Re: SMS Encryption

[Pawel Kot]

>>> address@hidden 6 May 2002 11:21:47 >>>
> The codebook approach sounds good enough for me, I can even maintain a large
> database of the same keys and pick them at random and then include the key
> to the key in the SMS message.

You should rather have ordered lists of the keys. One copy has the client, one 
is stored
in your system. And then you use sequent positions from the list. When there's 
a risk the
list was stolen, you deactivate the list.

> My messages do not have the same lengths - how does this affect me?

You need to fill in the rest of the message to the MAX_LEN with eg. spaces. It 
will enlarge
some messages though.

> Second but most important - does the XOR guarantee printable ASCII output?

Nope. But you can send it in the hex form - it will be printable.

pkot
PS. You can look into some cryptohraphical book to read more on such ciphers as
it is a bit off topic on gnokii maling list ;-)