hbbp_keygen: add own implementation of randombytes

Nacl requires an implementation of randombytes. The version offered by
nacl has a strange behaviour (e.g. indefinite blocking in case
/dev/urandom is unavailable) and is hard to portably link (.o file in
some lib directory). It is thus replaced with an own implementation
(that does proper error handling by the way).

1 files changed, 22 insertions, 1 deletions

diff --git a/hbbp_keygen.c b/hbbp_keygen.c
index 6bcde5c..f464441 100644
--- a/hbbp_keygen.c
+++ b/hbbp_keygen.c
@@ -2,9 +2,9 @@
 #include <sys/stat.h>
 #include <fcntl.h>
 
+#include "common.h"
 #include "crypto.h"
 
-
 #define pub_len  crypto_box_PUBLICKEYBYTES
 #define priv_len crypto_box_SECRETKEYBYTES
 
@@ -16,6 +16,27 @@ void error_cleanup(int num) {
     exit(1);
 }
 
+// used by nacl's crypto_box_keypair
+void randombytes(byte *buf, unsigned long long len)
+  __attribute__ ((externally_visible));
+
+void randombytes(byte *buf, unsigned long long len) {
+  int fd = open("/dev/urandom", O_RDONLY);
+  if (fd == -1) goto error;
+
+  while (len > 0) {
+    int sz = read(fd, buf, len);
+    if (sz < 1) goto error;
+    buf += sz;
+    len -= sz;
+  }
+  return;
+
+ error:
+  perror("failed accessing /dev/urandom");
+  error_cleanup(4);
+}
+
 int main() {
   int fd[4], i;
   byte key_pub [2][pub_len],