Check if two PDF documents are identical with Python

Python is an interpreted and general purpose programming language. It is a Object-Oriented and Procedural paradigms programming language. There are various types of modules imported in python such as difflib, hashlib.

Modules used:

• difflib : It is a module that contains function that allows to compare set of data.
• SequenceMatcher : It is used to compare pair of input sequences.

Function Used:

• hash_file ( string $algo , string $filename , bool $binary = false ): It is a function which has the hash of a file.
• object.hexdigest(): It is a function which returns string.
• fileObject.read(size): It is a function that returns the specified number of bytes of a file.

Approach

• Import module
• Declare a function with 2 arguments which is for file.
• Declare two objects for hashlib.sha1()
• Open files
• Read the file by breaking the line into smaller chunks
• Now return both file such as h1.hexdigest() which is of 160 bits.
• Use hash_file() function to store the hash of a file.
• Compare and generate appropriate message

Files in Use

• File 1

• File 2

Program:

Python3

import hashlib
from difflib import SequenceMatcher


def hash_file(fileName1, fileName2):

    # Use hashlib to store the hash of a file
    h1 = hashlib.sha1()
    h2 = hashlib.sha1()

    with open(fileName1, "rb") as file:

        # Use file.read() to read the size of file
        # and read the file in small chunks
        # because we cannot read the large files.
        chunk = 0
        while chunk != b'':
            chunk = file.read(1024)
            h1.update(chunk)

    with open(fileName2, "rb") as file:

        # Use file.read() to read the size of file a
        # and read the file in small chunks
        # because we cannot read the large files.
        chunk = 0
        while chunk != b'':
            chunk = file.read(1024)
            h2.update(chunk)

        # hexdigest() is of 160 bits
        return h1.hexdigest(), h2.hexdigest()


msg1, msg2 = hash_file("pd1.pdf ", "pd1.pdf")

if(msg1 != msg2):
    print("These files are not identical")
else:
    print("These files are identical")

Output

These files are not identical