17 ms·

Hacking a parking ticket system

140 points by ronreiter 11y ago

DrScump 11y ago
I'm sure this will be a big hit with the legitimate purchasers of the tickets to which those barcodes were assigned... who will find them mysteriously invalid when presented.
- ronreiter 11y ago
  Correct, unless you manage to hop out of the range of the assigned ranges.
troels 11y ago
Nice reasoning. How long did it take you to figure it out?
- ronreiter 11y ago
  About 10 minutes :)
nocsaer1 11y ago
Nice. You have a typo here: f(21) = (23 * 854) % 1000 = 17934 % 1000 = 934. I wouldn't be surprised if the last four digits are some form of built-in barcode error checking, and are not used anywhere else.
samwillis 11y ago
A really simple "hack" of a car park with an entry barrier that issues you a ticket is that you can usually exit the car park with an unpaid ticket if it's under 10 min old. So just get a new ticket from the entrance when you want to leave. They do this so you can get out if there are no spaces. I haven't done this myself and don't condone it. You will probably get in trouble and it's not nice.
- Sujan 11y ago
  And let's add the legal term for it here, so it's clear what this "hack" actually is: Fraud.
  - TeMPOraL 11y ago
    A very relevant xkcd: https://xkcd.com/1494/ https://xkcd.com/1494/.
- jschulenklopper 11y ago
  > 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.
  - tbyehl 11y ago
    Many automated garages ban motorcycles because they're unable to trigger the sensor.
    - bitdivision 11y ago
      Or they make the barriers slightly shorter so that motorcycles can park for free.
      - PantaloonFlames 11y ago
        Which they do, recognizing the fact that if there are a few motorcycles parked in your lot, it makes the whole lot look cooler.
    - clort 11y ago
      Interestingly, I find that on my bicycle I can trigger the sensors in roads (which in the UK seem to be marked by a line of tar, where the sensor has been cut in and sealed up) by angling my front wheel directly along the line - my belief is that it gives a pretty strong signal because the rim of the wheel is a lot closer than a car would be even though they are a heavier chunk of metal (inverse square relationship). In fact my impression at one place I worked was that the sensor gave a stronger signal doing this as the barrier to get out went up quicker for me than it did for cars. I have extrapolated this belief and also believe that the sensors that detect vehicles before traffic lights also give a stronger signal when the rim is close by and the lights choose to turn my way quicker as they think I'm a bus. I can't really verify this though, because I only ever travel by bicycle. Anyway, I guess motorcycles are not quite as maneuverable as a bicycle, so would find it harder to trigger the sensors in this deliberate way.
gus_massa 11y ago
> I'm sure there's a bit more elegant way to find the missing thousand component, but for me it would be just quicker to do a bit of brute-forcing: The calculation the author wants is LastThreeDigits(secret*23) = 642 that is equivalent to secret * 23 == 642 (mod 1000) that is equivalent to secret * 23 + dummy * 1000 = 642 The standard method is to solve this first for 1 instead of 642 other_secret * 23 + other_dummy * 1000 = 1 and this can be solved with the Extended Euclidean Algorithm: https://en.wikipedia.org/wiki/Extended_Euclidean_algorithm https://en.wikipedia.org/wiki/Extended_Euclidean_algorithm (But in this case, and with a computer, it's easier the brute force solution.)
- ronreiter 11y ago
  Thanks!
DanBC 11y ago
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 ticket machines.
- jo909 11y ago
  Car parking is unique because you can always (well ok with certain exceptions in some countries) connect it to a licence plate and thus to the car owner. Where I live the car owner is (again with some exceptions) held responsible, even if he did not drive - or he gives up the driver.
- Drdrdrq 11y ago
  They don't need it to be strong, you are leaving your car and license plate as collateral.
jo-han 11y ago
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 '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.
- nocsaer1 11y ago
  It is probably just a barcode checksum/error code, otherwise they wouldn't have to rely on the values of the first 8 digits. Instead they should generate 4 random digits and store them in the database along with other information, then it basically works like a pin number (and xor it with a proper checksum). Edit: If it is really a checksum, it is a crappy one.
  - jschwartzi 11y ago
    A lot of symbologies support some kind of modulo check digit. It's mostly there to detect erasure and substitution errors, because those are relatively common errors in decode. A modulo sum is better than nothing, considering that each additional digit increases the length of the barcode. If you're length-constrained, then adding more check-data is a difficult trade-off between stronger protection and smaller module size, meaning that you could add so much data that the barcode becomes too dense to print or read.
