add isValidHash field.

handlers/EventSigning.jsx

@@ -33,6 +33,11 @@ export default function EventSigning({value}) {
       return null
     }
   }, [value, privateKey])
+  let eventHash = useComputedState(() => getEventHash(evt), [value])
+  let isValidHash = useComputedState(
+    () => evt.id === eventHash,
+    [value, eventHash]
+  )
   let isValidSignature = useComputedState(async () => {
     if (evt.id && evt.sig) {
       try {
@@ -54,9 +59,16 @@ export default function EventSigning({value}) {
         {serializeEvent(evt)}
       </Item>
       <Item label="event id" hint="sha256 hash of serialized event">
-        {getEventHash(evt)}
+        {eventHash}
       </Item>
-      {evt.sig ? (
+      <Item
+        label="event id matches hash"
+        hint="the calculated hash from event data matches the 'id' in the body?"
+      >
+        {isValidHash?.toString()}
+      </Item>
+      {isValidHash &&
+        (evt.sig ? (
           <Item label="signature valid">
             {isValidSignature?.toString() || ''}
           </Item>
@@ -75,7 +87,7 @@ export default function EventSigning({value}) {
             <Item label="public key">{publicKey}</Item>
             <Item label="signature">{privateKeyIsValid ? signature : ''}</Item>
           </>
-      )}
+        ))}
     </>
   )
 }