I don't want to limit myself to 160 bits. I just don't like limits, regardless of what calculations you can make at how impossible it is to reach them.
If we are dealing only with KHKs, then 160 bits is too long anyways. A generous estimate says that language has 1.6 bits of entropy per character (and remember KHKs need to be structured), so a KHK that can't realisticly be more then 30 characters only contains 48 bits of entropy - meaning at most 96 bits is needed to make a collision unlikely even if every possible KHK is used. But for CHKs the situation is different. The hash that is the key HAS to be secure - otherwise the data can be faked. Even maliciously creating duplicates should not be possible. A birthday attack on 160 bits is only 2^80, and that is not impossible within 20 years for all we know. Also, we don't know that SHA won't be cracked (unlikely as it seems), which might force us to choose a different hash function that creates a different standard length. As far as I can see, you are right that hashing the Public Key for an SVK should not hurt the security of it (since what is needed for an SVK is actually just a unique identifier to a single Public Key, which a hash is), but that is also dependent on being able to trust the security of the hash, which, IMO, requires that we do not limit it's theoretical length at closer then insanity. On Mon, 24 Apr 2000, Lee Daniel Crocker wrote: > > *Never* say never. Locking yourself into anything is generally a bad > > idea. 56 bits was plenty long for DES back in the day, and assuming that > > 160 bits is secure is a good idea, > > You are confusing two unrelated issues: encryption key size and > search key space. I do not for a moment suggest that we limit the > size of encryption keys, especially with quantum computing on the > rise lately. But even if we need 4K encryption, 160 bits is still > plenty to identify those documents. > > SVKs will probably have to carry the whole key in the Send.Insert > message, but the requests still only need a hash of it. > > -- > Lee Daniel Crocker <lee at piclab.com> <http://www.piclab.com/lcrocker.html> > "All inventions or works of authorship original to me, herein and past, > are placed irrevocably in the public domain, and may be used or modified > for any purpose, without permission, attribution, or notification."--LDC > > > _______________________________________________ > Freenet-dev mailing list > Freenet-dev at lists.sourceforge.net > http://lists.sourceforge.net/mailman/listinfo/freenet-dev -- Oskar Sandberg md98-osa at nada.kth.se #!/bin/perl -sp0777i<X+d*lMLa^*lN%0]dsXx++lMlN/dsM0<j]dsj $/=unpack('H*',$_);$_=`echo 16dio\U$k"SK$/SM$n\EsN0p[lN*1 lK[d2%Sa2/d0$^Ixp"|dc`;s/\W//g;$_=pack('H*',/((..)*)$/) _______________________________________________ Freenet-dev mailing list Freenet-dev at lists.sourceforge.net http://lists.sourceforge.net/mailman/listinfo/freenet-dev
