Secure iButton

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Revision as of 14:45, 29 December 2012 by Bertrik Sikken (Talk | contribs)

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Project Secure iButton
Status Initializing
Contact User:Bertrik Sikken
Last Update 2012-12-29

This project is about investigating and using the secure features of the iButton that people currently use for physical access to RevSpace.

Planned project phases are:

  • phase 1: investigate possbilities of the iButton and experiment with it
  • phase 2: write software for the iButton functionality and package it into a library
  • phase 3: apply knowledge and software for application within RevSpace

iButton investigation

The iButton used at RevSpace is the !DS1961, with the following features

  • 4 pages of 32-byte user data each
  • an 8-byte "secret"
  • SHA-1 algorithm that can calculate a hash over a 32-byte user data page, the 8-byte secret, a 3-byte "challenge" and the unique iButton id.

Basically authentication could work like this:

  • user presents iButton to the reader
  • reader reads the unique iButton id
  • ...

DS1961 library

This library provides an API for the DS1961 specific functions. It will be targeted at the Arduino microcontroller, to run on top of the existing 1-wire library.


We could apply this to improve the security of RevSpace access.