# Generate public/private keys, encrypt, decrypt, sign, verify

My program generates public private keys, encrypts, decrypts, signs and verifies, while using AES for the bulk for speed. Many operations were chosen for speed. This works out of the box on 3.6+ . Windows idle env disallows it from working there, but Linux and mac is ideal. I do call gzip which I know I can replace with a module. I almost want to do my own Huffman coding for it but I don’t know where to draw the line.

The RSA and DSA portions are written from number theory and don’t use the modules, that was the point.

I’m using this as an educational tool force the unwilling to kinetically understand public and private key cryptography when passed on a USB etc. in a classroom setting. To see the clicks in peoples eyes when they understand signing or the like, that’s why I’m sharing this code. I know there’s much better ways to handle the data concatenation, but am happy that I’m processing the data at a binary level.

I love the prime number theorem and so should you.

``#!/usr/bin/env python3 import os import sys import math import re import hashlib import random import base64 import string import getpass import multiprocessing as mp from Crypto.Cipher import AES from Crypto import Random from Crypto.Protocol.KDF import PBKDF2  #Primality testing, extended greatest common divisor and least common multiple def isprime(n):    if not n & 1:  #check if first bit is 1        return False    for i in (3,5,7,11):        if divmod(n, i)[1] == 0:            return False    #Fermat    if (pow(2, n-1, n)) != 1:        return False    #MilRab, x**2 = 1 mod P - ERH    s = 0    d = n-1    while not d & 1:        d>>=1 #shifts binary rep of number right one place, same as dividing by 2^d        s+=1    assert(2**s * d == n-1) #Process to find s and d    def trial_composite(a):        if pow(a, d, n) == 1:              return False        for i in range(s):            if pow(a, 2**i * d, n) == n-1:                return False        return True    for i in range(100):#Number of Rabin Witness's        a = random.randrange(2, n-1)        if trial_composite(a):            return False    return True  def get1prime(keysize):    while True:        p = random.randrange(1<<(keysize), 1<<(keysize+2))        if isprime(p):            return p  def modInverse(a, m) : #Euclid's Extended Algorithm    m0 = m    y = 0    x = 1    while (a > 1) :        q = a // m        t = m        m = divmod(a,m)[1]        a = t        t = y        y = x - q * y        x = t    if (x < 0) :        x = x + m0    return x  def lcm(x, y):   lcm = (x*y)//math.gcd(x,y)   return lcm  ##AES256CHUNK def get_private_key(password):    salt = b"We will know, we must know"    kdf = PBKDF2(password, salt, 64, 1000)    key = kdf[:32]    return key  def encryptaes(raw, password):    private_key = password    raw = pad(raw)    iv = Random.new().read(AES.block_size)    cipher = AES.new(private_key, AES.MODE_CBC, iv)    return base64.b64encode(iv + cipher.encrypt(raw))  def decryptaes(enc, password):    private_key = password    enc = base64.b64decode(enc)    iv = enc[:16]    cipher = AES.new(private_key, AES.MODE_CBC, iv)    return unpad(cipher.decrypt(enc[16:]))  BLOCK_SIZE = 128 #Block is 128 no matter what,this is multiple of 16 pad = lambda s: s + (BLOCK_SIZE - len(s) % BLOCK_SIZE) * chr(BLOCK_SIZE - len(s) % BLOCK_SIZE) unpad = lambda s: s[:-ord(s[len(s) - 1:])]  #RSA #Unique and Arbitrary Pub E, a prime. e = 66047 # because I can #e = 65537  def encryptit(e, n, thestring):#for sigining pass d as e    rbinlist = ['{0:08b}'.format(x) for x in thestring]     catstring = ''    catstring += rbinlist[0].lstrip('0')    del rbinlist[0]    for i in rbinlist:        catstring += str(i)    puttynumber = int(catstring,2)    cypherstring = str(pow(puttynumber, e, n))    return cypherstring  def decryptit(d, n, cynum):#for signing pass e as d    decryptmsg = ''    n = int(n)    d = int(d)    puttynum = pow(int(cynum), d, n)    puttynum = '{0:08b}'.format(puttynum)    while True:        if len(puttynum)%8 == 0:            break        puttynum = '0{0}'.format(puttynum)    locs = re.findall('[01]{8}', puttynum)    for x in locs:        letter = chr(int(x,2))        decryptmsg += letter    return decryptmsg  #Begin User Flow choice = input("""    Welcome to Dan's Cryptography Concept Program.  Generate/Encrypt/Decrypt/Sign RSA++/DSA++/AES/OTP/Double DH key exch w SHA Choose: A: Generate New Public/Private Key Pair B: Encrypt a File C: Decrypt a File => """)  if choice == 'A' or choice == 'a':    try:        keysize = (int(input("Enter a keysize:  "))>>1)    except ValueError as a:        print('Enter a number\n\n')        sys.exit()    pubkeyname = input('Input desired public key name: ')    pkey = input('Input desired private key name: ')    pwkey = get_private_key(getpass.getpass(prompt='Password to protect your private key: ', stream=None))    print('Generating Keys...')    primes = []    plist = []    for i in range(mp.cpu_count()):        plist.append(keysize)    workpool = mp.Pool(processes=mp.cpu_count())    reslist = workpool.imap_unordered(get1prime, plist)    workpool.close()    for res in reslist:        if res:              primes.append(res)            workpool.terminate()            break    workpool.join()    #    workpool1 = mp.Pool(processes=mp.cpu_count())    reslist = workpool1.imap_unordered(get1prime, plist)    workpool1.close()    for res in reslist:        if res:              primes.append(res)            workpool1.terminate()            break    workpool1.join()    if primes[0] != primes[1]:        p, q = primes[0], primes[1]    else:        print('Supremely Unlucky Try Again')        exit()    n = p*q    cm = lcm(p-1, q-1)    print('Computing Private key ...')    