⚠ SIMULATOR ONLY — NOT FOR PRODUCTION USE — All keys and values shown in cleartext

Callendina Visible Payments Explorer

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Card Scheme Simulator
HSM Simulator
AS2805.2 Decoder
⚠ This is an educational simulator (beta). All cryptographic keys and data are shown in cleartext. Never use real production keys or cardholder data. Report bugs to jonno@callendina.com.

Visible Payments Explorer

An open, educational simulator for payment HSM cryptography and payment network message flows. All keys are shown in cleartext so you can see exactly what each operation does.

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Card Scheme Simulator

Explore how terminals, acquirers, schemes and issuers communicate using AS2805 messages — for card issuance, PIN set, terminal provisioning and purchase transactions.

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HSM Simulator

Step through individual HSM operations — generate LMKs and zone keys, encrypt PIN blocks, compute MACs, wrap keys with TR-31, and more. All inputs and outputs are visible.

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AS2805.2 Decoder

Paste raw hex bytes from an AS2805.2 message and decode it into human-readable fields, bitmaps, and a colour-coded hex dump.

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AS2805 • DUKPT • TR-31 • TR-34 • ISO 9797 • RSA — Educational use only
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Larger Screen Required

The payment scheme simulator needs a screen width of at least 900px to display the network topology, activity records, and key material properly.

Try rotating to landscape, or use a tablet / desktop browser.

Test Cards
Network Topology — Simplified AS2805.2 Payments Scheme
Complete setting up the scheme and CA/KIF, then add an Issuer or an Acquirer to get started. Or just press 'Quick Setup' to have the network built out automatically.

AS2805.2 Message Decoder

Paste the raw hex bytes of an AS2805.2 message (whitespace is ignored). Click Decode to parse it into human-readable fields.

Select a function

Choose an HSM function from the sidebar to get started.

Key Store
No saved keys

Save to Key Store