---
title: "Discussion on \"Defeating Reward Hacking in Coding Agents: Prompt-Only Rules vs. a Cryptographic SHA-256 Test Lock (2.46x Faster)\" | Hashnode"
description: "Discussion on \"Defeating Reward Hacking in Coding Agents: Prompt-Only Rules vs. a Cryptographic SHA-256 Test Lock (2.46x Faster)\". 💡 AI Labo Benchmark Series — Experiment E38 (Anti-Cheating & Test Integrity Locks)\nThis post is part of our empirical benchmark series testing AI coding agent harness patterns inside network-isolated"
url: "https://hashnode.com/posts/e38-cryptographic-test-tampering-lock/6af8701acc7f51bd215f0fca"
---

[Feed](https://hashnode.com/feed) /

Discussion

# [Defeating Reward Hacking in Coding Agents: Prompt-Only Rules vs. a Cryptographic SHA-256 Test Lock (2.46x Faster)](https://tappers.hashnode.dev/e38-cryptographic-test-tampering-lock?utm_source=hashnode&utm_medium=feed)

💡 AI Labo Benchmark Series — Experiment E38 (Anti-Cheating & Test Integrity Locks) This post is part of our empirical benchmark series testing AI coding agent harness patterns inside network-isolated

17h ago · 7 min read · tappers.hashnode.dev  
Read the article

-   [#agentic-ai](https://hashnode.com/tag/agentic-ai)
-   [#harness](https://hashnode.com/tag/harness)
-   [#benchmark](https://hashnode.com/tag/benchmark)
-   [#security](https://hashnode.com/tag/security)
-   [#testing](https://hashnode.com/tag/testing)

## Written by

[tappers](https://hashnode.com/@tappers)

@tappers · tokyo,japan

  
[View profile](https://hashnode.com/@tappers)

## Responses

Markdown supported · ⌘↵ to post

No responses yet.