A homoglyph is a character that looks identical or nearly identical to another but has a different Unicode code point. Latin 'a' (U+0061) and Cyrillic 'а' (U+0430) are a classic pair — indistinguishable on screen, distinct to a computer.

How does the message get hidden?

The secret is turned into bits. Walking through the cover text, each letter that has a Cyrillic lookalike carries one bit: a 1 substitutes the Cyrillic homoglyph, a 0 keeps the Latin original. The reader sees the same words either way.

One bit per swappable letter, and one secret character needs 8 bits. So you need cover text with at least 8 swappable letters (a, c, e, o, p, x, y and capitals A, C, E, O, P, X, Y) for every character of the secret.

Is the hidden data secure?

No. This is concealment, not encryption. Anyone who compares the code points or knows the scheme can recover the bits, so encrypt the secret first if you need real confidentiality.

Why might decoding give the wrong result?

If the text passed through a system that normalised confusable characters or auto-corrected the Cyrillic letters back to Latin, the bits are lost. Some search and spell-check tools do this, so verify your channel preserves the exact code points.

Homoglyph Steganography Encoder

What this tool does

This is a homoglyph steganography encoder and decoder. It hides a secret message inside ordinary-looking text by swapping certain Latin letters for visually identical Cyrillic homoglyphs. To a human the text reads the same; to a computer the swapped code points encode binary data.

How it works

A handful of letters have near-perfect Cyrillic twins:

a↔а  c↔с  e↔е  o↔о  p↔р  x↔х  y↔у
A↔А  C↔С  E↔Е  O↔О  P↔Р  X↔Х  Y↔У

The encoder converts the secret message to bits (8 per character). It then walks through the cover text. Each time it reaches a swappable letter, it consumes one bit: a 1 substitutes the Cyrillic homoglyph, a 0 leaves the Latin letter as-is. Non-swappable characters are left untouched and carry no data.

Decoding reverses this: it scans the text, and at every swappable position it emits a 1 if the character is the Cyrillic form and a 0 if it is the Latin form, then regroups the bits into bytes.

Example

The cover word peacock has swappable letters p e a c o c (six bits of capacity). Picking which of those become Cyrillic encodes six bits of your secret while the word still reads “peacock”.

Notes

Capacity is one bit per swappable letter and 8 bits per secret character — choose cover text rich in a c e o p x y.
This conceals, it does not encrypt. Combine with encryption for confidentiality.
Systems that normalise confusable characters can silently strip the hidden bits; test your delivery channel first.