- andrewla 11y ago
  A secret larger than 10,000 is not useful -- since the multiplication is mod 10,000, the first digit of the secret could be ignored anyway (54321 = 5 * 10000 + 4321 === 4321 mod 10000).
gloves 11y ago
I got about half way through this article before starting to feel inadequate and just looked at the big numbers thinking this guy seems clever.
geekamongus 11y ago
Reminds me of something you'd find in a copy of 2600.
esseti 11y ago
now the question is: why did they choose 854?
- protomyth 11y ago
  That's what I was wondering. ~$ factors 854 854: 2 x 7 x 61 Factoring 854 doesn't seem to help unless those meant something to the person who came up with it (old high school locker combo?).
mabbo 11y ago
A friend of mine in college did this, but it was even simpler- there was no barcode, just a number that increased by one for each ticket sold. He went the entire year just making his own to avoid paying $3 per day. Just take the last three days tickets, increment by the average difference, print and display. 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.
- superuser2 11y ago
  A much simpler "hack" occurred to me recently. Suppose you wanted to store your car for a long time in a gated garage that also holds ZipCars. Drive your car in and take a ticket as normal. When it's time to leave, book a ZipCar for one hour. Grab its parking pass and use it to exit the garage with your car. Park on the street nearby, walk the pass back to the ZipCar. Are there typically countermeasures in place for this? Match the pass to the license plate with ANPR? Don't allow an exit without a corresponding entrance? Sucks for the next person to use the ZipCar. But how will they know it was you? Are video archives good enough to find the plate associated with a particular card swipe without a ton of manual effort? (Assume you're trying to store a car for a month or more. At a fairly normal Chicago visitor parking rate of $25 for 2 hours, that would cost $9,000.)
  - maqr 11y ago
    Eventually, somebody would notice the car there and remove it by tow truck. Most garages need parking passes or have assigned numbers or something. When someone complains is usually when someone gets towed.
    - shkkmo 11y ago
      Your car does have a parking pass displayed, you just use a different one to exit.
  - mankyd 11y ago
interdrift 11y ago
That was too easy.
marnett 11y ago
Over my summer interning in NYC I found even weaker vulnerabilities with the the NY Waterway ferry's e-ticketing system. Trivially cost can go from greater than $296/month (for some routes) --> $0. Fortunate for those who instinctually think of weaknesses in systems.
kej 11y ago
This reminds me of the guy who was caught a few years ago for putting homemade UPC stickers over the printed UPC symbol for expensive LEGO sets so that they'd ring up as inexpensive LEGO sets. After the felony fraud charges, he would have been better off just shoplifting the sets instead.
- DanBC 11y ago
  I can find some stories on the Internet about a wealthy person doing this: http://lego.gizmodo.com/high-profile-silicon-valley-exec-guilty-of-mass-lego-th-1084170411 http://lego.gizmodo.com/high-profile-silicon-valley-exec-gui... http://gizmodo.com/5912141/multimillionaire-software-exec-arrested-in-lego-thieving-bar-code-scam http://gizmodo.com/5912141/multimillionaire-software-exec-ar... http://news.yahoo.com/blogs/technology-blog/incredibly-wealthy-silicon-valley-exec-arrested-complicated-high-185525605.html http://news.yahoo.com/blogs/technology-blog/incredibly-wealt... http://www.mercurynews.com/ci_20675946/silicon-valley-tech-executive-lego-theft-barcode-scheme-charged-sap-toys http://www.mercurynews.com/ci_20675946/silicon-valley-tech-e... But there's this earlier story too: http://www.eurobricks.com/forum/index.php?showtopic=29272 http://www.eurobricks.com/forum/index.php?showtopic=29272
  - soylentcola 11y ago
    Wasn't there a site years ago that hosted images of bar codes for just about any common item sold at chain stores? I seem to remember the idea being that you could just print out something with a lower price that's still believable and stick it on the item before checking out. The idea was that if anyone caught on, you would claim ignorance and apologize. From what I remember this didn't work out well for anyone and was handled as you might expect. I'm definitely not someone who would try to give himself a $500 discount on an HDTV but it got me musing about the scam when it crossed my radar. It always seemed to me that in order to be worth the risk and hassle you'd have to do it on a scale that dramatically increased your chances of getting busted. Like you couldn't give yourself a big discount (obvious at checkout) or give yourself lots of little discounts (more chances to get noticed) so aside from the "heehee I found a dirty trick" aspect, it seemed like kind of a terrible scheme (not even counting the fact that you're engaging in fraud).
deleted 11y ago
[deleted]
dsfyu404ed 11y ago
