Text Stego

Four ways to hide in text. Zero-width: each UTF-8 bit as U+200B or U+200C, bytes joined by U+200D, framed by U+FEFF. Whitespace: Matthew Kwan’s SNOW, three bits per run of spaces at line ends, read and written byte for byte. Homoglyphs: Cyrillic letters Unicode lists as confusable with Latin ones. Ave Maria: Trithemius’s 384 word tables (1518). Inspect also decodes Unicode tags and variation selectors.

• The Unicode Standard, Version 18.0, chapter 23, “Special Areas and Format Characters”
• Unicode Technical Standard #39, Unicode Security Mechanisms (confusables.txt)
• Matthew Kwan, SNOW: steganography in whitespace, version 20130616 (Apache License 2.0)
• Johannes Trithemius, Polygraphiae libri sex (Basel, 1518), book I, and Clavis polygraphiae; Wellcome Library copy