Cryptography: RSA & Vigenere Cipher

Full implementation of RSA encryption/decryption with cryptographic attacks including weak key detection, broadcast attacks using Chinese Remainder Theorem, and parity oracle exploits.

View on GitHub

Live RSA sandbox

Type any message and watch it round-trip through textbook RSA: byte-by-byte encryption with a public key, decryption with the private key, all computed as native JavaScript BigInt math right in your browser.

Public key (anyone can encrypt)

n = 1050589

e = 65537

Private key (only Max knows)

d = 60493

p = 1019

q = 1031

Math

c = m^e mod n

m = c^d mod n

Demo-sized primes — real RSA uses 2048+ bits.

Message to encrypt (max 128 bytes)

1. Plaintext bytes

72 101 108 108 111 32 87 111 114 108 100 33

2. Encrypted ciphertext

638431 323983 258070 258070 307208 633331 838127 307208 117970 258070 853027 684136

3. Decrypted plaintext

Hello World!

✓ matches the original

Each byte of your message is treated as an integer m, encrypted with the public key as c = m^e mod n, then decrypted with the private key as m = c^d mod n. All computation runs as JavaScript BigInt math in your browser — no server round-trip.

Overview

A comprehensive cryptography project implementing RSA and Vigenere cipher algorithms with various cryptographic attacks. The project demonstrates deep understanding of public-key cryptography, including key generation, encryption/decryption, and multiple attack vectors using advanced mathematical techniques like the Chinese Remainder Theorem and modular arithmetic.

Technologies

PythonCryptographyNumber TheoryDecimal ArithmeticHash Functions (SHA-256)Modular Arithmetic

Key Features

✓RSA key generation with large prime numbers
✓RSA encryption and decryption implementation
✓Vigenere cipher with dictionary-based cryptanalysis
✓Weak RSA key detection using GCD analysis
✓RSA broadcast attack using Chinese Remainder Theorem
✓Parity oracle attack for plaintext recovery

Challenges

Handling arbitrary-precision arithmetic for 2048+ bit RSA operations, implementing mathematically complex attacks on cryptographic systems, and managing precision issues with Python's Decimal module for extremely large numbers.

Results

Achieved 100% on the project. A textbook-RSA version is live on this page as an in-browser sandbox: type any message and watch it round-trip through encryption and decryption as native JavaScript BigInt math, fully client-side.

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