Over a summer I lived in "intern housing" at a university in the DC area. They wanted $150 for parking for 2mo, yeah, nope. A little bit of research told me that the parking services were a separate entity from the school and that the school would put a hold on my student account and transcripts if there were unpaid charges. I also found that they supposedly boot you after 3 tickets. Tickets are $100 minimum and go up by $50 for every unpaid 30 days. As someone who never took and classes from them they didn't have much leverage over me. I just pulled my front plate, got a few spare plates from the junkyard and slapped one over my real plate when I got home for the night making sure no one plate had more than three tickets. For ~$3 day it was well worth the hassle. They're still sending me notices every two months about my unpaid fine for the one time they ticketed me with my real plate. Seriously, the easiest way to abuse (private) parking systems is usually to make them write the ticket to a plate that doesn't come back to you. Another "hack" was that the parking gates at most public garages in the DC area had a rubber sweep on the bottom and were tall enough that most 90s compacts could squeeze under if you retract the antenna, saves about $6 per usage.
- rconti 11y ago
  That's risky because they may be able to look up your car by VIN. You'd probably need to randomize it by parking in different locations every day, hoping that you get different meter maids who wouldn't recognize your car. Your car would also have to be so generic in appearance (not just model/color but also condition) that it didn't stand out.
  - dsfyu404ed 11y ago
    My truck was anything but generic. I got tailed by the campus pigs (I'll call them that because that was my experience with them) and stopped several times for no reason (and let off with a "warning" because whatever I had done wasn't something one normally gets cited for, they basically wanted to check my papers and see who I was) because my truck was a decade too old and and several tax brackets too low to be common in that area. They always seemed to see me like I was some tweaker who might steal and scrap their aluminum hand rails to get my next fix. I figured out that parking way out back significantly reduced my chance of being ticketed. More than once I saw the parking services truck drive up and down the rows making sure everyone had something in each windshield, not actually scanning them. This was during the summer so there was always parking available and 90% of the enforcement I saw was during the first two weeks when everyone moved in. The permits were a paper with a bar-code displayed in the center of your dash (students got ones that hang from mirrors). I thought of just putting a piece of paper there but I figured any attempt fake would piss them off. The policy was worded such that it made it sound like you only got booted after three UNPAID violations so I think what was happening was that when they put each new plate (all three I used were from the same state) into the system it didn't tell them to boot it because no plate had more than three citations on it. I got six tickets over the course of the summer. Two, two and one on junkyard plates and one on my real plate. Parking in the same place with a ticket under your wiper would probably work for awhile too. When I looked on their online parking pass system I don't recall a way to input a VIN so I assume they didn't record it, just a photo that includes the plate and a description. Like I said, I wouldn't do this somewhere that the municipality does the parking enforcement.
stcredzero 11y ago
One of the Dr. Dobbs editors made the following confession years ago in an editorial, when Dr. Dobbs was still published on glossy magazine paper. (According to the text, the statute of limitations had already run out.) When faced with the situation of working on a mainframe at city hall, but not being issued a city parking permit due to bureaucratic oversight, he came up with a solution in code. It just so happened that the system he was working on issued the parking tickets, so he just added conditional logic to detect his name, then deleted the ticket! Problem solved, and no bureaucratic runaround to solve it!
wbsgrepit 11y ago
I think he is forgetting that the barcode is generated and exits not in a silo but with knowledge of a controller. I would be amazed if the system did not both track the barcode creation and exit events and trigger protocols on any outside system event. Print out your card at home, park at lot, scan to checkout, your barcode is in one of three states: 1: Not valid because it has not been issued by the controller, 2: Valid and first use (you left before the other car on the lot with the duplicated barcode has exited), 3: Invalid because it has already been used on exit (the duplicate barcode has already left the lot). In what scenario given an active controller that is not braindead would this give you any kind of advantage? You are more likely than not going to be in a situation where you trigger an alarm on exit.

