Same message. Different route through the standard.

Numeric, alphanumeric, and byte segments can sometimes express the same overt text. A normal reader joins them and returns only the message; a cooperating reader can treat the segmentation choice itself as a signal.

EDUCATIONAL IMPLEMENTATION / INSPIRED BY KOPTYRA & OGIELA 2024

REPRESENTATION LAB

Choose two hidden bits

All four symbols are forced to the same version and ECC level. Their overt semantic message is identical.

Predict first

The variants below all encode exactly the same text, and every one of them is standards-compliant. Will they produce the same symbol?

Yes, the text determines the symbol No, the symbols differ

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WHAT THE SCANNER SEES

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WHAT CHANGED UNDERNEATH

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WHAT A SECOND READER CAN RECOVER

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HOW AN ANALYST CAN NOTICE

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FINDING

The overt message and its QR representation are different layers.

A scanner reports the concatenated segment contents. It normally does not report which legal sequence of modes carried them. That representational choice can encode a small selection signal, but inefficient or unusual segmentation is itself an artifact an analyst can inspect.

Research basis: Koptyra & Ogiela, “Steganography in QR Codes—Information Hiding with Suboptimal Segmentation” (2024) [META], doi:10.3390/electronics13132658. This exhibit implements the same general technique with its own four transparent segment-selection rules; it is not a byte-for-byte reproduction of the paper.

Read the research note