diff --git a/src/utils/crypto.ts b/src/utils/crypto.ts
index e262459..c5d7c04 100644
--- a/src/utils/crypto.ts
+++ b/src/utils/crypto.ts
@@ -1,15 +1,7 @@
 import * as StellarSdk from "@stellar/stellar-sdk";
-import { getPlatformKeypair, getNetworkPassphrase } from "../config/stellar.js";
 import crypto from "node:crypto";
 
-/**
- * Sign an arbitrary message hash with the platform keypair.
- * Used for quiz proof signatures and reward authorization.
- */
-export function signWithPlatformKey(message: Buffer): string {
-  const keypair = getPlatformKeypair();
-  return keypair.sign(message).toString("base64");
-}
+
 
 /**
  * Verify a Stellar signature against a public key.
@@ -27,15 +19,6 @@ export function verifyStellarSignature(
   }
 }
 
-/**
- * Generate a deterministic challenge token for SEP-10 auth.
- */
-export function generateChallengeToken(account: string): string {
-  const nonce = crypto.randomBytes(32).toString("base64");
-  const timestamp = Date.now();
-  return JSON.stringify({ account, nonce, timestamp });
-}
-
 /**
  * Hash data for on-chain content references.
  */