Defeating a 40-year-old copy protection dongle
70 points by classichasclass
70 points by classichasclass
Great read. I love this stuff. I wish to see the source code when it’s ready.
Amazing, the dongle simply returned a fixed number, 0x7606.
Well no, the routine that talked to the dongle always returned that value. I haven't looked too closely but it seems that the code there may be doing some slightly more complex authentication. The one byte returned from the function (and a constant) was possibly just to make the code slightly harder to patch out as opposed to just returning 1/0.
Plus, a lot of dongles had a mode where you could send what is essentially a challenge-response mechanism and fail if the expected bytes were wrong. Some C64 software used this type of authentication with joystick dongles. Those routines tended to be heavily obfuscated or do unexpected protection checks later. This particular dongle usage was very simplistic, but maybe that's all it had to be for the target audience.
Lack of support or age does not make dmca anti-circumvention restrictions expire... That really bums me out.