Merge pull request #597 from hintjens/master

Problem: working with binary keys is painful

Makefile.am

@@ -1,12 +1,12 @@
 ACLOCAL_AMFLAGS = -I config
 
 if BUILD_PGM
-SUBDIRS = foreign/openpgm src doc perf tests
+SUBDIRS = foreign/openpgm src doc perf tests tools
 else
-SUBDIRS = src doc perf tests
+SUBDIRS = src doc perf tests tools
 endif
 
-DIST_SUBDIRS = foreign/openpgm src doc perf tests builds/msvc
+DIST_SUBDIRS = foreign/openpgm src doc perf tests tools builds/msvc
 
 EXTRA_DIST = \
 	autogen.sh	\

configure.ac

@@ -428,10 +428,14 @@ AC_SUBST(LIBZMQ_EXTRA_CFLAGS)
 AC_SUBST(LIBZMQ_EXTRA_CXXFLAGS)
 AC_SUBST(LIBZMQ_EXTRA_LDFLAGS)
 
-AC_CONFIG_FILES([Makefile src/Makefile doc/Makefile
+AC_CONFIG_FILES([Makefile \
-    perf/Makefile src/libzmq.pc \
+    src/Makefile \
-    builds/msvc/Makefile tests/Makefile \
+    src/libzmq.pc \
+    doc/Makefile \
+    perf/Makefile \
+    tests/Makefile \
+    tools/Makefile \
+    builds/msvc/Makefile \
     foreign/openpgm/Makefile \
     builds/redhat/zeromq.spec])
 AC_OUTPUT
-

doc/zmq_curve.txt

@@ -37,21 +37,43 @@ long-term key pair.
 If the server does authentication it will be based on the client's long
 term public key.
 
+KEY ENCODING
+------------
+The standard representation for keys in source code is either 32 bytes of
+base 256 (binary) data, or 40 characters of base 85 data encoded using the
+Z85 algorithm defined by http://rfc.zeromq.org/spec:32.
+
+The Z85 algorithm is designed to produce printable key strings for use in
+configuration files, the command line, and code. There is a reference
+implementation in C at https://github.com/zeromq/rfc/tree/master/src.
+
+    
 TEST KEY VALUES
 ---------------
-
+For test cases, the client shall use this long-term key pair (specified
-For test cases, the client shall use this long-term key pair:
+as hexadecimal and in Z85):
 
 ----
-public: BB88471D65E2659B30C55A5321CEBB5AAB2B70A398645C26DCA2B2FCB43FC518
+public: 
-secret: 7BB864B489AFA3671FBE69101F94B38972F24816DFB01B51656B3FEC8DFD0888
+    BB88471D65E2659B30C55A5321CEBB5AAB2B70A398645C26DCA2B2FCB43FC518
+    Yne@$w-vo<fVvi]a<NY6T1ed:M$fCG*[IaLV{hID
+
+secret: 
+    7BB864B489AFA3671FBE69101F94B38972F24816DFB01B51656B3FEC8DFD0888
+    D:)Q[IlAW!ahhC2ac:9*A}h:p?([4%wOTJ%JR%cs
 ----
 
-And the server shall use this long-term key pair:
+And the server shall use this long-term key pair (specified as hexadecimal 
+and in Z85):
 
 ----
-public: 54FCBA24E93249969316FB617C872BB0C1D1FF14800427C594CBFACF1BC2D652
+public: 
-secret: 8E0BDD697628B91D8F245587EE95C5B04D48963F79259877B49CD9063AEAD3B7
+    54FCBA24E93249969316FB617C872BB0C1D1FF14800427C594CBFACF1BC2D652
+    rq:rM>}U?@Lns47E1%kR.o@n%FcmmsL/@{H8]yf7
+
+secret: 
+    8E0BDD697628B91D8F245587EE95C5B04D48963F79259877B49CD9063AEAD3B7
+    JTKVSB%%)wK0E.X)V>+}o?pNmC{O&4W4b!Ni{Lh6
 ----
 
 SEE ALSO

doc/zmq_getsockopt.txt

@@ -486,8 +486,8 @@ Default value:: -1 (leave to OS default)
 Applicable socket types:: all, when using TCP transports.
 
