[rc5] yet more rc5-64 vs Something Else

Steve Trottier STROTTIER at novell.com
Wed Oct 1 19:36:07 EDT 1997

>> Daniel Baker <dbaker at wrangler.cuckoo.com> wrote:
>> Having gracefully made our point about encryption, let's retire from that
>> bit (unless someone can suggest another algorithm that merits attention -
>> perhaps some of those used in cellphones or some such?) and find
>> to do. Ideally, I'd like to see several different projects happening in
>> parallel, possibly including rc5-64, but let's not limit ourselves to the
>> very sterile (IMHO) exercise of breaking an algorithm a second time just
>> because we can.
>Right, but then we're saying "56 bit is hard, so 64 is enough".  All we're
>saying is "we've giving up when the going gets tough".  We need to continue
>proving the fact that we can break encryption standard after encryption

As far as I'm concerned 64-bit IS enough for what I use encryption for.  I
don't think any of us can dictate to anyone else how they should interpret
the results of our effort.  Whether or not we try the RC5-64bit contest (I
won't) we have shown that it takes months to find a single key for a single
tranmission encrypted with RC5-56.  I don't know about you, but the most
sensitive thing I will probably ever protect with encryption is my credit
card number and I only have a $10,000 limit so I doubt it would be worth it
for anyone to spend several times that for the effort needed to find my
56-bit key, let alone my 64-bit key.  On the other hand, the prize for this
contest is only $10,000...so I could be wrong.

I think we've given enough data to whoever wants to know about how much
effort is required to find a 56-bit key that they could extrapolate to
figure out what would be required to find a 64-bit key.  We wouldn't really
be providing any new or useful information, except possibly how easy or hard
it is to recruit additional computing power.

The distributed projects that sound the most intersting to me are (in

Steve Trottier <strottier at novell.com>
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