Very basic docs

Author: samczsun

CUSTOMTRANSFORMER.md

@@ -0,0 +1,33 @@
+# Custom Transformers
+So you need to deobfuscate some custom obfuscation? Maybe this repo isn't updated for the latest obfuscators?
+Here's some tips for writing a custom transformer.
+
+### Disassemble your target program  
+Try using [Krakatau](https://github.com/Storyyeller/Krakatau), it's pretty good.
+
+### Identify patterns  
+Most of the time obfuscations are applied with a very simple pattern. For example, string encryption may look like this    
+```jasmin
+ldc "someencryptedstring"
+invokestatic foo/DecryptorClass decrypt (Ljava/lang/String;)Ljava/lang/String;
+```
+```jasmin
+ldc "someencryptedstring"
+dup
+invokevirtual java/lang/String length ()I
+ldc 52
+sipush 29
+ixor
+imul
+invokestatic foo/DecryptorClass decrypt(Ljava/lang/String;I)Ljava/lang/String; 
+```
+If you can identify the common pattern being used, you can use [InstructionPattern](https://github.com/java-deobfuscator/deobfuscator/blob/master/src/main/java/com/javadeobfuscator/deobfuscator/matcher/InstructionPattern.java)
+to quickly isolate the relevant bytecodes.  
+For example, at the time of writing Stringer v3 follows some very simple [patterns](https://github.com/java-deobfuscator/deobfuscator/blob/master/src/main/java/com/javadeobfuscator/deobfuscator/transformers/stringer/v3/utils/Constants.java#L60).    
+### Deobfuscate it  
+[JavaVM](https://github.com/java-deobfuscator/javavm) provides a very easy way to execute unsafe bytecodes
+and intercept/modify results. Again, check out the [Stringer transformers](https://github.com/java-deobfuscator/deobfuscator/blob/master/src/main/java/com/javadeobfuscator/deobfuscator/transformers/stringer/v3/StringEncryptionTransformer.java) for sample usages
+
+### Open a ticket
+If that didn't work, or if you think the repo needs an update, open a ticket and provide the file (or a reproducible sample).
+This way, the next person who comes along can use an existing transformer!

README.md

@@ -10,6 +10,10 @@ The deobfuscator supports deobfuscation of transformations such as string litera
 
 Things like method names, class names, etc cannot be deobfuscated because their renaming is irreversible. The information needed to deobfuscate is removed.
 
+## My program wasn't deobfuscated
+
+Check out [this guide](CUSTOMTRANSFORMER.md)
+
 ## Examples
 
 ### As a library