Registering a windows application

[Cdudej]

Hello i have got a string that includes the date and the hard drive
key . I want to encrypt this into a short registration key short
enough for the customer to tell me the number over the phone then i
send back the activation key which allows the program to function for
another year. All the encryptions i have tried create to long and
complex keys. I would like something like this 2009/01/01AEO55P to be
encrypted into a 22 or somewhere around that length digit string.
Thanks in advance

 

[Peter Duniho]

Hello i have got a string that includes the date and the hard drive
key . I want to encrypt this into a short registration key short
enough for the customer to tell me the number over the phone then i
send back the activation key which allows the program to function for
another year. All the encryptions i have tried create to long and
complex keys. I would like something like this 2009/01/01AEO55P to be
encrypted into a 22 or somewhere around that length digit string.

You've only got 14 significant characters in your string. Perhaps the
main issue is that you're trying to encrypt it too strongly? There
should be simple encryptions you can use that would result in a
14-character string. Even Base64 shouldn't exceed 22.

What encryptions have you tried so far? How much security do you feel
you really need? Are you going to inconvenience a customer who just
wants to upgrade his hard drive by requiring them to reactivate their
software over the phone?

Maybe if you do some simple bit-shifting on the original data, then
encode that as Base64 to get back to mostly-alphanumerics (or a variant
thereof if you literally want only alphanumerics...Base64 includes two
extra non-alphanumeric characters), that would suffice. It won't be
strong, but then I doubt you're trying to keep the NSA from snooping the
data.

Pete

 

[Cdudej]

You've only got 14 significant characters in your string.  Perhaps the
main issue is that you're trying to encrypt it too strongly?  There
should be simple encryptions you can use that would result in a
14-character string.  Even Base64 shouldn't exceed 22.

What encryptions have you tried so far?  How much security do you feel
you really need?  Are you going to inconvenience a customer who just
wants to upgrade his hard drive by requiring them to reactivate their
software over the phone?

Maybe if you do some simple bit-shifting on the original data, then
encode that as Base64 to get back to mostly-alphanumerics (or a variant
thereof if you literally want only alphanumerics...Base64 includes two
extra non-alphanumeric characters), that would suffice.  It won't be
strong, but then I doubt you're trying to keep the NSA from snooping the
data.  

Pete

Thanks that is what i am looking for i have been using Rijndael etc
probably not the right on. I will try what you have suggested