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LF_EM4100RSWW — EM4100 Read/Simulate/Write/Wipe/Validate

Author: Łukasz "zabszk" Jurczyk Frequency: LF (125 kHz) Hardware: RDV4 (requires flash memory)

Back to Standalone Modes Index | Source Code | Development Guide

What

An EM4100 multi-tool that adds wipe and validate operations on top of read/simulate/write. Automatically saves read IDs to flash memory for persistence across power cycles.

Why

Unlike RSWB which focuses on brute forcing, RSWW focuses on the clone verification workflow: read a tag, write it to a T55x7, then validate the clone reads back correctly. The wipe function lets you reset T55x7 cards to a blank state. This is the mode to use when:

  • Quality-checking clones: Verify the written data matches the original
  • Preparing blank cards: Wipe T55x7 cards back to factory state
  • Field work with persistence: Read IDs survive reboots via flash

How

  1. READ: Listens for EM4100 tags and stores the ID to flash
  2. EMULATE: Broadcasts the stored ID (defaults to this mode if flash has data from a previous session)
  3. WRITE: Writes the stored ID to a T55x7 tag
  4. VALIDATE: Reads back a T55x7 and compares it to the stored ID to confirm a successful clone
  5. WIPE: Resets a T55x7 tag to its default (empty) configuration

LED Indicators

LED Meaning
A (solid) READ mode active
B (solid) EMULATE mode active
C (solid) VALIDATE mode active
D (solid) WIPE mode active
Blink pattern Success/failure indication after operations

Button Controls

Action Effect
Single click Advance mode (READ → EMULATE → WRITE/VALIDATE)
Hold Toggle between READ and EMULATE
Double-click in READ Enter WIPE mode
USB command Exit standalone mode

State Machine

stateDiagram-v2
    [*] --> READ : Startup (no flash data)
    [*] --> EMULATE : Startup (flash has saved ID)

    READ --> EMULATE : Single click\n(ID captured)
    EMULATE --> READ : Hold (toggle)
    
    EMULATE --> WRITE : Single click
    WRITE --> VALIDATE : Auto after write
    VALIDATE --> EMULATE : Validation complete

    READ --> WIPE : Double-click
    WIPE --> READ : Wipe complete

    READ --> [*] : USB data received
    EMULATE --> [*] : USB data received
Loading

Flash Storage

  • Automatically saves the most recent read ID to SPI flash
  • Loads stored ID on startup; if found, starts in EMULATE mode
  • One slot for persistent storage

Compilation

make clean
make STANDALONE=LF_EM4100RSWW -j
./pm3-flash-fullimage

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