--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/libtomcrypt/src/prngs/rng_get_bytes.c	Sat Mar 25 12:59:58 2006 +0000
@@ -0,0 +1,144 @@
+/* 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, [email protected], http://libtomcrypt.org
+ */
+#include "tomcrypt.h"
+
+/** 
+   @file rng_get_bytes.c
+   portable way to get secure random bits to feed a PRNG (Tom St Denis)
+*/
+
+#ifdef DEVRANDOM
+/* on *NIX read /dev/random */
+static unsigned long rng_nix(unsigned char *buf, unsigned long len, 
+                             void (*callback)(void))
+{
+#ifdef LTC_NO_FILE
+    return 0;
+#else
+    FILE *f;
+    unsigned long x;
+#ifdef TRY_URANDOM_FIRST
+    f = fopen("/dev/urandom", "rb");
+    if (f == NULL)
+#endif /* TRY_URANDOM_FIRST */
+       f = fopen("/dev/random", "rb");
+
+    if (f == NULL) {
+       return 0;
+    }
+    
+    /* disable buffering */
+    if (setvbuf(f, NULL, _IONBF, 0) != 0) {
+       fclose(f);
+       return 0;
+    }   
+ 
+    x = (unsigned long)fread(buf, 1, (size_t)len, f);
+    fclose(f);
+    return x;
+#endif /* LTC_NO_FILE */
+}
+
+#endif /* DEVRANDOM */
+
+/* on ANSI C platforms with 100 < CLOCKS_PER_SEC < 10000 */
+#if defined(CLOCKS_PER_SEC)
+
+#define ANSI_RNG
+
+static unsigned long rng_ansic(unsigned char *buf, unsigned long len, 
+                               void (*callback)(void))
+{
+   clock_t t1;
+   int l, acc, bits, a, b;
+
+   if (XCLOCKS_PER_SEC < 100 || XCLOCKS_PER_SEC > 10000) {
+      return 0;
+   }
+
+   l = len;
+   bits = 8;
+   acc  = a = b = 0;
+   while (len--) {
+       if (callback != NULL) callback();
+       while (bits--) {
+          do {
+             t1 = XCLOCK(); while (t1 == XCLOCK()) a ^= 1;
+             t1 = XCLOCK(); while (t1 == XCLOCK()) b ^= 1;
+          } while (a == b);
+          acc = (acc << 1) | a;
+       }
+       *buf++ = acc; 
+       acc  = 0;
+       bits = 8;
+   }
+   acc = bits = a = b = 0;
+   return l;
+}
+
+#endif 
+
+/* Try the Microsoft CSP */
+#ifdef WIN32
+#define _WIN32_WINNT 0x0400
+#include <windows.h>
+#include <wincrypt.h>
+
+static unsigned long rng_win32(unsigned char *buf, unsigned long len, 
+                               void (*callback)(void))
+{
+   HCRYPTPROV hProv = 0;
+   if (!CryptAcquireContext(&hProv, NULL, MS_DEF_PROV, PROV_RSA_FULL, 
+                            (CRYPT_VERIFYCONTEXT | CRYPT_MACHINE_KEYSET)) && 
+       !CryptAcquireContext (&hProv, NULL, MS_DEF_PROV, PROV_RSA_FULL, 
+                            CRYPT_VERIFYCONTEXT | CRYPT_MACHINE_KEYSET | CRYPT_NEWKEYSET))
+      return 0;
+
+   if (CryptGenRandom(hProv, len, buf) == TRUE) {
+      CryptReleaseContext(hProv, 0);
+      return len;
+   } else {
+      CryptReleaseContext(hProv, 0);
+      return 0;
+   }
+}
+
+#endif /* WIN32 */
+
+/**
+  Read the system RNG
+  @param out       Destination
+  @param outlen    Length desired (octets)
+  @param callback  Pointer to void function to act as "callback" when RNG is slow.  This can be NULL
+  @return Number of octets read
+*/     
+unsigned long rng_get_bytes(unsigned char *out, unsigned long outlen, 
+                            void (*callback)(void))
+{
+   unsigned long x;
+
+   LTC_ARGCHK(out != NULL);
+
+#if defined(DEVRANDOM)
+   x = rng_nix(out, outlen, callback);   if (x != 0) { return x; }
+#endif
+#ifdef WIN32
+   x = rng_win32(out, outlen, callback); if (x != 0) { return x; }
+#endif
+#ifdef ANSI_RNG
+   x = rng_ansic(out, outlen, callback); if (x != 0) { return x; }
+#endif
+   return 0;
+}
+
+/* $Source: /cvs/libtom/libtomcrypt/src/prngs/rng_get_bytes.c,v $ */
+/* $Revision: 1.3 $ */
+/* $Date: 2005/05/05 14:35:59 $ */