zwtext | ZWT (Zero Width Text) encoder and decorder

ZWT (zero width text) is an invisible string encoding that allows embedding any data into text without visually affecting it, by utilizing zero-width characters in UNICODE.

Specification

• ZWT (zero-width-text) consists of the following three types of zero-width characters:
  • U+200B ZWSP (zero width space)
  • U+200C ZWJ (zero width joiner)
  • U+200D ZWNJ (zero width non-joiner)
• The structure of the zero width text string is ZWNJ 1* ( 8 ( ZWSP / ZWJ ) ) ZWNJ
  • Zero width text is intended to be embedded mainly at the boundaries of documents or words, so it is surrounded by ZWNJ to prevent unintended joining of adjacent characters with ZWJ.
  • The data part of the zero width text is a simple replacement of the bits 0/1 of the original data with the two characters ZWSP and ZWJ.
• The size of zero-width text will be 24 times the original size plus 6 bytes (very large)
• Zero-width text is a simple pattern string
  • Multiple zero-width text strings can be embedded within a single string
  • Easy to strip and reveal

Usage

import {
    encodeZW,
    decodeZW,
    decodeZWs,
    decodeZWsToUint8Array,
    revealZW,
    stripZW
} from 'zwtext'

secret1 = encodeZW(' secret world'); // looks like '', 106 characters, 318 bytes
secret2 = encodeZW(' こんにちわ✋'); // looks like '', 154 characters, 462 bytes
text = `Hello${secret1}!${secret2}?`; // looks like 'Hello!?', 267 characters, 787 bytes
decodeZW(text); // ' secret world'
revealZW(text); // 'Hello secret world! こんにちわ✋?'
striped = stripZW(text); // 'Hello!?'
decodeZWs(striped); // '' (length is 0)