Merge pull request #691 from minrk/curve_keygen

Expose zmq_curve_keypair via zmq_utils

include/zmq_utils.h

@@ -88,6 +88,10 @@ ZMQ_EXPORT char *zmq_z85_encode (char *dest, uint8_t *data, size_t size);
 /* Decode data with Z85 encoding. Returns decoded data                        */
 ZMQ_EXPORT uint8_t *zmq_z85_decode (uint8_t *dest, char *string);
 
+/* Generate z85-encoded public and private keypair with libsodium.            */
+/* Returns 0 on success.                                                      */
+ZMQ_EXPORT int zmq_curve_keypair (char* z85_public_key, char *z85_secret_key);
+
 #undef ZMQ_EXPORT
 
 #ifdef __cplusplus

src/zmq_utils.cpp

@@ -30,6 +30,10 @@
 #else
 #include "windows.hpp"
 #endif
+#ifdef HAVE_LIBSODIUM
+#   include <sodium.h>
+#endif
+
 
 void zmq_sleep (int seconds_)
 {
@@ -100,10 +104,14 @@ static uint8_t decoder [96] = {
 //  Encode a binary frame as a string; destination string MUST be at least
 //  size * 5 / 4 bytes long plus 1 byte for the null terminator. Returns
 //  dest. Size must be a multiple of 4.
+//  Returns NULL and sets errno = EINVAL for invalid input.
 
 char *zmq_z85_encode (char *dest, uint8_t *data, size_t size)
 {
-    assert (size % 4 == 0);
+    if (size % 4 != 0) {
+        errno = EINVAL;
+        return NULL;
+    }
     unsigned int char_nbr = 0;
     unsigned int byte_nbr = 0;
     uint32_t value = 0;
@@ -125,15 +133,20 @@ char *zmq_z85_encode (char *dest, uint8_t *data, size_t size)
     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.
+//  Returns NULL and sets errno = EINVAL for invalid input.
 
 uint8_t *zmq_z85_decode (uint8_t *dest, char *string)
 {
-    assert (strlen (string) % 5 == 0);
+    
+    if (strlen (string) % 5 != 0) {
+        errno = EINVAL;
+        return NULL;
+    }
     unsigned int byte_nbr = 0;
     unsigned int char_nbr = 0;
     uint32_t value = 0;
@@ -153,3 +166,34 @@ uint8_t *zmq_z85_decode (uint8_t *dest, char *string)
     assert (byte_nbr == strlen (string) * 4 / 5);
     return dest;
 }
+
+//  --------------------------------------------------------------------------
+//  Generate a public/private keypair with libsodium.
+//  Generated keys will be 40 byte z85-encoded strings.
+//  Returns 0 on success, -1 on failure, setting errno.
+//  Sets errno = ENOTSUP in the absence of libsodium.
+
+int zmq_curve_keypair (char* z85_public_key, char *z85_secret_key)
+{
+#ifdef HAVE_LIBSODIUM
+#   if crypto_box_PUBLICKEYBYTES != 32 \
+    || crypto_box_SECRETKEYBYTES != 32
+#       error "libsodium not built correctly"
+#   endif
+
+    uint8_t public_key [32];
+    uint8_t secret_key [32];
+
+    int rc = crypto_box_keypair (public_key, secret_key);
+    // is there a sensible errno to set here?
+    if (rc) return rc;
+    
+    zmq_z85_encode (z85_public_key, public_key, 32);
+    zmq_z85_encode (z85_secret_key, secret_key, 32);
+    
+    return 0;
+#else // requires libsodium
+    errno = ENOTSUP;
+    return -1;
+#endif
+}

tools/curve_keygen.c

@@ -26,19 +26,11 @@
 
 #include <assert.h>
 #include <platform.hpp>
+#include <zmq.h>
 #include <zmq_utils.h>
-#ifdef HAVE_LIBSODIUM
-#   include <sodium.h>
-#endif
 
 int main (void)
 {
-#ifdef HAVE_LIBSODIUM
-#   if crypto_box_PUBLICKEYBYTES != 32 \
-    || crypto_box_SECRETKEYBYTES != 32
-#   error "libsodium not built correctly"
-#   endif
-    
     puts ("This tool generates a CurveZMQ keypair, as two printable strings you can");
     puts ("use in configuration files or source code. The encoding uses Z85, which");
     puts ("is a base-85 format that is described in 0MQ RFC 32, and which has an");
@@ -46,23 +38,21 @@ int main (void)
     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.");
 
-    uint8_t public_key [32];
-    uint8_t secret_key [32];
+    char public_key [41];
+    char secret_key [41];
+    int rc = zmq_curve_keypair (public_key, secret_key);
+    if (rc != 0) {
+      if (zmq_errno () == ENOTSUP) {
+          puts ("To use curve_keygen, please install libsodium and then rebuild libzmq.");
+      }
+      exit (1);
+    }
 
-    int rc = crypto_box_keypair (public_key, secret_key);
-    assert (rc == 0);
-    
-    char encoded [41];
-    zmq_z85_encode (encoded, public_key, 32);
     puts ("\n== CURVE PUBLIC KEY ==");
-    puts (encoded);
+    puts (public_key);
     
-    zmq_z85_encode (encoded, secret_key, 32);
     puts ("\n== CURVE SECRET KEY ==");
-    puts (encoded);
+    puts (secret_key);
 
-#else
-    puts ("To build curve_keygen, please install libsodium and then rebuild libzmq.");
-#endif
     exit (0);
 }