 
-ZMQ_MECHANISM: Retrieve the current security mechanism
+ZMQ_MECHANISM: Retrieve current security mechanism
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 The 'ZMQ_MECHANISM' option shall retrieve the current security mechanism
 for the socket.
 
@@ -498,8 +498,8 @@ Default value:: ZMQ_NULL
 Applicable socket types:: all, when using TCP or IPC transports
 
 
-ZMQ_PLAIN_SERVER: Retrieve the PLAIN server role
+ZMQ_PLAIN_SERVER: Retrieve current PLAIN server role
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 Returns the 'ZMQ_PLAIN_SERVER' option, if any, previously set on the socket.
 
 [horizontal]
@@ -509,8 +509,8 @@ Default value:: int
 Applicable socket types:: all, when using TCP or IPC transports
 
 
-ZMQ_PLAIN_USERNAME: Retrieve the last username set
+ZMQ_PLAIN_USERNAME: Retrieve current PLAIN username
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 The 'ZMQ_PLAIN_USERNAME' option shall retrieve the last username set for
 the PLAIN security mechanism. The returned value shall be a NULL-terminated 
 string and MAY be empty. The returned size SHALL include the terminating
@@ -523,8 +523,8 @@ Default value:: null string
 Applicable socket types:: all, when using TCP or IPC transports
 
 
-ZMQ_PLAIN_PASSWORD: Retrieve the last password set
+ZMQ_PLAIN_PASSWORD: Retrieve current password
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 The 'ZMQ_PLAIN_PASSWORD' option shall retrieve the last password set for
 the PLAIN security mechanism. The returned value shall be a NULL-terminated 
 string and MAY be empty. The returned size SHALL include the terminating
@@ -537,6 +537,48 @@ Default value:: null string
 Applicable socket types:: all, when using TCP or IPC transports
 
 
+ZMQ_CURVE_PUBLICKEY: Retrieve current CURVE public key
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Retrieves the current long term public key for the socket. You can
+provide either a 32 byte buffer, to retrieve the binary key value, or 
+a 40 byte buffer, to retrieve the key in a printable Z85 format.
+
+[horizontal]
+Option value type:: binary data or Z85 text string
+Option value size:: 32 or 40
+Default value:: null
+Applicable socket types:: all, when using TCP transport
+
+
+ZMQ_CURVE_SECRETKEY: Retrieve current CURVE secret key
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Retrieves the current long term secret key for the socket. You can
+provide either a 32 byte buffer, to retrieve the binary key value, or 
+a 40 byte buffer, to retrieve the key in a printable Z85 format.
+
+[horizontal]
+Option value type:: binary data or Z85 text string
+Option value size:: 32 or 40
+Default value:: null
+Applicable socket types:: all, when using TCP transport
+
+
+ZMQ_CURVE_SERVERKEY: Retrieve current CURVE server key
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Retrieves the current server key for the client socket. You can
+provide either a 32 byte buffer, to retrieve the binary key value, or 
+a 40 byte buffer, to retrieve the key in a printable Z85 format.
+
+[horizontal]
+Option value type:: binary data or Z85 text string
+Option value size:: 32 or 40
+Default value:: null
+Applicable socket types:: all, when using TCP transport
+
+
 RETURN VALUE
 ------------
 The _zmq_getsockopt()_ function shall return zero if successful. Otherwise it

doc/zmq_setsockopt.txt

@@ -596,13 +596,17 @@ ZMQ_CURVE_PUBLICKEY: Set CURVE public key
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 Sets the socket's long term public key. You must set this on a CURVE
-client or server socket, see linkzmq:zmq_curve[7]. The key is 32 bytes.
+client or server socket, see linkzmq:zmq_curve[7]. You can provide the
-For servers, it must be persisted and shared through some unspecified
+key as 32 binary bytes, or as a 40-character string encoded in the Z85
-secure mechanism to clients.
+encoding format. For servers, the public key must be persisted and 
+shared through some unspecified but secure mechanism to clients. The
+public key must always be used with the matching secret key generated
+at the same time. To generate a public/secret key pair, use the 
+tools/curve_keygen tool.
 
