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.\" ========================================================================
.\"
.IX Title "SSL_CTX_SET_SRP_PASSWORD 3SSL"
.TH SSL_CTX_SET_SRP_PASSWORD 3SSL "2023-10-23" "3.0.11" "OpenSSL"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
.\" way too many mistakes in technical documents.
.if n .ad l
.nh
.SH "NAME"
SSL_CTX_set_srp_username,
SSL_CTX_set_srp_password,
SSL_CTX_set_srp_strength,
SSL_CTX_set_srp_cb_arg,
SSL_CTX_set_srp_username_callback,
SSL_CTX_set_srp_client_pwd_callback,
SSL_CTX_set_srp_verify_param_callback,
SSL_set_srp_server_param,
SSL_set_srp_server_param_pw,
SSL_get_srp_g,
SSL_get_srp_N,
SSL_get_srp_username,
SSL_get_srp_userinfo
\&\- SRP control operations
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 1
\& #include <openssl/ssl.h>
.Ve
.PP
The following functions have been deprecated since OpenSSL 3.0, and can be
hidden entirely by defining \fB\s-1OPENSSL_API_COMPAT\s0\fR with a suitable version value,
see \fBopenssl_user_macros\fR\|(7):
.PP
.Vb 10
\& int SSL_CTX_set_srp_username(SSL_CTX *ctx, char *name);
\& int SSL_CTX_set_srp_password(SSL_CTX *ctx, char *password);
\& int SSL_CTX_set_srp_strength(SSL_CTX *ctx, int strength);
\& int SSL_CTX_set_srp_cb_arg(SSL_CTX *ctx, void *arg);
\& int SSL_CTX_set_srp_username_callback(SSL_CTX *ctx,
\&                                       int (*cb) (SSL *s, int *ad, void *arg));
\& int SSL_CTX_set_srp_client_pwd_callback(SSL_CTX *ctx,
\&                                         char *(*cb) (SSL *s, void *arg));
\& int SSL_CTX_set_srp_verify_param_callback(SSL_CTX *ctx,
\&                                           int (*cb) (SSL *s, void *arg));
\&
\& int SSL_set_srp_server_param(SSL *s, const BIGNUM *N, const BIGNUM *g,
\&                              BIGNUM *sa, BIGNUM *v, char *info);
\& int SSL_set_srp_server_param_pw(SSL *s, const char *user, const char *pass,
\&                                 const char *grp);
\&
\& BIGNUM *SSL_get_srp_g(SSL *s);
\& BIGNUM *SSL_get_srp_N(SSL *s);
\&
\& char *SSL_get_srp_username(SSL *s);
\& char *SSL_get_srp_userinfo(SSL *s);
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
All of the functions described on this page are deprecated. There are no
available replacement functions at this time.
.PP
These functions provide access to \s-1SRP\s0 (Secure Remote Password) parameters,
an alternate authentication mechanism for \s-1TLS. SRP\s0 allows the use of usernames
and passwords over unencrypted channels without revealing the password to an
eavesdropper. \s-1SRP\s0 also supplies a shared secret at the end of the authentication
sequence that can be used to generate encryption keys.
.PP
The \s-1SRP\s0 protocol, version 3 is specified in \s-1RFC 2945. SRP\s0 version 6 is described
in \s-1RFC 5054\s0 with applications to \s-1TLS\s0 authentication.
.PP
The \fBSSL_CTX_set_srp_username()\fR function sets the \s-1SRP\s0 username for \fBctx\fR. This
should be called on the client prior to creating a connection to the server.
The length of \fBname\fR must be shorter or equal to 255 characters.
.PP
The \fBSSL_CTX_set_srp_password()\fR function sets the \s-1SRP\s0 password for \fBctx\fR. This
may be called on the client prior to creating a connection to the server.
This overrides the effect of \fBSSL_CTX_set_srp_client_pwd_callback()\fR.
