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---------

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: github-actions <${GITHUB_ACTOR}@users.noreply.github.com>
Co-authored-by: Tianyi Zheng <tianyizheng02@gmail.com>
Co-authored-by: Christian Clauss <cclauss@me.com>
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36
hashes/sha1.py
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@ -1,26 +1,28 @@
"""
Demonstrates implementation of SHA1 Hash function in a Python class and gives utilities
to find hash of string or hash of text from a file.
Implementation of the SHA1 hash function and gives utilities to find hash of string or
hash of text from a file. Also contains a Test class to verify that the generated hash
matches what is returned by the hashlib library
Usage: python sha1.py --string "Hello World!!"
python sha1.py --file "hello_world.txt"
When run without any arguments, it prints the hash of the string "Hello World!!
Welcome to Cryptography"
Also contains a Test class to verify that the generated Hash is same as that
returned by the hashlib library
SHA1 hash or SHA1 sum of a string is a cryptographic function which means it is easy
SHA1 hash or SHA1 sum of a string is a cryptographic function, which means it is easy
to calculate forwards but extremely difficult to calculate backwards. What this means
is, you can easily calculate the hash of a string, but it is extremely difficult to
know the original string if you have its hash. This property is useful to communicate
securely, send encrypted messages and is very useful in payment systems, blockchain
and cryptocurrency etc.
The Algorithm as described in the reference:
is you can easily calculate the hash of a string, but it is extremely difficult to know
the original string if you have its hash. This property is useful for communicating
securely, send encrypted messages and is very useful in payment systems, blockchain and
cryptocurrency etc.
The algorithm as described in the reference:
First we start with a message. The message is padded and the length of the message
is added to the end. It is then split into blocks of 512 bits or 64 bytes. The blocks
are then processed one at a time. Each block must be expanded and compressed.
The value after each compression is added to a 160bit buffer called the current hash
state. After the last block is processed the current hash state is returned as
The value after each compression is added to a 160-bit buffer called the current hash
state. After the last block is processed, the current hash state is returned as
the final hash.
Reference: https://deadhacker.com/2006/02/21/sha-1-illustrated/
"""
import argparse
@ -30,18 +32,18 @@ import struct
class SHA1Hash:
"""
Class to contain the entire pipeline for SHA1 Hashing Algorithm
Class to contain the entire pipeline for SHA1 hashing algorithm
>>> SHA1Hash(bytes('Allan', 'utf-8')).final_hash()
'872af2d8ac3d8695387e7c804bf0e02c18df9e6e'
"""
def __init__(self, data):
"""
Inititates the variables data and h. h is a list of 5 8-digit Hexadecimal
Initiates the variables data and h. h is a list of 5 8-digit hexadecimal
numbers corresponding to
(1732584193, 4023233417, 2562383102, 271733878, 3285377520)
respectively. We will start with this as a message digest. 0x is how you write
Hexadecimal numbers in Python
hexadecimal numbers in Python
"""
self.data = data
self.h = [0x67452301, 0xEFCDAB89, 0x98BADCFE, 0x10325476, 0xC3D2E1F0]
@ -90,7 +92,7 @@ class SHA1Hash:
For each block, the variable h that was initialized is copied to a,b,c,d,e
and these 5 variables a,b,c,d,e undergo several changes. After all the blocks
are processed, these 5 variables are pairwise added to h ie a to h[0], b to h[1]
and so on. This h becomes our final hash which is returned.
and so on. This h becomes our final hash which is returned.
"""
self.padded_data = self.padding()
self.blocks = self.split_blocks()
@ -135,7 +137,7 @@ def test_sha1_hash():
def main():
"""
Provides option 'string' or 'file' to take input and prints the calculated SHA1
hash. unittest.main() has been commented because we probably don't want to run
hash. unittest.main() has been commented out because we probably don't want to run
the test each time.
"""
# unittest.main()