Mifare represents a family of contactless smart cards manufactured by NXP Semiconductors that adhere to the ISO14443A international standard. This series includes multiple variants such as Mifare S50, S70, UltraLight, Pro, and Desfire, each designed for specific applications ranging from access control to electronic payments.
The Origins and Industry Impact of Mifare
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The Name "Mifare" and Its History
The terminology “Mifare” originated in 1998 when Philips acquired Mikron, a Swiss company that had developed the “MIkron FARE Collection System.” This electronic fare collection platform became abbreviated as “Mifare,” establishing the foundation for what would become a dominant force in RFID technology.
Industry Terminology and Card Classification
Within the industry, Mifare cards are commonly referred to using shorthand designations:
MF0: Mifare UltraLight
MF1: Mifare S50 and S70
MF2: Mifare Pro
MF3: Mifare Desfire
Due to Mifare’s market dominance, many RFID cards complying with ISO14443A standards are often generically called “Mifare” cards, particularly the Mifare S50, which has become virtually synonymous with the standard itself.
Technical Specifications: Core ISO14443A Compliance
All Mifare series cards share fundamental technical characteristics based on ISO14443A requirements:
Basic Operational Parameters
Card Type: Proximity Cards (PICC) with maximum read range of 10cm
Frequency: 13.56MHz ±7KHz carrier frequency
Power Source: Passive operation powered by reader’s RF field
Field Strength: Operational within 1.5A/m to 7.5A/m magnetic field intensity
Communication Protocols
Initialization: Cards initialize upon entering RF field then await commands
Communication Model: Reader-talks-first (RTF) protocol
Modulation: 100% ASK modulated Modified Miller code (reader to card)
Response: Subcarrier modulated Manchester code (card to reader)
Data Transfer Rates
Mifare cards support multiple communication speeds:
106 KBPS (mandatory before card selection)
212 KBPS
424 KBPS
847 KBPS
The fundamental 106Kbps rate derives from 128-frequency division of the 13.56MHz carrier frequency.
Card States and Operational Workflow
State Transition Diagram
Mifare cards progress through distinct operational states:
Power-Off: Outside RF field
Idle: Enters RF field, powered and reset
Ready: Receives reader call command
Active: Selected and operational
Halt: Enters sleep mode after hibernation command or unknown instruction
Global Identification and Anti-Collision
Each card contains a globally unique serial number (4, 7, or 10 bytes)
Multiple cards in RF field follow bit-oriented anti-collision mechanism
Readers can selectively operate on individual cards while putting others to sleep
Card Selection Process: Anti-Collision Mechanism
Initial Card Activation
The selection process involves two critical steps from field entry to card selection:
Reader Calling Methods:
REQA (0x26): Calls only Idle state cards
WAKE-UP (0x52): Activates all cards (Idle and Halt states)
ATQA Response:
After receiving call commands, cards respond with Answer To Request (ATQA):
First byte: Reserved for future use (RFU)
Second byte: b7b6 bits indicate serial number length, b4-b0 bits confirm anti-collision compliance
Common Card Type Identifiers
While ATQA values commonly identify card types, this practice isn’t strictly standardized:
Mifare S50: 0004H
Mifare S70: 0002H
Mifare UltraLight: 0044H
Mifare Light: 0010H
Mifare Desfire: 0344H
Anti-Collision and Selection Commands
The anti-collision process uses identical command codes with varying serial number confirmation:
Key Characteristics:
Each anti-collision cycle requires 32-bit serial number participation
Anti-collision commands lack CRC_A check; selection commands include it
Cascade levels accommodate different serial number lengths:
4 bytes: Command 0x93
7 bytes: Cascade Level 1 (0x93), Level 2 (0x95)
10 bytes: Three cascade levels (0x93, 0x95, 0x97)
Cascade Markers:
For 3-byte serial number segments, cards automatically prepend 0x88 cascade tag to complete 32-bit requirement.
Selection Acknowledgment (SAK)
After successful selection, cards respond with Select Acknowledge (SAK) indicating:
Need for additional anti-collision cycles
Compliance with ISO14443-4 standard
Summary Table: Mifare Card Series Comparison
| Feature | Mifare S50 | Mifare S70 | Mifare UltraLight | Mifare Desfire |
|---|---|---|---|---|
| Designation | MF1 | MF1 | MF0 | MF3 |
| ATQA Value | 0004H | 0002H | 0044H | 0344H |
| Memory Capacity | 1KB | 4KB | 512 bits | Variable (2KB-8KB) |
| Serial Number | 4 bytes | 4 bytes | 7 bytes | 7 bytes |
| Security | Crypto1 | Crypto1 | Basic | AES, 3DES |
| Anti-Collision | 1 level (0x93) | 1 level (0x93) | 2 levels (0x93, 0x95) | 2 levels (0x93, 0x95) |
| ISO14443-4 | No | No | No | Yes |
| Typical Use | Access Control, Transportation | High-capacity applications | disposable tickets, events | Secure applications, payments |
