IceCruelStuff · June 8, 2021 02:08 · Dec 19, 2020 · Jan 23, 2016 · Jan 23, 2016
diff --git a/README.md → Minecraft Accounts.md b/README.md → Minecraft Accounts.md
diff --git a/track.js b/track.js
@@ -11,7 +11,7 @@ function track(name, a, b, lastfail) {
 
   if(a === b) {
     check(name, a, function(ok) {
-      if (ok && lastfail < a) {
+      if (ok && lastfail === a-1) {
         console.log("found:", new Date(a*1000).toUTCString());
       } else {
         if (lastfail === 0) {

diff --git a/README.md b/README.md
@@ -0,0 +1,68 @@
+Tracks down when a Minecraft account was created.
+
+# How it works
+
+Mojang has an API endpoint for usernames:
+```
+https://api.mojang.com/users/profiles/minecraft/<name>?at=<timestamp>
+```
+It can be used to find the UUID of an account, by username it used at the given time.  
+It returns either `200 OK` or `204 No Content` – indicating that the username was not in use at the time.
+
+That means we can find out whether an account existed at a specific time.  
+We always look at a range of time, starting with Jan 2010 - now.  
+The range is then split in half, and a request is made for the intermediate time.  
+200 means the account already existed, thus created in the first half; 204 means the account did not yet exist, thus created in the second half.  
+This step is repeated with the respective time range until the exact second is found.  
+*See also: [Babylonian Method](https://en.wikipedia.org/wiki/Methods_of_computing_square_roots#Babylonian_method)*
+
+Currently it needs about 27 requests to find the creation date.
+
+# Caveats
+
+This works with nodejs, however it's not a proper module and the `track` function doesn't have a callback.
+
+Due to Mojang being Mojang, the API endpoint is horribly broken:
+
+- It does not work with legacy accounts
+- It does not work with accounts that have been renamed
+  - Except sometimes™
+  - The result may be inaccurate though
+
+# Example usage
+
+The arrow indicates in which half of the time range the account was created.
+
+```
+> track("dinnerbone")
+
+range: 1263146630	<-|  	1453566749
+range: 1263146630	<-|  	1358356689
+range: 1263146630	<-|  	1310751659
+range: 1263146630	  |->	1286949144
+range: 1275047888	  |->	1286949144
+range: 1280998517	  |->	1286949144
+range: 1283973831	<-|  	1286949144
+range: 1283973831	  |->	1285461487
+range: 1284717660	  |->	1285461487
+range: 1285089574	  |->	1285461487
+range: 1285275531	  |->	1285461487
+range: 1285368510	  |->	1285461487
+range: 1285414999	<-|  	1285461487
+range: 1285414999	  |->	1285438243
+range: 1285426622	<-|  	1285438243
+range: 1285426622	<-|  	1285432432
+range: 1285426622	  |->	1285429527
+range: 1285428075	<-|  	1285429527
+range: 1285428075	  |->	1285428801
+range: 1285428439	  |->	1285428801
+range: 1285428621	<-|  	1285428801
+range: 1285428621	  |->	1285428711
+range: 1285428667	  |->	1285428711
+range: 1285428690	  |->	1285428711
+range: 1285428701	  |->	1285428711
+range: 1285428707	<-|  	1285428711
+range: 1285428707	<-|  	1285428709
+range: 1285428707	<-|  	1285428708
+found: Sat, 25 Sep 2010 15:31:47 GMT
+```
diff --git a/track.js b/track.js
@@ -0,0 +1,36 @@
+function check(name, num, callback) {
+  https.get("https://api.mojang.com/users/profiles/minecraft/" + name + "?at=" + num, function(resp) {
+    callback(resp.statusCode === 200);
+  });
+};
+
+function track(name, a, b, lastfail) {
+  a = a || 1263146630; // notch sign-up
+  b = b || Math.floor(Date.now()/1000);
+  lastfail = lastfail || 0;
+
+  if(a === b) {
+    check(name, a, function(ok) {
+      if (ok && lastfail < a) {
+        console.log("found:", new Date(a*1000).toUTCString());
+      } else {
+        if (lastfail === 0) {
+          console.log("target is <= " + a);
+        } else {
+          console.log("target is > " + a);
+        }
+      }
+    });
+  } else {
+    var mid = a + Math.floor((b-a)/2);
+    check(name, mid, function(ok) {
+      if (ok) {
+        console.log("range: " + a + "\t<-|  \t" + b);
+        track(name, a, mid, lastfail);
+      } else {
+        console.log("range: " + a + "\t  |->\t" + b);
+        track(name, mid+1, b, mid);
+      }
+    });
+  }
+}