# x402 · Integra > The seller’s 402 challenge carries the ATR hash and a link to the ATR; the payment carries the ATR hash in the rail’s own field. URL: https://integraledger.com/protocols/x402 Protocol ## x402 The seller’s 402 challenge carries the ATR hash and a link to the ATR; the payment carries the ATR hash in the rail’s own field. [Source: lcp docs: x402⁠ (opens in a new tab)](https://github.com/IntegraLedger/integra-protocol/blob/66274bf/docs/guides/x402.md) x402 is a project of the x402 Foundation, under the Linux Foundation. [Source: LCP §C.4⁠ (opens in a new tab)](https://github.com/legal-context-protocol/legal-context-protocol/blob/c8df26d/spec/legal-context-protocol-v1.md#c4-x402) Integra is not affiliated; we read their published interfaces. **Sources (1)** [lcp docs: x402⁠ (opens in a new tab)](https://github.com/IntegraLedger/integra-protocol/blob/66274bf/docs/guides/x402.md) [The protocol’s own site⁠ (opens in a new tab)](https://www.x402.org) [The standard’s illustration of this protocol (LCP §C.4)⁠ (opens in a new tab)](https://github.com/legal-context-protocol/legal-context-protocol/blob/c8df26d/spec/legal-context-protocol-v1.md#c4-x402) ### What it is x402 is HTTP 402 payment: the seller answers a request with a `PaymentRequired` document listing the options it accepts, and the buyer retries with a payment for one of them. [Source: lcp docs: x402⁠ (opens in a new tab)](https://github.com/IntegraLedger/integra-protocol/blob/66274bf/docs/guides/x402.md) Version 2 carries an `extensions` object on the challenge, on the payment and on the settlement response, so a reference placed there is on the receipt as well as the offer. [Source: LCP §C.4⁠ (opens in a new tab)](https://github.com/legal-context-protocol/legal-context-protocol/blob/c8df26d/spec/legal-context-protocol-v1.md#c4-x402) **Sources (2)** [lcp docs: x402⁠ (opens in a new tab)](https://github.com/IntegraLedger/integra-protocol/blob/66274bf/docs/guides/x402.md) · [LCP §C.4⁠ (opens in a new tab)](https://github.com/legal-context-protocol/legal-context-protocol/blob/c8df26d/spec/legal-context-protocol-v1.md#c4-x402) ### Where the ATR hash rides In the seller’s payment request, beside a link to the ATR. On most chains the payer then signs it as part of the payment. #### The standard Every x402 pairing advertises the ATR hash in the challenge’s `extensions.legalContext`, with the link to the ATR beside it, and the buyer echoes it in its payment. [Source: lcp docs: x402⁠ (opens in a new tab)](https://github.com/IntegraLedger/integra-protocol/blob/66274bf/docs/guides/x402.md) The payment then carries it where the rail allows: on EVM chains the payer signs the ATR hash itself as the nonce of its EIP-3009 authorization; on Solana it is the transaction’s Memo instruction; on Stellar, the seller’s muxed address takes the first 8 bytes of the ATR hash as its id. [Source: lcp docs: rails⁠ (opens in a new tab)](https://github.com/IntegraLedger/integra-protocol/blob/66274bf/docs/guides/rails.md) One document has one legal context: a challenge offering options on several rails carries one ATR hash, H, so the buyer’s payment on any of them is bound to the same ATR. [Source: lcp docs: x402⁠ (opens in a new tab)](https://github.com/IntegraLedger/integra-protocol/blob/66274bf/docs/guides/x402.md) The ATR’s binding slot also commits to the request the challenge answers (method, path, query and a SHA-256 of the body) and to every option exactly as issued. [Source: lcp docs: binding⁠ (opens in a new tab)](https://github.com/IntegraLedger/integra-protocol/blob/66274bf/docs/concepts/binding.md) Carrying the reference inside x402’s signed Offer and Receipt artifacts is not available today: their EIP-712 types are closed, so it would need an upstream change. [Source: LCP §C.4⁠ (opens in a new tab)](https://github.com/legal-context-protocol/legal-context-protocol/blob/c8df26d/spec/legal-context-protocol-v1.md#c4-x402) #### The data Read from the published packages when the site was built; nothing here is typed by hand. The seller’s challenge for the site’s example sale: H and the link to the ATR, in `extensions.legalContext` ``` { "x402Version": 2, "resource": { "url": "https://api.seller.example/v1/market-data" }, "accepts": [ { "scheme": "exact", "network": "eip155:84532", "amount": "40000000", "asset": "0x036CbD53842c5426634e7929541eC2318f3dCF7e", "payTo": "0x209693Bc6afc0C5328bA36FaF03C514EF312287C", "maxTimeoutSeconds": 