North American Network Operators Group|
Date Prev | Date Next | Date Index | Thread Index | Author Index | Historical
Re: PKI operators anyone?
Erik Amundson wrote: > Validity periods aside, we have experimented quite a bit with putting > certs on everything we possibly can, and we've found that there are a > whole lot of products that can't handle root key sizes above 2048, some > can't even handle anything larger than 1024. > > Included in the 'can't handle your root' list are several Cisco products > (some products can handle 2048, some 1024, some 4096), and many software > products that use an older Java version that has a max of 2048. > > This has always raised the question: Why do software authors think to > implement PKI, but not think that key sizes will eventually grow over > time? Seems very short-sighted to me. Consider the hardware platforms some of these operations run on... It takes a long time to generate 1024 bit dsa keys on a 20mhz motorola 68020. Using them in a key exchange is also expnsive on such hardware... I think it's a safe assumption that there's some planned obsolence where the software and hardware elements of the platform meet in the cryptogrphic realm. > I guess the option to choose for full interoperability is 1024 keys on > all certs, but that is at a sacrifice of security on your higher-level > certs... > > - Erik Amundson > > > -----Original Message----- > From: [email protected] [mailto:[email protected]] On Behalf Of > Joe Maimon > Sent: Wednesday, September 05, 2007 9:06 AM > To: North American Networking and Offtopic Gripes List > Subject: PKI operators anyone? > > > MS-PRESS recommended design guidelines for multi-tier PKI systems for > validity periods are along the lines of > > 8 years for the root > 4 years for the "policy" > 2 years for the "issuing" > 1 year for the issued certificate > > This is ostensibly due to fears of brute force cracking of the private > keys over the root key's validity period. > > Accompanied with this recommendation is one for key lengths of > > 4096 for the root > 2048 for the policy > 1024 for the issuing and for the issued. > > I have found the downside to this: Constant renewals every single year > of either minor or major impact. > > While MS-AD pki client implementations seem to handle most of the > (except for the root) resigning just fine, external implementation > struggle with some details, such as "chaining up to the root" trusting > (thereby only requiring them to trust the root cert) and such as > trusting two different certs (for an issuing CA that gets resigned) but > that have the same common name, hence loads of fun every 11 months or > so. > > I am about to recommend a re implementation along these lines > > 80 years for the root, 4096bit key > 35 years for the policy, 4096bit key > 15 years for the issuing, ?bit key > <=5 years for the issued certificates. > > Good idea? Bad Idea? Comments? Are all pki client implementation in the > wild 4096bit compatible? > > Thanks in advance, > > Joe >