> How chaining is different then cross-certification ?. Chaining is a single link from an End Entity up to a root, or trust anchor: A --> CA1 --> CA2 --> ... --> Root
(where a-->b means "B has signed the certificate for A") Cross-certification is when you have multiple chains that intersect: A --> CA1 --> CA2 --> ... --> Root | ^ v | B --> CAi --> CAii --> ... --> Root' If B presents a cert to A, A can go up the B chain until it gets to Root' which is sees has signed by Root, which is one of A's trust anchors, so A trust B's credentials. (For convenience, we will ignore the complications added by CRL's or OCSP.) > If cross-certification means then two CAs sign each other then how we can > scale to a scenario of more than two CAs in a fully meshed > cross-certification model ?. Exactly. :) The US Government has a project to do this for some of their (Defense Dept?) PKI's. I forget the name. Put a new mega-root and have everyone cross-certify with that root. You still get full paths everywhere, but it's O(2N) instead of O(N**2) certifications. /r$ -- Zolera Systems, Your Key to Online Integrity Securing Web services: XML, SOAP, Dig-sig, Encryption http://www.zolera.com ______________________________________________________________________ OpenSSL Project http://www.openssl.org User Support Mailing List [EMAIL PROTECTED] Automated List Manager [EMAIL PROTECTED]