.\" $OpenBSD: wpa-psk.8,v 1.3 2010/08/27 07:50:38 jmc Exp $
.\"
.\" Copyright (c) 2008 Damien Bergamini <damien.bergamini@free.fr>
.\"
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.Dd $Mdocdate: August 27 2010 $
.Dt WPA-PSK 8
.Os
.Sh NAME
.Nm wpa-psk
.Nd passphrase to WPA pre-shared key mapping
.Sh SYNOPSIS
.Nm
.Ar ssid
.Ar passphrase
.Sh DESCRIPTION
.Nm
generates a 256-bit pre-shared key from a service set identifier (SSID) and
a passphrase.
The passphrase must be a sequence of between 8 and 63 ASCII-encoded
characters.
The length of the SSID must be between 1 and 32 octets.
.Pp
.Nm
prints the generated pre-shared key to stdout as a series of 64 hexadecimal
digits preceded by
.So 0x Sc .
The output is intended to be passed to
.Xr ifconfig 8
via the
.Cm wpapsk
option.
The
.Ar ssid
parameter should be the same as the
.Ar nwid
parameter passed to
.Xr ifconfig 8
via the
.Cm nwid
option.
.Pp
To generate the pre-shared key,
.Nm
uses the Password-Based Key Derivation Function 2 (PBKDF2).
The passphrase is hashed 4096 times using HMAC-SHA1.
.Sh SEE ALSO
.Xr ifconfig 8
.Rs
.%R IEEE Std 802.11i
.%T Medium Access Control (MAC) Security Enhancements
.%D 2004
.Re
.Rs
.%R PKCS #5 v2.0
.%T Password-Based Cryptography Standard
.%D 1999
.Re
.Rs
.%R RFC 3174
.%T US Secure Hash Algorithm 1 (SHA1)
.%D 2001
.Re