Detecting Verbatim LLM Copy-Paste in Homework

In three linesSteganoPrompt, an open-source web tool, detects verbatim copies of assignment prompts submitted to LLMs. It encodes an invisible instruction in the prompt via the Unicode Tags block (U+E0000–U+E007F), creating a detectable signature in the model's response. Tested across 7 LLM families, the approach bypasses limitations of post-hoc detectors and requires no cooperation from model providers.

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