60, "extra": { "name": "USDC", "version": "2" } } ], "extensions": { "legalContext": { "info": { "type": "sha256", "value": "0x8448dc1b716a5103287cb8f35e36b614ffd91e630ab8b7911833c54748ad5ca6", "legalContextUrl": "https://atr.seller.example/0x8448dc1b716a5103287cb8f35e36b614ffd91e630ab8b7911833c54748ad5ca6" }, "schema": { "$schema": "https://json-schema.org/draft/2020-12/schema", "type": "object", "properties": { "type": { "const": "sha256" }, "value": { "type": "string", "pattern": "^0x[0-9a-f]{64}$" }, "legalContextUrl": { "type": "string", "pattern": "^https://" } }, "required": [ "type", "value", "legalContextUrl" ] } } } } ``` #### The code Compiled against the published packages when the site is built. The seller writes the ATR and advertises the ATR hash in the challenge src/snippets/seller.ts ``` // The seller, for one sale: write the record, hash its exact bytes, and put the hash and the record's link in the // x402 challenge it answers the request with. import { assemble, hash, isRefusal, newAtrId } from '@integraledger/lcp'; import { exactEip3009, requestCommitment, tie, type HttpRequest, type PaymentRequired } from '@integraledger/lcp/x402'; export async function offer( challenge: PaymentRequired, request: HttpRequest, terms: Uint8Array, store: (bytes: Uint8Array) => Promise, // your storage: it serves these exact bytes at the link it returns ) { const answered = await requestCommitment(request); if (isRefusal(answered)) return answered; const record = await assemble(newAtrId(), tie(challenge.accepts, answered), [['terms', terms]]); if (isRefusal(record)) return record; const h = await hash(record.bytes); const link = await store(record.bytes); return exactEip3009.advertise(challenge, h, link, challenge.accepts[0]!); } ``` The buyer’s gate compares the ATR with the ATR hash before the wallet signs src/snippets/buyer.ts ``` // The buyer's agent, before its wallet signs: the gate fetches the record from its link, hashes the exact bytes, // compares them with the fingerprint the seller advertised, and only then hands the signer a payment that carries it. import { BINDINGS } from '@integraledger/lcp'; import { transact, type Signer } from '@integraledger/terms'; export async function pay(challenge: unknown, signer: Signer, keep: (record: Uint8Array) => Promise) { const binding = BINDINGS.find((b) => b.id === 'x402/exact/eip155/eip3009')!; const result = await transact(challenge, binding, signer, fetch); if ('decline' in result) throw new Error(`${result.decline.code}: ${result.decline.detail}`); if ('approve' in result) return result; // an agreement payment for the agent to approve first await keep(result.bytes); // the record it compared, byte for byte return result.signed; // the payment, carrying the fingerprint } ``` ### What a payment through it proves Each pairing’s record states what a payment through it shows, and what it does not, in the package’s own words. These are read from the package when the site is built. [Source: lcp docs: pairings reference⁠ (opens in a new tab)](https://github.com/IntegraLedger/integra-protocol/blob/66274bf/docs/reference/pairings.md) Of these 29 pairings, 23 have the buyer’s signature cover the ATR hash, 23 leave a public proof of it, and 16 let anyone read it back from the chain alone. [Source: lcp docs: pairings reference⁠ (opens in a new tab)](https://github.com/IntegraLedger/integra-protocol/blob/66274bf/docs/reference/pairings.md) Switch to Technical to see each pairing, and the sentence its record states about what a payment through it proves. **Sources (1)** [lcp docs: pairings reference⁠ (opens in a new tab)](https://github.com/IntegraLedger/integra-protocol/blob/66274bf/docs/reference/pairings.md) #### The standard - **`x402/exact/eip155/eip3009` Native Field Buyer signs H: yes H on chain: yes Public proof: yes Recoverable from chain: yes** Pattern: [Native Field (LCP §8.3.1)⁠ (opens in a new tab)](https://github.com/legal-context-protocol/legal-context-protocol/blob/c8df26d/spec/legal-context-protocol-v1.md#831-native-field) What a payment through it proves: The payer signed an EIP-3009 transfer authorization whose nonce is this ATR's hash. The token contract verified that signature when it executed the transfer, and the hash is on chain as the nonce topic of its AuthorizationUsed event in the settlement transaction. This does not show that amount, payee, asset or timing match the ATR's content. LCP profile: [x402/exact/eip155/eip3009⁠ (opens in a new tab)](https://github.com/IntegraLedger/integra-protocol/blob/66274bf/lcp/profiles/x402-exact-eip155-eip3009.md) - **`x402/auth-capture/eip155/eip3009` Id-Reuse