/* get plaintext using biginteger class. This is required because default int cannot handle large modpow function */
public byte[] getMyPlainText(int [] a, int d, int n)
{
int l = a.Length;
byte [] r = new byte[l];
for (int i = 0; i < a.Length; i++)
{
int temp = a[i];
/* if temp=199 which represents blankspace, handle it differently */
if (temp == 199 || temp == 200 || temp == 201)
{
r[i] = (byte)temp;
continue;
}
Mono.Math.BigInteger bi = temp;
bi = bi.ModPow(d, n);
string tempString = bi.ToString();
int g = Int32.Parse(tempString);
r[i] = (byte)g;
}
return(r);
}
static string ToDecimalString (string hexString)
{
#if TARGET_DOTNET
throw new NotImplementedException ();
#else
// http://tools.ietf.org/html/rfc5280#section-4.1.2.2
// We SHOULD support negative numbers
var bytes = FromBinHex (hexString);
var negative = bytes.Length > 0 && bytes [0] >= 0x80;
if (negative) {
for (int i = 0; i < bytes.Length; i++)
bytes [i] = (byte) ~ bytes [i];
}
var big = new BigInteger (bytes);
if (negative) {
big = big + 1;
return "-" + big.ToString ();
} else
return big.ToString ();
#endif
}
public static int GetTrailingZerosCount(BigInteger num)
{
int count = 0;
string numAsString = num.ToString ();
int len = numAsString.Length;
for (int i = 0; i < len; i++)
{
int digit = int.Parse (numAsString[len - i - 1].ToString());
if (digit != 0)
{
break;
}
count += 1;
}
return count;
}
public static string Convert(string source, int sourceRadix, int targetRadix)
{
/* Check if radix arguments are within the allowed range. */
if (sourceRadix < MIN_RADIX || sourceRadix > MAX_RADIX)
throw new ArgumentOutOfRangeException("sourceRadix", "Source radix needs to be in a range from " + MIN_RADIX + " to " + MAX_RADIX);
if (targetRadix < MIN_RADIX || targetRadix > MAX_RADIX)
throw new ArgumentOutOfRangeException("targetRadix", "Target radix needs to be in a range from " + MIN_RADIX + " to " + MAX_RADIX);
BigInteger radixFrom = new BigInteger((UInt32)sourceRadix);
BigInteger value = new BigInteger(0);
BigInteger multiplier = new BigInteger(1);
for (int i = source.Length - 1; i >= 0; i--)
{
int digit = Digit(source[i], sourceRadix);
if (digit == -1)
throw new ArgumentException("The character '" + source[i] + "' is not defined for the source radix.", "sourceRadix");
value += multiplier * digit;
multiplier = multiplier * radixFrom;
}
return value.ToString((UInt32)targetRadix, CHARACTERS.Substring(0, targetRadix));
}
