MyCrptool

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A python package that include commonly used cryptographic algorithm and tools.

This package is designed as a teaching tool, written in pure python. It means that it probably won't be as efficient as other similar python libraries which use C for low-level implementation and provide the same if not more functions. However, the author try to write clean and simple code to demonstrate how a cryptography algorithm works.

GitHub repository (and newest documentation) : https://github.com/ChopperCP/MyCryptool

Install

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pip install mycrptool

Problem with bitarray

This package use bitarray as an external library. When installing this library, you may fail to compile.

If that's the case, you can go to https://www.lfd.uci.edu/~gohlke/pythonlibs/ to download a pre-compiled version of bitarray, and then simply run:

pip install downloaded-precompiled-file.whl

Dependencies

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Here are external libraries that is used in this package.

bitarray

Usage

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This package consists of 4 parts: symmetric, asymetric, hash, and tools.

To import all modules, it is recommanded to run from mycryptool import *

symmetric

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This module includes 2 symmetric algorithms: AES128 and DES.

AES128

The Default scheme is CBC. if you want to try other schemes, welcome to explore the AES class (in symmetric.aes128).

Encrypt:

data = b'Jessie Pinkman in the house'
key = 'key'
cipher = symmetric.aes128.encrypt(key, data)

Decrypt:

symmetric.aes128.decrypt(key, cipher)

DES

DES only supports 2 schemes: CBC and ECB. Supported Features: encrypt and decrypt.

Encrypt:

key = b'chopperc'
iv = b'66666666'
data = b'Yo Yo Yo, Jessie Pinkman in the house!!!'

cipher = symmetric.des.des_cbc(data, iv, key, True)  # CBC

cipher = symmetric.des.des_ecb(data, key, True)  # ECB

Decrypt:

deciphered = symmetric.des.des_cbc(cipher, iv, key, False)  # CBC
deciphered = symmetric.des.des_ecb(cipher, key, False)  # ECB

asymmetric

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This module includes 2 asymmetric algorithms: RSA and Elliptic Curve.

Supported Features: encrypt, decrypt, generate signature, and validate signature.

RSA

Encrypt:

data = b'Jessie Pinkman in the house'
# Warning: it takes a while to generate key pairs ( large prime numbers).
pub, pri = asymmetric.rsa.generate_key_pair()
cipher = asymmetric.rsa.encrypt(data, pub)

Decrypt:

asymmetric.rsa.decrypt(cipher, pri)

Generate signature:

signature = asymmetric.rsa.get_signature(hash.md5.md5(data), pri)
print(signature)

Validate signature:

asymmetric.rsa.is_valid_signature(hash.md5.md5(data), signature, pub)

Elliptic Curve

As for now, this module only supports 1 curve: ecp256k1.

However, you can Implement your own curve derived from the EllipticCurve class.

Implement customize curve:

class ecp256k1(EllipticCurve):
	# ecp256k1 https://www.secg.org/sec2-v2.pdf
	def __init__(self):
		a = 0
		b = 7
		p = 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEFFFFFC2F
		Gx = 0x79BE667EF9DCBBAC55A06295CE870B07029BFCDB2DCE28D959F2815B16F81798
		Gy = 0x483ADA7726A3C4655DA4FBFC0E1108A8FD17B448A68554199C47D08FFB10D4B8
		n = 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEBAAEDCE6AF48A03BBFD25E8CD0364141

		super(ecp256k1, self).__init__(a, b, p, (Gx, Gy), n)

Encrypt:

ec = asymmetric.elliptic_curve.ecp256k1()
pri = ec.get_private_key()
pub = ec.get_public_key(pri)
ec_cipher = ec.encrypt(data, pub)
print(ec_cipher)

Decrypt:

ec.decrypt(ec_cipher, pri)

Generate signature:

signature = ec.get_signature(hash.sha1.sha1(data), pri)

Validate signature:

ec.is_valid_signature(hash.sha1.sha1(data), signature, pub)

hash

---

md5

This module provide 2 hashing algorithm: MD5 and SHA-1.

    hash.md5.md5(b'basdfasdfadsf')

sha1

    hash.sha1.sha1(b'basdfasdfadsf')