Hi David, Thanks for the info!
Yes, I'm already using the PkixCertPathBuiler to get a certificate chain and storing that on my "SecureMimeDigitalSignature" class that consumers of my library can access and validate. If you are interested, I would appreciate hearing your (or anyone else's on this list) thoughts on my S/MIME implementation so far at https://github.com/jstedfast/MimeKit The S/MIME stuff is all in MimeKit/Cryptography/* SecureMimeContext is the base class that does all of the encryption/decryption/signing/verifying/etc and has abstract methods for subclasses to implement for things like certificate, crl and private key lookups and other management of those things. The code I'm working on now is DefaultSecureMimeContext (it used to use .p12 files and a flat file of crls, but I had no way of storing S/MIME capabilities so gave up and am now re-implementing it using the X509CertificateDatabase class to store everything I need). Thanks to your answer to my question, my next step will be to get the CRL storage correct. Jeff On Sat, Nov 23, 2013 at 6:01 PM, David Hook <d...@autochthonous.org> wrote: > > It's a bit of both, some CRLs constitute full updates, others are referred > to as "delta CRLs", and represent a set of changes, so in the situation > where you have a delta CRL your actual set of revocations is ("update CRL" > + "delta CRL 1" + "delta CRL 2"...). > > A delta CRL is indicated by the Delta CRL Indicator - an extension defined > in section 5.2.4 of RFC 5280 > > One other thing that might help, if you're not doing it already, are you > using any of the CertPath support in BC C#? Validating a certificate > properly involves a lot more than checking a signature and a CRL. The > CertPath code is an attempt to deal with the now 151 pages of RFC 5280. > > Regards, > > David > > > On 24/11/13 01:44, Jeff Stedfast wrote: > > Okay... I've broken down and implemented a SQLite database for storing > certificates (along with the S/MIME Capabilities for the clients associated > with each certificate - this is needed to properly determine which > encryption algorithm to use) and the CRLs. > > It was just getting to be too much of a PITA to store each of these > things in different files and manage relationships between them. > > That said... I don't know a whole lot about CRLs and want to get this > correct. > > Can I assume that X509Crl's with an identical IssuerDN and a newer > ThisUpdate replaces an older X509Crl with the same IssuerDN? > > Or do I just need to keep collecting CRLs? > > In other words: if I have an X509Crl with an IssuerDN of "XYZ" and a > ThisUpdate of "Yesterday", would an X509Crl with an issuerDN of "XYZ" and a > ThisUpdate of "Today" contain the same list of certificates (plus any new > ones) as the first CRL? > > Thanks, > > Jeff > > > On Tue, Nov 12, 2013 at 4:45 PM, Jaroslav Imrich < > jaroslav.imr...@gmail.com> wrote: > >> Hello Sid, >> >> currently there is no "standard certificate store" available on Linux. >> Almost every application (cryptographic library) uses its own solution but >> there is an ongoing effort to solve this sad situation in p11-glue project >> [0] that promotes PKCS#11 as a glue between crypto libraries and security >> applications. I think you should take a look at its two suprojects P11-Kit >> [1] and TrustModule [2]. PKCS#11 interface is nowadays supported by almost >> every smartcard/HSM middleware and there are also pure software modules >> available such as SoftHSM [3] or NSS Internal PKCS#11 module (used by >> Mozilla products). Unmanaged PKCS#11 modules can be easily interfaced in C# >> via managed wrappers such as Pkcs11Interop [4]. Full disclosure: I am the >> author of Pkcs11Interop :) >> >> However if you are looking for a quickest, easy to understand, easy to >> implement and "truly" cross-platform solution (Android and iOS included) >> you will probably end up with something very similar to Jeff's solution >> with PKCS#12 file. >> >> [0] http://p11-glue.freedesktop.org/ >> [1] http://p11-glue.freedesktop.org/p11-kit.html >> [2] http://p11-glue.freedesktop.org/trust-module.html >> [3] http://www.opendnssec.org/softhsm/ >> [4] http://pkcs11interop.net/ >> >> -- >> Kind Regards / S pozdravom >> >> Jaroslav Imrich >> http://www.jimrich.sk >> >> >> On Tue, Nov 12, 2013 at 8:35 PM, Sid Shetye <sid...@outlook.com> wrote: >> >>> Thanks Jeff. >>> >>> >>> >>> Taking a step back before jumping into library details, did you find any >>> other alternatives before deciding to have your own cert store >>> implementation? I ask because it seems odd (to me) that you and I would be >>> the first ones to face the “cross platform certificate store” problem – >>> surely someone else might have solved this before. Especially in the Bouncy >>> Castle community? That’s my (perhaps naïve) thinking. So would appreciate >>> if you could share your learnings on this topic (and great job on the >>> GitHub repo!) >>> >>> >>> >>> Regards, >>> >>> Sid >>> >>> >>> >>> *From:* Jeff Stedfast [mailto:j...@xamarin.com] >>> *Sent:* Tuesday, November 12, 2013 11:05 AM >>> *To:* Sid Shetye >>> *Cc:* Bouncy Castle Developer List >>> *Subject:* Re: [dev-crypto-csharp] Certificate store for cross platform >>> designs >>> >>> >>> >>> Hi Sid, >>> >>> >>> >>> I asked this question just last week ;-) >>> >>> >>> >>> What I ended up doing is to use a pkcs12 file to store private >>> certs/keys and a file containing unencrypted certs for everything else >>> (like CAs and such). >>> >>> >>> >>> If you come up with a better way, I'd appreciate if you let me know. I'm >>> working on a cross-platform (Windows, Mac, Linux, iOS, and Android) MIME >>> library with support for S/MIME and PGP, so am really interested in a >>> cross-platform way of managing certificates. >>> >>> >>> >>> You can find my current cross-platform certificate management logic >>> here: >>> https://github.com/jstedfast/MimeKit/blob/master/MimeKit/Cryptography/DefaultSecureMimeContext.cs#L104 >>> >>> >>> >>> and here: >>> https://github.com/jstedfast/MimeKit/blob/master/MimeKit/Cryptography/X509CertificateStore.cs >>> >>> >>> >>> The first link creates 2 X509CertificateStores, one for root >>> certificates and one for user certs (equivalent, I suppose, of >>> StoreName.Root and StoreName.My). I should probably also have something >>> equivalent to StoreName.AddressBook, but right now they are stored in the >>> pkcs12 file along with the user's other personal certificates. >>> >>> >>> >>> Hope that helps, >>> >>> >>> >>> Jeff >>> >>> >>> >>> On Tue, Nov 12, 2013 at 1:42 PM, Sid Shetye <sid...@outlook.com> wrote: >>> >>> Hi folks, >>> >>> >>> >>> Although we do use BC for some crypto stuff, we haven’t explored >>> anything beyond the standard Windows cert store for certificate storage. So >>> at present we use the Windows certificate store as: >>> >>> >>> >>> var store = new X509Store(StoreName.My, StoreLocation.LocalMachine); >>> >>> store.Open(OpenFlags.OpenExistingOnly | OpenFlags.ReadOnly); >>> >>> var certs = store.Certificates.Find(X509FindType.FindBySubjectName, >>> subjectName, true); >>> >>> >>> >>> We’d like to switch to something that’s more cross platform (esp Linux >>> compatible). What are some good design patterns for a secure, cross >>> platform certificate storage? We need to store RSA and EC certificates as >>> well as their respective private keys (if they exist in the password >>> protected PFX). >>> >>> >>> >>> Regards >>> >>> Sid >>> >>> >>> >>> >>> >> > >
