RC5

public override void Decrypt(byte[] inData, byte[] outData, int bufferSize)
{
    if (bufferSize >= 16)
    {
        int v41 = 0;
        int v51 = 0;

        int blockCount = bufferSize >> 4;
        int inDataOffset = 8;
        int outDataOffset = 12;
        for (int block = 0; block < blockCount; block++)
        {
            int v8 = key[84];
            int v12 = (v8 ^ ReadDword(inData, inDataOffset / 4 - 2)) - key[82];
            int v10 = v8 ^ ReadDword(inData, inDataOffset / 4 - 1);
            int v9 = (v8 ^ ReadDword(inData, inDataOffset / 4 + 0)) - key[83];
            int v11 = v8 ^ ReadDword(inData, inDataOffset / 4 + 1);
            int arrIndex = 81;

            for (int j = 0; j < 8; j++)
            {
                int v14 = v11 - key[arrIndex - 1];
                int v16 = v10 - key[arrIndex];
                int v17 = (int) __ROL4__((uint) (v9 * (2 * v9 + 1)), 5);
                int v18 = (int) __ROL4__((uint) (v12 * (2 * v12 + 1)), 5);
                int v19 = v18 ^ (int) __ROR4__((uint) v14, v17);
                int v20 = v9 - key[arrIndex - 3];
                int v21 = v17 ^ (int) __ROR4__((uint) v16, v18);

                int v22 = v12 - key[arrIndex - 2];
                int v23 = (int) __ROL4__((uint) (v21 * (2 * v21 + 1)), 5);
                int v24 = (int) __ROL4__((uint) (v19 * (2 * v19 + 1)), 5);
                int v25 = v24 ^ (int) __ROR4__((uint) v20, v23);
                int v26 = v21 - key[arrIndex - 5];
                int v27 = v23 ^ (int) __ROR4__((uint) v22, v24);

                int v28 = v19 - key[arrIndex - 4];
                int v29 = (int) __ROL4__((uint) (v27 * (2 * v27 + 1)), 5);
                int v30 = (int) __ROL4__((uint) (v25 * (2 * v25 + 1)), 5);
                int v31 = v30 ^ (int) __ROR4__((uint) v26, v29);
                int v32 = v27 - key[arrIndex - 7];
                int v33 = v29 ^ (int) __ROR4__((uint) v28, v30);

                int v34 = (int) __ROL4__((uint) (v33 * (2 * v33 + 1)), 5);
                int v35 = (int) __ROL4__((uint) (v31 * (2 * v31 + 1)), 5);
                v51 = v35 ^ (int) __ROR4__((uint) v32, v34);
                v11 = v34 ^ (int) __ROR4__((uint) (v25 - key[arrIndex - 6]), v35);

                int v37 = v33 - key[arrIndex - 9];
                int v38 = (int) __ROL4__((uint) (v11 * (2 * v11 + 1)), 5);
                int v39 = (int) __ROL4__((uint) (v51 * (2 * v51 + 1)), 5);
                int v40 = (int) __ROR4__((uint) (v31 - key[arrIndex - 8]), v39);
                arrIndex -= 10;
                v9 = v38 ^ v40;
                v41 = v39 ^ (int) __ROR4__((uint) v37, v38);
                v12 = v41;
                v10 = v51;
            }

            WriteDword(outData, outDataOffset / 4 + -3, v41);
            WriteDword(outData, outDataOffset / 4 + -2, v51 - key[0]);
            WriteDword(outData, inDataOffset / 4, v9);
            WriteDword(outData, outDataOffset / 4 + 0, v11 - key[1]);
            inDataOffset += 16;
            outDataOffset += 16;
        }
    }
}