=== Delastelle's Bifid ===

(http://www.cryptogram.org/cdb/aca.info/aca.and.you/chap08.html#BIFID)

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=== Digrafid ===

(http://www.cryptogram.org/cdb/aca.info/aca.and.you/chap08.html#DIGRAF)

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=== Nihilist substitution ===

 - 1 2 3 4 5
 1 K R Y P T
 2 O S A B C
 3 D E F G H
 4 I L M N Q
 5 U V W X Z

Normally described as reading off the digit pairs, or perhaps adding a repeating numeric key. But you could do a transposition on the numbers and substitute back to letters using the same or a different square. Or add the numeric key with no carry base 5 (better start with numbers 0-4) and substitute back.

Similar ideas could be applied to the *Straddling Checkerboard*

 - 0 1 2 3 4 5 6 7 8
 - K R Y - P T O - S
 3 A B C D E F G H I
 7 L M N Q U V W X Z

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Back to* SectionFourAttempts

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