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Paper 2014/257

Handycipher: a Low-tech, Randomized, Symmetric-key Cryptosystem

Bruce Kallick

Abstract

Handycipher is a low-tech, randomized, symmetric-key, stream cipher, simple enough to permit pen-and-paper encrypting and decrypting of messages, while providing a significantly high level of security by using a nondeterministic encryption procedure, multiple encryption, and randomly generated session keys.

Note: This version of the cipher has been made highly resistant to statistically based hill-climbing attacks by adding ten characters to the ciphertext alphabet, using a 41-character key instead of 31, increasing the number of null characters from five to fifteen, increasing the number of diagonals used from two to ten, and alternating the direction of encoding plaintext characters between top-down/left-right and bottom-up/right-left.

Metadata
Available format(s)
PDF
Category
Secret-key cryptography
Publication info
Preprint.
Keywords
stream cipherssecret-key cryptographyrandomized homophonic substitutionhand ciphers
Contact author(s)
curmudgeon @ rudegnu com
History
2016-02-04: last of 12 revisions
2014-04-20: received
See all versions
Short URL
https://ia.cr/2014/257
License
Creative Commons Attribution
CC BY
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