d = modInverse(e, cm)    print('Private Key Size: {} bits'.format(keysize*2))    print('Functional Length of: {}'.format(len(bin((d)))))    keystring = encryptaes(str(d).encode('ascii', errors='ignore').decode('utf-8'),pwkey)    b64key = bytes.decode(base64.encodestring(bytes(str(hex(n)).encode())))    with open(pkey, 'w') as f1:        f1.write(str(n)+'\n')        f1.write(bytes.decode(keystring))    with open(pubkeyname, 'w') as f2:        f2.write(b64key)    print('Complete - {} and {} generated'.format(pubkeyname,pkey))    print('e exponent: {}'.format(str(e)))    print(""" -----BEGIN PUBLIC KEY----- {}-----END PUBLIC KEY----- """.format(b64key))    b64privkey = b64key = bytes.decode(base64.encodestring(bytes(str(hex(d)).encode())))    print(""" -----BEGIN PRIVATE KEY----- {}-----END PRIVATE KEY----- """.format(b64privkey))  if choice == 'B' or choice == 'b':    lineoutholder = []    pubkeyname = input('Enter PUBLIC key to encrypt with(recepient): ')    privkey = input('Enter your private KEY you wish to sign with(yours): ')    pwkey = get_private_key(getpass.getpass(prompt='Password for your private key: ', stream=None))    try:        with open(pubkeyname, 'r') as f1:            pubkey = f1.read()    except:        print('bad keyname')        exit()    uhaeskey = ''.join([random.choice(string.ascii_letters + string.digits) for n in range(32)])    n = int(bytes.decode(base64.decodestring(bytes(pubkey.encode()))), 16)    workfile = input('Enter the file to ENCRYPT: ')    outfile = input('Enter filename to WRITE out: ')    sha256_hash = hashlib.sha256()    try:        with open(workfile, 'rb') as f2:            wholefile = f2.read()        with open(workfile, 'rb') as f2:#open again to clear memory            for byte_block in iter(lambda: f2.read(4096),b""):                sha256_hash.update(byte_block)        HASH = sha256_hash.hexdigest()        with open(privkey) as f3:            priv = f3.readlines()    except Exception as x:        print(x)        exit()    d = int(bytes.decode(decryptaes(priv[1], pwkey)))    HASH = [ord(i) for i in HASH]    numhash = ''    for i in HASH:        numhash +=str(i)    signature = pow(int(numhash), d, int(priv[0]))    aeskey = get_private_key(uhaeskey)    plaintext = base64.encodestring(wholefile)    cyphertext = bytes.decode(encryptaes(plaintext.decode('ascii'), aeskey))    shippedpw = encryptit(e, n, uhaeskey.encode())    concat = str(str(signature)+'CUTcutCUTcutCUT'+shippedpw+'CUTcutCUTcutCUT'+cyphertext)    with open(outfile, 'w') as f3:        f3.write(concat)    os.system('gzip -9 {0};mv {0}.gz {0}'.format(outfile))    print('Wrote to {} ...'.format(outfile))  if choice == 'C' or choice == 'c':    dspubkeyname = input('Enter the PUBLIC key to verify the signature with(sender): ')    try:        with open(dspubkeyname, 'r') as f1:            pubkey = f1.read()    except:        print('bad keyname')        exit()    nsig = int(bytes.decode(base64.decodestring(bytes(pubkey.encode()))), 16)    privkey = input('YOUR private KEY filename to decrypt the data: ')    pwkey = get_private_key(getpass.getpass(prompt='Password for your private keyfile: ', stream=None))    workfile = input('Enter the file to DECRYPT: ')    outfile = input('Enter the filename to WRITE out: ')    print('DECRYPTING')    os.system('mv {0} {0}.gz;gzip -d {0}.gz'.format(workfile))    sha256_hash = hashlib.sha256()    try:        with open(workfile) as f1:            lineholder = f1.read().split('CUTcutCUTcutCUT')        signature, codedkey, cyphertext =lineholder[0], lineholder[1], lineholder[2]    except:        print('Bad file name or path')        exit()    try:        with open(privkey) as f2:            priv = f2.readlines()    except:        print('Bad private key location')    n = priv[0]    d = int(bytes.decode(decryptaes(priv[1], pwkey)))    sigdec = pow(int(signature), e, nsig)#Sig Verification step1     aeskey = decryptit(d, n, codedkey)    aeskey = get_private_key(aeskey)    decstr = bytes.decode(decryptaes(cyphertext, aeskey))    cleartext = base64.decodestring(bytes(decstr, 'ascii'))    with open(outfile, 'wb') as f1:        f1.write(cleartext)    with open(outfile, 'rb') as f2:        for byte_block in iter(lambda: f2.read(4096),b""):            sha256_hash.update(byte_block)        HASH = sha256_hash.hexdigest()    HASH = [ord(i) for i in HASH]    numhash = ''    for i in HASH:        numhash +=str(i)    if int(numhash) == int(sigdec):        print('Signature Verified')    else:        print('FAILURE, bad hash...')    print('Wrote out to {} '.format(outfile)) ``