Sunday, February 14, 2010

Yahoo Messenger EnScripts

There are a couple of publicly available Yahoo Messenger EnScripts/EnPacks out, such as:

Yahoo Decoder in unallocated by Lance Mueller

YahooMessenger-Parser by Paul Bobby

Pretty useful scripts, however they don't handle right-to-left languages like Hebrew and Arabic. Here are some before pics from my test run with Hebrew:

Lance Mueller's script's output:

Paul Bobby's scripts' output:

As you can see, (well if you know what Hebrew letters are supposed to look like) the letters come out as some gobbeldy-gook. This is something I've been meaning to comment on for a while, having written various chat EnScripts at the beginning of my GSI employment. I have just gotten around to it now... The "encryption" method is the same for all unicode languages in that it is a byte-by-byte xor with the local username. The problem is that the encoding becomes distorted when it is just saved in a string. For example the letters ש and ל with UTF-8 encodings d7a9 and d79c respectively become c397 and c2a9 (it is left as an exercise for the reader to figure out why). So here comes a solution that I have used in the past.

The EnScripting language has a class called MemoryFileClass, which allows you to have in memory buffers that you can treat as files. You can create them, open them, read and write to them as you would any other file. So the idea is simple enough: write to a memory buffer as you decrypt the message and then extract the message after all decryption has taken place. This is accomplished by adding a couple of helper functions to Paul Bobby's code:

bool WriteBuffer(MemoryFileClass &file, char msg) {
int temp = msg;
file.WriteBinaryInt(temp, 1);
return file.IsValid();

void ReadBuffer(MemoryFileClass &file, String &msg) {

Now we can just call the functions as appropriate when decrypting and outputting the messages. You can see the correct output after this modification below (yeah, the conversation is lame and is just a test ;-):

The complete modified EnScript is available on the GSI forum (registration required):

A thread on the GSI forum with Paul Bobby's fixed EnScript

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