I'm not sure I see the problem. Let's see, if an application with a certificate verification callback registered through SSL_CTX_set_cert_verify_callback() is built for an older OpenSSL (i.e. doesn't take a user argument), what will happen is that the callback gets an extra random argument that it ignores (if it's been constructed correctly). A new application will have to use the new interface which demands a user argument to be passed to the callback, and that should present no problems.
The only two other combinations that I can think of are: 1. application built for OpenSSL < 0.9.7 and linked with OpenSSL < 0.9.7. No problem there. 2. application built for OpenSSL >= 0.9.7 and linked with OpenSSL < 0.9.7. That alternative is absurd. So, what's left? What is it I don't see? -- Richard Levitte \ Spannvägen 38, II \ [EMAIL PROTECTED] Redakteur@Stacken \ S-168 35 BROMMA \ T: +46-8-26 52 47 \ SWEDEN \ or +46-733-72 88 11 Procurator Odiosus Ex Infernis -- [EMAIL PROTECTED] Member of the OpenSSL development team: http://www.openssl.org/ Software Engineer, GemPlus: http://www.gemplus.com/ Unsolicited commercial email is subject to an archival fee of $400. See <http://www.stacken.kth.se/~levitte/mail/> for more info. ______________________________________________________________________ OpenSSL Project http://www.openssl.org Development Mailing List [EMAIL PROTECTED] Automated List Manager [EMAIL PROTECTED]