 [horizontal]
-Option value type:: binary data
+Option value type:: binary data or Z85 text string
-Option value size:: 32
+Option value size:: 32 or 40
 Default value:: NULL
 Applicable socket types:: all, when using TCP transport
 
@@ -611,11 +615,13 @@ ZMQ_CURVE_SECRETKEY: Set CURVE secret key
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 Sets the socket's long term secret key. You must set this on a CURVE
-client socket, see linkzmq:zmq_curve[7]. The key is 32 bytes.
+client socket, 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. 
 
 [horizontal]
-Option value type:: binary data
+Option value type:: binary data or Z85 text string
-Option value size:: 32
+Option value size:: 32 or 40
 Default value:: NULL
 Applicable socket types:: all, when using TCP transport
 
@@ -624,12 +630,14 @@ ZMQ_CURVE_SERVERKEY: Set CURVE server key
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 Sets the socket's long term server key. You must set this on a CURVE
-client socket, see linkzmq:zmq_curve[7]. The key is 32 bytes. This
+client socket, see linkzmq:zmq_curve[7]. You can provide the key as 
-key must be the same as the public key set on the server socket.
+32 binary bytes, or as a 40-character string encoded in the Z85 encoding 
+format. This key must be the same as the public key set on the server 
+socket.
 
 [horizontal]
-Option value type:: binary data
+Option value type:: binary data or Z85 text string
-Option value size:: 32
+Option value size:: 32 or 40
 Default value:: NULL
 Applicable socket types:: all, when using TCP transport
 

src/Makefile.am

@@ -89,6 +89,7 @@ libzmq_la_SOURCES = \
     xsub.hpp \
     ypipe.hpp \
     yqueue.hpp \
+    z85_codec.hpp \
     address.cpp \
     clock.cpp \
     ctx.cpp \

src/options.cpp

@@ -21,6 +21,7 @@
 
 #include "options.hpp"
 #include "err.hpp"
+#include "z85_codec.hpp"
 
 zmq::options_t::options_t () :
     sndhwm (1000),
@@ -285,7 +286,7 @@ int zmq::options_t::setsockopt (int option_, const void *optval_,
             }
             break;
         
-//  If libsodium isn't installed, these options provoke EINVAL
+        //  If libsodium isn't installed, these options provoke EINVAL
 #       ifdef HAVE_LIBSODIUM
         case ZMQ_CURVE_SERVER:
             if (is_int && (value == 0 || value == 1)) {
@@ -301,6 +302,12 @@ int zmq::options_t::setsockopt (int option_, const void *optval_,
                 mechanism = ZMQ_CURVE;
                 return 0;
             }
+            else
+            if (optvallen_ == CURVE_KEYSIZE_Z85) {
+                Z85_decode (curve_public_key, (char *) optval_);
+                mechanism = ZMQ_CURVE;
+                return 0;
+            }
             break;
             
         case ZMQ_CURVE_SECRETKEY:
@@ -309,6 +316,12 @@ int zmq::options_t::setsockopt (int option_, const void *optval_,
                 mechanism = ZMQ_CURVE;
                 return 0;
             }
+            else
+            if (optvallen_ == CURVE_KEYSIZE_Z85) {
+                Z85_decode (curve_secret_key, (char *) optval_);
+                mechanism = ZMQ_CURVE;
+                return 0;
+            }
             break;
             
