t() :: %SNMP.USMCredential{ auth: nil | :md5 | :sha, auth_pass: nil | [byte()], priv: nil | :des | :aes, priv_pass: nil | [byte()], sec_level: :noAuthNoPriv | :authNoPriv | :authPriv, sec_model: :usm, sec_name: [byte()], version: :v3 }