[openssl-users] Two sessions in a single full handshake

[Matt Caswell]

On 30/09/18 06:05, John Jiang wrote:
> Now that full handshake sends two sessions, does that mean option
> -sess_out saves both of the sessions to a local file?

The last session received is the one in the sess_out file.

Matt


> If so, when resume session via option -sess_in, which session will be
> resumed?
> 
> On Sun, Sep 30, 2018 at 11:47 AM Benjamin Kaduk via openssl-users
> <openssl-users at openssl.org <mailto:openssl-users at openssl.org>> wrote:
> 
>     s_client has -sess_out and -sess_in options that can be used
>     to save session information to a file and read it in for a subsequent
>     connection.  Neither is used by default.
> 
>     -Ben
> 
>     On Sun, Sep 30, 2018 at 11:06:14AM +0800, John Jiang wrote:
>     > Does s_client resume any session in the local session file?
>     >
>     > On Sun, Sep 30, 2018 at 3:19 AM Salz, Rich via openssl-users <
>     > openssl-users at openssl.org <mailto:openssl-users at openssl.org>> wrote:
>     >
>     > >
>     > >    - The debug logs display two "SSL-Session" blocks in a full
>     handshake.
>     > >
>     > > Only one "SSL-Session" block is displayed in a resumption.
>     > >
>     > > Why does full handshake has two sessions?
>     > >
>     > >
>     > >
>     > > This is part of the TLS 1.3 standard.  A server can send back
>     multiple
>     > > sessions, so that a client may resume with a different session, and
>     > > therefore prevent an observer from “linking” two different
>     activities.
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>