Playground
Real cryptography, running in your browser
Most tools here use the Web Crypto API — your browser's own, audited cryptography implementation. Nothing is simulated and nothing is sent to a server: keys are generated, used, and discarded entirely on your device. Most of the Payments tools are the one exception: PIN blocks, CVV/CVC, and EMV cryptograms are all still built on DES/3DES in real production systems, and no browser exposes that through Web Crypto — so those run a small, from-scratch 3DES implementation instead, written and tested against the official FIPS 46 test vector rather than simulated with a different, unrelated cipher. Two tools go a step further and say so explicitly on the page: CAVV generation and network token cryptograms have never been publicly documented by any card network, so those two use a labeled, representative construction rather than a real algorithm — unlike the PIN block, CVV, and ARQC tools, which implement real public standards exactly. One tool is different again: Entropy Testing can optionally pull live bits from a third-party quantum random number generator over the network, and implements 3 of the 10 NIST SP 800-90B min-entropy estimators, ported from NIST's own reference source rather than a full certification-grade implementation — both noted on that tool's own page.
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.
What's happening under the hood →Hash any text live and watch the digest change completely when you edit a single character.
What's happening under the hood →Compute a real HMAC-SHA256 over a message and secret, then see why changing even one bit of the message makes verification fail.
What's happening under the hood →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.
What's happening under the hood →Generate a real P-256 key pair, sign a message, verify it — then tamper with the message and watch verification reject it.
What's happening under the hood →Simulate Alice and Bob generating independent key pairs and deriving the exact same shared secret — without ever transmitting it.
What's happening under the hood →Run a real ECDH exchange, feed it through real HKDF bound to a transcript hash, and use the result to AES-GCM-encrypt a record — the exact chain TLS 1.3 runs on every connection.
What's happening under the hood →Build a real HMAC-signed JWT from your own claims, or paste one in to decode its header and payload and verify its signature.
What's happening under the hood →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.
What's happening under the hood →Generate a real KMS-style KEK, wrap a fresh DEK with it via RSA-OAEP, encrypt data locally, then unwrap and decrypt — plus a second panel wrapping a key with real AES Key Wrap (RFC 3394).
What's happening under the hood →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.
What's happening under the hood →Build the same real three-link ECDSA chain as the certificate chain builder, then revoke the intermediate and watch a mathematically perfect signature still get rejected.
What's happening under the hood →Walk through an actual Cryptoki call sequence — login, generate a key pair, sign, and attempt to wrap a non-extractable private key — with real Web Crypto operations standing in for the hardware token.
What's happening under the hood →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.
What's happening under the hood →Build a real ISO-0 PIN block, encrypt it with real 3DES under a demo Terminal PIN Key, then translate it to a second key — the exact HSM operation a PIN performs at every hop between terminal and issuer.
What's happening under the hood →Compute a real CVV1, CVV2, and iCVV from the same PAN, expiry, and Card Verification Key — watch all three diverge from one formula, purely because the service code input differs.
What's happening under the hood →Play both sides of a chip transaction: derive a card's keys from an issuer master key, compute a real ARQC cryptogram, then watch the issuer independently re-derive everything and answer with an ARPC the card verifies on its own.
What's happening under the hood →Build a real EMV 3DS 2.x AReq, watch the ACS decide frictionless vs. challenge, sign a real ARes as a JWS with ECDSA, then verify it — or tamper with it and watch the signature catch it.
What's happening under the hood →See the shape of CAVV generation — PAN, ATC, amount, and ECI feeding a MAC-style construction — clearly labeled as representative, since no card network has ever published its real, proprietary algorithm.
What's happening under the hood →