Nodejs, asny to sync - node.js

Question

I am quite new to NodeJs and need some help regarding flow.
So, I need to change some lib as it does not work for me. I have asny call and then right a way i have sync code. The thing is that sync code starts executing before asny part return data.
asny:
xmlenc.encrypt(message, options509, function(err, result) {
console.log("error:", err)
message = result
return message;
})
sync right after asyn:
xml = "<?xml version=\"1.0\" encoding=\"utf-8\"?>" +
"<" + envelopeKey + ":Envelope " +
xmlnsSoap + " " +
"xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\" " +
encoding +
this.wsdl.xmlnsInEnvelope + '>' +
((self.soapHeaders || self.security) ?
(
"<" + envelopeKey + ":Header>" +
(self.soapHeaders ? self.soapHeaders.join("\n") : "") +
(self.security && !self.security.postProcess ? self.security.toXML() : "") +
"</" + envelopeKey + ":Header>"
)
:
''
) +
"<" + envelopeKey + ":Body" +
(self.bodyAttributes ? self.bodyAttributes.join(' ') : '') +
(self.security && self.security.postProcess ? ' Id="_0"' : '') +
">" +
genXML() +
"</" + envelopeKey + ":Body>" +
"</" + envelopeKey + ":Envelope>";
How to solve this that the progrem with wait for asyn part to return before moving to sync part.
thank you