Radius.log - encoding of the username

[snowyrain]

Hello,

i have this lines in the radius.log

Thu Jul 10 08:27:34 2014 : Auth: Login OK: [boetch/<via auth-type="EAP">] (from client WRT1 port 0 via TLS tunnel) username: boetch - shows the remaining output octets
Thu Jul 10 08:27:34 2014 : Auth: Login OK: [436872697374696e612042c3b6747463686572/<via auth-type="EAP">] (from client WRT1 port 1 cli F0-27-65-XX-XX-XX) username: 436872697374696e612042c3b6747463686572 - shows the remaining output octets

It seems that "436872697374696e612042c3b6747463686572" is boetch. But what encoding algorithm is used? I have tried MD5, SHA1, SHA-256 and BASE64. But it isn't.
How can I unencode the username? I use a little php-script to read the log-file. I need the username in cleartext.

Pfsense 2.1 
freeradius package: 2.1.12_1/2.2.0 pkg v1.6.7_2

Thank You

Snowyrain</via></via>