         case ZMQ_CURVE_SERVERKEY:
@@ -318,6 +331,13 @@ int zmq::options_t::setsockopt (int option_, const void *optval_,
                 mechanism = ZMQ_CURVE;
                 return 0;
             }
+            else
+            if (optvallen_ == CURVE_KEYSIZE_Z85) {
+                Z85_decode (curve_server_key, (char *) optval_);
+                as_server = 0;
+                mechanism = ZMQ_CURVE;
+                return 0;
+            }
             break;
 #       endif
     }
@@ -531,7 +551,7 @@ int zmq::options_t::getsockopt (int option_, void *optval_, size_t *optvallen_)
             }
             break;
             
-//  If libsodium isn't installed, these options provoke EINVAL
+        //  If libsodium isn't installed, these options provoke EINVAL
 #       ifdef HAVE_LIBSODIUM
         case ZMQ_CURVE_SERVER:
             if (is_int) {
@@ -545,6 +565,11 @@ int zmq::options_t::getsockopt (int option_, void *optval_, size_t *optvallen_)
                 memcpy (optval_, curve_public_key, CURVE_KEYSIZE);
                 return 0;
             }
+            else
+            if (*optvallen_ == CURVE_KEYSIZE_Z85) {
+                Z85_encode ((char *) optval_, curve_public_key, CURVE_KEYSIZE);
+                return 0;
+            }
             break;
             
         case ZMQ_CURVE_SECRETKEY:
@@ -552,6 +577,11 @@ int zmq::options_t::getsockopt (int option_, void *optval_, size_t *optvallen_)
                 memcpy (optval_, curve_secret_key, CURVE_KEYSIZE);
                 return 0;
             }
+            else
+            if (*optvallen_ == CURVE_KEYSIZE_Z85) {
+                Z85_encode ((char *) optval_, curve_secret_key, CURVE_KEYSIZE);
+                return 0;
+            }
             break;
             
         case ZMQ_CURVE_SERVERKEY:
@@ -559,6 +589,11 @@ int zmq::options_t::getsockopt (int option_, void *optval_, size_t *optvallen_)
                 memcpy (optval_, curve_server_key, CURVE_KEYSIZE);
                 return 0;
             }
+            else
+            if (*optvallen_ == CURVE_KEYSIZE_Z85) {
+                Z85_encode ((char *) optval_, curve_server_key, CURVE_KEYSIZE);
+                return 0;
+            }
             break;
 #       endif
     }

src/options.hpp

@@ -28,7 +28,10 @@
 #include "tcp_address.hpp"
 #include "../include/zmq.h"
 
+//  Normal base 256 key is 32 bytes
 #define CURVE_KEYSIZE       32
+//  Key encoded using Z85 is 40 bytes
+#define CURVE_KEYSIZE_Z85   40
 
