Real cryptography, running in your browser

Encrypt a real message with real AES-256-GCM, see the IV, ciphertext, and auth tag, then decrypt it back — or tamper with one byte and watch decryption fail.

Hash any text live and watch the digest change completely when you edit a single character.

Compute a real HMAC-SHA256 over a message and secret, then see why changing even one bit of the message makes verification fail.

Generate a real 2048-bit RSA key pair in your browser, encrypt a short message with the public key, and decrypt it with the private key.

Generate a real P-256 key pair, sign a message, verify it — then tamper with the message and watch verification reject it.

Simulate Alice and Bob generating independent key pairs and deriving the exact same shared secret — without ever transmitting it.

Build a real HMAC-signed JWT from your own claims, or paste one in to decode its header and payload and verify its signature.

Derive a real key from a password with a tunable iteration count, and feel the cost difference between 1,000 and 600,000 iterations yourself.

Build a real three-link chain of trust — root, intermediate, and leaf — each signed with real ECDSA, then tamper with the leaf and watch verification catch it.

Simulate Bob publishing a key bundle and going offline, then Alice computing a shared secret from it anyway — the mechanism behind Signal's first-message problem.