Implement simpler hash function

contract-message-predicate/src/main.sw

@@ -1,52 +1,25 @@
 predicate;
 
-use std::{
-    address::Address,
-    tx::{
-        INPUT_COIN,
-        INPUT_CONTRACT,
-        INPUT_MESSAGE,
-        OUTPUT_CHANGE,
-        OUTPUT_CONTRACT,
-        OUTPUT_VARIABLE,
-        b256_from_pointer_offset,
-        tx_gas_limit,
-        tx_input_pointer,
-        tx_input_type,
-        tx_inputs_count,
-        tx_output_type,
-        tx_outputs_count,
-    tx_script_bytecode}
-};
+dep utils;
 
-use std::assert::assert;
-use std::hash::sha256;
 use std::contract_id::ContractId;
+use std::assert::assert;
+use std::tx::{
+    INPUT_COIN,
+    INPUT_CONTRACT,
+    INPUT_MESSAGE,
+    OUTPUT_CHANGE,
+    OUTPUT_CONTRACT,
+    OUTPUT_VARIABLE,
+    tx_gas_limit,
+    tx_input_type,
+    tx_inputs_count,
+    tx_output_type,
+    tx_outputs_count,
+    tx_script_bytecode,
+};
 
-/// Get the ID of a contract input
-fn input_contract_id(index: u8) -> ContractId {
-    // Check that input at this index is a contract input
-    assert(tx_input_type(index) == INPUT_CONTRACT);
-    let ptr = tx_input_pointer(index);
-    let contract_id_bytes = b256_from_pointer_offset(ptr, 128); // Contract ID starts at 17th word: 16 * 8 = 128
-
-    // TODO: Replace with actual contract id
-    ~ContractId::from(0xf5dbe963c235c1e54f8732f1ecdc955df2ad8db8c9ab58eea8e1338762bf8bc2) //~ContractId::from(contract_id_bytes)
-}
-
-/// Get the contract ID from a message input's data
-fn contract_id_from_message_input(index: u8) -> ContractId {
-    // TODO: Replace with actual message check once input messages are enabled in the sdk
-    assert(tx_input_type(index) == INPUT_COIN);
-    ~ContractId::from(0xf5dbe963c235c1e54f8732f1ecdc955df2ad8db8c9ab58eea8e1338762bf8bc2)/*
-    // Check that input at this index is a message input
-    assert(tx_input_type(index) == INPUT_MESSAGE);
-
-    let ptr = tx_input_pointer(index);
-    let contract_id_bytes = b256_from_pointer_offset(ptr, 192); // Contract ID is at start of data, which is at 24th word: 24 * 8 = 192
-    ~ContractId::from(contract_id_bytes)
-    */
-}
+use utils::{contract_id_from_contract_input, contract_id_from_message_input, tx_script_bytecode_hash};
 
 /// Predicate verifying a message input is being spent according to the rules for a valid deposit
 fn main() -> bool {
@@ -59,17 +32,14 @@ fn main() -> bool {
 
     // The hash of the script which must spend the input belonging to this predicate
     // This ensures the coins can only be spent in a call to `TokenContract.finalizeDeposit()`
-    // Note: The script must be right-padded to the next full word before hashing, to match with `get_script_bytecode()`
-    const SPENDING_SCRIPT_HASH = 0x2d235589506d17993e0b7aca4407a5ac1c325efd9d704ff94696a8f7c012ab9d;
+    const SPENDING_SCRIPT_HASH = 0x6856bb03b84d876ee60c890be5b0602d0f7480d375917a660da3115e8e008ddb;
 
     ////////////////
     // CONDITIONS //
     ////////////////
 
     // Verify script bytecode hash matches
-    let script_bytcode: [u64;
-    32] = tx_script_bytecode(); // Note : Make sure length is script bytecode length rounded up to next word
-    assert(sha256(script_bytcode) == SPENDING_SCRIPT_HASH);
+    assert(tx_script_bytecode_hash() == SPENDING_SCRIPT_HASH);
 
     // Verify gas limit is high enough
     //TODO: does gas limit include InputMessage amount? might need to just check avail balance - InputMessage amount
@@ -79,7 +49,7 @@ fn main() -> bool {
     assert(tx_inputs_count() == 3);
     assert(tx_input_type(0) == INPUT_COIN);
     let message_data_contract_id = contract_id_from_message_input(1);
-    let input_contract_id = input_contract_id(2);
+    let input_contract_id = contract_id_from_contract_input(2);
 
