add payload-to-id.ts

packages/status-js/src/utils/payload-to-id.ts

@@ -0,0 +1,12 @@
+import { keccak256 } from 'ethereum-cryptography/keccak'
+import { bytesToHex } from 'ethereum-cryptography/utils'
+
+export function payloadToId(
+  publicKey: Uint8Array,
+  payload: Uint8Array
+): string {
+  const hash = keccak256(new Uint8Array([...publicKey, ...payload]))
+  const hex = bytesToHex(hash)
+
+  return `0x${hex}`
+}