```bash #!/bin/bash

Generate a purely whitespace password with 128 bits of symmetric security.

Characters are strictly non-control, non-graphical spaces/blanks. Both

nonzero- and zero-width characters are used. Two characters are technically

vertical characters, but aren't interpreted as such in the shell. They are

"\u2028" and "\u2029". You might need a font with good Unicode support to

prevent some of these characters creating tofu.

rng() { # Cryptographically secure RNG local min=$((2 ** 32 % 30)) # 30 = size of $s below local r=$SRANDOM while [ "$r" -lt "$min" ]; do r=$SRANDOM; done # Modulo with rejection echo "$(($r % 30))" }

s=( # Non-zero width characters "\u0009" # Character tabulation "\u0020" # Space "\u00A0" # Non-breaking space "\u2000" # En quad "\u2001" # Em quad "\u2002" # En space "\u2003" # Em space "\u2004" # Three-per-em space "\u2005" # Four-per-em space "\u2006" # Six-per-em space "\u2007" # Figure space "\u2008" # Punctuation space "\u2009" # Thin space "\u200A" # Hair space "\u2028" # Line separator "\u2029" # Paragraph separator "\u202F" # Narrow no-break space "\u205F" # Medium mathematical space "\u2800" # Braille pattern blank "\u3000" # Ideographic space "\u3164" # Hangul filler "\uFFA0" # Halfwidth hangul filler # Zero width characters "\u115F" # Hangul choseong filler "\u1160" # Hangul jungseong filler "\u180E" # Mongolian vowel separator "\u200B" # Zero width space "\u200C" # Zero width non-joiner "\u200D" # Zero width joiner "\u2060" # Word joiner "\uFEFF" # Zero width non-breaking space ) p=""

Generate 27 characters for at least 128 bits security

for i in {1..27}; do r=$(rng) c=${s[$r]} p="${p}${c}" done

tabs -1 # Tab width of 1 space

Wrap the password in braille pattern blanks for correctly handling zero-width

characters and to prevent whitespace stripping by the auth form.

echo -e "\"\u2800${p}\u2800\"" ```

Example:

$ bash whitespace.bash "⠀        ᅠ        ⠀　 ᅟ ᅠ​⠀"