>How about this for the back of the T-shirt:
>
> 10,000 people worked happily together on
> decrypting DES, but no ten of them could
> agree on what to have on this T-shirt...
>
>:-)
Or perhaps:
We tried 17,731,502,968,143,871 keys
to crack the Data Encrytion Standard and
all I got was this lousy T-Shirt!
}:)