cipherlink 1.0.1

A Python-based basic ciphering tool library

Cipherlink

A simple library for basic cybersecurity algorithms.

Project details

This project will be merged with a messaging protocol, hence the name. (See https://github.com/ahmeterdem1/SSL-Messager for details.)

pip install cipherlink

Usage

This library is not for real cybersecurity use. Tools inside here are not complicated and fast enough for that use. But this is a simple and fast enough library for small projects that requires a tint of security. It creates a bundle for ciphering, a little all-in-one. It has prime number generation functions, a hash function, RSA keygen function and encryption-decryption functions for RSA.

No useful initialization occurs in this class, creating a cipherlink object just prints the dir() function of the class.

hash(str)

Just an analogue of md5. Output is made of all the new internal state numbers, not just the last one. Pretty much only difference is that. Return is a string.

gcd(a, b)

Returns gcd of arguments

gcdExtended(a, b)

Returns gcd, x, y where x and y are coefficients of the equation:

ax + by = gcd(a, b)

This is used to implement a faster key generation in RSA.

primeByOrder(int)

Takes an integer as the order, then returns the prime in the order. Useful for generating large primes by just inputting their order. Default argument is a random 8-bit number plus one, in case 0 is choosen. If the argument is smaller than 1, raises RangeError.

primeByRange(int, int)

Returns a list of primes in given range. If the range is invalid, raises a RangeError.

isPrime(int)

Returns true if the argument is a prime. If the argument is smaller than 2, returns false.

keygenRsa(p, q, smallest)

Creates a tuple of public and private key and returns it. Public key is itself a tuple. p and q as primes can be given. smallest determines the e. If true, which is the default, e is the smallest number possible. If false, e is chosen randomly within the list. If randomly choosen, private key generation takes a lot of time, therefore the default is true.

If given p and q are not primes, raises an ArgError.

encryptorRsa(public, message)

Takes in the public key and the message, then encrypts the message. Returns the encrypted message as a tuple. Every element in this tuple represents a character.

decryptorRsa(public, private, message)

Takes in the keys and the encrypted message, then returns the decrypted message. Return type is string this time.

encryptorRsa2(public, message)

Same as the original one. Only difference is that, this works by grouping characters by 2, appending their ascii values, using the resultant integer. With this method, this function is not an overcomplicated caesar cipher anymore.

decryptorRsa2(public, private, message)

Decrypts RSA messages grouped in 2.

Known issues

Random Exceptions and Errors

Both decryptor functions rarely raise exceptions or result in an incorrect message. One of the reasons for that was, generated private key could be 1 sometimes. This makes the for loop exit immediately. So no decryption occurs. This is solved now. The only remaining reason known for this issue is the information loss during multiplications of large numbers. Frequency of this issue happening is measured to be around %4 with pypy3 as compiler.

Beware that every time this issue happens, indeed no decryption occurs. You can see this with debugging, for some reason the encrypted message is passed as the result in the decryptor despite the private key being larger than 2. This may be due to some mathematical problem in our method of private key calculation. But %4 is small enough to be practical.

Algorithm is annoyingly slow

Algorithm is not the only thing that is slow here. CPython is the real slow thing in here. Our recommendation is to use pypy as the compiler. Pypy is measured to be around 10 to 20 times faster than CPython during keygen, encryption and decryption combined. This is probably due to the optimizations on loops in pypy. CPython takes its time during the for and while loops of said operations. We have to sacrifice the speed here with that loops because otherwise we would have to do operations on really large numbers. That will result in the above said errors. Just using C/C++ is still an option.