Buyer signs H: yes H on chain: yes Public proof: yes Recoverable from chain: no** Pattern: [Id-Reuse (LCP §8.3.5)⁠ (opens in a new tab)](https://github.com/legal-context-protocol/legal-context-protocol/blob/c8df26d/spec/legal-context-protocol-v1.md#835-id-reuse-hashed-binding) What a payment through it proves: The payer signed a token authorization whose nonce commits, through the escrow's PaymentInfo, to a salt that is this ATR's hash when unbound, or a commitment over it with the receiver authorizer and policy when bound. The token contract or Permit2 verified the signature when the escrow collected the payment, and the escrow's event carries the salt. A holder of the ATR can confirm the hash from the salt; the chain alone does not reveal it. This record covers that first collection; capture, void, refund and reclaim are the operator's and the payer's. LCP profile: [x402/auth-capture/eip155⁠ (opens in a new tab)](https://github.com/IntegraLedger/integra-protocol/blob/66274bf/lcp/profiles/x402-auth-capture-eip155.md) - **`x402/auth-capture/eip155/permit2` Id-Reuse Buyer signs H: yes H on chain: yes Public proof: yes Recoverable from chain: no** Pattern: [Id-Reuse (LCP §8.3.5)⁠ (opens in a new tab)](https://github.com/legal-context-protocol/legal-context-protocol/blob/c8df26d/spec/legal-context-protocol-v1.md#835-id-reuse-hashed-binding) What a payment through it proves: The payer signed a token authorization whose nonce commits, through the escrow's PaymentInfo, to a salt that is this ATR's hash when unbound, or a commitment over it with the receiver authorizer and policy when bound. The token contract or Permit2 verified the signature when the escrow collected the payment, and the escrow's event carries the salt. A holder of the ATR can confirm the hash from the salt; the chain alone does not reveal it. This record covers that first collection; capture, void, refund and reclaim are the operator's and the payer's. LCP profile: [x402/auth-capture/eip155⁠ (opens in a new tab)](https://github.com/IntegraLedger/integra-protocol/blob/66274bf/lcp/profiles/x402-auth-capture-eip155.md) - **`x402/batch-settlement/cloudflare` Protocol Extension Buyer signs H: yes H on chain: no Public proof: no Recoverable from chain: no** Pattern: [Protocol Extension (LCP §8.3.6)⁠ (opens in a new tab)](https://github.com/legal-context-protocol/legal-context-protocol/blob/c8df26d/spec/legal-context-protocol-v1.md#836-protocol-extension) What a payment through it proves: Before this payment, the buyer signed and paid an agreement transaction carrying this ATR's hash on \, recorded in \. The buyer's agent signed, with the HTTP message signature key it registered with Cloudflare, a request whose PAYMENT-SIGNATURE header echoes this ATR's hash in the x402 legalContext extension. Cloudflare verifies that signature and bills the agent's registered identity off chain. This does not show that amount, asset or timing match the ATR's content. - **`x402/batch-settlement/eip155` Native Field Buyer signs H: yes H on chain: yes Public proof: yes Recoverable from chain: yes** Pattern: [Native Field (LCP §8.3.1)⁠ (opens in a new tab)](https://github.com/legal-context-protocol/legal-context-protocol/blob/c8df26d/spec/legal-context-protocol-v1.md#831-native-field) What a payment through it proves: The payer signed a token authorization for a deposit into an x402 batch-settlement channel whose identifier, the EIP-712 hash of the channel's configuration, commits to this ATR's hash as the configuration's salt. The token contract or Permit2 verified that signature when the channel contract collected the deposit, and the hash is on chain as the salt in the channel's ChannelCreated event. Later requests in this channel were paid under this ATR by vouchers the seller did not meter; each voucher signs a commitment to this ATR's hash. This does not show that amount, payee, asset or timing match the ATR's content. LCP profile: [x402/batch-settlement/eip155⁠ (opens in a new tab)](https://github.com/IntegraLedger/integra-protocol/blob/66274bf/lcp/profiles/x402-batch-settlement-eip155.md) - **`x402/batch-settlement/solana` Native Field Buyer signs H: yes H on chain: yes Public proof: yes Recoverable from chain: yes** Pattern: [Native Field (LCP §8.3.1)⁠ (opens in a new tab)](https://github.com/legal-context-protocol/legal-context-protocol/blob/c8df26d/spec/legal-context-protocol-v1.md#831-native-field) What a payment through it proves: The payer signed a Solana transaction whose one