Update private key generation

src/core/utils/x25519.ts

@@ -1,7 +1,13 @@
 import { x25519 } from "@noble/curves/ed25519";
 
 export function getX25519PrivateKey(): Uint8Array {
-  return x25519.utils.randomPrivateKey();
+  const key = x25519.utils.randomPrivateKey();
+
+  key[0] &= 248
+  key[31] &= 127
+  key[31] |= 64
+
+  return key;
 }
 
 export function getX25519PublicKey(privateKey: Uint8Array): Uint8Array {