The Philadelphia Parking Authority is often criticized for being one of the most taxing entities on everyday people in Philadelphia. In 2007, they reported a revenue of $192 million. Additionally, their expansion results in $11 million in annual red-light camera revenue. This indicates that they collect on average $212 per local driver per year. To understand this better, consider the number of licensed drivers and the population of Philadelphia.
Ticket processing
They manage this through a convenient online ticket payment website at philapark.org. By entering just a ticket number, you can obtain the offender’s license plate number, the date and location of the infraction, and a description of the offense. Due to the predictable sequence of the tickets and their immediate upload to the website, it becomes possible to enumerate all tickets and compile a list of license plates with parking violations, their physical locations, and a record of infractions. This system could potentially be misused to track vehicles.
Example of ticket enumeration
Here is an example of valid ticket numbers:
- 550491336
- 550491344
- 550491351
- 550491369
- 550491377
- 550491385
- 550491393
- 550491401
- 550491419
- 550491427
- 550491435
- 550491443
- 550491450
- 550491468
- 550491476
- 550491484
- 550491492
- 550491500
- 550491518
- 550491526
- 550491534
- 550491542
- 550491559
- 550491567
The last digit of these tickets is a checksum based on digit weights of 1, 2, 1, 2, 1, 2, 1, 2, 1, with an offset of 5 on the last digit. As a recent ticket number is 554682872, enumeration could start from there.
The solution
To address this issue, the following measures could be implemented:
- Restrict the amount of information available on the public web interface.
- Require users to input their license plate number to access ticket details, thereby preventing any unauthorized enumeration.
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Comments
Here is a famous parking ticket... you can use it to look up Justice Scalia's license plate!
William Entriken
https://articles.philly.com/2012-10-17/news/34527154_1_interpretation-of-legal-texts-justice-scalia-ppa-officer/2
Please discuss this topic anywhere and let me know any great comments or media coverage I should link here.