Working with the hashlib Library in Python

Hash functions play a crucial role in cryptography and data integrity verification. Python's hashlib library provides a convenient interface to work with various cryptographic hash functions. In this tutorial, we will explore how to use the hashlib library to calculate hash values of strings and files.

1. Introduction to hashlib

The hashlib module provides a common interface to many secure hash and message digest algorithms. These algorithms take arbitrary-sized data and return a fixed-size hash value. Some of the supported algorithms include MD5, SHA-1, SHA-224, SHA-256, SHA-384, and SHA-512.

2. Calculating Hashes of Strings

Let's start by calculating the hash of a string using hashlib. Here's a simple example:

import hashlib
# Define a string
my_string = "Hello, world!"
# Create a hash object
hash_object = hashlib.sha256()
# Update hash object with the string
hash_object.update(my_string.encode())
# Get the hexadecimal representation of the hash
hex_dig = hash_object.hexdigest()
print("Hash of the string:", hex_dig)

import hashlib
def file_hash(filename):
    # Create a hash object
    hash_object = hashlib.sha256()
    # Read the file in binary mode and update hash object
    with open(filename, 'rb') as f:
        while True:
            data = f.read(65536)  # Read in 64k chunks
            if not data:
                break
            hash_object.update(data)
    # Get the hexadecimal representation of the hash
    return hash_object.hexdigest()
# Calculate the hash of a file
file_path = "example.txt"
file_hash_value = file_hash(file_path)
print("Hash of the file:", file_hash_value)