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Cream of the Crop 3
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Cream of the Crop 3.iso
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crypchal.zip
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READ.ME
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Text File
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1994-04-17
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2KB
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39 lines
Packing list and instructions for CRYPCHAL.ZIP
HI-CRYPT.C -\
CRYPT.C \____ Used to build the HI_CRYPT program
CRC-16.C /
CANT.C -/
HI-CRYPT.COM -> Compiled version used for the test
SNIPPETS.NDX -> Plaintext from SNIP9404
SNIPNDX.CRY -> Ciphertext
The algorithm is pretty straightforward and may be deduced from reading the
code, but here's a synopsis anyway...
The S-Coder algorithm from CRYPT.C is embedded in an assymetrical block
transposition cipher. The block size is 16,384 (64 x 256) and the transpo-
sition is accomplished by manipulating the order and meaning of the rows and
columns. Since the ciphertext will always be a multiple of the block size,
the length of the plaintext file is embedded within the first block in
encrypted form. The location of the file length as well as the starting
rotor position for crypt() are derived from the key itself. As implemented,
the encryption key is a text string and is qualified to be at least 64 bits
long and contain at least 5 distinct characters. With this ~27K plaintext
file, encryption or decryption take about 1 second or less on my 486DX/50.
This is a commutative secret key algorithm so theory says it should be easy
to crack. The information in this file provides the best of all possible
starting points, a known plaintext attack. The challenge is to determine the
encryption key.
When you think you've got it, contact me at:
FidoNet 1:106/2000.6
Internet bobstout@neosoft.com