Allied Telesis AT-S63 - Manual (Page 201)

AT-S63 Management Software Features Guide
Section IV: SNMPv3 201
SNMPv3 Privacy Protocol
After you have configured an authentication protocol, you have the option
of assigning a privacy protocol if you have the encrypted version of the
AT-S63 software. In SNMPv3 protocol terminology, privacy is equivalent to
encryption. Currently, the DES protocol is the only encryption protocol
supported. The DES privacy protocol requires the authentication protocol
to be configured as either MD5 or SHA.
If you assign a DES privacy protocol to a user, then you are also required
to assign a privacy password. If you choose to not assign a privacy value,
then SNMPv3 messages are sent in plain text format.