private void RemoveInsert(int aLeftRemainingCount,
int aRigthRemainingCount,
string aStringToInsert)
{
Debug.Assert(aLeftRemainingCount >= 0);
if (mSecureString != null)
{
while (mSecureString.Length > (aLeftRemainingCount +
aRigthRemainingCount))
{
mSecureString.RemoveAt(aLeftRemainingCount);
}
for (int i = 0; i < aStringToInsert.Length; ++i)
{
mSecureString.InsertAt(aLeftRemainingCount + i, aStringToInsert[i]);
}
}
else
{
using (var newString =
new PinnedArray <char>(aLeftRemainingCount + aRigthRemainingCount +
aStringToInsert.Length)) {
Array.Copy(mAltSecureString.Data, newString.Data, aLeftRemainingCount);
using (var insertString =
new PinnedArray <char>(Encoding.Unicode.GetChars(
Encoding.Unicode.GetBytes(aStringToInsert)))) {
Array.Copy(insertString.Data, 0, newString.Data, aLeftRemainingCount,
insertString.Data.Length);
Array.Copy(mAltSecureString.Data,
mAltSecureString.Data.Length - aRigthRemainingCount,
newString.Data, aLeftRemainingCount +
insertString.Data.Length,
aRigthRemainingCount);
}
mAltSecureString.Clear();
mAltSecureString = newString.Clone() as PinnedArray <char>;
}
}
}
private void RemoveInsert(int aLeftRemainingCount,
int aRigthRemainingCount,
string aStringToInsert)
{
Debug.Assert(aLeftRemainingCount >= 0);
if (mSecureString != null) {
while (mSecureString.Length > (aLeftRemainingCount +
aRigthRemainingCount))
{
mSecureString.RemoveAt(aLeftRemainingCount);
}
for (int i = 0; i < aStringToInsert.Length; ++i) {
mSecureString.InsertAt(aLeftRemainingCount + i, aStringToInsert[i]);
}
} else {
using (var newString =
new PinnedArray<char>(aLeftRemainingCount + aRigthRemainingCount +
aStringToInsert.Length)) {
Array.Copy(mAltSecureString.Data, newString.Data, aLeftRemainingCount);
using (var insertString =
new PinnedArray<char>(Encoding.Unicode.GetChars(
Encoding.Unicode.GetBytes(aStringToInsert)))) {
Array.Copy(insertString.Data, 0, newString.Data, aLeftRemainingCount,
insertString.Data.Length);
Array.Copy(mAltSecureString.Data,
mAltSecureString.Data.Length - aRigthRemainingCount,
newString.Data, aLeftRemainingCount +
insertString.Data.Length,
aRigthRemainingCount);
}
mAltSecureString.Clear();
mAltSecureString = newString.Clone() as PinnedArray<char>;
}
}
}
/// <summary>
/// removes leading element from array if the value of that element is 0
/// </summary>
/// <param name="array"></param>
public static void TrimLeadingZero(PinnedArray<byte> array)
{
if (array != null && array.Data != null && array.Data.Length > 0) {
if (array.Data[0] == 0) {
PinnedArray<byte> arrayCopy = (PinnedArray<byte>)array.Clone();
array.Data = new byte[array.Data.Length - 1];
Array.Copy(arrayCopy.Data, 1, array.Data, 0, array.Data.Length);
arrayCopy.Dispose();
}
}
}
/// <summary>
/// Computes a % (b -1) of 2 large numbers
/// </summary>
/// <param name="a">variable a</param>
/// <param name="b">variable b</param>
/// <returns></returns>
public static PinnedArray<byte> ModMinusOne(PinnedArray<byte> a,
PinnedArray<byte> b)
{
using (PinnedArray<byte> bMinusOne = (PinnedArray<byte>)b.Clone()) {
PinnedArray<byte> result = (PinnedArray<byte>)a.Clone();
// shouldn't have to worry about borrowing because b should be prime and
// therefore not end in zero
bMinusOne.Data[bMinusOne.Data.Length - 1]--;
int bShift = a.Data.Length - b.Data.Length;
while (bShift >= 0) {
while (CompareBigInt(result.Data, bMinusOne.Data, bShift) >= 0) {
result.Data = SubtractBigInt(result.Data, bMinusOne.Data, bShift);
TrimLeadingZero(result);
}
bShift--;
}
return result;
}
}
