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Always turn off hyphenation; it makes .\" way too many mistakes in technical documents. .if n .ad l .nh .SH "NAME" SSL_key_update, SSL_get_key_update_type, SSL_renegotiate, SSL_renegotiate_abbreviated, SSL_renegotiate_pending \&\- initiate and obtain information about updating connection keys .SH "SYNOPSIS" .IX Header "SYNOPSIS" .Vb 1 \& #include <openssl/ssl.h> \& \& int SSL_key_update(SSL *s, int updatetype); \& int SSL_get_key_update_type(const SSL *s); \& \& int SSL_renegotiate(SSL *s); \& int SSL_renegotiate_abbreviated(SSL *s); \& int SSL_renegotiate_pending(const SSL *s); .Ve .SH "DESCRIPTION" .IX Header "DESCRIPTION" \&\fBSSL_key_update()\fR schedules an update of the keys for the current \s-1TLS\s0 connection. If the \fBupdatetype\fR parameter is set to \fB\s-1SSL_KEY_UPDATE_NOT_REQUESTED\s0\fR then the sending keys for this connection will be updated and the peer will be informed of the change. If the \fBupdatetype\fR parameter is set to \&\fB\s-1SSL_KEY_UPDATE_REQUESTED\s0\fR then the sending keys for this connection will be updated and the peer will be informed of the change along with a request for the peer to additionally update its sending keys. It is an error if \fBupdatetype\fR is set to \fB\s-1SSL_KEY_UPDATE_NONE\s0\fR. .PP \&\fBSSL_key_update()\fR must only be called after the initial handshake has been completed and TLSv1.3 has been negotiated. The key update will not take place until the next time an \s-1IO\s0 operation such as \fBSSL_read_ex()\fR or \fBSSL_write_ex()\fR takes place on the connection. Alternatively \fBSSL_do_handshake()\fR can be called to force the update to take place immediately. .PP \&\fBSSL_get_key_update_type()\fR can be used to determine whether a key update operation has been scheduled but not yet performed. The type of the pending key update operation will be returned if there is one, or \s-1SSL_KEY_UPDATE_NONE\s0 otherwise. .PP \&\fBSSL_renegotiate()\fR and \fBSSL_renegotiate_abbreviated()\fR should only be called for connections that have negotiated TLSv1.2 or less. Calling them on any other connection will result in an error. .PP When called from the client side, \fBSSL_renegotiate()\fR schedules a completely new handshake over an existing \s-1SSL/TLS\s0 connection. The next time an \s-1IO\s0 operation such as \fBSSL_read_ex()\fR or \fBSSL_write_ex()\fR takes place on the connection a check will be performed to confirm that it is a suitable time to start a renegotiation. If so, then it will be initiated immediately. OpenSSL will not attempt to resume any session associated with the connection in the new handshake. .PP When called from the client side, \fBSSL_renegotiate_abbreviated()\fR works in the same was as \fBSSL_renegotiate()\fR except that OpenSSL will attempt to resume the session associated with the current connection in the new handshake. .PP When called from the server side, \fBSSL_renegotiate()\fR and \&\fBSSL_renegotiate_abbreviated()\fR behave identically. They both schedule a request for a new handshake to be sent to the client. The next time an \s-1IO\s0 operation is performed then the same checks as on the client side are performed and then, if appropriate, the request is sent. The client may or may not respond with a new handshake and it may or may not attempt to resume an existing session. If a new handshake is started then this will be handled transparently by calling any OpenSSL \s-1IO\s0 function. .PP If an OpenSSL client receives a renegotiation request from a server then again this will be handled transparently through calling any OpenSSL \s-1IO\s0 function. For a \s-1TLS\s0 connection the client will attempt to resume the current session in the new handshake. For historical reasons, \s-1DTLS\s0 clients will not attempt to resume the session in the new handshake. .PP The \fBSSL_renegotiate_pending()\fR function returns 1 if a renegotiation or renegotiation request has been scheduled but not yet acted on, or 0 otherwise. .SH "RETURN VALUES" .IX Header "RETURN VALUES" \&\fBSSL_key_update()\fR, \fBSSL_renegotiate()\fR and \fBSSL_renegotiate_abbreviated()\fR return 1 on success or 0 on error. .PP \&\fBSSL_get_key_update_type()\fR returns the update type of the pending key update operation or \s-1SSL_KEY_UPDATE_NONE\s0 if there is none. .PP \&\fBSSL_renegotiate_pending()\fR returns 1 if a renegotiation or renegotiation request has been scheduled but not yet acted on, or 0 otherwise. .SH "SEE ALSO" .IX Header "SEE ALSO" \&\fBssl\fR\|(7), \fBSSL_read_ex\fR\|(3), \&\fBSSL_write_ex\fR\|(3), \&\fBSSL_do_handshake\fR\|(3) .SH "HISTORY" .IX Header "HISTORY" The \fBSSL_key_update()\fR and \fBSSL_get_key_update_type()\fR functions were added in OpenSSL 1.1.1. .SH "COPYRIGHT" .IX Header "COPYRIGHT" Copyright 2017\-2019 The OpenSSL Project Authors. All Rights Reserved. .PP Licensed under the OpenSSL license (the \*(L"License\*(R"). You may not use this file except in compliance with the License. You can obtain a copy in the file \s-1LICENSE\s0 in the source distribution or at <https://www.openssl.org/source/license.html>.