protected virtual byte[] GetLSub(int n)
{
while (n >= this.L.Count)
{
this.L.Add(OcbBlockCipher.OCB_double((byte[])this.L[this.L.Count - 1]));
}
return((byte[])this.L[n]);
}
public virtual void Init(bool forEncryption, ICipherParameters parameters)
{
bool flag = this.forEncryption;
this.forEncryption = forEncryption;
this.macBlock = null;
byte[] array;
KeyParameter keyParameter;
if (parameters is AeadParameters)
{
AeadParameters aeadParameters = (AeadParameters)parameters;
array = aeadParameters.GetNonce();
this.initialAssociatedText = aeadParameters.GetAssociatedText();
int num = aeadParameters.MacSize;
if (num < 64 || num > 128 || num % 8 != 0)
{
throw new ArgumentException("Invalid value for MAC size: " + num);
}
this.macSize = num / 8;
keyParameter = aeadParameters.Key;
}
else
{
if (!(parameters is ParametersWithIV))
{
throw new ArgumentException("invalid parameters passed to OCB");
}
ParametersWithIV parametersWithIV = (ParametersWithIV)parameters;
array = parametersWithIV.GetIV();
this.initialAssociatedText = null;
this.macSize = 16;
keyParameter = (KeyParameter)parametersWithIV.Parameters;
}
this.hashBlock = new byte[16];
this.mainBlock = new byte[forEncryption ? 16 : (16 + this.macSize)];
if (array == null)
{
array = new byte[0];
}
if (array.Length > 15)
{
throw new ArgumentException("IV must be no more than 15 bytes");
}
if (keyParameter != null)
{
this.hashCipher.Init(true, keyParameter);
this.mainCipher.Init(forEncryption, keyParameter);
this.KtopInput = null;
}
else if (flag != forEncryption)
{
throw new ArgumentException("cannot change encrypting state without providing key.");
}
this.L_Asterisk = new byte[16];
this.hashCipher.ProcessBlock(this.L_Asterisk, 0, this.L_Asterisk, 0);
this.L_Dollar = OcbBlockCipher.OCB_double(this.L_Asterisk);
this.L = Platform.CreateArrayList();
this.L.Add(OcbBlockCipher.OCB_double(this.L_Dollar));
int num2 = this.ProcessNonce(array);
int num3 = num2 % 8;
int num4 = num2 / 8;
if (num3 == 0)
{
Array.Copy(this.Stretch, num4, this.OffsetMAIN_0, 0, 16);
}
else
{
for (int i = 0; i < 16; i++)
{
uint num5 = (uint)this.Stretch[num4];
uint num6 = (uint)this.Stretch[++num4];
this.OffsetMAIN_0[i] = (byte)(num5 << num3 | num6 >> 8 - num3);
}
}
this.hashBlockPos = 0;
this.mainBlockPos = 0;
this.hashBlockCount = 0L;
this.mainBlockCount = 0L;
this.OffsetHASH = new byte[16];
this.Sum = new byte[16];
Array.Copy(this.OffsetMAIN_0, 0, this.OffsetMAIN, 0, 16);
this.Checksum = new byte[16];
if (this.initialAssociatedText != null)
{
this.ProcessAadBytes(this.initialAssociatedText, 0, this.initialAssociatedText.Length);
}
}