HF Legacy 
MIFARE Classic 1K
For existing access control and hotel systems with lower memory requirements. Only partially readable by smartphone.
Security Broken
Memory 1 KB
MIFARE Classic® EV1 4K: Technical Data, Security and Use
The MIFARE Classic EV1 4K from NXP is a contactless HF RFID chip with 13.56 MHz and 4 KB of EEPROM. It operates according to ISO/IEC 14443 Type A and, with 40 separately configurable sectors, offers significantly more memory than the 1K variant. NXP lists access control, employee ID cards, campus cards, parking systems, public transport and loyalty applications, among others, as fields of application.
Today, MIFARE Classic EV1 4K is mainly of interest for existing systems that need more memory than the 1K variant. The CRYPTO1 encryption it uses was already attacked in practice in 2008. NXP still lists the product family as “Active”, but no longer recommends it for new designs and refers instead to MIFARE® DESFire® Light.
| Feature | Value |
|---|---|
| Manufacturer | NXP Semiconductors |
| Product family | MIFARE Classic EV1 |
| Type designation | MF1S70yyX/V1 |
| RFID class | HF |
| Frequency | 13.56 MHz |
| Standard | ISO/IEC 14443 Type A |
| Data rate | 106 kbit/s |
| EEPROM | 4,096 bytes |
| Memory structure | 40 sectors: 32 × 4 blocks and 8 × 16 blocks, 16 bytes each |
| Standard data blocks | 215 blocks or 3,440 bytes outside the sector trailers and manufacturer block |
| Authentication | Mutual three-pass authentication |
| Encryption | CRYPTO1 |
| Key management | Key A and optionally Key B per sector |
| UID | 7-byte UID or 4-byte NUID, depending on the variant |
| Anti-collision | Yes |
| Read range | up to 100 mm according to NXP, depending on antenna and reader |
| Write cycles | At least 100,000, typically 200,000 at 22 °C |
| Data retention | At least 10 years at 22 °C |
| Smartphone NFC | Limited and device-dependent |
| Product status at NXP | Active – not recommended for new designs |
| Typical media | RFID card, key fob, wristband and special transponders |
| Security rating | Legacy |
| Recommendation | Mainly for existing installations with higher memory requirements |
For MIFARE Classic EV1 4K, NXP specifies 4 KB of EEPROM, 40 sectors, a data rate of 106 kbit/s and an operating distance of up to 100 mm. The memory consists of a total of 256 blocks of 16 bytes each. 40 of them are sector trailers, and block 0 contains the write-protected manufacturer data. This results in 215 regular data blocks with a total of 3,440 bytes.
Typical Applications and Media Formats
MIFARE Classic EV1 4K is used primarily where an existing MIFARE Classic installation needs more memory than the 1K variant. NXP lists access control, employee ID cards, campus cards, public transport systems, parking applications and loyalty systems, among others. The larger sectors can also be used for applications with more extensive data structures. The chip supports special value blocks with commands for incrementing and decrementing stored values.
Typical areas of use are:
- existing access control and ID card systems
- campus and employee ID cards with multiple data areas
- existing canteen and stored-value systems
- parking and ticketing applications
- loyalty and membership applications
Depending on the project, the chip can be used in RFID cards, key fobs, wristbands and special transponders, among others.
Security of MIFARE Classic 4K
Security level: Legacy
Like the 1K variant, MIFARE Classic EV1 4K uses the proprietary stream cipher CRYPTO1. Each of the 40 sectors has its own Key A and can additionally use a Key B. Before a sector is accessed, a mutual three-pass authentication takes place. After successful authentication, CRYPTO1 encrypts the further communication.
The cryptography is now considered broken. Researchers described practical attacks on MIFARE Classic as early as 2008. Further work showed that the complete 48-bit CRYPTO1 key can be reconstructed using known data.
With MIFARE Classic 4K, more memory therefore does not mean more security. The chip may still be required for existing installations. For new access control systems with security requirements, a current chip family should be considered. NXP itself no longer recommends MIFARE Classic EV1 for new designs.
Advantages and Disadvantages of MIFARE Classic 4K
| Advantages | Disadvantages |
|---|---|
|
4 KB EEPROM for existing applications with higher data requirements |
CRYPTO1 is considered cryptographically broken |
| 3,440 bytes of regular data area | More memory does not improve the security level |
| 40 separately configurable sectors | Not recommended by NXP for new designs |
| Value blocks for counter and stored-value applications | Smartphone support not universal |
Alternatives to MIFARE Classic 4K
Depending on the application, memory requirements and security needs, other chip types may be better suited.
HF / NFC Recommendation 
MIFARE DESFire EV3
For new access control, ID card and multi-application systems.
Security AES-128
Memory 2 / 4 / 8 / 16 KB
HF / NFC Recommendation 
NTAG 213 / 215 / 216
For NFC applications with smartphones and NDEF content.
Security PWD
Memory 144–888 B
Frequently Asked Questions about MIFARE Classic 4K
How much memory does MIFARE Classic 4K have?
