Invisible messages: text hidden in whitespace encodings can slip past humans and LLMs

NickPassig · x · 2026-09-17

A caution about secret text transmission on the internet and with LLMs: messages can be hidden in whitespace-based encodings, invisible to human readers but decodable by machines. The author demonstrates sending an invisible message to friends. This kind of whitespace steganography is a notable blind spot for LLM input/output auditing and prompt-injection detection.

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