public void addObfuscationToMethod(MethodCfg methodCfg) {
MethodCfg copyMethodCfg = new MethodCfg(methodCfg);
CfgManipulator cfgManipulator = new CfgManipulator(this.module, this.host, this.logger, methodCfg);
GraphRandomStateGenerator randomStateGenerator = new GraphRandomStateGenerator(this.module, this.host, this.logger, cfgManipulator, this.helperClass, this.graph, methodCfg, this.debugging);
// DEBUG
if (this.debugging) {
//this.logger.dumpMethodCfg(methodCfg, this.debuggingNumber.ToString().PadLeft(3, '0') + "_obfu_" + this.logger.makeFuncSigString(methodCfg.method));
this.debuggingNumber++;
}
// add local state variable
LocalDefinition intStateLocal = new LocalDefinition();
intStateLocal.IsReference = false;
intStateLocal.IsPinned = false;
intStateLocal.IsModified = false;
intStateLocal.Type = this.host.PlatformType.SystemInt32;
intStateLocal.MethodDefinition = methodCfg.method;
cfgManipulator.addLocalVariable(intStateLocal);
// add local current graph node variable
LocalDefinition currentNodeLocal = new LocalDefinition();
currentNodeLocal.IsReference = false;
currentNodeLocal.IsPinned = false;
currentNodeLocal.IsModified = false;
currentNodeLocal.Type = this.nodeInterface;
currentNodeLocal.MethodDefinition = methodCfg.method;
cfgManipulator.addLocalVariable(currentNodeLocal);
// create new basic block that sets the current node to the start node and get the state
// (will be the new starting basic block of the method)
BasicBlock startBasicBlock = new BasicBlock();
startBasicBlock.startIdx = 0;
startBasicBlock.endIdx = 0;
// set the current node pointer to the start node
startBasicBlock.operations.Add(this.helperClass.createNewOperation(OperationCode.Ldarg_0));
startBasicBlock.operations.Add(this.helperClass.createNewOperation(OperationCode.Callvirt, this.interfaceStartPointerGet));
startBasicBlock.operations.Add(this.helperClass.createNewOperation(OperationCode.Stloc, currentNodeLocal));
// initialize the random state generator
List<IOperation> tempOperations = randomStateGenerator.generateCodeInitializeRandomState();
startBasicBlock.operations.AddRange(tempOperations);
// set global state
tempOperations = randomStateGenerator.generateCodeSetRandomState(intStateLocal);
startBasicBlock.operations.AddRange(tempOperations);
// create exit branch for the new start basic block
NoBranchTarget startExitBranch = new NoBranchTarget();
startExitBranch.sourceBasicBlock = startBasicBlock;
startBasicBlock.exitBranch = startExitBranch;
// set the original start basic block as the target of the exit branch
startExitBranch.takenTarget = methodCfg.startBasicBlock;
methodCfg.startBasicBlock.entryBranches.Add(startExitBranch);
// set new start basic block as start basic block of the method cfg
methodCfg.startBasicBlock = startBasicBlock;
methodCfg.basicBlocks.Add(startBasicBlock);
// obfuscate the control flow
this.addMetadataIter(cfgManipulator, randomStateGenerator, copyMethodCfg, methodCfg, startBasicBlock, intStateLocal, currentNodeLocal);
this.processExitBranchesIter(cfgManipulator, randomStateGenerator, copyMethodCfg, methodCfg, startBasicBlock, intStateLocal, currentNodeLocal);
this.addOpaquePredicatesIter(cfgManipulator, randomStateGenerator, copyMethodCfg, methodCfg, startBasicBlock, intStateLocal, currentNodeLocal);
this.removeReplaceUnconditionalBranchesIter(cfgManipulator, randomStateGenerator, copyMethodCfg, methodCfg, startBasicBlock, intStateLocal, currentNodeLocal);
// fill dead code basic blocks with actual dead code
this.fillDeadCodeBasicBlocks(methodCfg);
this.obfuscateSemanticallyEquivalentBlocks(methodCfg);
// TODO QUICK FIX
// mutateBlocks() does not work when debugging is deactivated
// but since we only focus on probabilistic control flow, ignore it for now
this.debugging = true;
this.mutateBlocks(methodCfg);
this.debugging = false;
// if debugging is activated => add code that allows to trace the control flow through the method
if (this.debugging
|| this.trace) {
List<IOperation> traceWriterOperations = null;
// add code to the beginning of each basic block that writes to the trace file
for (int idx = 0; idx < methodCfg.basicBlocks.Count(); idx++) {
traceWriterOperations = new List<IOperation>();
traceWriterOperations.Add(this.helperClass.createNewOperation(OperationCode.Ldarg_0));
traceWriterOperations.Add(this.helperClass.createNewOperation(OperationCode.Ldfld, this.debuggingTraceWriter));
traceWriterOperations.Add(this.helperClass.createNewOperation(OperationCode.Ldstr, "BB" + idx.ToString() + ";ID" + methodCfg.basicBlocks.ElementAt(idx).id.ToString()));
traceWriterOperations.Add(this.helperClass.createNewOperation(OperationCode.Callvirt, this.helperClass.textWriterWriteLine));
methodCfg.basicBlocks.ElementAt(idx).operations.InsertRange(0, traceWriterOperations);
// check if the basic block has an exit branch
// => add code that closes the file handler of the trace file before the ret instruction
