MUMBAI, India, Jan. 9 -- Intellectual Property India has published a patent application (202511122212 A) filed by Abhishek; Dr. Ruchi Sehrawat; and Dr. Apoorvi Sood, New Delhi, on Dec. 4, 2025, for 'rainbow: a reversible ascii substitution system based on an 11x11 playfair matrix.'
Inventor(s) include Abhishek; Dr. Ruchi Sehrawat; and Dr. Apoorvi Sood.
The application for the patent was published on Jan. 9, under issue no. 02/2026.
According to the abstract released by the Intellectual Property India: "The present invention discloses a reversible ASCII-based substitution cipher system, termed the RAINBOW cipher, which extends Playfair-style digraph operations to the full ASCII domain through the use of an expanded 11x11 canonical matrix. The invention integrates a structured canonical merging scheme to reduce the 128-character ASCII set to 121 canonical symbols, alongside a lossless escape-encoding mechanism that preserves all non-canonical characters, literal escape markers, and control codes. An internal placeholder character is employed to resolve digraph conflicts and ensure compatibility with modified Playfair transformation rules, including same-row shifts, same-column shifts, and rectangle operations. The system provides fully invertible encryption and decryption processes, enabling exact reconstruction of the original ASCII plaintext, including duplicates and merged-pair aliases. The invention offers a robust, lightweight, and structurally consistent solution for reversible data transformation, text obfuscation, hybrid cryptography, and related computational applications."
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