Memo instruction carries this ATR's hash in LCP string form, and which opened an x402 batch-settlement payment channel; it executed without error. The memo is in the transaction's instruction data on chain. Later requests in this channel were paid under this ATR by vouchers the seller did not meter. This does not show that amount, recipient, mint or timing match the ATR's content. - **`x402/exact/algorand` Native Field Buyer signs H: yes H on chain: yes Public proof: yes Recoverable from chain: yes** Pattern: [Native Field (LCP §8.3.1)⁠ (opens in a new tab)](https://github.com/legal-context-protocol/legal-context-protocol/blob/c8df26d/spec/legal-context-protocol-v1.md#831-native-field) What a payment through it proves: The payer signed an Algorand asset transfer whose note is this ATR's hash in LCP string form. The ledger verified that signature when it confirmed the transaction, which is final on confirmation, and the note is on chain in it. This does not show that amount, receiver, asset or timing match the ATR's content. LCP profile: [x402/exact/algorand/note⁠ (opens in a new tab)](https://github.com/IntegraLedger/integra-protocol/blob/66274bf/lcp/profiles/x402-exact-algorand-note.md) - **`x402/exact/aptos` HTTP-layer advisory Buyer signs H: no H on chain: no Public proof: no Recoverable from chain: no** Pattern: [HTTP-layer advisory (LCP §8.3.7)⁠ (opens in a new tab)](https://github.com/legal-context-protocol/legal-context-protocol/blob/c8df26d/spec/legal-context-protocol-v1.md#837-http-layer-advisory-reference) What a payment through it proves: Before this payment, the buyer signed and paid an agreement transaction carrying this ATR's hash on \, recorded in \. The ATR was assembled and written to the seller's storage before the challenge went out, and the challenge advertised its hash and link. The payer's signed Aptos transaction does not carry the hash. The seller tied the hash to this payment when it claimed it for this request, and identified the settlement as the payer's committed transaction by sender, sequence number and a digest of its transfer. This does not show that the buyer's approval carried the hash, or that amount, payee, asset or timing match the ATR's content. - **`x402/exact/cardano` Native Field Buyer signs H: yes H on chain: yes Public proof: yes Recoverable from chain: yes** Pattern: [Native Field (LCP §8.3.1)⁠ (opens in a new tab)](https://github.com/legal-context-protocol/legal-context-protocol/blob/c8df26d/spec/legal-context-protocol-v1.md#831-native-field) What a payment through it proves: The payer signed a Cardano transaction whose body commits, through its auxiliary_data_hash, to a CIP-20 message (label 674) carrying this ATR's hash. The ledger included the transaction as valid, at the stated depth; the rail allows a rollback of fewer than k blocks. The hash is in the transaction's metadata on chain. This does not show that amount, payee, asset or timing match the ATR's content. LCP profile: [x402/exact/cardano⁠ (opens in a new tab)](https://github.com/IntegraLedger/integra-protocol/blob/66274bf/lcp/profiles/x402-exact-cardano.md) - **`x402/exact/casper` Native Field Buyer signs H: yes H on chain: yes Public proof: yes Recoverable from chain: yes** Pattern: [Native Field (LCP §8.3.1)⁠ (opens in a new tab)](https://github.com/legal-context-protocol/legal-context-protocol/blob/c8df26d/spec/legal-context-protocol-v1.md#831-native-field) What a payment through it proves: The payer signed a CEP-3009 transfer authorization whose nonce is this ATR's hash. The token contract verified that signature, and that the signing key is the payer's, when it executed the transfer, and the hash is on chain as the nonce argument of that call. This does not show that amount, payee, asset or timing match the ATR's content. LCP profile: [x402/exact/casper⁠ (opens in a new tab)](https://github.com/IntegraLedger/integra-protocol/blob/66274bf/lcp/profiles/x402-exact-casper.md) - **`x402/exact/ccd` Native Field Buyer signs H: yes H on chain: yes Public proof: yes Recoverable from chain: yes** Pattern: [Native Field (LCP §8.3.1)⁠ (opens in a new tab)](https://github.com/legal-context-protocol/legal-context-protocol/blob/c8df26d/spec/legal-context-protocol-v1.md#831-native-field) What a payment through it proves: The payer signed a Concordium transaction whose one transfer carries this ATR's hash, in LCP string form, as its memo. The chain accepted the transaction only with the sender's valid signature, and the memo is on chain in the finalized