1 files changed, 369 insertions, 0 deletions
diff --git a/botan/src/math/bigint/bigint.cpp b/botan/src/math/bigint/bigint.cpp
new file mode 100644
index 0000000..926bedc
--- /dev/null
+++ b/botan/src/math/bigint/bigint.cpp
@@ -0,0 +1,369 @@
+/*
+* BigInt Base
+* (C) 1999-2008 Jack Lloyd
+*
+* Distributed under the terms of the Botan license
+*/
+
+#include <botan/bigint.h>
+#include <botan/mp_core.h>
+#include <botan/loadstor.h>
+#include <botan/parsing.h>
+#include <botan/util.h>
+
+namespace Botan {
+
+/*
+* Construct a BigInt from a regular number
+*/
+BigInt::BigInt(u64bit n)
+   {
+   set_sign(Positive);
+
+   if(n == 0)
+      return;
+
+   const u32bit limbs_needed = sizeof(u64bit) / sizeof(word);
+
+   reg.create(4*limbs_needed);
+   for(u32bit j = 0; j != limbs_needed; ++j)
+      reg[j] = ((n >> (j*MP_WORD_BITS)) & MP_WORD_MASK);
+   }
+
+/*
+* Construct a BigInt of the specified size
+*/
+BigInt::BigInt(Sign s, u32bit size)
+   {
+   reg.create(round_up(size, 8));
+   signedness = s;
+   }
+
+/*
+* Construct a BigInt from a "raw" BigInt
+*/
+BigInt::BigInt(const BigInt& b)
+   {
+   const u32bit b_words = b.sig_words();
+
+   if(b_words)
+      {
+      reg.create(round_up(b_words, 8));
+      reg.copy(b.data(), b_words);
+      set_sign(b.sign());
+      }
+   else
+      {
+      reg.create(2);
+      set_sign(Positive);
+      }
+   }
+
+/*
+* Construct a BigInt from a string
+*/
+BigInt::BigInt(const std::string& str)
+   {
+   Base base = Decimal;
+   u32bit markers = 0;
+   bool negative = false;
+   if(str.length() > 0 && str[0] == '-') { markers += 1; negative = true; }
+
+   if(str.length() > markers + 2 && str[markers    ] == '0' &&
+                                    str[markers + 1] == 'x')
+      { markers += 2; base = Hexadecimal; }
+   else if(str.length() > markers + 1 && str[markers] == '0')
+      { markers += 1; base = Octal; }
+
+   *this = decode(reinterpret_cast<const byte*>(str.data()) + markers,
+                  str.length() - markers, base);
+
+   if(negative) set_sign(Negative);
+   else         set_sign(Positive);
+   }
+
+/*
+* Construct a BigInt from an encoded BigInt
+*/
+BigInt::BigInt(const byte input[], u32bit length, Base base)
+   {
+   set_sign(Positive);
+   *this = decode(input, length, base);
+   }
+
+/*
+* Construct a BigInt from an encoded BigInt
+*/
+BigInt::BigInt(RandomNumberGenerator& rng, u32bit bits)
+   {
+   set_sign(Positive);
+   randomize(rng, bits);
+   }
+
+/*
+* Swap this BigInt with another
+*/
+void BigInt::swap(BigInt& other)
+   {
+   reg.swap(other.reg);
+   std::swap(signedness, other.signedness);
+   }
+
+/*
+* Grow the internal storage
+*/
+void BigInt::grow_reg(u32bit n)
+   {
+   reg.grow_to(round_up(size() + n, 8));
+   }
+
+/*
+* Grow the internal storage
+*/
+void BigInt::grow_to(u32bit n)
+   {
+   if(n > size())
+      reg.grow_to(round_up(n, 8));
+   }
+
+/*
+* Comparison Function
+*/
+s32bit BigInt::cmp(const BigInt& n, bool check_signs) const
+   {
+   if(check_signs)
+      {
+      if(n.is_positive() && this->is_negative()) return -1;
+      if(n.is_negative() && this->is_positive()) return 1;
+      if(n.is_negative() && this->is_negative())
+         return (-bigint_cmp(data(), sig_words(), n.data(), n.sig_words()));
+      }
+   return bigint_cmp(data(), sig_words(), n.data(), n.sig_words());
+   }
+
+/*
+* Convert this number to a u32bit, if possible
+*/
+u32bit BigInt::to_u32bit() const
+   {
+   if(is_negative())
+      throw Encoding_Error("BigInt::to_u32bit: Number is negative");
+   if(bits() >= 32)
+      throw Encoding_Error("BigInt::to_u32bit: Number is too big to convert");
+
+   u32bit out = 0;
+   for(u32bit j = 0; j != 4; ++j)
+      out = (out << 8) | byte_at(3-j);
+   return out;
+   }
+
+/*
+* Return byte n of this number
+*/
+byte BigInt::byte_at(u32bit n) const
+   {
+   const u32bit WORD_BYTES = sizeof(word);
+   u32bit word_num = n / WORD_BYTES, byte_num = n % WORD_BYTES;
+   if(word_num >= size())
+      return 0;
+   else
+      return get_byte(WORD_BYTES - byte_num - 1, reg[word_num]);
+   }
+
+/*
+* Return bit n of this number
+*/
+bool BigInt::get_bit(u32bit n) const
+   {
