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HakanL/AraCrypt.cs

Created January 10, 2025 19:45
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  1. HakanL created this gist Jan 10, 2025.
    92 changes: 92 additions & 0 deletions AraCrypt.cs
    View file
    Original file line number Diff line number Diff line change
    @@ -0,0 +1,92 @@
    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;
    }
    }