 namespace zmq
 {

src/z85_codec.hpp

@@ -0,0 +1,108 @@
+/*
+    Copyright (c) 2007-2013 Contributors as noted in the AUTHORS file
+
+    This file is part of 0MQ.
+
+    0MQ is free software; you can redistribute it and/or modify it under
+    the terms of the GNU Lesser General Public License as published by
+    the Free Software Foundation; either version 3 of the License, or
+    (at your option) any later version.
+
+    0MQ is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Lesser General Public License for more details.
+
+    You should have received a copy of the GNU Lesser General Public License
+    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+//  Z85 codec, taken from 0MQ RFC project, implements RFC32 Z85 encoding
+
+#ifndef __ZMQ_Z85_CODEC_HPP_INCLUDED__
+#define __ZMQ_Z85_CODEC_HPP_INCLUDED__
+
+//  Maps base 256 to base 85
+static char encoder [85 + 1] = {
+    "0123456789" "abcdefghij" "klmnopqrst" "uvwxyzABCD"
+    "EFGHIJKLMN" "OPQRSTUVWX" "YZ.-:+=^!/" "*?&<>()[]{" 
+    "}@%$#"
+};
+
+//  Maps base 85 to base 256
+//  We chop off lower 32 and higher 128 ranges
+static uint8_t decoder [96] = {
+    0x00, 0x44, 0x00, 0x54, 0x53, 0x52, 0x48, 0x00, 
+    0x4B, 0x4C, 0x46, 0x41, 0x00, 0x3F, 0x3E, 0x45, 
+    0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 
+    0x08, 0x09, 0x40, 0x00, 0x49, 0x42, 0x4A, 0x47, 
+    0x51, 0x24, 0x25, 0x26, 0x27, 0x28, 0x29, 0x2A, 
+    0x2B, 0x2C, 0x2D, 0x2E, 0x2F, 0x30, 0x31, 0x32, 
+    0x33, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 0x3A, 
+    0x3B, 0x3C, 0x3D, 0x4D, 0x00, 0x4E, 0x43, 0x00, 
+    0x00, 0x0A, 0x0B, 0x0C, 0x0D, 0x0E, 0x0F, 0x10, 
+    0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 
+    0x19, 0x1A, 0x1B, 0x1C, 0x1D, 0x1E, 0x1F, 0x20, 
+    0x21, 0x22, 0x23, 0x4F, 0x00, 0x50, 0x00, 0x00
+};
+
+//  --------------------------------------------------------------------------
+//  Encode a binary frame as a string; destination string MUST be at least
+//  size * 5 / 4 bytes long. Returns dest. Size must be a multiple of 4.
+
+char *
+Z85_encode (char *dest, uint8_t *data, size_t size)
+{
+    assert (size % 4 == 0);
+    uint char_nbr = 0;
+    uint byte_nbr = 0;
+    uint32_t value = 0;
+    while (byte_nbr < size) {
+        //  Accumulate value in base 256 (binary)
+        value = value * 256 + data [byte_nbr++];
+        if (byte_nbr % 4 == 0) {
+            //  Output value in base 85
+            uint divisor = 85 * 85 * 85 * 85;
+            while (divisor) {
+                dest [char_nbr++] = encoder [value / divisor % 85];
+                divisor /= 85;
+            }
+            value = 0;
+        }
+    }
+    assert (char_nbr == size * 5 / 4);
+    dest [char_nbr] = 0;
+    return dest;
+}
+
+    
+//  --------------------------------------------------------------------------
+//  Decode an encoded string into a binary frame; dest must be at least
+//  strlen (string) * 4 / 5 bytes long. Returns dest. strlen (string) 
+//  must be a multiple of 5.
+
+uint8_t *
+Z85_decode (uint8_t *dest, char *string)
+{
+    assert (strlen (string) % 5 == 0);
+    uint byte_nbr = 0;
+    uint char_nbr = 0;
+    uint32_t value = 0;
+    while (char_nbr < strlen (string)) {
+        //  Accumulate value in base 85
+        value = value * 85 + decoder [(uint8_t) string [char_nbr++] - 32];
+        if (char_nbr % 5 == 0) {
+            //  Output value in base 256
+            uint divisor = 256 * 256 * 256;
+            while (divisor) {
+                dest [byte_nbr++] = value / divisor % 256;
+                divisor /= 256;
+            }
+            value = 0;
+        }
+    }
+    assert (byte_nbr == strlen (string) * 4 / 5);
+    return dest;
+}
+
+#endif

tests/test_security_curve.cpp

@@ -56,7 +56,7 @@ zap_handler (void *zap)
 int main (void)
 {
 #ifndef HAVE_LIBSODIUM
-    printf("libsodium not installed, skipping CURVE test\n");
+    printf ("libsodium not installed, skipping CURVE test\n");
     return 0;
 #endif
     int rc;
@@ -75,43 +75,24 @@ int main (void)
     void *client = zmq_socket (ctx, ZMQ_DEALER);
     assert (client);
 
