#cryptography

Topics tagged "cryptography".

• Caesar Cipher

  Shift every letter of the alphabet by a fixed amount — the oldest cipher, and one of the easiest to break.

• Substitution Cipher

  Replace each letter by any other under a fixed scrambled alphabet — an enormous keyspace that frequency analysis still cracks.

• One-Time Pad

  XOR a message with a truly random key as long as itself — the only cipher proven unbreakable, and the only one almost nobody can use.

• Modular Arithmetic

  Arithmetic that wraps around a fixed modulus — the finite-ring algebra that makes public-key cryptography possible.

• Diffie–Hellman

  Two strangers agree on a shared secret over a fully public channel — the paint-mixing trick that launched public-key cryptography.

• RSA

  Public-key encryption and signatures built on the difficulty of factoring a product of two large primes.

• Cryptography

  The art and mathematics of keeping secrets and proving identity — from a Roman shift cipher to the public-key algebra that secures the modern web.

• Public-Key Cryptography

  Split the key in two — a public lock anyone can close and a private key only you can open — using one-way functions with a hidden trapdoor.

• Hash Function

  A one-way fingerprint that turns any input into a fixed-size digest, where flipping one input bit scrambles roughly half the output.

• Digital Signature

  Sign a message's hash with your private key so anyone can verify, with your public key, that you wrote it and nobody altered it.