
Researchers can now reverse-engineer LLM prompts from output text with near-perfect accuracy
A team from IIT Bombay and Adobe Research created an inverse language model named "Previous-Token Prediction." It reconstructs original LLM prompts from generated text with high accuracy without requiring access to model weights.
Researchers from IIT Bombay and Adobe Research have introduced a new technique capable of reconstructing the original prompts used to generate text from large language models. The method, termed "Previous-Token Prediction," functions as an inverse language model designed to work backwards from the output to the input.
A key feature of this approach is that it does not require access to the underlying model weights. This distinction suggests the technique could be applied to various systems where internal parameters are not publicly available, broadening its potential scope.
The ability to recover prompts with high accuracy raises significant questions regarding prompt security and intellectual property. If proprietary instructions or sensitive data embedded in prompts can be extracted from public outputs, organizations may need to reconsider how they deploy generative AI tools.
This research highlights the growing field of LLM interpretability and security. As models become more integrated into enterprise workflows, understanding the relationship between inputs and outputs becomes critical for maintaining control over automated systems.
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