# OPIE Authentication System

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> Markdown URL: https://mediated.wiki/source/OPIE_Authentication_System.md
> Source: https://en.wikipedia.org/wiki/OPIE_Authentication_System
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> License: Creative Commons Attribution-ShareAlike 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/)

{{Short description|One-time password authentication system}}
{{more citations|date=May 2023}}
'''OPIE''' is the initialism of "One time Passwords In Everything". 
Opie is a [mature](/source/Capability_Maturity_Model), [Unix-like](/source/Unix-like) login and [password](/source/password) package 
installed on the server and the client which makes untrusted networks safer against password-sniffing [packet-analysis](/source/packet_analyzer) software like [dSniff](/source/dSniff) and safe against [shoulder surfing](/source/Shoulder_surfing_(computer_security)).
It works by circumventing the delayed attack method because the same password is never used twice after installing Opie.  
OPIE implements a [one-time password](/source/one-time_password) (OTP) scheme based on [S/KEY](/source/S%2FKEY), which will require a secret [passphrase](/source/passphrase) to generate a password for the current session, or a list of passwords.

OPIE uses an MD4 or MD5 [hash function](/source/hash_function) to generate passwords.

OPIE can restrict its logins based on IP address. It uses its own [passwd](/source/passwd_(command)) and login modules.

If the [Enter key](/source/Enter_key) {{keypress|Enter}} is pressed at the password prompt, it will turn echo on, so what is being typed can be seen when entering an unfamiliar password from a printout.

OPIE can improve security when accessing online banking at conferences, hotels and airports. Some countries require banks to implement OTP.

OPIE shipped with [DragonFly BSD](/source/DragonFly_BSD), [FreeBSD](/source/FreeBSD) and [OpenSUSE](/source/OpenSUSE). It can be installed on a Unix-like server and clients for improved security.

The commands are 
*<code>opiepasswd</code>
*<code>opiekey</code>

==See also==
* [OTPW](/source/OTPW)

==External links==
* [http://wiki.linuxquestions.org/wiki/Opie OPIE @ Linux wiki]
* [http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/one-time-passwords.html Opie text from FreeBSD Manual]

Cryptographic software | Password authentication

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{{Unix-stub}}

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Adapted from the Wikipedia article [OPIE Authentication System](https://en.wikipedia.org/wiki/OPIE_Authentication_System) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/OPIE_Authentication_System?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.