public byte[] Decrypt(byte[] startupInput, byte[] keyInput, int w, int r, int b)
{
var key = GetKey(keyInput, b);
for (int i = 0; i < keyInput.Length; i++)
{
keyInput[i] = 0;
}
var helper = new RC5Helper(w, r, key);
var input = GetEncryptingResultModel(startupInput, helper.BlockSize);
var result = new byte[input.EncryptedData.Length];
var IV = DecryptInitializeVector(input.IV, key, w, r);
for (int i = 0; i < input.EncryptedData.Length; i += helper.BlockSize)
{
var currentBlock = new byte[helper.BlockSize];
Array.Copy(input.EncryptedData, i, currentBlock, 0, helper.BlockSize);
var decryptedBlock = DecryptBlock(currentBlock, helper);
decryptedBlock = XOR(IV, decryptedBlock, helper.W);
Array.Copy(decryptedBlock, 0, result, i, helper.BlockSize);
IV = currentBlock;
}
return(RemoveAppending(result));
}
public EncryptingResultModel Encrypt(byte[] input, byte[] keyInput, int w, int r, int b)
{
var key = GetKey(keyInput, b);
for (int i = 0; i < keyInput.Length; i++)
{
keyInput[i] = 0;
}
var helper = new RC5Helper(w, r, key);
input = GetFullInput(input, helper.BlockSize);
var IV = GetInitializeVector(helper.BlockSize);
var resultData = new byte[input.Length];
var result = new EncryptingResultModel {
IV = EncryptInitializeVector(IV, key, w, r)
};
for (int i = 0; i < input.Length; i += helper.BlockSize)
{
var currentBlock = new byte[helper.BlockSize];
Array.Copy(input, i, currentBlock, 0, helper.BlockSize);
currentBlock = XOR(IV, currentBlock, helper.W);
IV = EncryptBlock(currentBlock, helper);
Array.Copy(IV, 0, resultData, i, helper.BlockSize);
}
result.EncryptedData = resultData;
return(result);
}
private byte[] DecryptInitializeVector(byte[] input, byte[] key, int w, int r)
{
var helper = new RC5Helper(w, r, key);
var result = new byte[input.Length];
for (int i = 0; i < input.Length; i += helper.BlockSize)
{
var currentBlock = new byte[helper.BlockSize];
Array.Copy(input, i, currentBlock, 0, helper.BlockSize);
currentBlock = DecryptBlock(currentBlock, helper);
Array.Copy(currentBlock, 0, result, i, helper.BlockSize);
}
return(result);
}
private byte[] EncryptBlock(byte[] block, RC5Helper helper)
{
var A = GetBlockPart(block, true, helper.W);
var B = GetBlockPart(block, false, helper.W);
A += helper.S[0];
B += helper.S[1];
for (int i = 1; i <= helper.R; i++)
{
A = helper.RotateLeft((A ^ B), (int)B, helper.W * 8) + helper.S[2 * i];
B = helper.RotateLeft((B ^ A), (int)A, helper.W * 8) + helper.S[2 * i + 1];
}
var result = new byte[2 * helper.W];
var partA = BitConverter.GetBytes(A);
var partB = BitConverter.GetBytes(B);
Array.Copy(partA, 0, result, 0, helper.W);
Array.Copy(partB, 0, result, helper.W, helper.W);
return(result);
}
private byte[] DecryptBlock(byte[] block, RC5Helper helper)
{
var A = GetBlockPart(block, true, helper.W);
var B = GetBlockPart(block, false, helper.W);
for (int i = helper.R; i > 0; i--)
{
B = helper.RotateRight(B - helper.S[2 * i + 1], (int)A, helper.W * 8) ^ A;
A = helper.RotateRight(A - helper.S[2 * i], (int)B, helper.W * 8) ^ B;
}
A -= helper.S[0];
B -= helper.S[1];
var result = new byte[2 * helper.W];
var partA = BitConverter.GetBytes(A);
var partB = BitConverter.GetBytes(B);
Array.Copy(partA, 0, result, 0, helper.W);
Array.Copy(partB, 0, result, helper.W, helper.W);
return(result);
}
