diff --git a/crates/blockchain/src/lib.rs b/crates/blockchain/src/lib.rs
index 998159c..6c23fb7 100644
--- a/crates/blockchain/src/lib.rs
+++ b/crates/blockchain/src/lib.rs
@@ -315,6 +315,12 @@ impl BlockChainServer {
             return;
         }
 
+        // Pre-check signatures for external blocks before processing
+        if let Err(err) = store::precheck_block_signatures(&self.store, &signed_block) {
+            warn!(%slot, %err, "Block signature verification failed");
+            return;
+        }
+
         // Parent exists, proceed with processing
         match self.process_block(signed_block) {
             Ok(_) => {
diff --git a/crates/blockchain/src/store.rs b/crates/blockchain/src/store.rs
index 04138a9..582d12b 100644
--- a/crates/blockchain/src/store.rs
+++ b/crates/blockchain/src/store.rs
@@ -140,6 +140,40 @@ fn validate_attestation(store: &Store, attestation: &Attestation) -> Result<(),
     Ok(())
 }
 
+/// Verify all cryptographic signatures in a block before processing.
+///
+/// This is a pre-check that can be called before `on_block()` to validate signatures early.
+/// It verifies:
+/// 1. Each attestation's aggregated signature proof
+/// 2. The proposer attestation signature
+///
+/// Returns `Ok(())` if all signatures are valid, otherwise returns an error.
+///
+/// If the feature `skip-signature-verification` is enabled, this function returns `Ok(())` immediately.
+pub fn precheck_block_signatures(
+    store: &Store,
+    signed_block: &SignedBlockWithAttestation,
+) -> Result<(), StoreError> {
+    // Skip verification if feature flag is enabled
+    if cfg!(feature = "skip-signature-verification") {
+        return Ok(());
+    }
+
+    let block = &signed_block.message.block;
+    let parent_root = block.parent_root;
+    let slot = block.slot;
+
+    // Retrieve parent state for validator pubkeys
+    let parent_state = store
+        .get_state(&parent_root)
+        .ok_or(StoreError::MissingParentState { parent_root, slot })?;
+
+    // Verify all cryptographic signatures
+    verify_signatures(&parent_state, signed_block)?;
+
+    Ok(())
+}
+
 /// Process a tick event.
 pub fn on_tick(store: &mut Store, timestamp: u64, has_proposal: bool) {
     let time = timestamp - store.config().genesis_time;
@@ -346,13 +380,6 @@ pub fn on_block(
                 slot,
             })?;
 
-    // Validate cryptographic signatures
-    // TODO: extract signature verification to a pre-checks function
-    // to avoid the need for this
-    if cfg!(not(feature = "skip-signature-verification")) {
-        verify_signatures(&parent_state, &signed_block)?;
-    }
-
     // Execute state transition function to compute post-block state
     let mut post_state = parent_state.clone();
     ethlambda_state_transition::state_transition(&mut post_state, &block)?;
diff --git a/crates/blockchain/tests/signature_spectests.rs b/crates/blockchain/tests/signature_spectests.rs
index 40ec7aa..362d69c 100644
--- a/crates/blockchain/tests/signature_spectests.rs
+++ b/crates/blockchain/tests/signature_spectests.rs
@@ -52,8 +52,16 @@ fn run(path: &Path) -> datatest_stable::Result<()> {
         let block_time = signed_block.message.block.slot * SECONDS_PER_SLOT + genesis_time;
         store::on_tick(&mut st, block_time, true);
 
-        // Process the block (this includes signature verification)
-        let result = store::on_block(&mut st, signed_block);
+        // Pre-check signatures before processing the block
+        let precheck_result = store::precheck_block_signatures(&st, &signed_block);
+
+        // If pre-check failed, use that as the result
+        let result = if precheck_result.is_err() {
+            precheck_result
+        } else {
+            // Otherwise, process the block
+            store::on_block(&mut st, signed_block)
+        };
 
         // Step 3: Check that it succeeded or failed as expected
         match (result.is_ok(), test.expect_exception.as_ref()) {