     // Check contract ID from the contract input matches the one specified in the message data
     assert(input_contract_id == message_data_contract_id);

contract-message-predicate/src/utils.sw

@@ -0,0 +1,65 @@
+library utils;
+
+use std::{
+    address::Address,
+    tx::{
+        INPUT_COIN,
+        INPUT_CONTRACT,
+        INPUT_MESSAGE,
+        OUTPUT_CHANGE,
+        OUTPUT_CONTRACT,
+        OUTPUT_VARIABLE,
+        b256_from_pointer_offset,
+        tx_gas_limit,
+        tx_input_pointer,
+        tx_input_type,
+        tx_inputs_count,
+        tx_output_type,
+        tx_outputs_count,
+    tx_script_bytecode}
+};
+
+use std::assert::assert;
+use std::hash::sha256;
+use std::contract_id::ContractId;
+
+/// Get the ID of a contract input
+pub fn contract_id_from_contract_input(index: u8) -> ContractId {
+    // Check that input at this index is a contract input
+    assert(tx_input_type(index) == INPUT_CONTRACT);
+    let ptr = tx_input_pointer(index);
+    let contract_id_bytes = b256_from_pointer_offset(ptr, 128); // Contract ID starts at 17th word: 16 * 8 = 128
+
+    // TODO: Replace with actual contract id
+    ~ContractId::from(0xf5dbe963c235c1e54f8732f1ecdc955df2ad8db8c9ab58eea8e1338762bf8bc2) //~ContractId::from(contract_id_bytes)
+}
+
+/// Get the contract ID from a message input's data
+pub fn contract_id_from_message_input(index: u8) -> ContractId {
+    // TODO: Replace with actual message check once input messages are enabled in the sdk
+    assert(tx_input_type(index) == INPUT_COIN);
+    ~ContractId::from(0xf5dbe963c235c1e54f8732f1ecdc955df2ad8db8c9ab58eea8e1338762bf8bc2)/*
+    // Check that input at this index is a message input
+    assert(tx_input_type(index) == INPUT_MESSAGE);
+
+    let ptr = tx_input_pointer(index);
+    let contract_id_bytes = b256_from_pointer_offset(ptr, 192); // Contract ID is at start of data, which is at 24th word: 24 * 8 = 192
+    ~ContractId::from(contract_id_bytes)
+    */
+}
+
+// From sway repo: tx.sw
+use std::core::num::*;
+const TX_SCRIPT_LENGTH_OFFSET = 10280;
+const TX_SCRIPT_START_OFFSET = 10352;
+
+/// Get the hash of the script bytecode
+pub fn tx_script_bytecode_hash() -> b256 {
+    let mut result_buffer: b256 = ~b256::min();
+
+    asm(hash: result_buffer, script_offset: TX_SCRIPT_START_OFFSET, length_offset: TX_SCRIPT_LENGTH_OFFSET, length) {
+        lw length length_offset i0; // Load the length value at the length_offset
+        s256 hash script_offset length; // Hash the an array of length "length" starting from "script_offset" into "hash"
+        hash: b256 // Return
+    }
+}

contract-message-test/tests/harness.rs

@@ -31,18 +31,13 @@ async fn spend_predicate_with_script_constraint() {
     let provider = wallet.get_provider().unwrap();
     let client = &provider.client;
 
-    // Get padded bytecode root that must be hardcoded into the predicate to constrain the spending transaction
-    let mut script_bytecode =
+    // Get bytecode root that must be hardcoded into the predicate to constrain the spending transaction
+    let script_bytecode =
         std::fs::read("../contract-message-script/out/debug/contract_message_script.bin")
             .unwrap()
             .to_vec();
-    let padding = script_bytecode.len() % 8;
-    let script_bytecode_unpadded = script_bytecode.clone();
-    script_bytecode.append(&mut vec![0; padding]);
-    let script_hash = Hasher::hash(&script_bytecode);
-
-    println!("Padded script length: {}", script_bytecode.len());
-    println!("Padded script hash   : 0x{:?}", script_hash);
+    let script_hash = Hasher::hash(&script_bytecode.clone());
+    println!("script hash   : 0x{:?}", script_hash);
 
     // Deploy test contract
     let test_contract_id = Contract::deploy(
@@ -152,7 +147,7 @@ async fn spend_predicate_with_script_constraint() {
         maturity: 0,
         byte_price: 0,
         receipts_root: Default::default(),
-        script: script_bytecode_unpadded,
+        script: script_bytecode,
         script_data: vec![],
         inputs: vec![input_coin, input_coin_message, input_contract],
         outputs: vec![output_variable, output_contract, output_change],