Is it possible to emulate a single ticket with mobile NFC?

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Example: Instead of being necessary to pass the ticket in the bus machine, pass the cell phone! Or better.. the TAG identification would be the same on both devices, both ticket and mobile!

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I would say that the best answer to this question is that it is not possible.

Because this is not possible?

To understand this you first need to know how the card used by them works.

I can’t say for sure the card model used by the single ticket, but for information found on the internet it is the most likely that they use the smartcard MIFARE Classic 4K.

Simplifying the functioning of the card let’s just say that this is a card that has 4KB of memory that can have any data written on it, this memory can be read and written by a compatible device, as for example the machine used in buses, at recharging points or even mobile phones with NFC.

But these data are protected, no matter how much a mobile phone with NFC may be able to read and record this data you will not be able to do this with your mobile.

You could try reading the data with some application such as NFC Mifare Classic Scanner, however as the description itself says it needs a key to be able to read and write, and it is this key that protects the data so that they are not read and changed by anyone.

How the card is used?

Contrary to what one might think the card does not only have a TAG that is used to identify the card, in fact the credit information itself is recorded on the card.

I can’t tell you exactly how it was implemented, but it should read your balance directly on the card, subtract the value of the ticket and then record the information back on the card. This probably also includes the date and time when it was last used to allow the cases where they let you change buses for a certain time without having to pay another ticket.

All this is done offline, I do not know if at some point the system present in the bus connects to another system to synchronize some information, but I would say it is very likely that it never happens.

And it’s not hard to understand that their system can actually work offline, as much as one might think that it should connect with a center, it’s easy to realize that it never happens. If he needed to check the balance in a power station he would need some kind of connection with it, as much as you could have a 2G or 3G connection, there will always be areas of shadow, where the network coverage is not good or even does not work, and the response time would be high, the cards usually respond in instants when they approach the reader.

So it’s really not possible?

Perhaps it was possible if you had access to the key used by the card, because it would be necessary for your mobile phone to emulate the functioning of the card, but in practice this is not possible because it would be very easy to defraud the system so.

A person in possession of this key can read and write cards, so it would be possible to copy all the data from the card, so maybe it would be possible to create a software that emulates the card, but it would be a copy of the data, which would work independent of the original, would be the easiest way to defraud their system, if you simply discarded the modifications made during the recording after using the card you would always have the same balance on the card.

Even a few years ago there were news (technoblog,Info) about a possible security breach on these tickets, where a hacker said he was able to read all the data on the card, and as much as he wasn’t able to modify the amount of the balance for example, he said he was able to back up the data, then used all the credit card and finally returned the backup to the card as a result the credits were again available on the card.

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    By the question these solutions are not what he is looking for, since they allow you to check the balance of the ticket on the mobile and charge the same, what he wants seems to me to be a way to use the mobile in place of the ticket on the bus.

  • His comment is valid, @Leandrogodoyrosa, but I think his doubt was a little more basic. In my understanding: "The implementation present on current mobile devices supports emulation of the same behavior presented by the NFC tags used in the Single Ticket service?"

  • from what I understood the solutions posted by you makes the phone work in a way similar to the card reader present in the bus, so it can really be said that it can simulate this same behavior, however the opposite is not valid, make the phone identify itself as if it were the card, which to my understanding is what he wants, simply touch the phone to the bus machine and she read it as if reading the card. I will formulate a reply explaining why this is not possible since it has to do with how the card works.

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Hello. After long nights of study on technology, I believe it is possible to copy the card! It is not possible through a mobile phone, but through a reading and recording device of the same frequency as Mifare. The idea is to capture all the data from the original card, save as file. Then, write the copied data on a second card with the same capacity. When you finish the credits just reset the recorded card through the previous data image...

I believe that the capture of the data in the magnetic field through the complete copy, "without need of any encryption" is possible yes.

  • I don’t think that’s possible because the card requires a key to read the data, the way you say it looks like it simply works as a data storage device, but actually it is more for a hardware that you request the data by passing a password and if the password is correct it returns the data

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