(file)-1))

    data = open("KeyN.txt", "w")
    data.write(str(N))
    data = open("KeyE.txt", "w")
    data.write(str(E))
    data = open("KeyD.txt", "w")
    data.write(str(D))
    print "Numbers E, N and D was sucessfully saved in separate files."