I'm no ssl guru either but I'll make some brief comments and let others jump in if I'm too far off the mark.
1. If you use the standard verify and the peer presents an expired certificate, the certificate will not be verified and the connection will fail. 2. The verification callback is called after the "regular" verification is performed, here's a simple example I posted with my own question yesterday: static int verify_callback(int ok, X509_STORE_CTX *stor) { if(!ok) { printf("verify_callback Certificate Verification Error: %s\n", X509_verify_cert_error_string(stor->error)); } else { printf("verify_callback Certificate Verification Success\n"); } return ok; } The ok parameter tells you whether the certificate passed so that if it's not ok (didn't pass) you can examine the reason/error and the certificate itself to see whether or not you want to over-rule that result. The return value indicates whether you want to accept it or not - the above example only reports the result (without changing it) and (if it fails) the reason for failure without changing anything. If it's not ok and you look at the cert and it's expired but you don't care, return 1 and it will be accepted. Look at the examples in the pdf for some examples. As I said earlier, standard warnings apply - you're overruling standard security mechanisms for your own purposes which can be dangerous if you're not careful. 3. I think I've answered that above .... N --- Nou Dadoun ndad...@teradici.com 604-628-1215 -----Original Message----- From: owner-openssl-us...@openssl.org [mailto:owner-openssl-us...@openssl.org] On Behalf Of Dinh, Thao V CIV NSWCDD, K72 Sent: April 11, 2012 4:19 AM To: openssl-users@openssl.org Subject: RE: expired ssl certificate Hi Nou Please help me understand more about this subject ( I am new to Openssl) 1. What happen if the peer presents an expired certificate and we do not implement callback using SSL_CTX_set_verify with SSL_VERIFY_PEER flag set, will the SSL_connect or SSL_accept fail ??? 2. What is the function of verification callback ? Just "report" error of expired certificate or actually let expired certificate be accepted ?? what is X509_.. function shoud I uses to let expired cert being accept ?? 3. what is the different between standard verify operation and the verify callback ??? Thank You Thao Dinh -----Original Message----- From: owner-openssl-us...@openssl.org [mailto:owner-openssl-us...@openssl.org] On Behalf Of Nou Dadoun Sent: Tuesday, April 10, 2012 3:15 PM To: openssl-users@openssl.org Subject: RE: expired ssl certificate You can use a verification callback to look at the certificate after the standard verify operation has been performed to decide whether or not to allow the certificate anyway. Look at the O'Reilly book (http://doc.hackbbs.org/Reseaux/O_Reilly_-_Network_Security_with_OpenSSL.pdf ) page 132 or so has some sample code you can probably modify. Standard warnings apply .. N --- Nou Dadoun ndad...@teradici.com 604-628-1215 ________________________________ From: owner-openssl-us...@openssl.org [mailto:owner-openssl-us...@openssl.org] On Behalf Of Srihari, Gautam Sent: April 10, 2012 3:04 AM To: openssl-...@openssl.org; openssl-users@openssl.org Subject: expired ssl certificate Hi, I have a server application and the client uses https to connect to the server. For this I had created an openssl self signed certificate cacert.pem which has been distributed to all the client applications. Now unfortunately the certificate has expired. I can create a new certificate. But distributing to all the clients is going to be difficult. Is there some way by using open ssl, I can make the server ignore expired certificates so I don't have to ask each client to update to a new certificate? The crux of the problem is that I want to continue to allow clients to use the server without Having them to upgrade anything i.e change should be done only on the server side. Reg., Gautam ______________________________________________________________________ OpenSSL Project http://www.openssl.org User Support Mailing List openssl-users@openssl.org Automated List Manager majord...@openssl.org