var bitcore = require('bitcore-lib');
var ECIES = require('bitcore-ecies');
var message = "foobar";

var testIdentity= {
            type: 'ethereum',
            display: '0xedc8774555d634ec3cdc755296382d572de2a492',
            privateKey: '1d71471e33462a2484cd828643da29f2f643e2f55f6922c16c9a9df2982f408c',
            publicKey: '644c70f5c80c0e0d950659fc3a5ca3e4079072af5b89bdc3d74bf4c43cda5202d294070d3712dc15a1667f1be8541ea5d587b9c041670ce351d031e5c9df563d',
            foreign: false
        };


    /**
     * encrypt the message with the publicKey of identity
     * @param  {{privateKey: ?string, publicKey: string}} identity
     * @param  {string} message
     * @return {string}
     */
    var pkiEncrypt = function(identity, message) {

        /*
         * this key is used as false sample, because bitcore would crash when alice has no privateKey
         */
        var privKey = new bitcore.PrivateKey('1d71471e33462a2484cd828643da29f2f643e2f55f6922c16c9a9df2982f408c');
          console.log("private key=>" + privKey);
        var alice = ECIES().privateKey(privKey).publicKey(new bitcore.PublicKey(identity.publicKey));
        console.log("Alice's public key=>" + alice);
        var encrypted = alice.encrypt(message);
        console.log("encrypted message by public key of Alice=>"+ encrypted.toString('hex'));

        return encrypted.toString('hex');
    };

    /**
     * decrypt the message with the privateKey of identity
     * @param  {{privateKey: ?string, publicKey: string}}   identity
     * @param  {string}   encrypted
     * @return {string}   message
     */
    var pkiDecrypt = function(identity, encrypted) {
        var privKey = new bitcore.PrivateKey(identity.privateKey);
        console.log("Alice Private key=> " + privKey);
        var alice = ECIES().privateKey(privKey);
        console.log("Allice private key again=>" + alice);
        var decryptMe = new Buffer(encrypted, 'hex');
        console.log("decrypted message=>" + decryptMe);
        var decrypted = alice.decrypt(decryptMe);
        console.log("final decrypted message=>"+decrypted.toString('ascii'));
        return decrypted.toString('ascii');
    };


var enc = pkiEncrypt(testIdentity, message);
var dec = pkiDecrypt(testIdentity, enc);

if(dec!=message){
  console.log("failure");
}else{
  console.log("Success");
}

$ node pki_Stack_Exchange.js
private key=>1d71471e33462a2484cd828643da29f2f643e2f55f6922c16c9a9df2982f408c
/home/vikas/nodeExamples/nodeJS10Project/API_Handling_working_fine_7_JUL/node_modules/bitcore-lib/lib/publickey.js:176
    throw new TypeError('Invalid DER format public key');

    ^

TypeError: Invalid DER format public key
    at Function.PublicKey._transformDER (/home/vikas/nodeExamples/nodeJS10Project/API_Handling_working_fine_7_JUL/node_modules/bitcore
-lib/lib/publickey.js:176:11)
    at PublicKey._classifyArgs (/home/vikas/nodeExamples/nodeJS10Project/API_Handling_working_fine_7_JUL/node_modules/bitcore-lib/lib/
publickey.js:81:22)
    at new PublicKey (/home/vikas/nodeExamples/nodeJS10Project/API_Handling_working_fine_7_JUL/node_modules/bitcore-lib/lib/publickey.
js:50:19)
    at pkiEncrypt (/home/vikas/nodeExamples/nodeJS10Project/API_Handling_working_fine_7_JUL/routes/pki_Stack_Exchange.js:27:59)
    at Object.<anonymous> (/home/vikas/nodeExamples/nodeJS10Project/API_Handling_working_fine_7_JUL/routes/pki_Stack_Exchange.js:54:11
)
    at Module._compile (module.js:570:32)
    at Object.Module._extensions..js (module.js:579:10)
    at Module.load (module.js:487:32)
    at tryModuleLoad (module.js:446:12)
    at Function.Module._load (module.js:438:3)