transfer event. This does not show that amount, payee, token or timing match the ATR's content. LCP profile: [x402/exact/ccd⁠ (opens in a new tab)](https://github.com/IntegraLedger/integra-protocol/blob/66274bf/lcp/profiles/x402-exact-ccd.md) - **`x402/exact/eip155/erc7710` HTTP-layer advisory Buyer signs H: no H on chain: no Public proof: no Recoverable from chain: no** Pattern: [HTTP-layer advisory (LCP §8.3.7)⁠ (opens in a new tab)](https://github.com/legal-context-protocol/legal-context-protocol/blob/c8df26d/spec/legal-context-protocol-v1.md#837-http-layer-advisory-reference) What a payment through it proves: Before this payment, the buyer signed and paid an agreement transaction carrying this ATR's hash on \, recorded in \. The ATR was assembled, written to the seller's storage and linked in the challenge before approval, and the buyer's payment payload echoed this ATR's hash in the x402 legalContext extension. The buyer's delegation does not sign the hash, and the settlement transaction does not carry it. - **`x402/exact/eip155/erc7710-salt` Native Field Buyer signs H: yes H on chain: yes Public proof: yes Recoverable from chain: yes** Pattern: [Native Field (LCP §8.3.1)⁠ (opens in a new tab)](https://github.com/legal-context-protocol/legal-context-protocol/blob/c8df26d/spec/legal-context-protocol-v1.md#831-native-field) What a payment through it proves: The leaf delegation of the permission context redeemed for this payment, made through MetaMask's DelegationManager, carries this ATR's hash as its signed salt. The manager verified every delegation's signature when it redeemed them, and the leaf, with its salt, is in a RedeemedDelegation event in the settlement transaction. The leaf's signer is its delegator, which may be an account the paying account authorised rather than the paying account itself. This does not show that amount, payee, asset or timing match the ATR's content. LCP profile: [x402/exact/eip155/erc7710-salt⁠ (opens in a new tab)](https://github.com/IntegraLedger/integra-protocol/blob/66274bf/lcp/profiles/x402-exact-eip155-erc7710-salt.md) - **`x402/exact/eip155/permit2` Native Field Buyer signs H: yes H on chain: yes Public proof: yes Recoverable from chain: no** Pattern: [Native Field (LCP §8.3.1)⁠ (opens in a new tab)](https://github.com/legal-context-protocol/legal-context-protocol/blob/c8df26d/spec/legal-context-protocol-v1.md#831-native-field) What a payment through it proves: The payer signed a Permit2 witness transfer whose nonce is this ATR's hash, with the scheme's x402 proxy as spender and the payee in the witness. Permit2 verified the signature when the proxy executed the transfer, and the hash is in the settlement transaction's calldata as the Permit2 nonce; no event carries it. This does not show that amount, payee, asset or timing match the ATR's content. LCP profile: [x402/exact/eip155/permit2⁠ (opens in a new tab)](https://github.com/IntegraLedger/integra-protocol/blob/66274bf/lcp/profiles/x402-exact-eip155-permit2.md) - **`x402/exact/hedera` Native Field Buyer signs H: yes H on chain: yes Public proof: yes Recoverable from chain: yes** Pattern: [Native Field (LCP §8.3.1)⁠ (opens in a new tab)](https://github.com/legal-context-protocol/legal-context-protocol/blob/c8df26d/spec/legal-context-protocol-v1.md#831-native-field) What a payment through it proves: The payer signed a Hedera transaction body whose memo carries this ATR's hash in LCP string form, and the transaction reached consensus with SUCCESS. The memo is in the public transaction record. This does not show that amount, recipient, token or timing match the ATR's content. The seller read the landed entry by its transaction id and memo; the fee payer, the seller's facilitator, could land another body under the same id. LCP profile: [x402/exact/hedera⁠ (opens in a new tab)](https://github.com/IntegraLedger/integra-protocol/blob/66274bf/lcp/profiles/x402-exact-hedera.md) - **`x402/exact/hedera/transfer-executor` HTTP-layer advisory Buyer signs H: no H on chain: no Public proof: no Recoverable from chain: no** Pattern: [HTTP-layer advisory (LCP §8.3.7)⁠ (opens in a new tab)](https://github.com/legal-context-protocol/legal-context-protocol/blob/c8df26d/spec/legal-context-protocol-v1.md#837-http-layer-advisory-reference) What a payment through it proves: Before this payment, the buyer signed and paid an agreement transaction carrying this ATR's hash on \, recorded in \. The payment is an x402 transferExecutor payment on Hedera: the payer's executor contract moved the