How to re-key in paper&pencil cipher?

From: Markus Jansson (jansson_markus_at_ziplip.com)
Date: 06/21/03


Date: Sat, 21 Jun 2003 02:21:34 +0300

Im not good explaining this in english so excuse me... :)

Ciphers like AES use CBC, CFB, etc. modes to kinda "re-key" the
encryption key for the next block to be encrypted to avoid ECB mode
which is not that secure. But how can one do the same thing with
paper&pencil ciphers easily and securely?

Im planning one encryption method that combines homophone encryption
(substitution) with Vigenere, shuffle and substitution. I have tought
about using 16*16bit blocks and re-keying the keys (2 Vigenere and 2
shuffle) between every block. But how? Should I XOR the previous
plaintext to Vigenere keys? XOR the previous ciphertext to Vigenere
keys? How?

-- 
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http://www.markusjansson.net
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