https://github.com/zvxvx/crypt
Command line application written in python to encrypt and decrypt messages with different techniques.
https://github.com/zvxvx/crypt
Last synced: 10 months ago
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Command line application written in python to encrypt and decrypt messages with different techniques.
- Host: GitHub
- URL: https://github.com/zvxvx/crypt
- Owner: zvxvx
- Created: 2024-07-25T04:30:03.000Z (almost 2 years ago)
- Default Branch: main
- Last Pushed: 2024-08-09T20:51:50.000Z (almost 2 years ago)
- Last Synced: 2025-03-21T19:45:15.877Z (over 1 year ago)
- Language: Python
- Homepage:
- Size: 83 KB
- Stars: 0
- Watchers: 1
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
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README
Crypt includes traditional ciphers such as the Caesar Cipher, Autokey Cipher, and Railfence Cipher, as well as modern ciphers like AES, DES, and the asymmetrical cipher RSA.
## How to:
#### Clone this repo.
#### Install pycryptodome if not installed already.
##### Note: $ is to denote terminal commands. Do not include it as part of the command.
```sh
$ pip install pycryptodome
```
- Python 3.x
```sh
$ pip3 install pycryptodome
```
#### Run the application.
```sh
$ python main.py
```
- Python 3.x
```sh
$ python3 main.py
```
#### Follow the instructions given in the command-line application.
##### Note: RSA will output keys and encrypted data to the subdirectory /rsa
# Symmetric Encryption
## Traditional Ciphers
### Caesar Cipher
The Caesar Cipher is a substitution cipher where each letter in the plaintext is shifted a certain number of places down or up the alphabet.
#### Encryption:
Each letter in the plaintext is shifted by a fixed number, known as the key. For example, with a key of 3, 'A' would be encrypted to 'D', 'B' to 'E', and so on.
#### Decryption:
Each letter in the ciphertext is shifted back by the same fixed number.
##### Example:
- Plaintext: HELLO
- Key: 3
- Ciphertext: KHOOR
### Autokey Cipher
The Autokey Cipher is a polyalphabetic substitution cipher that uses a keyword followed by the plaintext itself to create the key.
#### Encryption:
A keyword is chosen and appended to the plaintext (after removing the keyword length) to create a running key. Each letter of the plaintext is shifted by the corresponding letter of the running key, where 'A' represents a shift of 0, 'B' a shift of 1, and so on.
#### Decryption:
The keyword is used to decipher the first part of the message. The plaintext itself is then used to decipher the remaining part.
##### Example:
- Plaintext: HELLO
- Keyword: KEY
- Ciphertext: RIJSS
### Railfence Cipher
The Railfence Cipher is a transposition cipher that arranges the plaintext in a zigzag pattern across multiple "rails" and then reads it off row by row.
#### Encryption:
The plaintext is written in a zigzag pattern across a fixed number of rails. The ciphertext is obtained by reading the pattern row by row.
#### Decryption:
The ciphertext is written in the zigzag pattern and read off in the original order.
##### Example:
- Plaintext: HELLO WORLD
- Number of Rails: 3
- Ciphertext: HOREL OLLWD
## Modern Ciphers
### AES (Advanced Encryption Standard)
AES is a symmetric key encryption standard adopted by the U.S. government. It supports key sizes of 128, 192, and 256 bits and operates on 128-bit blocks.
#### Encryption:
The plaintext is divided into 128-bit blocks. Each block undergoes multiple rounds of substitution, permutation, mixing, and key addition.
#### Decryption:
The process is reversed using the same key to retrieve the original plaintext.
#### Key Features:
- Strong security
- Widely used in various applications
### DES (Data Encryption Standard)
DES is a symmetric key encryption algorithm that uses a 56-bit key and operates on 64-bit blocks.
#### Encryption:
The plaintext is divided into 64-bit blocks. Each block undergoes 16 rounds of permutation and substitution based on the key.
#### Decryption:
The process is reversed using the same key to retrieve the original plaintext.
#### Key Features:
- Less secure by modern standards due to short key length
- Superseded by AES
# Asymmetric Encryption
## RSA (Rivest–Shamir–Adleman)
RSA is an asymmetric key encryption algorithm that uses a pair of keys: a public key for encryption and a private key for decryption.
#### Encryption:
The plaintext is encrypted using the recipient's public key. Only the recipient can decrypt the ciphertext using their private key.
#### Decryption:
The ciphertext is decrypted using the recipient's private key.
#### Key Features:
- Based on the mathematical difficulty of factoring large prime numbers
- Widely used for secure data transmission