funds under an authorization the seller did not read, and the facilitator submitted the transaction. The hash reached the payer only in the challenge's extension, and nothing the payer signed carries it. The seller read the merged consensus record of the named transaction, and found the transfer whose payer, payee and amount match the digest recorded at claim. This does not show that amount, recipient, token or timing match the ATR's content. - **`x402/exact/lnbtc` Native Field Buyer signs H: no H on chain: no Public proof: no Recoverable from chain: no** Pattern: [Native Field (LCP §8.3.1)⁠ (opens in a new tab)](https://github.com/legal-context-protocol/legal-context-protocol/blob/c8df26d/spec/legal-context-protocol-v1.md#831-native-field) What a payment through it proves: Before this payment, the buyer signed and paid an agreement transaction carrying this ATR's hash on \, recorded in \. The seller's node signed a BOLT11 invoice whose payment metadata is this ATR's hash, and whose description hash is x402's request hash. The payer paid that invoice, and its node checked the node signature before paying. The payer signed nothing that carries the hash, and the seller did not verify the invoice signature. The invoice and its preimage, which the parties hold, are the proof of the payment. No public ledger shows it. This does not show that amount, payee or timing match the ATR's content. LCP profile: [x402/exact/lnbtc⁠ (opens in a new tab)](https://github.com/IntegraLedger/integra-protocol/blob/66274bf/lcp/profiles/x402-exact-lnbtc.md) - **`x402/exact/lnbtc/invoice-named` HTTP-layer advisory Buyer signs H: no H on chain: no Public proof: no Recoverable from chain: no** Pattern: [HTTP-layer advisory (LCP §8.3.7)⁠ (opens in a new tab)](https://github.com/legal-context-protocol/legal-context-protocol/blob/c8df26d/spec/legal-context-protocol-v1.md#837-http-layer-advisory-reference) What a payment through it proves: Before this payment, the buyer signed and paid an agreement transaction carrying this ATR's hash on \, recorded in \. The ATR names this payment: its binding slot holds the payment option as issued, including the seller node's signed BOLT11 invoice, whose payment hash the payer paid and whose description hash is x402's request hash. The invoice does not carry this ATR's hash, and the payer signed nothing that does. The buyer's gate paid only an invoice its ATR names, and the seller checked that the paid invoice is the one issued with this ATR. The invoice and its preimage, which the parties hold, are the proof of the payment. No public ledger shows it. This does not show that amount, payee or timing match the ATR's content. - **`x402/exact/near` Native Field Buyer signs H: yes H on chain: yes Public proof: yes Recoverable from chain: yes** Pattern: [Native Field (LCP §8.3.1)⁠ (opens in a new tab)](https://github.com/legal-context-protocol/legal-context-protocol/blob/c8df26d/spec/legal-context-protocol-v1.md#831-native-field) What a payment through it proves: The payer signed a NEP-366 delegate action whose one ft_transfer carries this ATR's hash in its memo, in LCP string form. The runtime verified that signature and executed the transfer on the token contract, and the memo is on chain in the delegated call's arguments. This does not show that amount, receiver, token or timing match the ATR's content. LCP profile: [x402/exact/near/memo⁠ (opens in a new tab)](https://github.com/IntegraLedger/integra-protocol/blob/66274bf/lcp/profiles/x402-exact-near-memo.md) - **`x402/exact/polkadot/lcp-assets-remark` Native Field Buyer signs H: yes H on chain: yes Public proof: yes Recoverable from chain: yes** Pattern: [Native Field (LCP §8.3.1)⁠ (opens in a new tab)](https://github.com/legal-context-protocol/legal-context-protocol/blob/c8df26d/spec/legal-context-protocol-v1.md#831-native-field) What a payment through it proves: The payer signed one Polkadot Asset Hub extrinsic whose call is an atomic batch of a transfer of the asset and an on-chain remark whose bytes are this ATR's hash in LCP string form. The chain verified the signature, which covers the call, and executed the batch, which applies both calls or neither. Its Remarked event carries the BLAKE2b-256 of the remark, and its Transferred event names the asset, at the finality recorded. This does not show that amount, payee, asset or timing match the ATR's content. LCP profile: [x402/exact/polkadot/lcp-assets-remark⁠ (opens in a new