Introduction

What is IncoPay?

IncoPay is private X402 on Solana: confidential SPL token transfers with message-based authorization and gasless submission via Kora as fee payer. It is powered by Inco Network and the Inco Lightning program for encrypted amounts and confidential transfers.

We built private X402 on Solana using Inco Network. The stack uses the Inco Lightning program for confidential SPL token transfers and Kora only as the facilitator service—fee payer and transaction submission—so users get a gasless, one-sign flow.

On the facilitator we added full support for ciphertext and the payment lifecycle: getAmount returns an encrypted amount (ciphertext) for the transfer; verify validates the user’s Ed25519 signature over the payment message (ciphertext, amount, recipient); and settle runs in two steps—it first returns an unsigned transaction for the user to sign once, then accepts the signed transaction and forwards it to Kora for fee-payer signature and submission. Ciphertext is read and passed through the whole flow so amounts stay confidential until settlement; Kora is used only for paying fees and sending the transaction, not for generating or verifying ciphertext.

On-chain, the flow uses Ed25519 signature verification and the IncoToken program’s transfer_with_authorization so the confidential transfer is tied to the signed message.

How it works (high level)

1. User connects a Solana wallet and requests a payment (e.g. Pay 1 INCO on /started).
2. Facilitator returns ciphertext for the amount (/getAmount).
3. User signs a message authorizing the payment; facilitator verifies the signature (/verify).
4. Facilitator builds an unsigned transaction; user signs the transaction once.
5. Kora adds the fee-payer signature and submits the transaction—user pays no gas.

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Next steps