Cryptographic Algorithms

This project implements custom cryptographic algorithms in Python, specifically SHA-256 and SHA-512. It includes PyTest to verify the correctness of the implementations by comparing them with Python's built-in hashlib library.

Overview

Cryptographic hashing functions like SHA-256 and SHA-512 are fundamental to various fields, including data integrity, digital signatures, and password hashing. This project explores these algorithms by creating custom implementations.

SHA-256

The following components make up the SHA-256 implementation in this project:

• SHA-256 Constants: A list of predefined constants, derived from the fractional parts of the cube roots of the first 64 prime numbers.
• Right Rotate Function (right_rotate): A helper function for circular bitwise shifts, which is used extensively in the compression process.
• Compression Function (sha256_compress): This function processes each 512-bit chunk of the message and updates the hash values according to the SHA-256 algorithm.
• Padding Function (sha256_pad): Ensures that the input message is padded correctly to a multiple of 512 bits, as required by the SHA-256 algorithm.
• Main Hash Function (sha256): The core function that computes the SHA-256 hash of a given message, using the compression function iteratively on each message chunk.

SHA-512

The SHA-512 implementation follows a structure similar to the SHA-256 implementation, with some key differences:

• SHA-512 Constants: A list of predefined constants, derived from the first 80 prime numbers, used for 64-bit word operations.
• Right Rotate Function (right_rotate): As in SHA-256, a helper function for bitwise shifts but adapted for 64-bit words.
• Compression Function (sha512_compress): This function processes each 1024-bit chunk of the message and updates the hash values according to the SHA-512 algorithm.
• Padding Function (sha512_pad): Pads the input message to a multiple of 1024 bits as required by the SHA-512 algorithm.
• Main Hash Function (sha512): The core function that computes the SHA-512 hash of a given message.

Examples

To use the custom implementations, simply import the relevant functions from the sha256.py or sha512.py files. Below are examples for both:

SHA-256

def example1():
    message = b"Hello World!"
    print(f"Example 1: Hello World! = {sha256(message)}")

Example 1: Hello World! = 7f83b1657ff1fc53b92dc18148a1d65dfc2d4b1fa3d677284addd200126d9069

SHA-512

def example1():
    message = b"Hello World!"
    print(f"Example 1: Hello World! = {sha512(message)}")

Example 1: Hello World! = 861844d6704e8573fec34d967e20bcfef3d424cf48be04e6dc08f2bd58c729743371015ead891cc3cf1c9d34b49264b510751b1ff9e537937bc46b5d6ff4ecc8