Index: build/chrome/cackey.js
==================================================================
--- build/chrome/cackey.js
+++ build/chrome/cackey.js
@@ -79,11 +79,11 @@
 
 	for (idx = 0; idx < message.certificates.length; idx++) {
 		certificates.push(
 			{
 				certificate: message.certificates[idx],
-				supportedHashes: ['SHA1', 'SHA256', 'MD5_SHA1']
+				supportedHashes: ['SHA1', 'SHA256', 'SHA512', 'MD5_SHA1']
 			}
 		);
 	}
 
 	chromeCallback(certificates,
@@ -485,10 +485,29 @@
 function cackeySignMessage(signRequest, chromeCallback) {
 	var callbackId;
 	var command;
 	var certificateId;
 	var digest, digestHeader;
+	var promiseHandle = null, promiseResolve, promiseReject;
+
+	if (!chromeCallback) {
+		/*
+		 * If no callback supplied, arrange for a promise to be returned instead
+		 */
+		promiseHandle = new Promise(function(resolve, reject) {
+			promiseResolve = resolve;
+			promiseReject = reject;
+		});
+
+		chromeCallback = function(payload) {
+			if (!payload) {
+				promiseReject(new Error("Signing payload is empty or not supplied"));
+			} else {
+				promiseResolve(payload);
+			}
+		};
+	}
 
 	/*
 	 * Prefix the digest with the ASN.1 header required of it
 	 */
 	switch (signRequest.hash) {
@@ -496,19 +515,23 @@
 			digestHeader = new Uint8Array([0x30, 0x21, 0x30, 0x09, 0x06, 0x05, 0x2b, 0x0e, 0x03, 0x02, 0x1a, 0x05, 0x00, 0x04, 0x14]);
 			break;
 		case "SHA256":
 			digestHeader = new Uint8Array([0x30, 0x31, 0x30, 0x0d, 0x06, 0x09, 0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x01, 0x05, 0x00, 0x04, 0x20]);
 			break;
+		case "SHA512":
+			digestHeader = new Uint8Array([0x30, 0x51, 0x30, 0x0d, 0x06, 0x09, 0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x03, 0x05, 0x00, 0x04, 0x40]);
+			break;
 		case "MD5_SHA1":
+		case "RAW":
 			digestHeader = new Uint8Array();
 			break;
 		default:
 			console.error("[cackey] Asked to sign a message with a hash we do not support: " + signRequest.hash);
 
 			chromeCallback();
 
-			return;
+			return(promiseHandle);
 	}
 
 	digest = new Uint8Array(digestHeader.length + signRequest.digest.byteLength);
 	digest.set(digestHeader, 0);
 	digest.set(new Uint8Array(signRequest.digest), digestHeader.length);
@@ -545,11 +568,11 @@
 		if (goog.DEBUG) {
 			console.log("[cackey] Thrown.");
 		}
 	}, chromeCallback);
 
-	return;
+	return(promiseHandle);
 }
 
 /*
  * Unititalizes the CACKey PCSC connection
  */