-    as_server = 1;
+    //  Test keys from the zmq_curve man page
-    rc = zmq_setsockopt(server, ZMQ_CURVE_SERVER, &as_server, sizeof(int));
+    char client_public [] = "Yne@$w-vo<fVvi]a<NY6T1ed:M$fCG*[IaLV{hID";
-    // Test key from the zmq_curve man page.
+    char client_secret [] = "D:)Q[IlAW!ahhC2ac:9*A}h:p?([4%wOTJ%JR%cs";
-    uint8_t server_secret[32] = {
+    char server_public [] = "rq:rM>}U?@Lns47E1%kR.o@n%FcmmsL/@{H8]yf7";
-      0x8E, 0x0B, 0xDD, 0x69, 0x76, 0x28, 0xB9, 0x1D, 0x8F, 0x24,
+    char server_secret [] = "JTKVSB%%)wK0E.X)V>+}o?pNmC{O&4W4b!Ni{Lh6";
-      0x55, 0x87, 0xEE, 0x95, 0xC5, 0xB0, 0x4D, 0x48, 0x96, 0x3F,
-      0x79, 0x25, 0x98, 0x77, 0xB4, 0x9C, 0xD9, 0x06, 0x3A, 0xEA, 
-      0xD3, 0xB7  
-    };
-    rc = zmq_setsockopt(server, ZMQ_CURVE_SECRETKEY, server_secret, sizeof(server_secret));
-    assert(rc == 0);
         
-    // Test client keys from the zmq_curve man page.
+    as_server = 1;
-    uint8_t server_public[32] = {
+    rc = zmq_setsockopt (server, ZMQ_CURVE_SERVER, &as_server, sizeof (int));
-        0x54, 0xFC, 0xBA, 0x24, 0xE9, 0x32, 0x49, 0x96, 0x93, 0x16,
+    assert (rc == 0);
-        0xFB, 0x61, 0x7C, 0x87, 0x2B, 0xB0, 0xC1, 0xD1, 0xFF, 0x14,
+    rc = zmq_setsockopt (server, ZMQ_CURVE_SECRETKEY, server_secret, 40);
-        0x80, 0x04, 0x27, 0xC5, 0x94, 0xCB, 0xFA, 0xCF, 0x1B, 0xC2,
+    assert (rc == 0);
-        0xD6, 0x52
+
-    };
+    rc = zmq_setsockopt (client, ZMQ_CURVE_SERVERKEY, server_public, 40);
-    rc = zmq_setsockopt(client, ZMQ_CURVE_SERVERKEY, server_public, sizeof(server_public));
+    assert (rc == 0);
-    assert(rc == 0);
+    rc = zmq_setsockopt (client, ZMQ_CURVE_PUBLICKEY, client_public, 40);
-    uint8_t client_public[32] = {
+    assert (rc == 0);
-        0xBB, 0x88, 0x47, 0x1D, 0x65, 0xE2, 0x65, 0x9B, 0x30, 0xC5,
+    rc = zmq_setsockopt (client, ZMQ_CURVE_SECRETKEY, client_secret, 40);
-        0x5A, 0x53, 0x21, 0xCE, 0xBB, 0x5A, 0xAB, 0x2B, 0x70, 0xA3,
+    assert (rc == 0);
-        0x98, 0x64, 0x5C, 0x26, 0xDC, 0xA2, 0xB2, 0xFC, 0xB4, 0x3F,
-        0xC5, 0x18
-    };
-    rc = zmq_setsockopt(client, ZMQ_CURVE_PUBLICKEY, client_public, sizeof(client_public));
-    assert(rc == 0);
-    uint8_t client_secret[32] = {
-        0x7B, 0xB8, 0x64, 0xB4, 0x89, 0xAF, 0xA3, 0x67, 0x1F, 0xBE,
-        0x69, 0x10, 0x1F, 0x94, 0xB3, 0x89, 0x72, 0xF2, 0x48, 0x16,
-        0xDF, 0xB0, 0x1B, 0x51, 0x65, 0x6B, 0x3F, 0xEC, 0x8D, 0xFD,
-        0x08, 0x88
-    };
-    rc = zmq_setsockopt(client, ZMQ_CURVE_SECRETKEY, client_secret, sizeof(client_secret));
-    assert(rc == 0);
 
