The tx Module

A Miden transaction is a local operation that consumes zero or more input notes and produces state changes plus output notes for a single account. The transaction executes entirely on the client — the VM runs the code, generates a ZK proof, and only the proof is submitted to the network. The tx module provides access to block information, note commitments, and expiration controls. Transaction scripts (#[tx_script]) serve as standalone entry points that orchestrate the transaction.

The tx module

use miden::tx;

Block information

// Current block number
let block_num: Felt = tx::get_block_number();

// Block commitment (hash of block header)
let commitment: Word = tx::get_block_commitment();

// Block timestamp (seconds since epoch)
let timestamp: Felt = tx::get_block_timestamp();

Note commitments

// Commitment over all input notes in this transaction
let input_commit: Word = tx::get_input_notes_commitment();

// Commitment over all output notes in this transaction
let output_commit: Word = tx::get_output_notes_commitment();

// Number of input/output notes
let num_inputs: Felt = tx::get_num_input_notes();
let num_outputs: Felt = tx::get_num_output_notes();

Transaction expiration

Control how long a transaction remains valid:

// Get current expiration delta (in blocks)
let delta: Felt = tx::get_expiration_block_delta();

// Set a new expiration delta
tx::update_expiration_block_delta(felt!(100));

The expiration delta determines how many blocks after creation the transaction remains valid. If the transaction isn't included within this window, it expires.

Transaction scripts

Transaction scripts use the #[tx_script] macro to define a top-level entry point for the transaction. See Transaction Scripts for the full #[tx_script] API and examples.

Complete tx module reference

Function	Signature	Description
get_block_number	fn() -> Felt	Current block number
get_block_commitment	fn() -> Word	Block header commitment
get_block_timestamp	fn() -> Felt	Block timestamp (seconds)
get_input_notes_commitment	fn() -> Word	Hash of all input notes
get_output_notes_commitment	fn() -> Word	Hash of all output notes
get_num_input_notes	fn() -> Felt	Number of input notes
get_num_output_notes	fn() -> Felt	Number of output notes
get_expiration_block_delta	fn() -> Felt	Current expiration delta
update_expiration_block_delta	fn(delta: Felt)	Set expiration delta

For signature verification using the transaction context, see Authentication. For time-based patterns using tx::get_block_number(), see Patterns & Security — Rate limiting. For the complete function table, see the Cheatsheet.

Full API docs on docs.rs: miden::tx