SYMMETRIX-Encryption-Engine

Created an encryption algorithm, utilising substitution and bitwise XOR operations, implemented the prototype in Python featuring custom functions for two-way encryption and decryption of arbitrary strings. View Project Demo

Methodology

1. Caesar Cipher for Substitution:

• Encryption: Each alphabetical character in the plaintext is shifted by a fixed number of positions (the key) in the alphabet. The shift wraps around the alphabet, so a character shifted past 'Z' starts again at 'A'. Non-alphabetical characters remain unchanged.
• Decryption: To reverse the encryption, each character is shifted back by the same number of positions. This is achieved by using a negative shift value.

2. Bitwise XOR Operation:

• Encryption: After the substitution step, each character in the resulting text is XORed with the key to produce the final encrypted text. XOR is a bitwise operation that compares each bit of its operands and returns 1 if the bits are different and 0 if they are the same.
• Decryption: The XOR operation is reversible using the same key. By applying XOR again with the same key to the encrypted text, the original substituted text is retrieved.

Flow of the Code

1. Encryption Function:

Substitution Step: The caesar_cipher function performs a Caesar cipher shift on the input text using the specified key. XOR Step: The resulting text from the substitution step is then XORed with the key. Each character is transformed based on the XOR operation, producing the final encrypted text.

2. Decryption Function:

XOR Step: The encrypted text undergoes an XOR operation with the same key used during encryption to retrieve the substituted text. Reverse Substitution Step: The caesar_cipher function is called with a negative shift value to reverse the Caesar cipher substitution, restoring the original plaintext.

Detailed Flow

Encryption:

• Input: plain_text = "Arya Patel.", key = 5
• Caesar Cipher Substitution:
• Each character in the plaintext is shifted by 5 positions.
• Example: 'A' -> 'F', 'r' -> 'w', 'y' -> 'd', 'a' -> 'f', 'P' -> 'U', 'a' -> 'f', 't' -> 'y', 'e' -> 'j', 'l' -> 'q'
• Non-alphabetical character '.' remains unchanged.
• Bitwise XOR Operation:
• Each character in the substituted text is XORed with the key (5).
• Example: 'F' -> 'B', 'w' -> 'r', 'd' -> 'a', 'f' -> 'c', 'U' -> 'Q', 'f' -> 'c', 'y' -> '}', 'j' -> 'e', 'q' -> 'q'

Decryption:

• Input: encrypted_text = "BrcacQw^q"
• Bitwise XOR Operation:
• Each character in the encrypted text is XORed with the key (5) to retrieve the substituted text.
• Example: 'B' -> 'F', 'r' -> 'w', 'a' -> 'd', 'c' -> 'f', 'Q' -> 'U', 'c' -> 'f', '^' -> 'y', 'q' -> 'j', 'q' -> 'q'
• Reverse Caesar Cipher Substitution:
• Each character in the substituted text is shifted back by 5 positions.
• Example: 'F' -> 'A', 'w' -> 'r', 'd' -> 'y', 'f' -> 'a', 'U' -> 'P', 'f' -> 'a', 'y' -> 't', 'j' -> 'e', 'q' -> 'l'
• Non-alphabetical character remains unchanged.

Example Usage:

Plain Text: "Arya Patel."
Encrypted Text: Result after substitution and XOR operations.
Decrypted Text: Restored to original plaintext after XOR and reverse substitution.

This encryption and decryption methodology ensures a two-layer security approach by combining substitution and bitwise operations, making it robust against simple cryptographic attacks. The flow of the code highlights the step-by-step transformation of the text, ensuring clarity and understanding of the custom algorithm implemented.

Output