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🧪 Python File Hashing: Or How to Give Your Files a Digital Fingerprint 🔍​

Ever wish you could tell if a file's been tampered with, like a secret agent checking for bugs in their phone? 💼🔎 That’s where file hashes come in! They’re like a file's unchangeable signature (unless the file is changed 👀).

In this laughably serious tutorial, you’ll:

  • Learn what a hash/checksum/digest is (spoiler: not a gym move).
  • See how to use Python’s hashlib module like a pro.
  • Generate file hashes that look as secure as Fort Knox 🔐.

📚 Read More (but not now): [File checksum in Java]
(Because if it's not Java, is it really a programming tutorial?)

1. 🧠 What Are Hash Algorithms?​

A hash function is a cryptographic spell 🧙‍♂️ that takes any input and returns a fixed-length string of gibberish that’s always the same for the same input — no matter how many times you run it!

Why is that cool?

  • It's used to store passwords without actually storing passwords 🔒.
  • It lets you verify if a file was altered during transmission (a.k.a. anti-hacker wizardry).
  • It makes your app look 10x smarter with just one import.

So the next time you’re transferring a top-secret file, don’t forget to pass its hash along for a security handshake 🤝. If the hash matches, it’s legit. If it doesn’t—RUN! 🏃‍♀️💨

2. 🔍 hashlib — Your Python Hashing Toolbox​

Python makes hashing easier than reheating pizza 🍕. Just use the built-in hashlib module.

Wanna see all the cool algorithms it supports?​

import hashlib

print(hashlib.algorithms_guaranteed)

🖨️ Output:

{'shake_256', 'sha1', 'blake2s', 'sha3_224', 'sha512', 
 'sha3_256', 'sha224', 'sha256', 'sha3_384', 
 'sha384', 'blake2b', 'sha3_512', 'shake_128', 'md5'}

These aren’t spell names from Hogwarts—they’re cryptographic power tools 💥.

3. 🧑‍💻 Python File Hash Examples​

Let’s get our hands dirty and generate some serious hashes! 🔐

🥇 Example 1: SHA256 — The Gold Standard of File Hashing​

This is like the Schwarzenegger of hash functions. Strong. Reliable. Future-proof.

import hashlib # hashlib module
import os.path # For file handling
from os import path
 
def hash_file(filename):
 
  if path.isfile(filename) is False:
    raise Exception("File not found for hash operation") 
 
  # make a hash object
  h_sha256 = hashlib.sha256()
 
  # open file for reading in binary mode
  with open(filename,'rb') as file:
 
    # read file in chunks and update hash
    chunk = 0
    while chunk != b'':
      chunk = file.read(1024) 
      h_sha256.update(chunk)
 
  # return the hex digest
  return h_sha256.hexdigest()
 
####### Example Usage
message = hash_file("Python")
print(message)

🖨️ Output:

8964ed69cac034a6bc88ad33089500b6a26a62f19e1574f2f8fbfddeb9a30667

Not bad, huh? That’s one solid, chunky hash 🧱.

⚠️ Example 2: SHA1 — The “Hey Grandpa” of Hashing (Not Recommended)​

SHA1 had its time, but it's now mostly used by museums and retro computing enthusiasts.

import hashlib # hashlib module
import os.path # For file handling
from os import path
 
def hash_file(filename):
 
  if path.isfile(filename) is False:
    raise Exception("File not found for hash operation") 
 
  # make a hash object
  h = hashlib.sha1()
 
  # open file for reading in binary mode
  with open(filename,'rb') as file:
 
    # read file in chunks and update hash
    chunk = 0
    while chunk != b'':
      chunk = file.read(1024) 
      h.update(chunk)
 
  # return the hex digest
  return h.hexdigest()
 
####### Example Usage
message = hash_file("Python")
print(message)

🖨️ Output:

498fd2d318447f9d0fac30c6e0997c03861c679b

Yep, it still works… but maybe stick to SHA256, unless you're feeling nostalgic 🧓.

🚫 Example 3: MD5 — The Retired Champion of the Internet (Also Not Recommended)​

MD5 used to be cool until hackers got really good at math. Now it’s just hanging out in the cryptographic nursing home 🧓📼.

import hashlib # hashlib module
import os.path # For file handling
from os import path
 
def hash_file(filename):
 
  if path.isfile(filename) is False:
    raise Exception("File not found for hash operation") 
 
  # make a hash object
  md5_h = hashlib.md5()
 
  # open file for reading in binary mode
  with open(filename,'rb') as file:
 
    # read file in chunks and update hash
    chunk = 0
    while chunk != b'':
      chunk = file.read(1024) 
      md5_h.update(chunk)
 
  # return the hex digest
  return md5_h.hexdigest()
 
####### Example Usage
message = hash_file("Python")
print(message)

🖨️ Output:

ee6dcaf64b270667125a33f9b7bebb75

Nice try, MD5. You were great in the ‘90s. But it’s 2025. Go home, you’re drunk.

🥳 That’s a Wrap​

You now know how to:

  • Create file hashes with Python like a cryptographic ninja 🥷
  • Compare digests like a detective 🕵️
  • Avoid outdated algorithms that are basically made of tissue paper 🧻

Now go forth, protect your files, and throw SHA256 at anyone who tries to mess with them.

Happy Hashing! 🔐🚀