1 files changed, 152 insertions, 0 deletions
diff --git a/src/math/bigint/big_code.cpp b/src/math/bigint/big_code.cpp
new file mode 100644
index 000000000..e7a5e4946
--- /dev/null
+++ b/src/math/bigint/big_code.cpp
@@ -0,0 +1,152 @@
+/*************************************************
+* BigInt Encoding/Decoding Source File           *
+* (C) 1999-2007 Jack Lloyd                       *
+*************************************************/
+
+#include <botan/bigint.h>
+#include <botan/divide.h>
+#include <botan/charset.h>
+#include <botan/hex.h>
+
+namespace Botan {
+
+/*************************************************
+* Encode a BigInt                                *
+*************************************************/
+void BigInt::encode(byte output[], const BigInt& n, Base base)
+   {
+   if(base == Binary)
+      n.binary_encode(output);
+   else if(base == Hexadecimal)
+      {
+      SecureVector<byte> binary(n.encoded_size(Binary));
+      n.binary_encode(binary);
+      for(u32bit j = 0; j != binary.size(); ++j)
+         Hex_Encoder::encode(binary[j], output + 2*j);
+      }
+   else if(base == Octal)
+      {
+      BigInt copy = n;
+      const u32bit output_size = n.encoded_size(Octal);
+      for(u32bit j = 0; j != output_size; ++j)
+         {
+         output[output_size - 1 - j] = Charset::digit2char(copy % 8);
+         copy /= 8;
+         }
+      }
+   else if(base == Decimal)
+      {
+      BigInt copy = n;
+      BigInt remainder;
+      copy.set_sign(Positive);
+      const u32bit output_size = n.encoded_size(Decimal);
+      for(u32bit j = 0; j != output_size; ++j)
+         {
+         divide(copy, 10, copy, remainder);
+         output[output_size - 1 - j] =
+            Charset::digit2char(remainder.word_at(0));
+         if(copy.is_zero())
+            break;
+         }
+      }
+   else
+      throw Invalid_Argument("Unknown BigInt encoding method");
+   }
+
+/*************************************************
+* Encode a BigInt                                *
+*************************************************/
+SecureVector<byte> BigInt::encode(const BigInt& n, Base base)
+   {
+   SecureVector<byte> output(n.encoded_size(base));
+   encode(output, n, base);
+   if(base != Binary)
+      for(u32bit j = 0; j != output.size(); ++j)
+         if(output[j] == 0)
+            output[j] = '0';
+   return output;
+   }
+
+/*************************************************
+* Encode a BigInt, with leading 0s if needed     *
+*************************************************/
+SecureVector<byte> BigInt::encode_1363(const BigInt& n, u32bit bytes)
+   {
+   const u32bit n_bytes = n.bytes();
+   if(n_bytes > bytes)
+      throw Encoding_Error("encode_1363: n is too large to encode properly");
+
+   const u32bit leading_0s = bytes - n_bytes;
+
+   SecureVector<byte> output(bytes);
+   encode(output + leading_0s, n, Binary);
+   return output;
+   }
+
+/*************************************************
+* Decode a BigInt                                *
+*************************************************/
+BigInt BigInt::decode(const MemoryRegion<byte>& buf, Base base)
+   {
+   return BigInt::decode(buf, buf.size(), base);
+   }
+
+/*************************************************
+* Decode a BigInt                                *
+*************************************************/
+BigInt BigInt::decode(const byte buf[], u32bit length, Base base)
+   {
+   BigInt r;
+   if(base == Binary)
+      r.binary_decode(buf, length);
+   else if(base == Hexadecimal)
+      {
+      SecureVector<byte> hex;
+      for(u32bit j = 0; j != length; ++j)
+         if(Hex_Decoder::is_valid(buf[j]))
+            hex.append(buf[j]);
+
+      u32bit offset = (hex.size() % 2);
+      SecureVector<byte> binary(hex.size() / 2 + offset);
+
+      if(offset)
+         {
+         byte temp[2] = { '0', hex[0] };
+         binary[0] = Hex_Decoder::decode(temp);
+         }
+
+      for(u32bit j = offset; j != binary.size(); ++j)
+         binary[j] = Hex_Decoder::decode(hex+2*j-offset);
+      r.binary_decode(binary, binary.size());
+      }
+   else if(base == Decimal || base == Octal)
+      {
+      const u32bit RADIX = ((base == Decimal) ? 10 : 8);
+      for(u32bit j = 0; j != length; ++j)
+         {
+         if(Charset::is_space(buf[j]))
+            continue;
+
+         if(!Charset::is_digit(buf[j]))
+            throw Invalid_Argument("BigInt::decode: "
+                                   "Invalid character in decimal input");
+
+         byte x = Charset::char2digit(buf[j]);
+         if(x >= RADIX)
+            {
+            if(RADIX == 10)
+               throw Invalid_Argument("BigInt: Invalid decimal string");
+            else
+               throw Invalid_Argument("BigInt: Invalid octal string");
+            }
+
+         r *= RADIX;
+         r += x;
+         }
+      }
+   else
+      throw Invalid_Argument("Unknown BigInt decoding method");
+   return r;
+   }
+
+}