.PP
The \fBSSL_CTX_set_srp_strength()\fR function sets the \s-1SRP\s0 strength for \fBctx\fR. This
is the minimal length of the \s-1SRP\s0 prime in bits. If not specified 1024 is used.
If not satisfied by the server key exchange the connection will be rejected.
.PP
The \fBSSL_CTX_set_srp_cb_arg()\fR function sets an extra parameter that will
be passed to all following callbacks as \fBarg\fR.
.PP
The \fBSSL_CTX_set_srp_username_callback()\fR function sets the server side callback
that is invoked when an \s-1SRP\s0 username is found in a ClientHello.
The callback parameters are the \s-1SSL\s0 connection \fBs\fR, a writable error flag \fBad\fR
and the extra argument \fBarg\fR set by \fBSSL_CTX_set_srp_cb_arg()\fR.
This callback should setup the server for the key exchange by calling
\&\fBSSL_set_srp_server_param()\fR with the appropriate parameters for the received
username. The username can be obtained by calling \fBSSL_get_srp_username()\fR.
See \fBSRP_VBASE_init\fR\|(3) to parse the verifier file created by \fBopenssl\-srp\fR\|(1) or
\&\fBSRP_create_verifier\fR\|(3) to generate it.
The callback should return \fB\s-1SSL_ERROR_NONE\s0\fR to proceed with the server key exchange,
\&\fB\s-1SSL3_AL_FATAL\s0\fR for a fatal error or any value < 0 for a retryable error.
In the event of a \fB\s-1SSL3_AL_FATAL\s0\fR the alert flag given by \fB*al\fR will be sent
back. By default this will be \fB\s-1SSL_AD_UNKNOWN_PSK_IDENTITY\s0\fR.
.PP
The \fBSSL_CTX_set_srp_client_pwd_callback()\fR function sets the client password
callback on the client.
The callback parameters are the \s-1SSL\s0 connection \fBs\fR and the extra argument \fBarg\fR
set by \fBSSL_CTX_set_srp_cb_arg()\fR.
The callback will be called as part of the generation of the client secrets.
It should return the client password in text form or \s-1NULL\s0 to abort the connection.
The resulting memory will be freed by the library as part of the callback resolution.
This overrides the effect of \fBSSL_CTX_set_srp_password()\fR.
.PP
The \fBSSL_CTX_set_srp_verify_param_callback()\fR sets the \s-1SRP\s0 gN parameter verification
callback on the client. This allows the client to perform custom verification when
receiving the server \s-1SRP\s0 proposed parameters.
The callback parameters are the \s-1SSL\s0 connection \fBs\fR and the extra argument \fBarg\fR
set by \fBSSL_CTX_set_srp_cb_arg()\fR.
The callback should return a positive value to accept the server parameters.
Returning 0 or a negative value will abort the connection. The server parameters
can be obtained by calling \fBSSL_get_srp_N()\fR and \fBSSL_get_srp_g()\fR.
Sanity checks are already performed by the library after the handshake
(B % N non zero, check against the strength parameter) and are not necessary.
If no callback is set the g and N parameters will be checked against
known \s-1RFC 5054\s0 values.
.PP
The \fBSSL_set_srp_server_param()\fR function sets all \s-1SRP\s0 parameters for
the connection \fBs\fR. \fBN\fR and \fBg\fR are the \s-1SRP\s0 group parameters, \fBsa\fR is the
user salt, \fBv\fR the password verifier and \fBinfo\fR is the optional user info.
.PP
The \fBSSL_set_srp_server_param_pw()\fR function sets all \s-1SRP\s0 parameters for the
connection \fBs\fR by generating a random salt and a password verifier.
\&\fBuser\fR is the username, \fBpass\fR the password and \fBgrp\fR the \s-1SRP\s0 group parameters
identifier for \fBSRP_get_default_gN\fR\|(3).
