Harden reusable keychain API

crates/geth-node/src/lib.rs

@@ -10505,20 +10505,29 @@ fn verify_keychain_sigchain_with_ssh(
     store: &Store,
     node: &LocalNode,
 ) -> Result<geth_keychain::KeychainSigchainReport, NodeError> {
-    let ops = load_keychain_ops(store)?;
-    let signatures = load_keychain_signatures(store)?;
-    Ok(geth_keychain::verify_sigchain(
-        &ops,
-        &signatures,
-        &|op, signature| {
+    struct SshKeychainVerifier<'a> {
+        node: &'a LocalNode,
+    }
+
+    impl geth_keychain::KeychainSignatureVerifier for SshKeychainVerifier<'_> {
+        fn verify_keychain_signature(
+            &self,
+            op: &KeychainOp,
+            signature: &KeychainOpSignature,
+        ) -> bool {
             verify_keychain_signature_with_ssh(
-                node,
+                self.node,
                 op,
                 &stored_keychain_signature_from_signature(signature),
             )
             .unwrap_or(false)
-        },
-    ))
+        }
+    }
+
+    let ops = load_keychain_ops(store)?;
+    let signatures = load_keychain_signatures(store)?;
+    let verifier = SshKeychainVerifier { node };
+    Ok(geth_keychain::verify_sigchain(&ops, &signatures, &verifier))
 }
 
 fn store_and_sign_keychain_ops(