MIFARE Classic EV1 4K has 4,096 bytes of EEPROM. The memory consists of 40 sectors. The first 32 sectors each contain four blocks, the last eight sectors 16 blocks each. Each block is 16 bytes in size. Of the total of 256 blocks, 40 are reserved as sector trailers for keys and access rights. In addition, there is the manufacturer block in sector 0. Outside these areas, 215 regular data blocks with a total of 3,440 bytes remain. Depending on the configuration, individual bytes of the sector trailers can also be used for data.
How secure is MIFARE Classic 4K?
MIFARE Classic 4K uses the same CRYPTO1 cryptography as the 1K variant. The larger memory therefore brings no security advantage. Practical attacks on CRYPTO1 have been published since 2008. Among other things, the research describes reading out protected memory areas and reconstructing the 48-bit key. The chip should therefore not be used for new applications with high security requirements. NXP still lists MIFARE Classic EV1 as an active product, but no longer recommends it for new designs.
Can MIFARE Classic 4K be read with a smartphone?
Partially. With MifareClassic, Android has its own interface for MIFARE Classic 4K and explicitly lists the 4K variant with 4,096 bytes and 40 sectors. However, implementing this interface is optional for device manufacturers. An Android smartphone with NFC therefore does not automatically support full access to MIFARE Classic. Via Core NFC, Apple provides an interface for sending native commands to compatible ISO/IEC 14443-A tags. However, MIFARE Classic is not listed separately in Apple's list of individually specified product families. For a smartphone application, the desired function should therefore be tested with the intended devices. For simple NFC applications such as URLs or digital business cards, chips from the NTAG family are usually the more suitable choice.
Which readers support MIFARE Classic 4K?
The reader must operate at 13.56 MHz and ISO/IEC 14443 Type A and be able to process MIFARE Classic authentication and memory commands. Support for ISO/IEC 14443 Type A alone is not enough to guarantee functionality in an existing installation. Before each memory access, the system authenticates itself for the respective sector with Key A or Key B. For a replacement order or reorder, the existing reader, the encoding, the key structure and the UID variant used should therefore be checked.
What is the difference between MIFARE Classic 4K and 1K?
The biggest difference is the available memory.
| Feature | Classic 1K | Classic 4K |
|---|---|---|
| EEPROM | 1,024 bytes | 4,096 bytes |
| Sectors | 16 | 40 |
| Regular data blocks | 47 | 215 |
| Regular data area | 752 bytes | 3,440 bytes |
| Cryptography | CRYPTO1 | CRYPTO1 |
The 4K variant is therefore suitable for existing applications that require more data or more separate memory areas. The security level is the same for both variants, as both use CRYPTO1. NXP and Android document the different memory organizations of the two variants.
What is the difference between MIFARE Classic 4K and MIFARE DESFire?
The key difference lies in the security architecture. MIFARE Classic works with CRYPTO1 and a sector-based memory structure. Current products from the MIFARE DESFire family rely on newer cryptographic methods and are therefore better suited for new applications with higher security requirements. NXP itself no longer recommends MIFARE Classic EV1 for new designs and refers to MIFARE DESFire Light as an alternative. For an existing installation, MIFARE Classic 4K can nevertheless be the right choice if the readers and backend expect exactly this chip.
When does MIFARE Classic 4K still make sense today?
The chip makes sense primarily when an existing installation expects MIFARE Classic 4K or the 1K variant offers too little memory for the existing application. Typical cases are replacement cards, additional employee ID cards, existing stored-value or campus applications and a change of media format from card to key fob or wristband. For a new security-critical access control installation, on the other hand, a current chip family should be considered. NXP itself labels MIFARE Classic EV1 as not recommended for new designs.
Is MIFARE Classic 4K still being produced?
Yes. NXP currently lists the MIFARE Classic EV1 1K / 4K product family with the status “Active”. At the same time, the product page notes that it is not recommended for new designs. As an alternative, NXP names MIFARE DESFire Light. MIFARE Classic EV1 4K therefore remains available for existing installations and replacement needs, while a current chip family should be considered for new projects.
Technical sources
Data as of: August 2026
The technical information is based on the NXP product data sheet MF1S70YYX_V1, MIFARE Classic EV1 4K, Rev. 3.2 dated 23 November 2017. Among other things, the data sheet describes the 4,096 bytes of EEPROM, the division into 40 sectors, UID variants, CRYPTO1, operating distance, write cycles and memory organization.
As of August 2026, NXP lists MIFARE Classic EV1 as Active, but as “not recommended for new designs”.
The security assessment takes into account the papers published in 2008 A Practical Attack on the MIFARE Classic by Gerhard de Koning Gans, Jaap-Henk Hoepman and Flavio D. Garcia and Algebraic Attacks on the Crypto-1 Stream Cipher in MiFare Classic and Oyster Cards by Nicolas T. Courtois, Karsten Nohl and Sean O'Neil.
The information on smartphone support is based on the current Android documentation on MifareClassic and Apple's Core NFC documentation. Android explicitly describes the 4K variant with 4,096 bytes and 40 sectors and points out that implementing MifareClassic on an NFC device is optional.
Trademark notice
MIFARE and MIFARE Classic are trademarks of NXP B.V.
The spelling on this page follows the MIFARE Trademark and Branding Guidelines, Rev. 5.2 dated 10 March 2025.