disable ltc_rng by default

src/headers/tomcrypt_custom.h

@@ -304,6 +304,9 @@
 /* rng_make_prng() */
 #define LTC_RNG_MAKE_PRNG
 
+/* enable the ltc_rng hook to integrate e.g. embedded hardware RNG's easily */
+/* #define LTC_PRNG_ENABLE_LTC_RNG */
+
 #endif /* LTC_NO_PRNGS */
 
 #ifdef LTC_YARROW

src/headers/tomcrypt_prng.h

@@ -193,8 +193,10 @@ unsigned long rng_get_bytes(unsigned char *out,
 
 int rng_make_prng(int bits, int wprng, prng_state *prng, void (*callback)(void));
 
+#ifdef LTC_PRNG_ENABLE_LTC_RNG
 extern unsigned long (*ltc_rng)(unsigned char *out, unsigned long outlen,
       void (*callback)(void));
+#endif
 
 
 /* $Source$ */

src/misc/crypt/crypt.c

@@ -371,6 +371,9 @@ const char *crypt_build_settings =
 #if defined(LTC_RNG_MAKE_PRNG)
     " LTC_RNG_MAKE_PRNG "
 #endif
+#if defined(LTC_PRNG_ENABLE_LTC_RNG)
+    " LTC_PRNG_ENABLE_LTC_RNG "
+#endif
 #if defined(LTC_HASH_HELPERS)
     " LTC_HASH_HELPERS "
 #endif

src/misc/crypt/crypt_prng_rng_descriptor.c

@@ -10,4 +10,6 @@
  */
 #include "tomcrypt.h"
 
+#ifdef LTC_PRNG_ENABLE_LTC_RNG
 unsigned long (*ltc_rng)(unsigned char *out, unsigned long outlen, void (*callback)(void));
+#endif

src/prngs/rng_get_bytes.c

@@ -135,12 +135,14 @@ unsigned long rng_get_bytes(unsigned char *out, unsigned long outlen,
 
    LTC_ARGCHK(out != NULL);
 
+#ifdef LTC_PRNG_ENABLE_LTC_RNG
    if (ltc_rng) {
       x = ltc_rng(out, outlen, callback);
       if (x != 0) {
          return x;
       }
    }
+#endif
 
 #if defined(_WIN32) || defined(_WIN32_WCE)
    x = rng_win32(out, outlen, callback); if (x != 0) { return x; }