ton proof kotlin validation

Test.kt

    @Test
    fun `ton proof validation test`() {
        val payload = """
			{
			    "proof": {
					"timestamp": 1678206305,
					"domain": {
						"lengthBytes": 10,
						"value": "tonplay.io"
					},
					"signature": "VJPpOKHfg79Z1We7SCnI+qwSShIm8uyFpUM5H5tnTxKzafsHrXkg2ivoouXeCSlgZoHj/y9utZh9vEh4oo5LAQ==",
					"payload": "nmqQIzwMkZaOWonYxHXFtrXyziCbxOj9zlUfR7x5B1sQCUtG8Bk5zmMPkcbEzmCJ"
				},
				"address": "EQBDMWTZnPVO5ccZIb6ttsVArQa1_Pwe47fBggvhG8OtgOf0"
			}
		""".trimIndent()

        val d = ObjectMapper().readValue(payload, TonConnectRequestDTO::class.java)

        println(d)

        val pubKey = runBlocking {
            liteContract.getWalletPublicKey(AddrStd(d.address))
        }.let { key ->
            CellBuilder.createCell {
                storeUInt(key, 256)
            }.bits
        }
        val address = AddrStd(d.address)

        val tonProofPrefix = "ton-proof-item-v2/"
        val tonConnectPrefix = "ton-connect"

        val wc = ByteBuffer.allocate(4).order(ByteOrder.BIG_ENDIAN).putInt(address.workchain_id).array()
        val addr = ByteBuffer.allocate(32).order(ByteOrder.BIG_ENDIAN).put(address.address.toByteArray()).array()
        val ts = ByteBuffer.allocate(8).order(ByteOrder.LITTLE_ENDIAN).putLong(d.proof.timestamp).array()
        val dl = ByteBuffer.allocate(4).order(ByteOrder.LITTLE_ENDIAN).putInt(d.proof.domain.lengthBytes).array()
        assertEquals(0, hex(wc).toInt())

        val message = tonProofPrefix.toByteArray() +
                wc +
                addr +
                dl +
                d.proof.domain.value.toByteArray() +
                ts +
                d.proof.payload.toByteArray()

        val messageHash = hash256(message)
        val fullMessage = byteArrayOf( (0xff).toByte(), (0xff).toByte() ) +
                tonConnectPrefix.toByteArray() +
                messageHash

        val fullMessageHash = hash256(fullMessage)

        val result = PublicKeyEd25519(pubKey.toByteArray()).verify(
                fullMessageHash, Base64Utils.decodeFromString(d.proof.signature)
        )

        assertTrue(result)
    }

    fun hash256(x: ByteArray) =
            MessageDigest.getInstance("sha256").digest(x)