     // Test the client and server both have the right mechanism.
     optsize = sizeof (int);

tools/Makefile.am

@@ -0,0 +1 @@
+EXTRA_DIST = curve_keygen.c z85_codec.h

tools/curve_keygen.c

@@ -3,6 +3,16 @@
 
     This file is part of 0MQ.
 
+    This tool generates a keypair for the libzmq CURVE security mechanism, 
+    and encodes the keypair to give two printable strings that you can use 
+    in configuration files or source code. The encoding uses Z85, which is 
+    a base-85 format that is described in 0MQ RFC 32, and which has an 
+    implementation in the Z85.c source used by this tool. The keypair 
+    always works with the secret key held by one party and the public key 
+    distributed (securely!) to peers wishing to connect to it. CURVE is 
+    defined by http://rfc.zeromq.org/spec:25. Z85 is defined by 
+    http://rfc.zeromq.org/spec:32.
+
     0MQ is free software; you can redistribute it and/or modify it under
     the terms of the GNU Lesser General Public License as published by
     the Free Software Foundation; either version 3 of the License, or
@@ -21,6 +31,7 @@
 #include <stdlib.h>
 #include <assert.h>
 #include <sodium.h>
+#include "z85_codec.h"
 
 int main (void)
 {
@@ -29,19 +40,30 @@ int main (void)
 #   error "libsodium not built correctly"
 #   endif
     
+    puts ("This tool generates a keypair for the libzmq CURVE security mechanism,");
+    puts ("and encodes the keypair to give two printable strings that you can use");
+    puts ("in configuration files or source code. The encoding uses Z85, which is");
+    puts ("a base-85 format that is described in 0MQ RFC 32, and which has an");
+    puts ("implementation in the Z85.c source used by this tool. The keypair");
+    puts ("always works with the secret key held by one party and the public key");
+    puts ("distributed (securely!) to peers wishing to connect to it. CURVE is");
+    puts ("defined by http://rfc.zeromq.org/spec:25. Z85 is defined by");
+    puts ("http://rfc.zeromq.org/spec:32.");
+
     uint8_t public_key [32];
     uint8_t secret_key [32];
 
     int rc = crypto_box_keypair (public_key, secret_key);
     assert (rc == 0);
-    int byte_nbr;
+    
-    printf ("public: ");
+    char encoded [40];
-    for (byte_nbr = 0; byte_nbr < 32; byte_nbr++) 
+    Z85_encode (encoded, public_key, 32);
-        printf ("%02X", public_key [byte_nbr]);
+    puts ("\n== CURVE PUBLIC KEY ==");
-    printf ("\n");
+    puts (encoded);
-    printf ("secret: ");
+    
-    for (byte_nbr = 0; byte_nbr < 32; byte_nbr++) 
+    Z85_encode (encoded, secret_key, 32);
-        printf ("%02X", secret_key [byte_nbr]);
+    puts ("\n== CURVE SECRET KEY ==");
-    printf ("\n");
+    puts (encoded);
+
     exit (0);
 }

