[SNMP4J] Problem Receicing V3 traps - please help

[Scott VanWart]

Hello,

 

I am using SNMP4J to receive V3 traps using MD5 and DES. I am able to
accept the data and I can get up time from the device and the OID, but I
cannot figure out how to decrypt the message being sent by the device.
Below is my code, any suggestions would GREATLY appreciated as I have
been stuck for some days now.

 

 

public synchronized void processPdu(CommandResponderEvent e) 

                        {

                                    PDU command = e.getPDU();

                                    Address source = e.getPeerAddress();

                                    e.setProcessed(true);

                                    String payload = "";

                                    VariableBinding varBinding;

                                    Variable var;

                        

                                    int length = command.size();

 

                                    

                                    

                                    for(int i = 0; i < length; i++)

                                    {

                                                varBinding =
command.get(i);

                                                var =
varBinding.getVariable();

                                                payload =
var.toString();

                                    //          logger.info("SNMP V3
TRAp data:" + payload);

                                    }

                                    

                                    

                                    byte[] data = new
byte[payload.length()];

                                    byte[] ciphertext = null;

                                    data = payload.getBytes();

                                    byte[] result = null;

                                    

                                    try

                                    {

            

                                                

                                    

                                                byte[] dec = new
sun.misc.BASE64Decoder().decodeBuffer(payload);

                                                

                                                PrivDES des = new
PrivDES();

            

                                                

                                                UsmUserEntry user =
snmp.getUSM().getUser(new OctetString("dragon-admin"), new
OctetString("dragon-admin"));

                                                byte[] key =
user.getAuthenticationKey();

                                                byte[] p = new
byte[des.getDecryptParamsLength()];

                                                DecryptParams params =
new DecryptParams(p,0,des.getDecryptParamsLength());

                                                long enginetime = 0;

                                                long engineboots = 0;

                                                

                                                result =
des.decrypt(dec,0,dec.length,key,engineboots,enginetime,params);

                                                

 

 

 

Thanks,

Scott

 

Scott Van Wart

Software Engineer

Direct: 506-462-9117

Email: scott.vanwart at q1labs.com

Q1 Labs Inc - The Nexus of Security and Networking