nip04 string key is actually x and y, so we must get only 32 bytes of x.

nip04.js

@@ -37,6 +37,6 @@ export function decrypt(privkey, pubkey, ciphertext) {
 
 function getNormalizedX(key) {
   return typeof key === 'string'
-    ? key.substr(2)
+    ? key.substr(2, 64)
     : Buffer.from(key.slice(1)).toString('hex')
 }

package.json

@@ -1,6 +1,6 @@
 {
   "name": "nostr-tools",
-  "version": "0.21.2",
+  "version": "0.21.3",
   "description": "Tools for making a Nostr client.",
   "repository": {
     "type": "git",