140 points by ronreiter 11y ago

I'm sure this will be a big hit with the legitimate purchasers of the tickets to which those barcodes were assigned... who will find them mysteriously invalid when presented.

ronreiter 11y ago
Correct, unless you manage to hop out of the range of the assigned ranges.

troels 11y ago

Nice reasoning. How long did it take you to figure it out?

ronreiter 11y ago
About 10 minutes :)

nocsaer1 11y ago

Nice. You have a typo here: f(21) = (23 * 854) % 1000 = 17934 % 1000 = 934. I wouldn't be surprised if the last four digits are some form of built-in barcode error checking, and are not used anywhere else.

samwillis 11y ago

A really simple "hack" of a car park with an entry barrier that issues you a ticket is that you can usually exit the car park with an unpaid ticket if it's under 10 min old. So just get a new ticket from the entrance when you want to leave. They do this so you can get out if there are no spaces. I haven't done this myself and don't condone it. You will probably get in trouble and it's not nice.

Sujan 11y ago
And let's add the legal term for it here, so it's clear what this "hack" actually is: Fraud.
- TeMPOraL 11y ago
  A very relevant xkcd: https://xkcd.com/1494/ https://xkcd.com/1494/.
jschulenklopper 11y ago
> 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.
- tbyehl 11y ago
  Many automated garages ban motorcycles because they're unable to trigger the sensor.
  - bitdivision 11y ago
    Or they make the barriers slightly shorter so that motorcycles can park for free.
    - PantaloonFlames 11y ago
      Which they do, recognizing the fact that if there are a few motorcycles parked in your lot, it makes the whole lot look cooler.
  - clort 11y ago
    Interestingly, I find that on my bicycle I can trigger the sensors in roads (which in the UK seem to be marked by a line of tar, where the sensor has been cut in and sealed up) by angling my front wheel directly along the line - my belief is that it gives a pretty strong signal because the rim of the wheel is a lot closer than a car would be even though they are a heavier chunk of metal (inverse square relationship). In fact my impression at one place I worked was that the sensor gave a stronger signal doing this as the barrier to get out went up quicker for me than it did for cars. I have extrapolated this belief and also believe that the sensors that detect vehicles before traffic lights also give a stronger signal when the rim is close by and the lights choose to turn my way quicker as they think I'm a bus. I can't really verify this though, because I only ever travel by bicycle. Anyway, I guess motorcycles are not quite as maneuverable as a bicycle, so would find it harder to trigger the sensors in this deliberate way.

gus_massa 11y ago

> I'm sure there's a bit more elegant way to find the missing thousand component, but for me it would be just quicker to do a bit of brute-forcing: The calculation the author wants is LastThreeDigits(secret*23) = 642 that is equivalent to secret * 23 == 642 (mod 1000) that is equivalent to secret * 23 + dummy * 1000 = 642 The standard method is to solve this first for 1 instead of 642 other_secret * 23 + other_dummy * 1000 = 1 and this can be solved with the Extended Euclidean Algorithm: https://en.wikipedia.org/wiki/Extended_Euclidean_algorithm https://en.wikipedia.org/wiki/Extended_Euclidean_algorithm (But in this case, and with a computer, it's easier the brute force solution.)

ronreiter 11y ago
Thanks!

DanBC 11y ago

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 ticket machines.

jo909 11y ago
Car parking is unique because you can always (well ok with certain exceptions in some countries) connect it to a licence plate and thus to the car owner. Where I live the car owner is (again with some exceptions) held responsible, even if he did not drive - or he gives up the driver.
Drdrdrq 11y ago
They don't need it to be strong, you are leaving your car and license plate as collateral.

jo-han 11y ago

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 '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.

nocsaer1 11y ago
It is probably just a barcode checksum/error code, otherwise they wouldn't have to rely on the values of the first 8 digits. Instead they should generate 4 random digits and store them in the database along with other information, then it basically works like a pin number (and xor it with a proper checksum). Edit: If it is really a checksum, it is a crappy one.
- jschwartzi 11y ago
  A lot of symbologies support some kind of modulo check digit. It's mostly there to detect erasure and substitution errors, because those are relatively common errors in decode. A modulo sum is better than nothing, considering that each additional digit increases the length of the barcode. If you're length-constrained, then adding more check-data is a difficult trade-off between stronger protection and smaller module size, meaning that you could add so much data that the barcode becomes too dense to print or read.
andrewla 11y ago
A secret larger than 10,000 is not useful -- since the multiplication is mod 10,000, the first digit of the secret could be ignored anyway (54321 = 5 * 10000 + 4321 === 4321 mod 10000).