.PP
The \fBSSL_get_srp_g()\fR function returns the \s-1SRP\s0 group generator for \fBs\fR, or from
the underlying \s-1SSL_CTX\s0 if it is \s-1NULL.\s0
.PP
The \fBSSL_get_srp_N()\fR function returns the \s-1SRP\s0 prime for \fBs\fR, or from
the underlying \s-1SSL_CTX\s0 if it is \s-1NULL.\s0
.PP
The \fBSSL_get_srp_username()\fR function returns the \s-1SRP\s0 username for \fBs\fR, or from
the underlying \s-1SSL_CTX\s0 if it is \s-1NULL.\s0
.PP
The \fBSSL_get_srp_userinfo()\fR function returns the \s-1SRP\s0 user info for \fBs\fR, or from
the underlying \s-1SSL_CTX\s0 if it is \s-1NULL.\s0
.SH "RETURN VALUES"
.IX Header "RETURN VALUES"
All SSL_CTX_set_* functions return 1 on success and 0 on failure.
.PP
\&\fBSSL_set_srp_server_param()\fR returns 1 on success and \-1 on failure.
.PP
The SSL_get_SRP_* functions return a pointer to the requested data, the memory
is owned by the library and should not be freed by the caller.
.SH "EXAMPLES"
.IX Header "EXAMPLES"
Setup \s-1SRP\s0 parameters on the client:
.PP
.Vb 1
\& #include <openssl/ssl.h>
\&
\& const char *username = "username";
\& const char *password = "password";
\&
\& SSL_CTX *ctx = SSL_CTX_new(TLS_client_method());
\& if (!ctx)
\&     /* Error */
\& if (!SSL_CTX_set_srp_username(ctx, username))
\&     /* Error */
\& if (!SSL_CTX_set_srp_password(ctx, password))
\&     /* Error */
.Ve
.PP
Setup \s-1SRP\s0 server with verifier file:
.PP
.Vb 2
\& #include <openssl/srp.h>
\& #include <openssl/ssl.h>
\&
\& const char *srpvfile = "password.srpv";
\&
\& int srpServerCallback(SSL *s, int *ad, void *arg)
\& {
\&     SRP_VBASE *srpData = (SRP_VBASE*) arg;
\&     char *username = SSL_get_srp_username(s);
\&
\&     SRP_user_pwd *user_pwd = SRP_VBASE_get1_by_user(srpData, username);
\&     if (!user_pwd)
\&         /* Error */
\&         return SSL3_AL_FATAL;
\&
\&     if (SSL_set_srp_server_param(s, user_pwd\->N, user_pwd\->g,
\&         user_pwd\->s, user_pwd\->v, user_pwd\->info) < 0)
\&         /* Error */
\&
\&     SRP_user_pwd_free(user_pwd);
\&     return SSL_ERROR_NONE;
\& }
\&
\& SSL_CTX *ctx = SSL_CTX_new(TLS_server_method());
\& if (!ctx)
\&     /* Error */
\&
\& /*
\&  * seedKey should contain a NUL terminated sequence
\&  * of random non NUL bytes
\&  */
\& const char *seedKey;
\&
\& SRP_VBASE *srpData = SRP_VBASE_new(seedKey);
\& if (SRP_VBASE_init(srpData, (char*) srpvfile) != SRP_NO_ERROR)
\&    /* Error */
\&
\& SSL_CTX_set_srp_cb_arg(ctx, srpData);
\& SSL_CTX_set_srp_username_callback(ctx, srpServerCallback);
.Ve
.SH "SEE ALSO"
.IX Header "SEE ALSO"
\&\fBssl\fR\|(7),
\&\fBopenssl\-srp\fR\|(1),
\&\fBSRP_VBASE_new\fR\|(3),
\&\fBSRP_create_verifier\fR\|(3)
.SH "HISTORY"
.IX Header "HISTORY"
These functions were added in OpenSSL 1.0.1 and deprecated in OpenSSL 3.0.
.SH "COPYRIGHT"
.IX Header "COPYRIGHT"
Copyright 2018\-2021 The OpenSSL Project Authors. All Rights Reserved.
.PP
Licensed under the Apache License 2.0 (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>.