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Wherever money is involved, even the small amounts for carparking[1], you're going to have people attacking the system to get free stuff.
And car park machines[2] have extensive audit trails.
[1] an individual stay is quite cheap. Over a year it's a lot of cash.
[2] At least, the Almex Control Systems machines did. As did the TIMTronic and System B and System C and Delta bus ticket machines.
Tips to improve: f(x) = ( x * secret) mod 1000
- mod 10000 instead of mod 1000 (as mentioned in the article)
- make sure the 'x' varies between 0-9999 (e.g. by splitting the number in half and adding the parts 03001909 > 0300+1909 = 2209)
- make sure the 'secret' is larger than 10000 and non-divisible by factors of 10000 (2 and 5) (e.g.: 54321)
Pretty sure it wouldn't be so easy to hack then.
The checksum algorithm they used will only produce 73 different checksums (00000000-99999999: 0-72) - and all of them even. There is space for 9999 different values. Tips to improve: f(x) = ( x * secret) mod 1000 - mod 10000 instead of mod 1000 (as mentioned in the article) - make sure the 'x' varies between 0-9999 (e.g. by splitting the number in half and adding the parts 03001909 > 0300+1909 = 2209) - make sure the…
Edit: If it is really a checksum, it is a crappy one.
Earlier quoted context omitted.
> So just get a new ticket from the entrance Getting a new ticket from the printer before the barrier will be hard if your car is inside the car park. Often the ticket printer will only work if it notices a large metal object (such as a car) in front of the barrier.
Many automated garages ban motorcycles because they're unable to trigger the sensor.
I'm surprised the scheme is so weak. Wherever money is involved, even the small amounts for carparking[1], you're going to have people attacking the system to get free stuff. And car park machines[2] have extensive audit trails. [1] an individual stay is quite cheap. Over a year it's a lot of cash. [2] At least, the Almex Control Systems machines did. As did the TIMTronic and System B and System C and Delta bus ticke…
When they caught him (he parked in the wrong lot or something) he admitted everything, paid $80, and offered to help them catch others doing the same thing.
He told them to change the end-of-day expiry time to 1 minute earlier than normal, tow everyone with a ticket that expires at the usual time.
I'm surprised the scheme is so weak. Wherever money is involved, even the small amounts for carparking[1], you're going to have people attacking the system to get free stuff. And car park machines[2] have extensive audit trails. [1] an individual stay is quite cheap. Over a year it's a lot of cash. [2] At least, the Almex Control Systems machines did. As did the TIMTronic and System B and System C and Delta bus ticke…