gloves 11y ago

I got about half way through this article before starting to feel inadequate and just looked at the big numbers thinking this guy seems clever.

geekamongus 11y ago

Reminds me of something you'd find in a copy of 2600.

esseti 11y ago

now the question is: why did they choose 854?

protomyth 11y ago
That's what I was wondering. ~$ factors 854 854: 2 x 7 x 61 Factoring 854 doesn't seem to help unless those meant something to the person who came up with it (old high school locker combo?).

mabbo 11y ago

A friend of mine in college did this, but it was even simpler- there was no barcode, just a number that increased by one for each ticket sold. He went the entire year just making his own to avoid paying $3 per day. Just take the last three days tickets, increment by the average difference, print and display. 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.

superuser2 11y ago
A much simpler "hack" occurred to me recently. Suppose you wanted to store your car for a long time in a gated garage that also holds ZipCars. Drive your car in and take a ticket as normal. When it's time to leave, book a ZipCar for one hour. Grab its parking pass and use it to exit the garage with your car. Park on the street nearby, walk the pass back to the ZipCar. Are there typically countermeasures in place for this? Match the pass to the license plate with ANPR? Don't allow an exit without a corresponding entrance? Sucks for the next person to use the ZipCar. But how will they know it was you? Are video archives good enough to find the plate associated with a particular card swipe without a ton of manual effort? (Assume you're trying to store a car for a month or more. At a fairly normal Chicago visitor parking rate of $25 for 2 hours, that would cost $9,000.)
- maqr 11y ago
  Eventually, somebody would notice the car there and remove it by tow truck. Most garages need parking passes or have assigned numbers or something. When someone complains is usually when someone gets towed.
  - shkkmo 11y ago
    Your car does have a parking pass displayed, you just use a different one to exit.
- mankyd 11y ago

interdrift 11y ago

That was too easy.

marnett 11y ago

Over my summer interning in NYC I found even weaker vulnerabilities with the the NY Waterway ferry's e-ticketing system. Trivially cost can go from greater than $296/month (for some routes) --> $0. Fortunate for those who instinctually think of weaknesses in systems.

kej 11y ago

This reminds me of the guy who was caught a few years ago for putting homemade UPC stickers over the printed UPC symbol for expensive LEGO sets so that they'd ring up as inexpensive LEGO sets. After the felony fraud charges, he would have been better off just shoplifting the sets instead.

DanBC 11y ago
I can find some stories on the Internet about a wealthy person doing this: http://lego.gizmodo.com/high-profile-silicon-valley-exec-guilty-of-mass-lego-th-1084170411 http://lego.gizmodo.com/high-profile-silicon-valley-exec-gui... http://gizmodo.com/5912141/multimillionaire-software-exec-arrested-in-lego-thieving-bar-code-scam http://gizmodo.com/5912141/multimillionaire-software-exec-ar... http://news.yahoo.com/blogs/technology-blog/incredibly-wealthy-silicon-valley-exec-arrested-complicated-high-185525605.html http://news.yahoo.com/blogs/technology-blog/incredibly-wealt... http://www.mercurynews.com/ci_20675946/silicon-valley-tech-executive-lego-theft-barcode-scheme-charged-sap-toys http://www.mercurynews.com/ci_20675946/silicon-valley-tech-e... But there's this earlier story too: http://www.eurobricks.com/forum/index.php?showtopic=29272 http://www.eurobricks.com/forum/index.php?showtopic=29272
- soylentcola 11y ago
  Wasn't there a site years ago that hosted images of bar codes for just about any common item sold at chain stores? I seem to remember the idea being that you could just print out something with a lower price that's still believable and stick it on the item before checking out. The idea was that if anyone caught on, you would claim ignorance and apologize. From what I remember this didn't work out well for anyone and was handled as you might expect. I'm definitely not someone who would try to give himself a $500 discount on an HDTV but it got me musing about the scam when it crossed my radar. It always seemed to me that in order to be worth the risk and hassle you'd have to do it on a scale that dramatically increased your chances of getting busted. Like you couldn't give yourself a big discount (obvious at checkout) or give yourself lots of little discounts (more chances to get noticed) so aside from the "heehee I found a dirty trick" aspect, it seemed like kind of a terrible scheme (not even counting the fact that you're engaging in fraud).

