1 files changed, 69 insertions, 0 deletions
diff --git a/src/prngs/rng_make_prng.c b/src/prngs/rng_make_prng.c
new file mode 100644
index 0000000..51b6e6c
--- /dev/null
+++ b/src/prngs/rng_make_prng.c
@@ -0,0 +1,69 @@
+/* LibTomCrypt, modular cryptographic library -- Tom St Denis
+ *
+ * LibTomCrypt is a library that provides various cryptographic
+ * algorithms in a highly modular and flexible manner.
+ *
+ * The library is free for all purposes without any express
+ * guarantee it works.
+ *
+ * Tom St Denis, tomstdenis@gmail.com, http://libtomcrypt.org
+ */
+#include "tomcrypt.h"
+
+/** 
+  @file rng_make_prng.c
+  portable way to get secure random bits to feed a PRNG  (Tom St Denis)
+*/
+
+/**
+  Create a PRNG from a RNG
+  @param bits     Number of bits of entropy desired (64 ... 1024)
+  @param wprng    Index of which PRNG to setup
+  @param prng     [out] PRNG state to initialize
+  @param callback A pointer to a void function for when the RNG is slow, this can be NULL
+  @return CRYPT_OK if successful
+*/  
+int rng_make_prng(int bits, int wprng, prng_state *prng, 
+                  void (*callback)(void))
+{
+   unsigned char buf[256];
+   int err;
+   
+   LTC_ARGCHK(prng != NULL);
+
+   /* check parameter */
+   if ((err = prng_is_valid(wprng)) != CRYPT_OK) {
+      return err;
+   }
+
+   if (bits < 64 || bits > 1024) {
+      return CRYPT_INVALID_PRNGSIZE;
+   }
+
+   if ((err = prng_descriptor[wprng].start(prng)) != CRYPT_OK) {
+      return err;
+   }
+
+   bits = ((bits/8)+((bits&7)!=0?1:0)) * 2;
+   if (rng_get_bytes(buf, (unsigned long)bits, callback) != (unsigned long)bits) {
+      return CRYPT_ERROR_READPRNG;
+   }
+
+   if ((err = prng_descriptor[wprng].add_entropy(buf, (unsigned long)bits, prng)) != CRYPT_OK) {
+      return err;
+   }
+
+   if ((err = prng_descriptor[wprng].ready(prng)) != CRYPT_OK) {
+      return err;
+   }
+
+   #ifdef LTC_CLEAN_STACK
+      zeromem(buf, sizeof(buf));
+   #endif
+   return CRYPT_OK;
+}
+
+
+/* $Source: /cvs/libtom/libtomcrypt/src/prngs/rng_make_prng.c,v $ */
+/* $Revision: 1.3 $ */
+/* $Date: 2005/05/05 14:35:59 $ */