Re: encryption program question

> Just to explain that a little more. If you only used keys that were
> prime digits long you'd be pretty seriously constraining your keyspace
> so the only thing you'd be really doing is making your system less
> secure by knocking out a large swathe of potential keys.
that's a good point John, I hadn't thought of that. Any thoughts on the
relative security of encrypting a file several times over with different
keys of different lengths and different complexities? I thought about
building that functionality into this system just for fun (and to see if I
can do it) Plus, this seems like it would make cracking the encryption
through brute-force much harder. Also, my program does not seem to be
subject to "patterns". For example if you had a file with two strings of
say 5 'a's each, when you encrypted the file, each symbol in the encrypted
file would be different, so cracking the encryption by looking for
repeating symbols would be pretty hard.



On Tue, Feb 28, 2012 at 4:08 AM, John Elliot <[email protected]> wrote:

> **
>
>
> On 2012-02-28 18:41, John Elliot wrote:
> > Anyway, I've never heard anything about keys needing to be a prime
> > number of digits long and from what I understand such a requirement
> > wouldn't make any sense at all.
>
> Just to explain that a little more. If you only used keys that were
> prime digits long you'd be pretty seriously constraining your keyspace
> so the only thing you'd be really doing is making your system less
> secure by knocking out a large swathe of potential keys.
>
> I've also heard, although I don't remember where or why, that it's not
> considered good practice to use a key longer than the maximum key size.
> I think usually ciphers just wrap to apply the extra data in longer keys
> and I've heard there is a minor concern about the fact that happens.
> Sorry to be vague but I didn't pay much attention to the detail I just
> took away "don't use keys longer than the supported key length."
>
>  
>