docs: fix message type hash in snip12 guide #1273

[trishtzy]

Fixes #1273

This PR updates the SNIP-12 documentation guide with a corrected message type hash value. Here are the key changes:

1. Typed Message Update:

   • Changed the typed message in the selector from
     • "expiry\":\"u64\" to "expiry\":\"u128\" and,
     • "u256"("low":"felt","high":"felt") to "u256"("low":"u128","high":"u128")
   • Added a clarifying comment explaining that since SNIP-12 doesn't support u64, u128 is used for the expiry field instead.

2. Hash Value Update:

   • The message type hash constant was updated throughout the document from: 0x120ae1bdaf7c1e48349da94bb8dad27351ca115d6605ce345aee02d68d99ec1 to: 0x28bf13f11bba405c77ce010d2781c5903cbed100f01f72fcff1664f98343eb6

PR Checklist

• Tests
• Documentation
• Added entry to CHANGELOG.md
• Tried the feature on a public network

[andrew-fleming]

Suggested change

	let message_type_hash = 0xa2a7036c1f406af7c47722b209f23bd2f2d6ac21423c8c73bd92cf28409ee2;
	let message_type_hash = 0x1bd8318a34d524539867e6c110cb97d385c745575910b6c2afec623432ee55;

This is the hash I'm getting^

Can you confirm?

use core::to_byte_array::FormatAsByteArray;

let res = selector!("\"Message\"(\"recipient\":\"ContractAddress\",\"amount\":\"u256\",\"nonce\":\"felt\",\"expiry\":\"u128\")\"u256\"(\"low\":\"felt\",\"high\":\"felt\")");
println!("res: {}", res); // 49196983552140144393093620210836098680955957904181459224647480219440180821

let hex = res.format_as_byte_array(16);
println!("hex: 0x{}", hex); // 0x1bd8318a34d524539867e6c110cb97d385c745575910b6c2afec623432ee55

[trishtzy]

Sorry! I was using timestamp for expiry and forgot to re-generate the hash.

The expected hash should be 0x28bf13f11bba405c77ce010d2781c5903cbed100f01f72fcff1664f98343eb6, where u256 is broken down to u128 low, high values instead of felt (ref).

(Updated PR description too)

use core::to_byte_array::FormatAsByteArray;

let res = selector!("\"Message\"(\"recipient\":\"ContractAddress\",\"amount\":\"u256\",\"nonce\":\"felt\",\"expiry\":\"u128\")\"u256\"(\"low\":\"u128\",\"high\":\"u128\")");
println!("res: {}", res); // 1151882460384444625458237696336527865031165261341111302013491262776159780534

let hex = res.format_as_byte_array(16);
println!("hex: 0x{}", hex); // 0x28bf13f11bba405c77ce010d2781c5903cbed100f01f72fcff1664f98343eb6

[andrew-fleming]

Good catch!

[andrew-fleming]

LGTM! Thanks, @trishtzy!