Refactor BigInt

4 files changed, 94 insertions, 9 deletions

diff --git a/src/lib/math/bigint/big_rand.cpp b/src/lib/math/bigint/big_rand.cpp
index ab66c6cdd..074c368e0 100644
--- a/src/lib/math/bigint/big_rand.cpp
+++ b/src/lib/math/bigint/big_rand.cpp
@@ -7,6 +7,7 @@
 
 #include <botan/bigint.h>
 #include <botan/parsing.h>
+#include <botan/internal/rounding.h>
 
 namespace Botan {
 
@@ -19,15 +20,18 @@ void BigInt::randomize(RandomNumberGenerator& rng,
    set_sign(Positive);
 
    if(bitsize == 0)
+      {
       clear();
+      }
    else
       {
-      secure_vector<byte> array = rng.random_vec((bitsize + 7) / 8);
+      secure_vector<byte> array = rng.random_vec(round_up(bitsize, 8) / 8);
 
       if(bitsize % 8)
          array[0] &= 0xFF >> (8 - (bitsize % 8));
       array[0] |= 0x80 >> ((bitsize % 8) ? (8 - bitsize % 8) : 0);
-      binary_decode(array.data(), array.size());
+
+      binary_decode(array);
       }
    }
 
diff --git a/src/lib/math/bigint/bigint.cpp b/src/lib/math/bigint/bigint.cpp
index 045117cbd..242a7fe0b 100644
--- a/src/lib/math/bigint/bigint.cpp
+++ b/src/lib/math/bigint/bigint.cpp
@@ -173,6 +173,11 @@ void BigInt::clear_bit(size_t n)
       m_reg[which] &= ~mask;
    }
 
+size_t BigInt::bytes() const
+   {
+   return round_up(bits(), 8) / 8;
+   }
+
 /*
 * Count how many bits are being used
 */
@@ -253,6 +258,12 @@ BigInt BigInt::abs() const
    return x;
    }
 
+void BigInt::grow_to(size_t n)
+   {
+   if(n > size())
+      m_reg.resize(round_up(n, 8));
+   }
+
 /*
 * Encode this number into bytes
 */
diff --git a/src/lib/math/bigint/bigint.h b/src/lib/math/bigint/bigint.h
index 4a37425f5..d866698b3 100644
--- a/src/lib/math/bigint/bigint.h
+++ b/src/lib/math/bigint/bigint.h
@@ -42,7 +42,7 @@ class BOTAN_DLL BigInt
      /**
      * Create empty BigInt
      */
-     BigInt() { m_signedness = Positive; }
+     BigInt() {}
 
      /**
      * Create BigInt from 64 bit integer
@@ -400,7 +400,7 @@ class BOTAN_DLL BigInt
      * Give byte length of the integer
      * @result byte length of the represented integer value
      */
-     size_t bytes() const { return (bits() + 7) / 8; }
+     size_t bytes() const;
 
      /**
      * Get the bit length of the integer
@@ -427,11 +427,7 @@ class BOTAN_DLL BigInt
      * Increase internal register buffer to at least n words
      * @param n new size of register
      */
-     void grow_to(size_t n)
-        {
-        if(n > size())
-           m_reg.resize(n + (8 - n % 8));
-        }
+     void grow_to(size_t n);
 
      /**
      * Fill BigInt with a random number with size of bitsize
diff --git a/src/tests/catchy/test_bigint.cpp b/src/tests/catchy/test_bigint.cpp
new file mode 100644
index 000000000..5f4c960cf
--- /dev/null
+++ b/src/tests/catchy/test_bigint.cpp
@@ -0,0 +1,74 @@
+// (C) 2015 Simon Warta (Kullo GmbH)
+// Botan is released under the Simplified BSD License (see license.txt)
+
+#include "catch.hpp"
+
+#include <botan/build.h>
+
+#if defined(BOTAN_HAS_BIGINT)
+
+#include <botan/bigint.h>
+
+using namespace Botan;
+
+TEST_CASE("Bigint basics", "[bigint]")
+   {
+   SECTION("in 0-bit border")
+      {
+      BigInt a(0u);
+      CHECK(( a.bits() == 0 ));
+      CHECK(( a.bytes() == 0 ));
+      CHECK(( a.to_u32bit() == 0 ));
+      }
+   SECTION("above 0-bit border")
+      {
+      BigInt a(1u);
+      CHECK(( a.bits() == 1 ));
+      CHECK(( a.bytes() == 1 ));
+      CHECK(( a.to_u32bit() == 1 ));
+      }
+   SECTION("in 8-bit border")
+      {
+      BigInt a(255u);
+      CHECK(( a.bits() == 8 ));
+      CHECK(( a.bytes() == 1 ));
+      CHECK(( a.to_u32bit() == 255 ));
+      }
+   SECTION("above 8-bit border")
+      {
+      BigInt a(256u);
+      CHECK(( a.bits() == 9 ));
+      CHECK(( a.bytes() == 2 ));
+      CHECK(( a.to_u32bit() == 256 ));
+      }
+   SECTION("in 16-bit border")
+      {
+      BigInt a(65535u);
+      CHECK(( a.bits() == 16 ));
+      CHECK(( a.bytes() == 2 ));
+      CHECK(( a.to_u32bit() == 65535 ));
+      }
+   SECTION("above 16-bit border")
+      {
+      BigInt a(65536u);
+      CHECK(( a.bits() == 17 ));
+      CHECK(( a.bytes() == 3 ));
+      CHECK(( a.to_u32bit() == 65536 ));
+      }
+   SECTION("in 32-bit border")
+      {
+      BigInt a(4294967295u);
+      CHECK(( a.bits() == 32 ));
+      CHECK(( a.bytes() == 4 ));
+      CHECK(( a.to_u32bit() == 4294967295u ));
+      }
+   SECTION("above 32-bit border")
+      {
+      BigInt a(4294967296u);
+      CHECK(( a.bits() == 33 ));
+      CHECK(( a.bytes() == 5 ));
+      CHECK_THROWS( a.to_u32bit() );
+      }
+   }
+
+#endif