In today's daily lives, in order to standardize management, and the safety of personnel and property, the access control is more and more.
When we go out every day, whether it is work or learning, we have to bring a number of access to the card, so when you have a full-featured NFC phone, you can say that all has been changed. Let's talk about how to use the mobile NFC to simulate the principle of the access card.
ID card: Identification Card, mostly low frequency (125kHz), is a unwrewable induction card, including fixed number, mainly in the EM format of Taiwan Syris, US HID, TI, MOTOROLA, etc. Class ID card.
IC card: Integrated Circuit Card, also known as smart card. Most of the high frequency (13.56MHz), readable and write data, large capacity, encryption function, reliable data record, more convenient, such as one card system, consumption system, etc., currently have a Philips MIFARE series card.
Main difference:
ID card, low frequency, unwrapping data, its record content (card number) can only be written once by chip production plant, and developers can only read the card number, and the new number management system cannot be developed according to the actual needs of the system;
IC card, high frequency, not only to read a lot of data from authorized users, but also written to a large amount of data (such as new card users, user information, etc.), the IC card records can be repeatedly erased;
The IC card can also be divided into contact IC cards and non-contact IC cards.
Contact IC card: This class card is read and blind after contacting the contact of the IC card read and write device;
Non-contact IC card: Also known as RF card, inductive IC card, the class card is not connected to the card device, but read / write (eg, RFID, NFC) through non-contact read / write technology, in-chip In addition to the CPU, logical unit, the storage unit, the radio frequency receiving circuit is increased. This type of card is generally used frequently, and the amount of information is relatively small, and the reliability requires high.
Take the M1 card as an example, introduce the IC card data structure.
The M1 card has 16 sectors from 0 to 15, each sector equipped with 4 data segments from 0 to 3, and each data segment can save 16 bytes of content;
Segments in each sector are numbered in 0 ~ 3, in the fourth segment contains Keya (Key A 6 bytes), control bit (4 bytes), keyb (key B 6 bytes), each fan The area can be encrypted separately by the key A or key B which contains it;
The conventional IC card cracking process is as follows:
We can use mobile phones with full-featured NFC to simulate access control cards
In the case of ROOT, you can read the UID and non-encrypted data of the encryption card directly using the App NFC card, and write the UID to the mobile phone NFC.
In the case of unavatable, the door card simulation function comes with the millet system is not allowed to make any operations for the encryption card for security considerations. The NFC of the phone, theoretically read the UID of the encryption IC card, so you can read the UID using third-party software MIFARECLASSICTOL, because there is no root, can not write NFC, but you can write the IC card, so you need a CUID card (cannot be used UID card), a piece of a baby, the idea is to read the UID of the encryption card, read the data of the CUID card, then change the UID of the CUID card to the same UID, will change the modified data Write back to the CUID card, and finally use the door card simulation function that comes with the millet system to copy the unneeded CUID card.
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