MIFARE Chip Security

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MIFARE Chip Security

• David Carpenter
• April 22, 2008

COSC 4553 Spring 2008 Assignment 11
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Where were headed

• The Chip
• The Crypto
• The Problem
• The Implications
• The Solution

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MIFARE Chips
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Three Concerns

• Authentication
• One Token, One Identifier
• Privacy
• Dont want to send your passport number or fare
  card balance sent in plain text
• Integrity
• Data Stored on Card can only be changed by
  authorized sources
• Oh yeah, and It has to be really, really small

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How does it work?
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Taking it Apart
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Taking it Apart
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Chip Crypto
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The Problem

• Crypto is based on a random number
• Which is only 16 bits
• And is generated based on the time since the card
  was powered on
• Entire Cipher is Linear
• Flaws in Cryptographic function
• Even with only a brute force attack a 100 FPGA
  can crack it in 1 week

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Implications

• Authentication your unique personal ID can be
  discovered and a clone device created
• Privacy Any data sent can be decrypted
• Integrity Protocol weaknesses allow you to
  modify data on the card

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The Solution

• There really isnt a good one the chips are
  just too small
• Currently your best option is a modified DES
  using a single S box
• Some development in porting AES

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Bibliography

• www.nxp.com/products/identification/mifare/
• www.mifare.net
• Henryk Plötz and Karsten Nohl at the Chaos
  Communication Congress in December 2007