Hello, Actually, block ciphers encrypting blocks of *decimal* numbers exist:

- TOY100 [1] encrypts blocks of 32 decimal digits - DEAN18 [2] encrypts blocks of 18 decimal digits - DEAN27 [3] encrypts blocks of 27 decimal digits

`TOY100 is (almost) broken by the generalized linear cryptanalysis`

`described in [2]. Both versions of DEAN are based on a substitution`

`permutation network very close to that of the AES and are provably`

`secure against linear cryptanalysis. These ciphers are only "toy"`

`ciphers. Consequently, there is no official implementation (no test-`

`vector, etc.).`

Here are the references:

`[1] Granboulan, Levieil, Piret: Pseudorandom Permutation Families over`

`Abelian Groups. FSE 2006: 57-77`

`[2] Baignères, Stern, Vaudenay: Linear Cryptanalysis of Non Binary`

`Ciphers. Selected Areas in Cryptography 2007: 184-211 (available here: http://lasecwww.epfl.ch/~tbaigner/papers/groupLC.pdf`

`)`

`[3] Baignères (PhD Thesis): Quantitative Security of Block Ciphers:`

`Designs and Security Tools (to be published)`

`I hope this helps. I'm of course available for any question regarding`

`DEANxx.`

Best regards, Thomas Baignères -- http://lasecwww.epfl.ch/~tbaigner On Aug 27, 2008, at 5:05 PM, Philipp Gühring wrote:

Hi,I am searching for symmetric encryption algorithms for decimalstrings.Let's say we have various 40-digit decimal numbers: 2349823966232362361233845734628834823823 3250920019325023523623692235235728239462 0198230198519248209721383748374928601923 As far as I calculated, a decimal has the equivalent of about 3,3219 bits, so with 40 digits, we have about 132,877 bits.Now I would like to encrypt those numbers in a way that the resultis adecimal number again (that's one of the basic rules of symmetric encryption algorithms as far as I remember).Since the 132,877 bits is similar to 128 bit encryption (like eg.AES),I would like to use an algorithm with a somewhat comparable strengthto AES.But the problem is that I have 132,877 bits, not 128 bits. And I can'tcut it off or enhance it, since the result has to be a 40 digitdecimalnumber again.Does anyone know a an algorithm that has reasonable strength and isableto operate on non-binary data? Preferrably on any chosen number-base? Best regards, Philipp Gühring --------------------------------------------------------------------- The Cryptography Mailing List Unsubscribe by sending "unsubscribe cryptography" to [EMAIL PROTECTED]

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