tab)](https://github.com/IntegraLedger/integra-protocol/blob/66274bf/lcp/profiles/x402-exact-polkadot-lcp-assets-remark.md) - **`x402/exact/solana` Native Field Buyer signs H: yes H on chain: yes Public proof: yes Recoverable from chain: yes** Pattern: [Native Field (LCP §8.3.1)⁠ (opens in a new tab)](https://github.com/legal-context-protocol/legal-context-protocol/blob/c8df26d/spec/legal-context-protocol-v1.md#831-native-field) What a payment through it proves: The payer signed a Solana transaction whose one Memo instruction carries this ATR's hash in LCP string form, and the transaction executed without error, carrying a token or SOL transfer. The memo is in the transaction's instruction data on chain. This does not show that amount, recipient, mint or timing match the ATR's content. - **`x402/exact/starknet` Native Field, truncated Buyer signs H: yes H on chain: yes Public proof: yes Recoverable from chain: no** Pattern: [Native Field, truncated (LCP §B.1)⁠ (opens in a new tab)](https://github.com/legal-context-protocol/legal-context-protocol/blob/c8df26d/spec/legal-context-protocol-v1.md#b1-native-field) What a payment through it proves: The payer signed a SNIP-12 outside execution whose nonce is the low 250 bits of this ATR's hash. The payer's account contract verified that signature when it executed the transfer call, and the nonce is in the settlement transaction's calldata. A holder of the ATR can confirm the hash from the nonce; the chain alone does not reveal all of it, and no event indexes it. This does not show that amount, payee, asset or timing match the ATR's content. LCP profile: [x402/exact/starknet⁠ (opens in a new tab)](https://github.com/IntegraLedger/integra-protocol/blob/66274bf/lcp/profiles/x402-exact-starknet.md) - **`x402/exact/stellar` Native Field, truncated Buyer signs H: no H on chain: yes Public proof: yes Recoverable from chain: no** Pattern: [Native Field, truncated (LCP §B.1)⁠ (opens in a new tab)](https://github.com/legal-context-protocol/legal-context-protocol/blob/c8df26d/spec/legal-context-protocol-v1.md#b1-native-field) What a payment through it proves: The ATR was assembled, written to the seller's storage and linked in the challenge before approval, and its hash is in the payment challenge, which the payer did not sign. The payer signed a transfer to the seller's muxed address whose 8-byte id is the first 8 bytes of this ATR's hash, and the transaction succeeded. The id binds this hash only through its first 8 bytes: whoever assembles the ATR can construct a second ATR whose hash begins with the same 8 bytes. This does not show that amount, asset or timing match the ATR's content. - **`x402/exact/sui` Native Field Buyer signs H: yes H on chain: yes Public proof: yes Recoverable from chain: yes** Pattern: [Native Field (LCP §8.3.1)⁠ (opens in a new tab)](https://github.com/legal-context-protocol/legal-context-protocol/blob/c8df26d/spec/legal-context-protocol-v1.md#831-native-field) What a payment through it proves: The payer signed a Sui transaction whose one unused Pure input is this ATR's hash. The network executed that transaction successfully, and the hash is on chain in its input list, readable by its digest while a node retains it. This does not show that amount, payee, coin type or timing match the ATR's content. LCP profile: [x402/exact/sui⁠ (opens in a new tab)](https://github.com/IntegraLedger/integra-protocol/blob/66274bf/lcp/profiles/x402-exact-sui.md) - **`x402/exact/tron/lcp-trc20-memo` Native Field Buyer signs H: yes H on chain: yes Public proof: yes Recoverable from chain: yes** Pattern: [Native Field (LCP §8.3.1)⁠ (opens in a new tab)](https://github.com/legal-context-protocol/legal-context-protocol/blob/c8df26d/spec/legal-context-protocol-v1.md#831-native-field) What a payment through it proves: The payer signed a Tron transaction whose memo is this ATR's hash in LCP string form, and whose one contract calls transfer on the token. The network verified the signature, which covers the memo through the transaction id. The call succeeded with the token's Transfer event, at the finality recorded. The memo is on chain in the transaction. This does not show that amount, payee, token or timing match the ATR's content. LCP profile: [x402/exact/tron/lcp-trc20-memo⁠ (opens in a new tab)](https://github.com/IntegraLedger/integra-protocol/blob/66274bf/lcp/profiles/x402-exact-tron-lcp-trc20-memo.md) - **`x402/exact/tvm` Native Field Buyer signs H: yes H on chain: yes Public proof: yes Recoverable from chain: yes** Pattern: [Native Field (LCP §8.3.1)⁠ (opens in a new