deleted 11y ago

[deleted]

dsfyu404ed 11y ago

Over a summer I lived in "intern housing" at a university in the DC area. They wanted $150 for parking for 2mo, yeah, nope. A little bit of research told me that the parking services were a separate entity from the school and that the school would put a hold on my student account and transcripts if there were unpaid charges. I also found that they supposedly boot you after 3 tickets. Tickets are $100 minimum and go up by $50 for every unpaid 30 days. As someone who never took and classes from them they didn't have much leverage over me. I just pulled my front plate, got a few spare plates from the junkyard and slapped one over my real plate when I got home for the night making sure no one plate had more than three tickets. For ~$3 day it was well worth the hassle. They're still sending me notices every two months about my unpaid fine for the one time they ticketed me with my real plate. Seriously, the easiest way to abuse (private) parking systems is usually to make them write the ticket to a plate that doesn't come back to you. Another "hack" was that the parking gates at most public garages in the DC area had a rubber sweep on the bottom and were tall enough that most 90s compacts could squeeze under if you retract the antenna, saves about $6 per usage.

rconti 11y ago
That's risky because they may be able to look up your car by VIN. You'd probably need to randomize it by parking in different locations every day, hoping that you get different meter maids who wouldn't recognize your car. Your car would also have to be so generic in appearance (not just model/color but also condition) that it didn't stand out.
- dsfyu404ed 11y ago
  My truck was anything but generic. I got tailed by the campus pigs (I'll call them that because that was my experience with them) and stopped several times for no reason (and let off with a "warning" because whatever I had done wasn't something one normally gets cited for, they basically wanted to check my papers and see who I was) because my truck was a decade too old and and several tax brackets too low to be common in that area. They always seemed to see me like I was some tweaker who might steal and scrap their aluminum hand rails to get my next fix. I figured out that parking way out back significantly reduced my chance of being ticketed. More than once I saw the parking services truck drive up and down the rows making sure everyone had something in each windshield, not actually scanning them. This was during the summer so there was always parking available and 90% of the enforcement I saw was during the first two weeks when everyone moved in. The permits were a paper with a bar-code displayed in the center of your dash (students got ones that hang from mirrors). I thought of just putting a piece of paper there but I figured any attempt fake would piss them off. The policy was worded such that it made it sound like you only got booted after three UNPAID violations so I think what was happening was that when they put each new plate (all three I used were from the same state) into the system it didn't tell them to boot it because no plate had more than three citations on it. I got six tickets over the course of the summer. Two, two and one on junkyard plates and one on my real plate. Parking in the same place with a ticket under your wiper would probably work for awhile too. When I looked on their online parking pass system I don't recall a way to input a VIN so I assume they didn't record it, just a photo that includes the plate and a description. Like I said, I wouldn't do this somewhere that the municipality does the parking enforcement.

stcredzero 11y ago

One of the Dr. Dobbs editors made the following confession years ago in an editorial, when Dr. Dobbs was still published on glossy magazine paper. (According to the text, the statute of limitations had already run out.) When faced with the situation of working on a mainframe at city hall, but not being issued a city parking permit due to bureaucratic oversight, he came up with a solution in code. It just so happened that the system he was working on issued the parking tickets, so he just added conditional logic to detect his name, then deleted the ticket! Problem solved, and no bureaucratic runaround to solve it!

wbsgrepit 11y ago

I think he is forgetting that the barcode is generated and exits not in a silo but with knowledge of a controller. I would be amazed if the system did not both track the barcode creation and exit events and trigger protocols on any outside system event. Print out your card at home, park at lot, scan to checkout, your barcode is in one of three states: 1: Not valid because it has not been issued by the controller, 2: Valid and first use (you left before the other car on the lot with the duplicated barcode has exited), 3: Invalid because it has already been used on exit (the duplicate barcode has already left the lot). In what scenario given an active controller that is not braindead would this give you any kind of advantage? You are more likely than not going to be in a situation where you trigger an alarm on exit.