tools/z85_codec.h

@@ -0,0 +1,108 @@
+/*
+    Copyright (c) 2007-2013 Contributors as noted in the AUTHORS file
+
+    This file is part of 0MQ.
+
+    0MQ is free software; you can redistribute it and/or modify it under
+    the terms of the GNU Lesser General Public License as published by
+    the Free Software Foundation; either version 3 of the License, or
+    (at your option) any later version.
+
+    0MQ is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Lesser General Public License for more details.
+
+    You should have received a copy of the GNU Lesser General Public License
+    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+//  Z85 codec, taken from 0MQ RFC project, implements RFC32 Z85 encoding
+
+#include <stdlib.h>
+#include <stdint.h>
+#include <string.h>
+#include <assert.h>
+
+//  Maps base 256 to base 85
+static char encoder [85 + 1] = {
+    "0123456789" "abcdefghij" "klmnopqrst" "uvwxyzABCD"
+    "EFGHIJKLMN" "OPQRSTUVWX" "YZ.-:+=^!/" "*?&<>()[]{" 
+    "}@%$#"
+};
+
+//  Maps base 85 to base 256
+//  We chop off lower 32 and higher 128 ranges
+static uint8_t decoder [96] = {
+    0x00, 0x44, 0x00, 0x54, 0x53, 0x52, 0x48, 0x00, 
+    0x4B, 0x4C, 0x46, 0x41, 0x00, 0x3F, 0x3E, 0x45, 
+    0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 
+    0x08, 0x09, 0x40, 0x00, 0x49, 0x42, 0x4A, 0x47, 
+    0x51, 0x24, 0x25, 0x26, 0x27, 0x28, 0x29, 0x2A, 
+    0x2B, 0x2C, 0x2D, 0x2E, 0x2F, 0x30, 0x31, 0x32, 
+    0x33, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 0x3A, 
+    0x3B, 0x3C, 0x3D, 0x4D, 0x00, 0x4E, 0x43, 0x00, 
+    0x00, 0x0A, 0x0B, 0x0C, 0x0D, 0x0E, 0x0F, 0x10, 
+    0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 
+    0x19, 0x1A, 0x1B, 0x1C, 0x1D, 0x1E, 0x1F, 0x20, 
+    0x21, 0x22, 0x23, 0x4F, 0x00, 0x50, 0x00, 0x00
+};
+
+//  --------------------------------------------------------------------------
+//  Encode a binary frame as a string; destination string MUST be at least
+//  size * 5 / 4 bytes long. Returns dest. Size must be a multiple of 4.
+
+char *
+Z85_encode (char *dest, uint8_t *data, size_t size)
+{
+    assert (size % 4 == 0);
+    uint char_nbr = 0;
+    uint byte_nbr = 0;
+    uint32_t value = 0;
+    while (byte_nbr < size) {
+        //  Accumulate value in base 256 (binary)
+        value = value * 256 + data [byte_nbr++];
+        if (byte_nbr % 4 == 0) {
+            //  Output value in base 85
+            uint divisor = 85 * 85 * 85 * 85;
+            while (divisor) {
+                dest [char_nbr++] = encoder [value / divisor % 85];
+                divisor /= 85;
+            }
+            value = 0;
+        }
+    }
+    assert (char_nbr == size * 5 / 4);
+    dest [char_nbr] = 0;
+    return dest;
+}
+
+    
+//  --------------------------------------------------------------------------
+//  Decode an encoded string into a binary frame; dest must be at least
+//  strlen (string) * 4 / 5 bytes long. Returns dest. strlen (string) 
+//  must be a multiple of 5.
+
+uint8_t *
+Z85_decode (uint8_t *dest, char *string)
+{
+    assert (strlen (string) % 5 == 0);
+    uint byte_nbr = 0;
+    uint char_nbr = 0;
+    uint32_t value = 0;
+    while (char_nbr < strlen (string)) {
+        //  Accumulate value in base 85
+        value = value * 85 + decoder [(uint8_t) string [char_nbr++] - 32];
+        if (char_nbr % 5 == 0) {
+            //  Output value in base 256
+            uint divisor = 256 * 256 * 256;
+            while (divisor) {
+                dest [byte_nbr++] = value / divisor % 256;
+                divisor /= 256;
+            }
+            value = 0;
+        }
+    }
+    assert (byte_nbr == strlen (string) * 4 / 5);
+    return dest;
+}