# Starknet · Integra

> On Starknet, the outside execution’s nonce holds the low 250 bits of the ATR hash.

URL: https://integraledger.com/rails/starknet

Payment rail

## Starknet

On Starknet, the outside execution’s nonce holds the low 250 bits of the ATR hash. [Source: lcp docs: rails⁠ (opens in a new tab)](https://github.com/IntegraLedger/integra-protocol/blob/66274bf/docs/guides/rails.md)

**Sources (1)**

[lcp docs: rails⁠ (opens in a new tab)](https://github.com/IntegraLedger/integra-protocol/blob/66274bf/docs/guides/rails.md)

### Where the ATR hash rides

On this rail, the ATR hash rides in the outside execution’s nonce.

#### The standard

A felt is narrower than 32 bytes, so the chain confirms an ATR hash a party holds rather than recovering it. [Source: lcp docs: rails⁠ (opens in a new tab)](https://github.com/IntegraLedger/integra-protocol/blob/66274bf/docs/guides/rails.md) · [Source: LCP §8.3.8⁠ (opens in a new tab)](https://github.com/legal-context-protocol/legal-context-protocol/blob/c8df26d/spec/legal-context-protocol-v1.md#838-how-to-choose)

- The SNIP-9 outside execution’s nonce: H’s low 250 bits. [Source: lcp docs: rails⁠ (opens in a new tab)](https://github.com/IntegraLedger/integra-protocol/blob/66274bf/docs/guides/rails.md)

  `x402/exact/starknet`

Entry points: `@integraledger/lcp/starknet`

#### The data

Read from the published packages when the site was built; nothing here is typed by hand.

The ATR hash of the site’s example ATR, as this rail carries it

H’s low 250 bits, as one felt

0x48dc1b716a5103287cb8f35e36b614ffd91e630ab8b7911833c54748ad5ca6

Computed from the site’s example ATR by this rail’s own helper in the package, when the site was built.

### What a payment on this rail proves

Of these 1 pairings, 1 have the buyer’s signature cover the ATR hash, 1 leave a public proof of it, and 0 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.

#### The standard

- **`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)

  Where the ATR hash rides: The SNIP-9 outside execution’s nonce: H’s low 250 bits.

  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)

### Reading the settlement

The package reads a payment’s settlement through a reader you supply: the endpoint, the credentials, the timeouts and the retries are yours. A reader that fails never makes a payment read as failed. [Source: lcp docs: reading settlement⁠ (opens in a new tab)](https://github.com/IntegraLedger/integra-protocol/blob/66274bf/docs/guides/rails.md#reading-settlement)

**Sources (1)**

[lcp docs: reading settlement⁠ (opens in a new tab)](https://github.com/IntegraLedger/integra-protocol/blob/66274bf/docs/guides/rails.md#reading-settlement)

#### The standard

**Reader**

`StarknetReader`

**Its calls**

`starknet_getTransactionReceipt` with its `Transfer` events, `starknet_traceTransaction`

**A settled read carries**

`ACCEPTED_ON_L2` or `ACCEPTED_ON_L1` [Source: lcp docs: reading settlement⁠ (opens in a new tab)](https://github.com/IntegraLedger/integra-protocol/blob/66274bf/docs/guides/rails.md#reading-settlement)

### The protocols that pay on it

- [x402](https://integraledger.com/protocols/x402)

[lcp docs: rails⁠ (opens in a new tab)](https://github.com/IntegraLedger/integra-protocol/blob/66274bf/docs/guides/rails.md)