From 776800678ea8df131a6ec0f6ee0a35209c9978f2 Mon Sep 17 00:00:00 2001
From: Ariel Elperin <ariel@starkware.co>
Date: Thu, 7 May 2026 12:01:36 +0300
Subject: [PATCH] starknet_committer: compute and store accessed keys digest

---
 crates/starknet_committer/Cargo.toml          |  4 ++
 .../src/db/serde_db_utils.rs                  | 55 +++++++++++++++++++
 2 files changed, 59 insertions(+)

diff --git a/crates/starknet_committer/Cargo.toml b/crates/starknet_committer/Cargo.toml
index 906ede3d156..9e11750a48e 100644
--- a/crates/starknet_committer/Cargo.toml
+++ b/crates/starknet_committer/Cargo.toml
@@ -7,9 +7,13 @@ license.workspace = true
 description = "Computes and manages Starknet state."
 
 [features]
+os_input = ["dep:bincode", "dep:blake2", "dep:digest"]
 testing = ["starknet_patricia/testing"]
 
 [dependencies]
+bincode = { workspace = true, optional = true }
+blake2 = { workspace = true, optional = true }
+digest = { workspace = true, optional = true }
 apollo_config.workspace = true
 async-trait.workspace = true
 derive_more = { workspace = true, features = ["as_ref", "from", "into"] }
diff --git a/crates/starknet_committer/src/db/serde_db_utils.rs b/crates/starknet_committer/src/db/serde_db_utils.rs
index 67babb06e9d..6ff11c04a8f 100644
--- a/crates/starknet_committer/src/db/serde_db_utils.rs
+++ b/crates/starknet_committer/src/db/serde_db_utils.rs
@@ -1,8 +1,22 @@
+#[cfg(feature = "os_input")]
+use std::collections::HashMap;
+
+#[cfg(feature = "os_input")]
+use blake2::Blake2s256;
+#[cfg(feature = "os_input")]
+use digest::Digest;
 use serde::{Deserialize, Serialize};
 use starknet_api::block::BlockNumber;
+#[cfg(feature = "os_input")]
+use starknet_api::core::{ClassHash, ContractAddress};
+#[cfg(feature = "os_input")]
+use starknet_api::state::StorageKey;
 use starknet_patricia_storage::storage_trait::DbValue;
 use starknet_types_core::felt::Felt;
 
+#[cfg(feature = "os_input")]
+use crate::block_committer::input::StarknetStorageKey;
+
 #[derive(Clone, Debug, Default, Deserialize, Eq, PartialEq, Hash, Serialize)]
 pub struct DbBlockNumber(pub BlockNumber);
 
@@ -23,3 +37,44 @@ pub fn serialize_felt_no_packing(felt: Felt) -> DbValue {
 pub fn deserialize_felt_no_packing(value: &DbValue) -> Felt {
     Felt::from_bytes_be_slice(&value.0)
 }
+
+/// Wire layout for [`accessed_keys_digest`]. Field order and sorting are part of the digest.
+#[cfg(feature = "os_input")]
+#[derive(Serialize, Deserialize)]
+struct AccessedKeysCanonical {
+    class_hashes: Vec<ClassHash>,
+    /// Contract trie reads (e.g. class / nonce), sorted.
+    contract_addresses: Vec<ContractAddress>,
+    /// Storage-slot reads: sorted by contract address; each key list sorted by underlying felt.
+    contract_storage: Vec<(ContractAddress, Vec<StorageKey>)>,
+}
+
+/// BLAKE2s-256 digest of canonical serialized accessed read keys (replay fingerprint).
+#[cfg(feature = "os_input")]
+pub fn accessed_keys_digest(
+    class_hashes: &[ClassHash],
+    contract_addresses: &[ContractAddress],
+    contract_storage_keys: &HashMap<ContractAddress, Vec<StarknetStorageKey>>,
+) -> [u8; 32] {
+    let mut class_hashes: Vec<ClassHash> = class_hashes.iter().copied().collect();
+    class_hashes.sort();
+
+    let mut contract_addresses: Vec<ContractAddress> = contract_addresses.iter().copied().collect();
+    contract_addresses.sort();
+
+    let mut contract_storage: Vec<(ContractAddress, Vec<StorageKey>)> = contract_storage_keys
+        .iter()
+        .map(|(addr, keys)| {
+            let mut keys: Vec<StorageKey> = keys.iter().map(|k| k.0).collect();
+            keys.sort_by_key(|k| Felt::from(*k));
+            (*addr, keys)
+        })
+        .collect();
+    contract_storage.sort_by_key(|(addr, _)| *addr);
+
+    let canonical = AccessedKeysCanonical { class_hashes, contract_addresses, contract_storage };
+    let bytes = bincode::serialize(&canonical).expect("accessed keys bincode serialization");
+
+    let hash = Blake2s256::digest(&bytes);
+    hash.into()
+}