Payment puzzle · Route the payment · Medium

Can you deliver a chip’s cryptogram to the only system able to check it?

Route it through a real card network, one hop at a time. Free, no sign-up.

Mission

The chip signed this payment with an ARQC cryptogram. Deliver it to the one system that can check it, and don’t hand it to anyone who can’t.

Start at Chip card and click connected systems one hop at a time until you reach the goal. Some routes reach the goal and still fail. Par: 5 hops.

CustomerMerchantAcquirer / PSPCard schemeIssuerEMV chip: signs each transaction with an ARQC cryptogram.💳Chip cardSTARTHolds a device token (DPAN), never the real card number.📱Phone walletThe shopper at an online checkout.🌐BrowserReads the card or phone and builds the authorization request.🏪POS terminalThe merchant’s online payment page.🛒Web checkoutHardware security module: translates PIN blocks between keys.🔐Acquirer HSMThe merchant’s bank: routes requests to the right card network.🏦Acquirer hostConnects checkouts and terminals to the acquirer.⚙️Payment gatewayRuns 3-D Secure for the merchant or its PSP.🛡️3DS ServerToken vault: maps device tokens back to real card numbers.🪙Token serviceRoutes authorizations between acquirers and issuers by BIN.🔗Card network3-D Secure router: finds the issuer’s ACS for a card range.🧭Directory ServerVerifies PINs, ARQCs and CAVVs without exposing keys.🔑Issuer HSMGOALThe cardholder’s bank: approves or declines.🏛️Issuer hostAccess Control Server: the issuer’s 3-D Secure authenticator.✅ACS

Your route · 0 hops

  1. Chip card

All puzzles and what they teach

  1. Route the payment

    Chip at the counterWarm-up

    Can you get a chip payment from the counter to the card’s bank?

    PlayRead: ISO 8583 Protocol

  2. Route the payment

    Verify the chipMedium

    Can you deliver a chip’s cryptogram to the only system able to check it?

    PlayRead: NFC in Payments

  3. Route the payment

    Tap with a phoneMedium

    Can you get a phone tap approved by a bank that has never seen the phone’s card number?

    PlayRead: Payment Tokenization

  4. Route the payment

    Online PINHard

    Can you get an encrypted PIN to the issuer without anyone reading it on the way?

    PlayRead: TR-31 & TR-34 Key Standards

  5. Route the payment

    Checkout with 3-D SecureExpert

    Can you authenticate and authorize an online payment in the right order?

    PlayRead: 3D Secure (EMV 3DS)

  6. Put it in order

    Chip transaction, step by stepMedium

    Can you put the steps of a chip payment in the order the card and terminal run them?

    PlayRead: EMV Contactless Kernels 2–8

  7. Set the bits

    Read the TVRMedium

    Can you set the TVR bits that record what the terminal found?

    PlayRead: EMV Contactless Kernels 2–8

  8. Diagnose

    Diagnose the declineHard

    Can you find the root cause of three real-world payment failures from the logs?

    PlayRead: ISO 8583 Protocol