Re: SSL_connect with TLS 1.3 and client Certificates
On 14/07/2021 13:31, Matt Caswell wrote: > > > On 13/07/2021 19:44, Christian Schmidt wrote: >> Hello all, >> >> I am currently trying to build both client and server of an application >> that uses TLS 1.3 and mutual authentication using certificates. The >> application works so far - I can establish connections, certificates are >> verified, data is successfully transmitted, etc. >> >> However, I have an issue, or maybe two. >> >> 1. SSL_connect returns successfully before the client certificate is >> sent from the client to the server. The client certificate is only sent >> on the first SSL_write_ex with > 0 bytes, and as such, at this point the >> server can generate SSL alerts like access denied, etc. > > TLSv1.3 supports two types of certificate request. It can occur during > the initial handshake, or it can occur as a post-handshake request. It > sounds like you are doing the latter, but you want the former. Is that > correct? > > What are you doing in your code to request the certificate from the client? I may have interpreted what I was seeing wrong. I was assuming that openssl was sending the client certificate together with the first data frame, but it seems that some coalescing happens on the kernel side, causing the server to retrieve both SSL records at once. The asynchronous nature of TLS implies that after sending the client certificate, SSL_connect() does not have to wait for a positive confirmation. Adding a sufficiently large usleep() between SSL_connect() and the first data record makes this visible. Please ignore my question. Best regards, Christian
Re: SSL_connect with TLS 1.3 and client Certificates
On 13/07/2021 19:44, Christian Schmidt wrote: Hello all, I am currently trying to build both client and server of an application that uses TLS 1.3 and mutual authentication using certificates. The application works so far - I can establish connections, certificates are verified, data is successfully transmitted, etc. However, I have an issue, or maybe two. 1. SSL_connect returns successfully before the client certificate is sent from the client to the server. The client certificate is only sent on the first SSL_write_ex with > 0 bytes, and as such, at this point the server can generate SSL alerts like access denied, etc. TLSv1.3 supports two types of certificate request. It can occur during the initial handshake, or it can occur as a post-handshake request. It sounds like you are doing the latter, but you want the former. Is that correct? What are you doing in your code to request the certificate from the client? Matt
SSL_connect with TLS 1.3 and client Certificates
Hello all, I am currently trying to build both client and server of an application that uses TLS 1.3 and mutual authentication using certificates. The application works so far - I can establish connections, certificates are verified, data is successfully transmitted, etc. However, I have an issue, or maybe two. 1. SSL_connect returns successfully before the client certificate is sent from the client to the server. The client certificate is only sent on the first SSL_write_ex with > 0 bytes, and as such, at this point the server can generate SSL alerts like access denied, etc. 2. When trying to benchmark latency on the application, the first roundtrip is extended by the client certificate verification. Is there any way I can complete the handshake, and thus validate the full connection, without sending data? I must say that even after reading RFC8446 I am not sure if there is a positive confirmation after the client certificate is sent, so I am not sure if what I am asking for is even possible. Best regards, Chris
