game.sv4_common{% highlight "cxml" %}
-
- ...placeholder
+
+
{% endhighlight %}
game.sv4_hiscore{% highlight "cxml" %}
-
- ...placeholder
+
+
{% endhighlight %}
{% highlight "cxml" %}
- ...placeholder
+
+
+
{% endhighlight %}
diff --git a/templates/pages/proto/package.html b/templates/pages/proto/package.html
index d399f43..87a3676 100644
--- a/templates/pages/proto/package.html
+++ b/templates/pages/proto/package.html
@@ -11,10 +11,44 @@
{% highlight "cxml" %}
-
{% endhighlight %}
A list of all packages available for download.
+url |
+ + |
desc |
+ + |
size |
+ Size of the resource at url in bytes |
+
pkgtype |
+ + |
sumtype |
+ Only allowable value is md5. |
+
sum |
+ The sumtype digest of the file at url. |
+
from |
+ + |
till |
+ + |
package.intendlobby2netlogglobbyposeeventI'll try and figure these out in due course, promise!
{% endblock %} \ No newline at end of file diff --git a/templates/pages/transport.html b/templates/pages/transport.html index ad0c921..cdb2c73 100644 --- a/templates/pages/transport.html +++ b/templates/pages/transport.html @@ -28,13 +28,83 @@Encryption is not performed using a single static key. Instead, each request and response has its own key that is generated.
These keys are generated baesd on the X-Eamuse-Info header.
This header loosely follows the format 1-[0-9a-f]{8}-[0-9a-f]{4}. This corresponds to
- [version]-[serial]-[salt]. TODO: Confirm this
+
Keys follow thge format 1-[0-9a-f]{8}-[0-9a-f]{4}. This corresponds to
+ [version]-[seconds]-[salt]. The salt is generated by a simple PRNG.
Our per-packet key is then generated using md5(serial | salt | KEY). Identifying KEY is
- left as an exercise for the reader, however should not be especially challenging. Check
- the page source if you're stuck.
{% highlight "c" %}
+uint32_t PRNG_STATE = 0x41c64e6d;
+
+uint32_t prng() {
+ int upper = (PRNG_STATE * 0x838c9cda) + 0x6072;
+ PRNG_STATE = (PRNG_STATE * 0x41c64e6d + 0x3039) * 0x41c64e6d + 0x3039;
+ return upper & 0x7fff0000 | PRNG_STATE >> 0xf & 0xffff;
+}
+{% endhighlight %}
+ This is a simple linear conguential pseudorandom number generator (what a mouthful) being stepped twice every + call. The constants being used for the main LCPRNG are taken from glibc, along with the dropping of the "least + random" bit. Where this implementation differs however is that the LCPRNG is stepped twice every call, and that + a second LCPRNG is used for the upper 2 bytes.
+One interesting observation is that the "least random" bit, that is typically discarded by the
+ 0x7ff... mask is not actually being discarded here, as the upper two bytes of
+ PRNG_STATE, not the lower two, are used unmasked.
+
Another interseting observation is that due to the nature of LCGs, stepping it twice is no more secure than once.
+ The implementation presented here is actually just a single step of
+ PRNG_STATE = (PRNG_STATE * 0xc2a29a69) + 0xd3dc167e. Make sure to understand cryptography before
+ trying to roll your own!
+
Our per-packet key is then generated using md5(seconds | salt | ENC_KEY). Identifying
+ ENC_KEY is left as an exercise for the reader, however should not be especially challenging.
+
The interesting stuff can be found at libavs-win32-ea3.dll:0x1002a800. Rather than screenshots, I've
+ gone and tidied up the code somewhat to make it easier to follow. eamuse_info is pre-populated with
+ "X-Eamuse-Info: 1-" by the calling function (0x1000eeed) after which the pointer is
+ incremented to leave it right after that -, ready for us to vsnprintf into it.
+
{% highlight "c" %}
+static const char *ENC_KEY[26] = "Wait you didn't think I'd put this here, did you?";
+
+int xrpc_crypt(char *packet, char *xeamuse_info) {
+ char md5_key[16];
+ char key[32];
+
+ // Copy the {8}-{4} hex char pairs into key as 6 bytes
+ if (copy_from_hex(key, 4, xeamuse_info) == -1)
+ return -1;
+ if (xeamuse_info[8] != '-')
+ return -1;
+ if (copy_from_hex(key + 4, 2, xeamuse_info + 9) == -1)
+ return -1;
+
+ // Add our constant key after the two variable parts...
+ strncpy(key + 6, ENC_KEY, 26);
+ // ...MD5 it all...
+ mdigest_create_local(0, key, 32, md5_key, 16);
+ // ...and use that digest as the key for RC4
+ arc4(packet, md5_key, 16);
+ return 0;
+}
+
+int xrpc_key_and_crypt(char *packet, char *eamuse_info, size_t size) {
+ uint64_t miliseconds = read_timer(0);
+ uint32_t seconds = __aulldiv(miliseconds, 1000, 0);
+ uint16_t salt = prng() & 0xffff;
+
+ int bytes_formatted = vsnprintf(eamuse_info, size, "%08x-%04x", seconds, salt);
+ if (bytes_formatted < size) {
+ xrpc_crypt(packet, eamuse_info);
+ }
+ return bytes_formatted;
+}
+{% endhighlight %}
+
+
+Packets are compressed using lzss. The compressed data structure is a repeating cycle of an 8 bit flags byte,