{
  "url": "https://proudtek.com/guides/mifare-classic-1k-4k-chip-encyclopedia/",
  "sourceUrl": "https://proudtek.com/guides/mifare-classic-1k-4k-chip-encyclopedia/",
  "title": "MIFARE Classic 1K / 4K — HF Chip Encyclopedia",
  "description": "The legacy 13.56 MHz access-control chip is the HF 13.56 MHz chip that defined the first two decades of contactless access control. Shipping in volume...",
  "kind": "article",
  "imageUrl": "https://proudtek.com/landing-images/mifare-classic-1k-card.jpg",
  "imageAlt": "NXP MIFARE Classic 1K and 4K card with ISO 14443-A antenna layout",
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    {
      "url": "https://proudtek.com/landing-images/mifare-classic-1k-card.jpg",
      "alt": "NXP MIFARE Classic 1K and 4K card with ISO 14443-A antenna layout"
    }
  ],
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    {
      "name": "MIFARE Classic 1K / 4K — HF Chip Encyclopedia",
      "url": "https://proudtek.com/guides/mifare-classic-1k-4k-chip-encyclopedia/"
    }
  ],
  "summary": [
    "The legacy 13.56 MHz access-control chip is the HF 13.56 MHz chip that defined the first two decades of contactless access control."
  ],
  "faq": [
    {
      "question": "Is MIFARE Classic still safe to use in 2026?",
      "answer": "Not for security-critical deployments. CRYPTO1 was publicly broken in 2008 and commodity tools (Proxmark3, mfoc, mfcuk, hardnested) recover sector keys in seconds to minutes. Classic is still acceptable for low-threat-model uses (canteen loyalty stamps, library checkout, printer-quota cards) where the operational cost of a cloned card is negligible. For hotel locks, building access, transit, or anything touching money or personal data, migrate to MIFARE Plus EV2 or DESFire EV3."
    },
    {
      "question": "What's the difference between MIFARE Classic 1K and 4K?",
      "answer": "Memory size and sector layout. 1K has 16 sectors of 64 bytes each (1,024 bytes total). 4K has 32 small sectors (64 bytes each) plus 8 large sectors (256 bytes each) for 4,096 bytes total. The larger 4K sectors are well-suited to value-block-heavy applications like transit rides or canteen wallets. Command set, CRYPTO1, and 14443-A behavior are identical; the choice is capacity-driven."
    },
    {
      "question": "Can I upgrade a Classic installation to Plus without reissuing cards?",
      "answer": "Partially. MIFARE Plus EV2 in SL1 (Security Level 1) mode is byte-for-byte CRYPTO1-compatible, so an existing reader fleet with CRYPTO1 support can read Plus SL1 cards without firmware changes. Readers then upgrade over time to SL3 (AES-128), and cards are re-keyed to SL3 on next encounter. This lets you replace the card fleet with Plus in one sweep, then retire CRYPTO1 across the reader fleet without a hard cutover. See NXP AN1305 for the canonical migration recipe."
    },
    {
      "question": "Does the Classic UID alone provide any security?",
      "answer": "No. UID can be read by any 14443-A reader without authentication, and UID-changeable clones exist (often sold as 'magic' or 'UID-writable' cards). UID-based whitelists are therefore bypassable by any attacker with a Proxmark3 or similar. Real security on Classic comes from CRYPTO1 authentication, and CRYPTO1 itself is broken. Hence the Plus / DESFire migration recommendation for any deployment where cloning matters."
    },
    {
      "question": "Why does Classic have both Key A and Key B per sector?",
      "answer": "Role separation. The access bits in each Sector Trailer map operations (Read, Write, Increment, Decrement, Transfer, Restore, block-level read of the trailer) to one or both keys. A typical configuration: Key A is the 'read' key (known to many readers in the field), Key B is the 'write' key (known only to a central personalization station). Losing Key A compromises read access for that sector only; Key B remains intact, preventing unauthorized writes. This two-key model is a design advantage Classic retains over simpler HF chips like Ultralight."
    },
    {
      "question": "What is a Value Block and when should I use it?",
      "answer": "A Value Block is a Classic memory block formatted for atomic integer operations: a 4-byte signed value stored twice (inverted) for redundancy, plus a 1-byte address for fault-tolerance. Supported commands are Read, Write, Increment, Decrement, Restore, Transfer. Use them for stored-value wallets and stamp counters where you need a transactional guarantee that an increment survives a power interruption. Regular Data Blocks don't have this atomicity guarantee."
    },
    {
      "question": "Can I tell authentic NXP MIFARE Classic apart from clone silicon?",
      "answer": "Partially. Authentic NXP Classic returns SAK = 0x08 (1K) or 0x18 (4K) and ATQA = 0x0004 / 0x0002, and the manufacturer block 0 first byte is 0x04 on 7-byte UID silicon. Clone silicon (Fudan FM11RF08, Huahong SHC1102, and others) typically matches these externally-visible values because 14443-A compliance requires them. Cryptographic behavior under edge-case commands (like block 0 write attempts or specific timing patterns) can differ. For high-integrity procurement, request NXP-authorized-distributor chain of custody rather than relying on fingerprinting."
    }
  ],
  "procurementFields": [],
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  "coreGuidanceFields": [],
  "articleGuidanceFields": [
    {
      "label": "Best for",
      "value": "MIFARE Classic 1K / 4K — HF Chip Encyclopedia supports RFID and NFC evaluation, comparison, and sourcing decisions."
    },
    {
      "label": "Compare first",
      "value": "Compare MIFARE Classic 1K / 4K — HF Chip Encyclopedia against reader compatibility, chip family, material, and deployment environment."
    },
    {
      "label": "What to confirm",
      "value": "Confirm target application, compatibility requirements, customization needs, quantity, and sample expectations before quoting MIFARE Classic 1K / 4K — HF Chip Encyclopedia."
    }
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  "machineJsonUrl": "https://proudtek.com/machine/guides/mifare-classic-1k-4k-chip-encyclopedia.json",
  "machineTextUrl": "https://proudtek.com/machine/guides/mifare-classic-1k-4k-chip-encyclopedia.txt",
  "author": {
    "name": "Proud Tek Editorial Team",
    "title": "RFID & NFC Technical Content Team",
    "expertise": [
      "RFID manufacturing",
      "NFC technology",
      "Access control systems",
      "Smart card engineering"
    ]
  },
  "publisher": "Proud Tek Co., Limited",
  "datePublished": "2026-04-19",
  "dateModified": "2026-06-10T18:00:00Z",
  "lastReviewedDate": "2026-06-10T18:00:00Z",
  "credentials": [
    "ISO 9001:2015",
    "ISO 14001:2015",
    "RoHS Compliant",
    "CE Marking",
    "REACH Compliant"
  ],
  "generatedAt": "2026-03-16T01:42:30.697Z"
}