Abstract: Challenge-response can be a secure way of protecting access to any privileged material if implemented correctly. In this document, many options for challenge-response access control are discussed but the most secure method given is presenting a different random challenge on each access attempt and having a response that only the host can interpret without giving out any secrets. This document shows why Dallas Semiconductor/Maxim’s SHA-1 iButtons® and 1-Wire® devices are ideal choices when implementing this kind of challenge-response system. The application note you have requested is available in Acrobat PDF format: APPLICATION NOTE 190: Challenge and Response with 1-Wire SHA devices (PDF, 114kB) A free Acrobat PDF reader is available from: http://www.adobe.com/products/acrobat/readstep.html We Want Your Feedback! Automatic Updates Would you like to be automatically notified when new application notes are published in your areas of interest? Sign up for EE-Mail™. More Information   APP 190: Mar 12, 2002 DS1961S 1kb Protected EEPROM iButton with SHA-1 Engine   DS1963S SHA iButton DS2432 1Kb Protected 1-Wire EEPROM with SHA-1 Engine Abridged Data Sheet (PDF, 408kB)   Download, PDF Format (114kB)  AN190, AN 190, APP190, Appnote190, Appnote 190