Python Create MD5 Hash of File[with Code Examples]

What is MD5 Hash ?

MD5 (Message Digest 5) is a widely used cryptographic hash function that produces a 128-bit hash value, also known as a message digest.

It is a one-way function, which means that it is not possible to retrieve the original message from its hash value.

MD5 is used for various purposes, such as verifying the integrity of files or messages, generating digital signatures, and storing passwords securely.

It takes an input message of any length and produces a fixed-length output, which is typically represented as a 32-digit hexadecimal number.

How MD5 Hash Works ?

MD5 works by processing the input message in 512-bit blocks and applying a series of mathematical operations that transform the input into a fixed-length hash value.

The resulting hash value is unique to the input message and any change to the input message will result in a completely different hash value.

Different Methods to Python Create MD5 Hash of File

Method 1: Using the hashlib module

The hashlib module in Python provides a simple and efficient way to create an MD5 hash of a file.

You can use the md5() method of the hashlib module to create an MD5 hash object, and then read the file in chunks to update the hash object.

For Example:

import hashlib
def convert_to_md5(filename):
    # create an MD5 hash object
    md5_hash = hashlib.md5()# read the file in chunks and update the hash object
    with open(filename, 'rb') as f:
        for chunk in iter(lambda: f.read(4096), b""):
            md5_hash.update(chunk)
    # get the hexadecimal representation of the hash value
    md5_hash_hex = md5_hash.hexdigest()
    return md5_hash_hex
file_path = "/path/to/file"
hash_md5 = convert_to_md5(file_path)
print(hash_md5)

In this example, we use the hashlib module to compute the MD5 hash of a file. The file is read in binary mode and processed in chunks of 4096 bytes to avoid reading the entire file into memory at once.

Method 2: Using the built-in open function and the hashlib module

This is a shorter version of the previous method, which uses the with open() statement to read the file in chunks and update the hash object.

import hashlib
def convert_to_md5(file_path):
    with open(file_path, "rb") as f:
        contents = f.read()
    return hashlib.md5(contents).hexdigest()
file_path = "/path/to/file"
hash_md5 = convert_to_md5(file_path)
print(hash_md5)

Method 3: Using the hashlib module with mmap module

This method uses the mmap module in Python to map the file into memory and calculate the MD5 hash of the memory-mapped file.

For Eaxmple:

import hashlib
import mmap
filename = "/path/to/file"
with open(filename, "rb") as f:
   with mmap.mmap(f.fileno(), 0, access=mmap.ACCESS_READ) as m:
       md5 = hashlib.md5(m).hexdigest()print(md5)

MD5 hash applications

1. Message Integrity

MD5 is widely used to verify the integrity of messages, files, and data by generating a unique hash value that represents the contents of the message or file. Any changes to the message or file will result in a different hash value, making it possible to detect tampering or data corruption.

2. Digital Signatures

MD5 can be used to generate digital signatures that authenticate the identity of the sender and ensure the integrity of the message or file. The sender can compute the hash value of the message or file using MD5 and then encrypt the hash value using their private key to create a digital signature. The receiver can decrypt the digital signature using the sender’s public key and verify the hash value to ensure that the message or file has not been tampered with.

3. Password Storage

MD5 can be used to store passwords securely by generating a hash value of the password and storing the hash value instead of the password itself. This way, even if an attacker gains access to the hash value, they will not be able to retrieve the original password.