1=pod 2 3=head1 NAME 4 5SSL_key_update, 6SSL_get_key_update_type, 7SSL_renegotiate, 8SSL_renegotiate_abbreviated, 9SSL_renegotiate_pending 10- initiate and obtain information about updating connection keys 11 12=head1 SYNOPSIS 13 14 #include <openssl/ssl.h> 15 16 int SSL_key_update(SSL *s, int updatetype); 17 int SSL_get_key_update_type(const SSL *s); 18 19 int SSL_renegotiate(SSL *s); 20 int SSL_renegotiate_abbreviated(SSL *s); 21 int SSL_renegotiate_pending(const SSL *s); 22 23=head1 DESCRIPTION 24 25SSL_key_update() schedules an update of the keys for the current TLS connection. 26If the B<updatetype> parameter is set to B<SSL_KEY_UPDATE_NOT_REQUESTED> then 27the sending keys for this connection will be updated and the peer will be 28informed of the change. If the B<updatetype> parameter is set to 29B<SSL_KEY_UPDATE_REQUESTED> then the sending keys for this connection will be 30updated and the peer will be informed of the change along with a request for the 31peer to additionally update its sending keys. It is an error if B<updatetype> is 32set to B<SSL_KEY_UPDATE_NONE>. 33 34SSL_key_update() must only be called after the initial handshake has been 35completed and TLSv1.3 or QUIC has been negotiated, at the same time, the 36application needs to ensure that the writing of data has been completed. The key 37update will not take place until the next time an IO operation such as 38SSL_read_ex() or SSL_write_ex() takes place on the connection. Alternatively 39SSL_do_handshake() can be called to force the update to take place immediately. 40 41SSL_get_key_update_type() can be used to determine whether a key update 42operation has been scheduled but not yet performed. The type of the pending key 43update operation will be returned if there is one, or SSL_KEY_UPDATE_NONE 44otherwise. 45 46SSL_renegotiate() and SSL_renegotiate_abbreviated() should only be called for 47connections that have negotiated TLSv1.2 or less. Calling them on any other 48connection will result in an error. 49 50When called from the client side, SSL_renegotiate() schedules a completely new 51handshake over an existing SSL/TLS connection. The next time an IO operation 52such as SSL_read_ex() or SSL_write_ex() takes place on the connection a check 53will be performed to confirm that it is a suitable time to start a 54renegotiation. If so, then it will be initiated immediately. OpenSSL will not 55attempt to resume any session associated with the connection in the new 56handshake. 57 58When called from the client side, SSL_renegotiate_abbreviated() works in the 59same was as SSL_renegotiate() except that OpenSSL will attempt to resume the 60session associated with the current connection in the new handshake. 61 62When called from the server side, SSL_renegotiate() and 63SSL_renegotiate_abbreviated() behave identically. They both schedule a request 64for a new handshake to be sent to the client. The next time an IO operation is 65performed then the same checks as on the client side are performed and then, if 66appropriate, the request is sent. The client may or may not respond with a new 67handshake and it may or may not attempt to resume an existing session. If 68a new handshake is started then this will be handled transparently by calling 69any OpenSSL IO function. 70 71If an OpenSSL client receives a renegotiation request from a server then again 72this will be handled transparently through calling any OpenSSL IO function. For 73a TLS connection the client will attempt to resume the current session in the 74new handshake. For historical reasons, DTLS clients will not attempt to resume 75the session in the new handshake. 76 77The SSL_renegotiate_pending() function returns 1 if a renegotiation or 78renegotiation request has been scheduled but not yet acted on, or 0 otherwise. 79 80=head1 USAGE WITH QUIC 81 82SSL_key_update() can also be used to perform a key update when using QUIC. The 83function must be called on a QUIC connection SSL object. This is normally done 84automatically when needed. Since a locally initiated QUIC key update always 85causes a peer to also trigger a key update, passing 86B<SSL_KEY_UPDATE_NOT_REQUESTED> as B<updatetype> has the same effect as passing 87B<SSL_KEY_UPDATE_REQUESTED>. 88 89The QUIC connection must have been fully established before a key update can be 90performed, and other QUIC protocol rules govern how frequently QUIC key update 91can be performed. SSL_key_update() will fail if these requirements are not met. 92 93Because QUIC key updates are always handled immediately, 94SSL_get_key_update_type() always returns SSL_KEY_UPDATE_NONE when called on a 95QUIC connection SSL object. 96 97=head1 RETURN VALUES 98 99SSL_key_update(), SSL_renegotiate() and SSL_renegotiate_abbreviated() return 1 100on success or 0 on error. 101 102SSL_get_key_update_type() returns the update type of the pending key update 103operation or SSL_KEY_UPDATE_NONE if there is none. 104 105SSL_renegotiate_pending() returns 1 if a renegotiation or renegotiation request 106has been scheduled but not yet acted on, or 0 otherwise. 107 108=head1 SEE ALSO 109 110L<ssl(7)>, L<SSL_read_ex(3)>, 111L<SSL_write_ex(3)>, 112L<SSL_do_handshake(3)> 113 114=head1 HISTORY 115 116The SSL_key_update() and SSL_get_key_update_type() functions were added in 117OpenSSL 1.1.1. 118 119=head1 COPYRIGHT 120 121Copyright 2017-2023 The OpenSSL Project Authors. All Rights Reserved. 122 123Licensed under the Apache License 2.0 (the "License"). You may not use 124this file except in compliance with the License. You can obtain a copy 125in the file LICENSE in the source distribution or at 126L<https://www.openssl.org/source/license.html>. 127 128=cut 129
