Want to secure communication using CoAP DTLS, this is the other bosses, the source of the down but no matter what happen to the server and client connection, seek a solution, there is something wrong with the certificate??
Server:

 const coap=the require (' coap)//or coap 
Const path=the require (" path "); 

//var SegfaultHandler=the require (' segfault - handler '); 

//SegfaultHandler. RegisterHandler (" crash log ");//With no argument, SegfaultHandler will generate a generic log file name 

Const dtls_opts={
Key: the path. The join (__dirname, '../test/private. Der '), 
The debug: 1, 
HandshakeTimeoutMin: 3000 
}; 


Const server=coap. CreateServer (
{
DTLS: dtls_opts, 
Port: 5684, 
} 
); 

Server on (' request ', function (the req, res) {
The console. The log (' request arrives: \ n '+ JSON. The stringify (the req)); 
Res. The end (' Hello '+ the req. Url. The split ('/') [1] +' \ n ') 
}) 

Server. Listen (function () {
The console. The log (' server started ') 
}); 

Client:

 var coap=the require (' coap)//or coap 


//var SegfaultHandler=the require (' segfault - handler '); 

//SegfaultHandler. RegisterHandler (" crash log ");//With no argument, SegfaultHandler will generate a generic log file name 

Var dtls_opts={
//PSK: new Buffer (' AAAAAAAAAAAAAAAA), 
//PSKIdent: new Buffer (" 32323232-3232-3232-3232-323232323232), 
PSK: Buffer. The from (" AAAAAAAAAAAAAAAA "), 
PSKIdent: Buffer. The from (" 32323232-3232-3232-3232-323232323232), 
Key: null, 
PeerPublicKey: null 
}; 

Var the req=coap. Request (' coaps://127.0.0.1:5684/client ', 
Dtls_opts, 
(the req)=& gt; {
The req. On (' response ', function (res) {
Res. Pipe (process. Stdout) 
}); 
The req. End (); 
} 
);