Initial checkin1.5.6

1 files changed, 86 insertions, 0 deletions

diff --git a/src/big_rand.cpp b/src/big_rand.cpp
new file mode 100644
index 000000000..2cb4cfd77
--- /dev/null
+++ b/src/big_rand.cpp
@@ -0,0 +1,86 @@
+/*************************************************
+* BigInt Random Generation Source File           *
+* (C) 1999-2006 The Botan Project                *
+*************************************************/
+
+#include <botan/bigint.h>
+#include <botan/parsing.h>
+#include <botan/numthry.h>
+#include <botan/rng.h>
+
+namespace Botan {
+
+/*************************************************
+* Construct a BigInt of a specific form          *
+*************************************************/
+BigInt::BigInt(NumberType type, u32bit bits)
+   {
+   set_sign(Positive);
+   if(type == Random && bits)
+      randomize(bits);
+   else if(type == Power2)
+      set_bit(bits);
+   else
+      throw Invalid_Argument("BigInt(NumberType): Unknown type");
+   }
+
+/*************************************************
+* Randomize this number                          *
+*************************************************/
+void BigInt::randomize(u32bit bitsize)
+   {
+   set_sign(Positive);
+
+   if(bitsize == 0)
+      clear();
+   else
+      {
+      SecureVector<byte> array((bitsize + 7) / 8);
+      Global_RNG::randomize(array, array.size());
+      if(bitsize % 8)
+         array[0] &= 0xFF >> (8 - (bitsize % 8));
+      array[0] |= 0x80 >> ((bitsize % 8) ? (8 - bitsize % 8) : 0);
+      binary_decode(array, array.size());
+      }
+   }
+
+/*************************************************
+* Generate a random integer                      *
+*************************************************/
+BigInt random_integer(u32bit bits)
+   {
+   BigInt x;
+   x.randomize(bits);
+   return x;
+   }
+
+/*************************************************
+* Generate a random integer within given range   *
+*************************************************/
+BigInt random_integer(const BigInt& min, const BigInt& max)
+   {
+   BigInt range = max - min;
+
+   if(range <= 0)
+      throw Invalid_Argument("random_integer: invalid min/max values");
+
+   return (min + (random_integer(range.bits() + 2) % range));
+   }
+
+/*************************************************
+* Generate a random safe prime                   *
+*************************************************/
+BigInt random_safe_prime(u32bit bits)
+   {
+   if(bits <= 64)
+      throw Invalid_Argument("random_safe_prime: Can't make a prime of " +
+                             to_string(bits) + " bits");
+
+   BigInt p;
+   do
+      p = (random_prime(bits - 1) << 1) + 1;
+   while(!is_prime(p));
+   return p;
+   }
+
+}