tab)](https://github.com/legal-context-protocol/legal-context-protocol/blob/c8df26d/spec/legal-context-protocol-v1.md#831-native-field) What a payment through it proves: The payer's W5 wallet signed a request whose one Jetton transfer carries this ATR's hash in its forward payload, as a TEP-74 text comment in LCP string form. The payer's Jetton wallet executed that transfer, and the payee's Jetton wallet accepted it. The comment is on chain in the transfer's message bodies. This does not show that amount, payee, asset or timing match the ATR's content. - **`x402/exact/xrpl` Id-Reuse Buyer signs H: yes H on chain: yes Public proof: yes Recoverable from chain: no** Pattern: [Id-Reuse (LCP §8.3.5)⁠ (opens in a new tab)](https://github.com/legal-context-protocol/legal-context-protocol/blob/c8df26d/spec/legal-context-protocol-v1.md#835-id-reuse-hashed-binding) What a payment through it proves: The payer signed, with a single key, an XRPL Payment whose InvoiceID is the SHA-256 of this ATR's hash in LCP string form, and the Payment is in a validated ledger with tesSUCCESS. The hash can be confirmed from the ATR's bytes but not recovered from the ledger alone. This does not show that amount, destination, asset or timing match the ATR's content. - **`x402/upto/eip155/permit2` Native Field Buyer signs H: yes H on chain: yes Public proof: yes Recoverable from chain: no** Pattern: [Native Field (LCP §8.3.1)⁠ (opens in a new tab)](https://github.com/legal-context-protocol/legal-context-protocol/blob/c8df26d/spec/legal-context-protocol-v1.md#831-native-field) What a payment through it proves: The payer signed a Permit2 witness transfer whose nonce is this ATR's hash, with the scheme's x402 proxy as spender and the payee in the witness. Permit2 verified the signature when the proxy executed the transfer, and the hash is in the settlement transaction's calldata as the Permit2 nonce; no event carries it. This does not show that amount, payee, asset or timing match the ATR's content. The amount settled is the facilitator's, at most the signed maximum. LCP profile: [x402/upto/eip155/permit2⁠ (opens in a new tab)](https://github.com/IntegraLedger/integra-protocol/blob/66274bf/lcp/profiles/x402-upto-eip155-permit2.md) - **`x402/upto/solana` Native Field Buyer signs H: yes H on chain: yes Public proof: yes Recoverable from chain: yes** Pattern: [Native Field (LCP §8.3.1)⁠ (opens in a new tab)](https://github.com/legal-context-protocol/legal-context-protocol/blob/c8df26d/spec/legal-context-protocol-v1.md#831-native-field) What a payment through it proves: The payer signed a Solana transaction whose one Memo instruction carries this ATR's hash in LCP string form, and which opened a one-request payment channel escrowing the signed maximum; it executed without error. The memo is in the transaction's instruction data on chain. The amount charged from the escrow, which may be zero, is the seller's metering, settled by the facilitator in a later transaction that does not carry the hash, and the rest returns to the payer. This does not show that amount, recipient, mint or timing match the ATR's content. Where a sentence names `` and ``, the pairing’s record fills them in: they name the agreement payment the buyer made first. [Source: lcp docs: pairings reference⁠ (opens in a new tab)](https://github.com/IntegraLedger/integra-protocol/blob/66274bf/docs/reference/pairings.md) · [Source: lcp docs: the agreement URL⁠ (opens in a new tab)](https://github.com/IntegraLedger/integra-protocol/blob/66274bf/docs/concepts/buyer-gate.md#the-agreement-url) ### The rails it settles on - [EVM chains](https://integraledger.com/rails/evm) - [Solana](https://integraledger.com/rails/solana) - [Stellar](https://integraledger.com/rails/stellar) - [XRP Ledger](https://integraledger.com/rails/xrpl) - [Hedera](https://integraledger.com/rails/hedera) - [Algorand](https://integraledger.com/rails/algorand) - [Aptos](https://integraledger.com/rails/aptos) - [Cardano](https://integraledger.com/rails/cardano) - [Casper](https://integraledger.com/rails/casper) - [Concordium](https://integraledger.com/rails/concordium) - [NEAR](https://integraledger.com/rails/near) - [Polkadot Asset Hub](https://integraledger.com/rails/polkadot) - [Starknet](https://integraledger.com/rails/starknet) - [Sui](https://integraledger.com/rails/sui) - [Tron](https://integraledger.com/rails/tron) - [TON](https://integraledger.com/rails/ton) - [Lightning](https://integraledger.com/rails/lightning) The live demonstrations are not running on this site at the moment.