Added getDeviceID

README.md

@@ -52,3 +52,21 @@ Queries the Steam servers for their time, then subtracts our local time from it
 The offset is how many seconds we are **behind** Steam. Therefore, **add** this number to our local time to get Steam time.
 
 You can pass this value to `time()` or to `getAuthCode()` as-is with no math involved.
+
+## getDeviceID(steamID)
+- `steamID` - Your SteamID as a string or an object (such as a `SteamID` object) which has a `toString()` method that returns the SteamID as a 64-bit integer string.
+
+**v1.3.0 or later is required to use this function**
+
+Returns a standardized device ID in the same format as Android device IDs from Valve's official mobile app. Steam will
+likely soon stop allowing you to send a different device ID each time you load the page, instead requiring you to
+consistently use the same device ID. If you use this function's algorithm everywhere you use a confirmation device ID,
+then your experience should be fine.
+
+The algorithm used is:
+
+1. Convert the SteamID to a string
+2. SHA-1 hash it and encode the resulting hash as a lowercase hex value
+3. Truncate the hash to 32 characters
+4. Insert dashes such that the resulting value has 5 groups of hexadecimal values containing 8, 4, 4, 4, and 12 characters, respectively
+5. Prepend "android:" to the resulting value

index.js

@@ -120,6 +120,16 @@ exports.getTimeOffset = function(callback) {
 	req.end();
 };
 
+/**
+ * Get a standardized device ID based on your SteamID.
+ * @param {string|object} steamID - Your SteamID, either as a string or as an object which has a toString() method that returns the SteamID
+ * @returns {string}
+ */
+exports.getDeviceID = function(steamID) {
+	return "android:" + Crypto.createHash('sha1').update(steamID.toString()).digest('hex')
+			.replace(/^([a-z0-9]{8})([a-z0-9]{4})([a-z0-9]{4})([a-z0-9]{4})([a-z0-9]{12}).*$/, '$1-$2-$3-$4-$5');
+};
+
 function bufferizeSecret(secret) {
 	if(typeof secret === 'string') {
 		// Check if it's hex