'\" t
.\"     Title: zmq_curve_public
.\"    Author: [see the "AUTHORS" section]
.\" Generator: DocBook XSL Stylesheets v1.79.1 <http://docbook.sf.net/>
.\"      Date: 09/06/2020
.\"    Manual: 0MQ Manual
.\"    Source: 0MQ 4.3.1
.\"  Language: English
.\"
.TH "ZMQ_CURVE_PUBLIC" "3" "09/06/2020" "0MQ 4\&.3\&.1" "0MQ Manual"
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.SH "NAME"
zmq_curve_public \- derive the public key from a private key
.SH "SYNOPSIS"
.sp
\fBint zmq_curve_public (char *z85_public_key, char *z85_secret_key);\fR
.SH "DESCRIPTION"
.sp
The \fIzmq_curve_public()\fR function shall derive the public key from a private key\&. The caller provides two buffers, each at least 41 octets large\&. In z85_secret_key the caller shall provide the private key, and the function will store the public key in z85_public_key\&. The keys are encoded using \fBzmq_z85_encode\fR(3)\&.
.SH "RETURN VALUE"
.sp
The \fIzmq_curve_public()\fR function shall return 0 if successful, else it shall return \-1 and set \fIerrno\fR to one of the values defined below\&.
.SH "ERRORS"
.PP
\fBENOTSUP\fR
.RS 4
The libzmq library was not built with cryptographic support (libsodium)\&.
.RE
.SH "EXAMPLE"
.PP
\fBDeriving the public key from a CURVE private key\fR. 
.sp
.if n \{\
.RS 4
.\}
.nf
char public_key [41];
char secret_key [41];
int rc = zmq_curve_keypair (public_key, secret_key);
assert (rc == 0);
char derived_public[41];
rc = zmq_curve_public (derived_public, secret_key);
assert (rc == 0);
assert (!strcmp (derived_public, public_key));
.fi
.if n \{\
.RE
.\}
.sp
.SH "SEE ALSO"
.sp
\fBzmq_z85_decode\fR(3) \fBzmq_z85_encode\fR(3) \fBzmq_curve_keypair\fR(3) \fBzmq_curve\fR(7)
.SH "AUTHORS"
.sp
This page was written by the 0MQ community\&. To make a change please read the 0MQ Contribution Policy at \m[blue]\fBhttp://www\&.zeromq\&.org/docs:contributing\fR\m[]\&.