Cryptography Calculators
Cryptography is the science of protecting information. Classical ciphers such as Caesar, Vigenère, Affine and Hill show how keys and modular arithmetic work, while RSA, Diffie-Hellman and ElGamal introduce the ideas behind modern public-key systems.
Every tool here is a teaching demonstration. The calculators show each intermediate value so you can check homework, prepare for exams or understand how an algorithm really works. They are not meant for protecting real data.
A natural study path is: Caesar and Vigenère ciphers, the Affine and Hill ciphers (which need modular inverses), then modular exponentiation, RSA, Diffie-Hellman and ElGamal.
Cryptography tools
Square & Multiply
Fast modular exponentiation a^b mod n with the binary breakdown of b and a step table.
Caesar Cipher
Encrypt or decrypt with a shift of 0–25, or brute-force all 25 shifts when the key is unknown. Every letter is shown.
Vigenère Cipher
Encrypt or decrypt with a keyword. Shows the repeated key and the shift applied to every letter.
Affine Cipher
Encrypt or decrypt with E(x) = (ax + b) mod 26. Shows the modular inverse of a and every letter step.
Hill Cipher
Encrypt or decrypt with a 2×2 or 3×3 key matrix. Shows the determinant, the key inverse mod 26 and every block.
RSA Calculator
Generate an RSA key pair from two primes and encrypt or decrypt an integer, with every calculation shown.
Diffie-Hellman Key Exchange
Walk through a Diffie–Hellman key exchange: public values, shared secret and a check that both sides agree.
ElGamal Encryption Calculator
Generate ElGamal keys and encrypt or decrypt a number modulo a prime, with every calculation shown.