/*
* Decode a BigInt
*/
BigInt BigInt::decode(const uint8_t buf[], size_t length, Base base)
{
BigInt r;
if(base == Binary)
{
r.binary_decode(buf, length);
}
else if(base == Hexadecimal)
{
secure_vector<uint8_t> binary;
if(length % 2)
{
// Handle lack of leading 0
const char buf0_with_leading_0[2] =
{ '0', static_cast<char>(buf[0]) };
binary = hex_decode_locked(buf0_with_leading_0, 2);
binary += hex_decode_locked(cast_uint8_ptr_to_char(&buf[1]),
length - 1,
false);
}
else
binary = hex_decode_locked(cast_uint8_ptr_to_char(buf),
length, false);
r.binary_decode(binary.data(), binary.size());
}
else if(base == Decimal)
{
for(size_t i = 0; i != length; ++i)
{
if(Charset::is_space(buf[i]))
continue;
if(!Charset::is_digit(buf[i]))
throw Invalid_Argument("BigInt::decode: "
"Invalid character in decimal input");
const uint8_t x = Charset::char2digit(buf[i]);
if(x >= 10)
throw Invalid_Argument("BigInt: Invalid decimal string");
r *= 10;
r += x;
}
}
else
throw Invalid_Argument("Unknown BigInt decoding method");
return r;
}
/*************************************************
* Decode a BigInt *
*************************************************/
BigInt BigInt::decode(const byte buf[], u32bit length, Base base)
{
BigInt r;
if(base == Binary)
r.binary_decode(buf, length);
#ifndef BOTAN_MINIMAL_BIGINT
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());
}
#endif
else if(base == Decimal || base == Octal)
{
const u32bit RADIX = ((base == Decimal) ? 10 : 8);
for(u32bit j = 0; j != length; ++j)
{
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;
}
