Problem: no documentation for zmq_curve_public

Solution: add manpage

doc/Makefile.am

@@ -14,7 +14,7 @@ MAN3 = zmq_bind.3 zmq_unbind.3 zmq_connect.3 zmq_disconnect.3 zmq_close.3 \
  zmq_errno.3 zmq_strerror.3 zmq_version.3 \
  zmq_sendmsg.3 zmq_recvmsg.3 \
  zmq_proxy.3 zmq_proxy_steerable.3 \
- zmq_z85_encode.3 zmq_z85_decode.3 zmq_curve_keypair.3 \
+ zmq_z85_encode.3 zmq_z85_decode.3 zmq_curve_keypair.3 zmq_curve_public.3 \
  zmq_has.3 \
  zmq_atomic_counter_new.3 zmq_atomic_counter_set.3 \
  zmq_atomic_counter_inc.3 zmq_atomic_counter_dec.3 \

doc/zmq.txt

@@ -199,6 +199,9 @@ Elliptic curve authentication and encryption::
 Generate a CURVE keypair in armored text format::
  linkzmq:zmq_curve_keypair[3]
 
+Derive a CURVE public key from a secret key:
+ linkzmq:zmq_curve_public[3]
+
 Converting keys to/from armoured text strings::
  linkzmq:zmq_z85_decode[3]
  linkzmq:zmq_z85_encode[3]

doc/zmq_curve_public.txt

@@ -0,0 +1,62 @@
+zmq_curve_public(3)
+===================
+
+
+NAME
+----
+zmq_curve_public - derive the public key from a private key
+
+
+SYNOPSIS
+--------
+*int zmq_curve_public (char *z85_public_key, char *z85_secret_key);*
+
+
+DESCRIPTION
+-----------
+The _zmq_curve_public()_ 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 linkzmq:zmq_z85_encode[3].
+
+
+RETURN VALUE
+------------
+The _zmq_curve_public()_ function shall return 0 if successful, else it
+shall return `-1` and set 'errno' to one of the values defined below.
+
+
+ERRORS
+------
+*ENOTSUP*::
+The libzmq library was not built with cryptographic support (libsodium).
+
+
+EXAMPLE
+-------
+.Deriving the public key from a CURVE private key
+----
+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));
+----
+
+
+SEE ALSO
+--------
+linkzmq:zmq_z85_decode[3]
+linkzmq:zmq_z85_encode[3]
+linkzmq:zmq_curve_keypair[3]
+linkzmq:zmq_curve[7]
+
+
+AUTHORS
+-------
+This page was written by the 0MQ community. To make a change please
+read the 0MQ Contribution Policy at <http://www.zeromq.org/docs:contributing>.

doc/zmq_setsockopt.txt

@@ -132,7 +132,8 @@ sockets, see linkzmq:zmq_curve[7]. You can provide the key as 32 binary
 bytes, or as a 40-character string encoded in the Z85 encoding format and
 terminated in a null byte. The public key must always be used with the
 matching secret key. To generate a public/secret key pair, use
-linkzmq:zmq_curve_keypair[3].
+linkzmq:zmq_curve_keypair[3]. To derive the public key from a secret key,
+use linkzmq:zmq_curve_public[3].
 
 NOTE: an option value size of 40 is supported for backwards compatibility,
 though is deprecated.
@@ -150,7 +151,8 @@ Sets the socket's long term secret key. You must set this on both CURVE
 client and server sockets, see linkzmq:zmq_curve[7]. You can provide the
 key as 32 binary bytes, or as a 40-character string encoded in the Z85
 encoding format and terminated in a null byte. To generate a public/secret
-key pair, use linkzmq:zmq_curve_keypair[3].
+key pair, use linkzmq:zmq_curve_keypair[3]. To derive the public key from
+a secret key, use linkzmq:zmq_curve_public[3].
 
 NOTE: an option value size of 40 is supported for backwards compatibility,
 though is deprecated.

doc/zmq_z85_decode.txt

@@ -41,6 +41,7 @@ SEE ALSO
 --------
 linkzmq:zmq_z85_decode[3]
 linkzmq:zmq_curve_keypair[3]
+linkzmq:zmq_curve_public[3]
 linkzmq:zmq_curve[7]
 
 

doc/zmq_z85_encode.txt

@@ -48,6 +48,7 @@ SEE ALSO
 --------
 linkzmq:zmq_z85_decode[3]
 linkzmq:zmq_curve_keypair[3]
+linkzmq:zmq_curve_public[3]
 linkzmq:zmq_curve[7]