ARACrypt C# implementation

AraCrypt.cs

public class ARACrypt
{
    private uint lfsrA = 0x13579BDF;
    private uint lfsrB = 0x2468ACE0;
    private uint lfsrC = 0xFDB97531;
    private uint maskA = 0x80000062;
    private uint maskB = 0x40000020;
    private uint maskC = 0x10000002;
    private uint rot0A = 0x7FFFFFFF;
    private uint rot0B = 0x3FFFFFFF;
    private uint rot0C = 0x0FFFFFFF;
    private uint rot1A = 0x80000000;
    private uint rot1B = 0xC0000000;
    private uint rot1C = 0xF0000000;
    private string key = "";

    public void SetKey(string key)
    {
        if (string.IsNullOrEmpty(key))
            throw new ArgumentNullException(nameof(key));

        this.key = key;

        string csSeed = this.key;

        int nIdx = 0;
        while (csSeed.Length < 12)
        {
            csSeed += csSeed[nIdx++];
        }

        for (nIdx = 0; nIdx < 4; nIdx++)
        {
            this.lfsrA = ((this.lfsrA <<= 8) | csSeed[nIdx + 0]);
            this.lfsrB = ((this.lfsrB <<= 8) | csSeed[nIdx + 4]);
            this.lfsrC = ((this.lfsrC <<= 8) | csSeed[nIdx + 8]);
        }

        if (this.lfsrA == 0x00000000)
            this.lfsrA = 0x13579BDF;
        if (this.lfsrB == 0x00000000)
            this.lfsrB = 0x2468ACE0;
        if (this.lfsrC == 0x00000000)
            this.lfsrC = 0xFDB97531;
    }

    public byte TransformChar(byte input)
    {
        byte crypto = 0;
        uint outB = (this.lfsrB & 0x00000001);
        uint outC = (this.lfsrC & 0x00000001);

        for (int i = 0; i < 8; i++)
        {
            if ((this.lfsrA & 0x00000001) != 0)
            {
                this.lfsrA = (((this.lfsrA ^ this.maskA) >> 1) | this.rot1A);
                if ((this.lfsrB & 0x00000001) != 0)
                {
                    this.lfsrB = (((this.lfsrB ^ this.maskB) >> 1) | this.rot1B);
                    outB = 0x00000001;
                }
                else
                {
                    this.lfsrB = ((this.lfsrB >> 1) & this.rot0B);
                    outB = 0x00000000;
                }
            }
            else
            {
                this.lfsrA = ((this.lfsrA >> 1) & this.rot0A);
                if ((this.lfsrC & 0x00000001) != 0)
                {
                    this.lfsrC = (((this.lfsrC ^ this.maskC) >> 1) | this.rot1C);
                    outC = 0x00000001;
                }
                else
                {
                    this.lfsrC = ((this.lfsrC >> 1) & this.rot0C);
                    outC = 0x00000000;
                }
            }
            crypto = (byte)((byte)(crypto << 1) | (outB ^ outC));
        }

        input = (byte)(input ^ crypto);
        if (input == 0)
            input = (byte)(input ^ crypto);

        return input;
    }
}