try replicating changes from first two commits from #529

miden-lib/src/transaction/mod.rs

@@ -102,13 +102,13 @@ impl TransactionKernel {
     ///   tuples for the notes consumed by the transaction.
     pub fn build_input_stack(
         acct_id: AccountId,
-        init_acct_hash: Digest,
+        init_acct_hash: Option<Digest>,
         input_notes_hash: Digest,
         block_hash: Digest,
     ) -> StackInputs {
         let mut inputs: Vec<Felt> = Vec::with_capacity(13);
         inputs.extend(input_notes_hash);
-        inputs.extend_from_slice(init_acct_hash.as_elements());
+        inputs.extend_from_slice(init_acct_hash.unwrap_or_default().as_elements());
         inputs.push(acct_id.into());
         inputs.extend_from_slice(block_hash.as_elements());
         StackInputs::new(inputs)

miden-tx/src/prover/mod.rs

@@ -1,3 +1,5 @@
+use core::ops::Not;
+
 use miden_lib::transaction::{ToTransactionKernelInputs, TransactionKernel};
 use miden_objects::{
     notes::Nullifier,
@@ -48,7 +50,7 @@ impl TransactionProver {
         let input_notes: InputNotes<Nullifier> = (tx_witness.tx_inputs().input_notes()).into();
 
         let account_id = tx_witness.account().id();
-        let initial_account_hash = tx_witness.account().hash();
+        let initial_hash = tx_witness.account().is_new().not().then(|| tx_witness.account().hash());
         let block_hash = tx_witness.block_header().hash();
         let tx_script_root = tx_witness.tx_args().tx_script().map(|script| *script.hash());
 
@@ -65,12 +67,6 @@ impl TransactionProver {
             TransactionKernel::from_transaction_parts(&stack_outputs, &map.into(), output_notes)
                 .map_err(TransactionProverError::InvalidTransactionOutput)?;
 
-        let initial_hash = if tx_witness.account().is_new() {
-            Digest::default()
-        } else {
-            initial_account_hash
-        };
-
         let builder = ProvenTransactionBuilder::new(
             account_id,
             initial_hash,

objects/src/accounts/mod.rs

@@ -1,3 +1,5 @@
+use core::ops::Not;
+
 use crate::{
     assembly::{Assembler, AssemblyContext, ModuleAst},
     assets::AssetVault,
@@ -96,12 +98,8 @@ impl Account {
     /// against a new account, public input for the initial account state is set to [ZERO; 4] to
     /// distinguish new accounts from existing accounts. The actual hash of the initial account
     /// state (and the initial state itself), are provided to the VM via the advice provider.
-    pub fn proof_init_hash(&self) -> Digest {
-        if self.is_new() {
-            Digest::default()
-        } else {
-            self.hash()
-        }
+    pub fn proof_init_hash(&self) -> Option<Digest> {
+        self.is_new().not().then(|| self.hash())
     }
 
     /// Returns unique identifier of this account.

objects/src/transaction/proven_tx.rs

@@ -34,7 +34,7 @@ pub struct ProvenTransaction {
     /// The hash of the account before the transaction was executed.
     ///
     /// Set to `Digest::default()` for new accounts.
-    initial_account_hash: Digest,
+    initial_account_hash: Option<Digest>,
 
     /// The hash of the account after the transaction was executed.
     final_account_hash: Digest,
@@ -74,7 +74,7 @@ impl ProvenTransaction {
     }
 
     /// Returns the initial account state hash.
-    pub fn initial_account_hash(&self) -> Digest {
+    pub fn initial_account_hash(&self) -> Option<Digest> {
         self.initial_account_hash
     }
 
@@ -129,7 +129,7 @@ impl ProvenTransaction {
                     ))
                 },
                 Some(ref details) => {
-                    let is_new_account = self.initial_account_hash == Digest::default();
+                    let is_new_account = self.initial_account_hash.is_none();
 
                     match (is_new_account, details) {
                         (true, AccountDetails::Delta(_)) => {
@@ -180,7 +180,7 @@ pub struct ProvenTransactionBuilder {
     account_id: AccountId,
 
     /// The hash of the account before the transaction was executed.
-    initial_account_hash: Digest,
+    initial_account_hash: Option<Digest>,
 
     /// The hash of the account after the transaction was executed.
     final_account_hash: Digest,
@@ -211,11 +211,12 @@ impl ProvenTransactionBuilder {
     /// Returns a [ProvenTransactionBuilder] used to build a [ProvenTransaction].
     pub fn new(
         account_id: AccountId,
-        initial_account_hash: Digest,
+        initial_account_hash: Option<Digest>,
         final_account_hash: Digest,
         block_ref: Digest,
         proof: ExecutionProof,
     ) -> Self {
+        debug_assert_ne!(initial_account_hash, Some(Digest::default()));
         Self {
             account_id,
             initial_account_hash,
@@ -346,7 +347,7 @@ impl Serializable for ProvenTransaction {
 impl Deserializable for ProvenTransaction {
     fn read_from<R: ByteReader>(source: &mut R) -> Result<Self, DeserializationError> {
         let account_id = AccountId::read_from(source)?;
-        let initial_account_hash = Digest::read_from(source)?;
+        let initial_account_hash = <Option<Digest>>::read_from(source)?;
         let final_account_hash = Digest::read_from(source)?;
         let account_details = <Option<AccountDetails>>::read_from(source)?;
 

objects/src/transaction/transaction_id.rs

@@ -24,13 +24,14 @@ pub struct TransactionId(Digest);
 impl TransactionId {
     /// Returns a new [TransactionId] instantiated from the provided transaction components.
     pub fn new(
-        init_account_hash: Digest,
+        init_account_hash: Option<Digest>,
         final_account_hash: Digest,
         input_notes_hash: Digest,
         output_notes_hash: Digest,
     ) -> Self {
+        debug_assert_ne!(init_account_hash, Some(Digest::default()));
         let mut elements = [ZERO; 4 * WORD_SIZE];
-        elements[..4].copy_from_slice(init_account_hash.as_elements());
+        elements[..4].copy_from_slice(init_account_hash.unwrap_or_default().as_elements());
         elements[4..8].copy_from_slice(final_account_hash.as_elements());
         elements[8..12].copy_from_slice(input_notes_hash.as_elements());
         elements[12..].copy_from_slice(output_notes_hash.as_elements());
@@ -89,7 +90,7 @@ impl From<&ExecutedTransaction> for TransactionId {
         let input_notes_hash = tx.input_notes().commitment();
         let output_notes_hash = tx.output_notes().commitment();
         Self::new(
-            tx.initial_account().hash(),
+            tx.initial_account().proof_init_hash(),
             tx.final_account().hash(),
             input_notes_hash,
             output_notes_hash,