Tim Churches wrote: > Thomas Beale wrote: > >> Let me pose the question another way: >> >> * what standard or other open specification can openEHR point to that >> accurately specifies the format of digital digests and signatures of EHR >> data? It has to be something avalable to everyone, and implementable >> (preferably already implemented)? >> > > Surely one (or more) of the X.509 pkix RFCs covers this? See > http://www.ietf.org/html.charters/pkix-charter.html > > Or the very widely used and implemented RSA Labs PKCS "standards" - see > http://en.wikipedia.org/wiki/PKCS > we might be discussing at cross purposes here Tim - at the moment, we want to achieve one very simple thing in openEHR: specify (by pointing to some published specification) the contents of digital signatures and hashes as we want to use them in openEHR (which is to say: in a completely orthodox fashion). My main concern is that there be a specification which shows how multiple encryption, hashing, compression etc algorithms can be used together in a reliable way, so that both encoder and decoder are guaranteed to be able to write and read the data, verify digests, authenticate authors and so on. So while there are all these standards for dozen well-known encryption algorithms, another dozen digital signature algorithms, various compression algorithms, etc etc, I believe we need to be able to say how they are all used together. openPGP seems to do a good job of this.
This issue of how to mechanically sign etc is one aspect of a full security infrastructure. Clearly, if there is digital signing with private and public keys, there needs to be key management and certification....all I want to recognise is that we should not (I don't think) solve both issues at once - we should solve them relatively independently - in other words, if all the e-Health programmes decide in 2 years time to go with some particular kind of PKI then we can do it, regardless of what choices we make now for digital signature. If we end up using X.509 certificates, great. But we still need a specification for the actual hashing and signing strings that get created and stored with the data or sent in messages. It may be that we do need to have the debate about "how does openEHR integrate with PKI etc"; if so, my hope is that we can treat it relatively independently from the more basic subject above, allowing us to at least make the models security-enabled / aware without having to solve the PKI problem first. > And I dare say that the openSSL library implements whichever one of > these standards is relevant. Sorry, no time to research exactly which > standard you should look at, and its not the sort of information I like > to have hanging around in my cranium (if I can help it). > > PGP/GPG is fab but mention it is not "enterprise-friendly" - mention it > in any large corporate setting and the IT people will wrinkle their > noses and claim not to have heard of it or mutter disparaging remarks > about hackers who ought to be in gaol. Whether they would react the same > way to the mere use of a GnuPG signature format is another question, but > if you mention X.509, PKCS or pkix compliance then there will be nods > and smiles all round from the corporate IT guys. > Sure - but as I have said before I don't believe that using openPGP message format (RFC2440) that we are advocating or pre-supposing any particular key management infrastructure (I am happy to be shown wrong...). So - openPGP is a straw man option for interoperable signature and hash fields in data (there are only 2 or 3 in the whole reference model). What is the alternative? X.509 doesn't specify the way to sign things... - thomas
