Reolink NVR super password

nvrpass.cs

// Calculates the password reset "super password" that reolink support can give you if you forget your NVR password.
// May work only on specific models.
// Original code can be found in the router binary in the firmware files, look for constant 3703 or string "MSG_AUTH_FORGET_PWD_LOGIN"

var key = "1987304876298745017645449830875611094356923076019854398671285463";

string find_key(string seed)
{
    char[] pass = new char[4 * 8];

    pass[0] = key[seed[0] >> 2];
    pass[1] = key[((16 * seed[0]) & 0x30) + (seed[1] >> 4)];
    pass[2] = key[((4 * seed[1]) & 0x3C) + (seed[2] >> 6)];
    pass[3] = key[seed[2] & 0x3F];
    pass[4] = key[seed[3] >> 2];
    pass[5] = key[((16 * seed[3]) & 0x30) + (seed[4] >> 4)];
    pass[6] = key[((4 * seed[4]) & 0x3C) + (seed[5] >> 6)];
    pass[7] = key[seed[5] & 0x3F];
    pass[8] = key[seed[6] >> 2];
    pass[9] = key[((16 * seed[6]) & 0x30) + (seed[7] >> 4)];
    pass[10] = key[(4 * seed[7]) & 0x3C];
    var sum = seed.Select(x => (int)x).Sum();
    pass[11] = key[sum % 10];
    for (int i = 0; i != 12; ++i)
        pass[i] = key[(pass[i]) % 10];
    pass[12] = '\0';
    return new string(pass);
}