Hi, Would all this extra signing lead to unnecessary leakage of the CA private key? Do private keys become "stale" after too many uses and/or time?
thanks! Robert -----Original Message----- From: [EMAIL PROTECTED] on behalf of Martin Bartosch Sent: Wed 8/18/2004 8:41 AM To: [EMAIL PROTECTED] Cc: Subject: [OpenCA-Devel] Design issue: Role signatures and conflicts with key usage bits for CA certificates Hi, the (now fixed) recent problem with the signed role for a new certificate raises several interesting problem, at least for me. In OpenCA standard configuration the CA certificate itself is issued with the following key usages: digitalSignature, nonRepudiation, cRLSign, keyCertSign However, I believe that CA certs should NOT be used for anything else than signing CRLs and certificates, and this would only require the CA cert to have the key usage bits cRLSign, keyCertSign These are also the only key usages that are allowed according to ISIS-MTT for CA certificates, and I believe that there will be environments that will want to adhere to this standard. This has several implications: * OpenCA uses the CA certificate for signing the cert Role. (BTW: openca-sv does use the CA cert regardless of its key usage bits - and can create invalid signatures this way!) * Verification of this signature (correctly) fails as reported by openca-sv verify) because of incorrect key usage bits in the CA certificate if the ISIS-MTT conforming profile is used. * The CA private key usage should IMHO be limited to the absolutely necessary minimum, and this is cert signing and CRL signature only. Using the CA key for creating PKCS#7 signatures violates this principle and introduces not really necessary audit events once we have implemented the private key counter. * I am somewhat unsure if the signature on the Role is really necessary - what is the rationaly behind this anyway? The CA signed the cert, so it has expressed consent that this certificate (with the attached cert policy) is valid. A signed "Role" seems redundant to this policy to me. * I may be wrong, but I think the signature on the Role does not add any security, because the clear text seems to be only the Role name, making it possible to copy the signature and use it for another certificate. To sum this up I think that using the CA cert is a bad idea and that it should either be possible to switch it off or at least to specify a dedicated CA auxiliary certificate that is issued by the CA when setting up the system and then used to sign such stuff. What do you think? Martin ------------------------------------------------------- SF.Net email is sponsored by Shop4tech.com-Lowest price on Blank Media 100pk Sonic DVD-R 4x for only $29 -100pk Sonic DVD+R for only $33 Save 50% off Retail on Ink & Toner - Free Shipping and Free Gift. http://www.shop4tech.com/z/Inkjet_Cartridges/9_108_r285 _______________________________________________ OpenCA-Devel mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/openca-devel
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