+   return ((word_at(n / MP_WORD_BITS) >> (n % MP_WORD_BITS)) & 1);
+   }
+
+/*
+* Return bits {offset...offset+length}
+*/
+u32bit BigInt::get_substring(u32bit offset, u32bit length) const
+   {
+   if(length > 32)
+      throw Invalid_Argument("BigInt::get_substring: Substring size too big");
+
+   u64bit piece = 0;
+   for(u32bit j = 0; j != 8; ++j)
+      piece = (piece << 8) | byte_at((offset / 8) + (7-j));
+
+   u64bit mask = (1 << length) - 1;
+   u32bit shift = (offset % 8);
+
+   return static_cast<u32bit>((piece >> shift) & mask);
+   }
+
+/*
+* Set bit number n
+*/
+void BigInt::set_bit(u32bit n)
+   {
+   const u32bit which = n / MP_WORD_BITS;
+   const word mask = static_cast<word>(1) << (n % MP_WORD_BITS);
+   if(which >= size()) grow_to(which + 1);
+   reg[which] |= mask;
+   }
+
+/*
+* Clear bit number n
+*/
+void BigInt::clear_bit(u32bit n)
+   {
+   const u32bit which = n / MP_WORD_BITS;
+   const word mask = static_cast<word>(1) << (n % MP_WORD_BITS);
+   if(which < size())
+      reg[which] &= ~mask;
+   }
+
+/*
+* Clear all but the lowest n bits
+*/
+void BigInt::mask_bits(u32bit n)
+   {
+   if(n == 0) { clear(); return; }
+   if(n >= bits()) return;
+
+   const u32bit top_word = n / MP_WORD_BITS;
+   const word mask = (static_cast<word>(1) << (n % MP_WORD_BITS)) - 1;
+
+   if(top_word < size())
+      for(u32bit j = top_word + 1; j != size(); ++j)
+         reg[j] = 0;
+
+   reg[top_word] &= mask;
+   }
+
+/*
+* Count how many bytes are being used
+*/
+u32bit BigInt::bytes() const
+   {
+   return (bits() + 7) / 8;
+   }
+
+/*
+* Count how many bits are being used
+*/
+u32bit BigInt::bits() const
+   {
+   if(sig_words() == 0)
+      return 0;
+
+   u32bit full_words = sig_words() - 1, top_bits = MP_WORD_BITS;
+   word top_word = word_at(full_words), mask = MP_WORD_TOP_BIT;
+
+   while(top_bits && ((top_word & mask) == 0))
+      { mask >>= 1; top_bits--; }
+
+   return (full_words * MP_WORD_BITS + top_bits);
+   }
+
+/*
+* Calcluate the size in a certain base
+*/
+u32bit BigInt::encoded_size(Base base) const
+   {
+   static const double LOG_2_BASE_10 = 0.30102999566;
+
+   if(base == Binary)
+      return bytes();
+   else if(base == Hexadecimal)
+      return 2*bytes();
+   else if(base == Octal)
+      return ((bits() + 2) / 3);
+   else if(base == Decimal)
+      return static_cast<u32bit>((bits() * LOG_2_BASE_10) + 1);
+   else
+      throw Invalid_Argument("Unknown base for BigInt encoding");
+   }
+
+/*
+* Set the sign
+*/
+void BigInt::set_sign(Sign s)
+   {
+   if(is_zero())
+      signedness = Positive;
+   else
+      signedness = s;
+   }
+
+/*
+* Reverse the value of the sign flag
+*/
+void BigInt::flip_sign()
+   {
+   set_sign(reverse_sign());
+   }
+
+/*
+* Return the opposite value of the current sign
+*/
+BigInt::Sign BigInt::reverse_sign() const
+   {
+   if(sign() == Positive)
+      return Negative;
+   return Positive;
+   }
+
+/*
+* Return the negation of this number
+*/
+BigInt BigInt::operator-() const
+   {
+   BigInt x = (*this);
+   x.flip_sign();
+   return x;
+   }
+
+/*
+* Return the absolute value of this number
+*/
+BigInt BigInt::abs() const
+   {
+   BigInt x = (*this);
+   x.set_sign(Positive);
+   return x;
+   }
+
+/*
+* Encode this number into bytes
+*/
+void BigInt::binary_encode(byte output[]) const
+   {
+   const u32bit sig_bytes = bytes();
+   for(u32bit j = 0; j != sig_bytes; ++j)
+      output[sig_bytes-j-1] = byte_at(j);
+   }
+
+/*
+* Set this number to the value in buf
+*/
+void BigInt::binary_decode(const byte buf[], u32bit length)
+   {
+   const u32bit WORD_BYTES = sizeof(word);
+
+   reg.create(round_up((length / WORD_BYTES) + 1, 8));
+
+   for(u32bit j = 0; j != length / WORD_BYTES; ++j)
+      {
+      u32bit top = length - WORD_BYTES*j;
+      for(u32bit k = WORD_BYTES; k > 0; --k)
+         reg[j] = (reg[j] << 8) | buf[top - k];
+      }
+   for(u32bit j = 0; j != length % WORD_BYTES; ++j)
+      reg[length / WORD_BYTES] = (reg[length / WORD_BYTES] << 8) | buf[j];
+   }
+
+/*
+* Set this number to the value in buf
+*/
+void BigInt::binary_decode(const MemoryRegion<byte>& buf)
+   {
+   binary_decode(buf, buf.size());
+   }
+
+}