if ((methodCfg.basicBlocks.ElementAt(idx).exitBranch as ExitBranchTarget) != null) {
traceWriterOperations = new List<IOperation>();
traceWriterOperations.Add(this.helperClass.createNewOperation(OperationCode.Ldarg_0));
traceWriterOperations.Add(this.helperClass.createNewOperation(OperationCode.Ldfld, this.debuggingTraceWriter));
traceWriterOperations.Add(this.helperClass.createNewOperation(OperationCode.Callvirt, this.helperClass.textWriterClose));
methodCfg.basicBlocks.ElementAt(idx).operations.InsertRange(methodCfg.basicBlocks.ElementAt(idx).operations.Count() - 1, traceWriterOperations);
}
}
// create local integer variable needed for the trace file code
LocalDefinition intLocal = new LocalDefinition();
intLocal.IsReference = false;
intLocal.IsPinned = false;
intLocal.IsModified = false;
intLocal.Type = this.host.PlatformType.SystemInt32;
intLocal.MethodDefinition = methodCfg.method;
cfgManipulator.addLocalVariable(intLocal);
traceWriterOperations = new List<IOperation>();
// get the hash code of this instance as unique object id
traceWriterOperations.Add(this.helperClass.createNewOperation(OperationCode.Ldarg_0));
traceWriterOperations.Add(this.helperClass.createNewOperation(OperationCode.Callvirt, this.helperClass.objectGetHashCode));
traceWriterOperations.Add(this.helperClass.createNewOperation(OperationCode.Stloc, intLocal));
// initialize io stream writer for trace file (use object hash as id for this trace and only append)
traceWriterOperations.Add(this.helperClass.createNewOperation(OperationCode.Ldarg_0));
traceWriterOperations.Add(this.helperClass.createNewOperation(OperationCode.Ldstr, this.debuggingDumpLocation + "\\" + this.debuggingTraceFilePrefix + "_"));
// cast random integer to string and store in object id
traceWriterOperations.Add(this.helperClass.createNewOperation(OperationCode.Ldloca, intLocal));
traceWriterOperations.Add(this.helperClass.createNewOperation(OperationCode.Call, this.helperClass.int32ToString));
traceWriterOperations.Add(this.helperClass.createNewOperation(OperationCode.Ldstr, ".txt"));
traceWriterOperations.Add(this.helperClass.createNewOperation(OperationCode.Call, this.helperClass.stringConcatThree));
// only append to file
traceWriterOperations.Add(this.helperClass.createNewOperation(OperationCode.Ldc_I4_1));
traceWriterOperations.Add(this.helperClass.createNewOperation(OperationCode.Newobj, this.helperClass.streamWriterCtorAppend));
traceWriterOperations.Add(this.helperClass.createNewOperation(OperationCode.Stfld, this.debuggingTraceWriter));
// write marker to trace file that marks the beginning of this trace
traceWriterOperations.Add(this.helperClass.createNewOperation(OperationCode.Ldarg_0));
traceWriterOperations.Add(this.helperClass.createNewOperation(OperationCode.Ldfld, this.debuggingTraceWriter));
traceWriterOperations.Add(this.helperClass.createNewOperation(OperationCode.Ldstr, "\n------NEWSTART------\n"));
traceWriterOperations.Add(this.helperClass.createNewOperation(OperationCode.Callvirt, this.helperClass.textWriterWriteLine));
// add code to the beginning of the start basic block
methodCfg.startBasicBlock.operations.InsertRange(0, traceWriterOperations);
}
logger.dumpMethodCfg(copyMethodCfg, "copy_final");
return;
}
// this function generates code for the "state change"
private void createCodeStateChange(ref BasicBlock outStateChangeBasicBlock, ref SwitchBranchTarget outStateChangeExitBranch, GraphRandomStateGenerator randomStateGenerator, BasicBlockGraphNodeLink link, LocalDefinition intStateLocal) {
// create a basic block to change the current global state
BasicBlock stateChangeBasicBlock = new BasicBlock();
stateChangeBasicBlock.startIdx = 0;
stateChangeBasicBlock.endIdx = 0;
// create graph transformer metadata for the basic block
GraphTransformerStateChangeBasicBlock metadataChange = new GraphTransformerStateChangeBasicBlock();
metadataChange.correspondingGraphNodes.Add(link);
stateChangeBasicBlock.transformationMetadata.Add(metadataChange);
// generate code for setting the new global state
List<IOperation> tempOperations = randomStateGenerator.generateCodeSetRandomState(intStateLocal);
stateChangeBasicBlock.operations.AddRange(tempOperations);
// create switch statement for the "state switch"
stateChangeBasicBlock.operations.Add(this.helperClass.createNewOperation(OperationCode.Ldloc, intStateLocal));
uint[] switchSize = new uint[this.graph.graphValidPathCount];
stateChangeBasicBlock.operations.Add(this.helperClass.createNewOperation(OperationCode.Switch, switchSize));
// create exit branch for the new state basic block
SwitchBranchTarget stateChangeExitBranch = new SwitchBranchTarget();
stateChangeExitBranch.sourceBasicBlock = stateChangeBasicBlock;
stateChangeBasicBlock.exitBranch = stateChangeExitBranch;
// create the dead code for this "state switch"
BasicBlock deadCodeBasicBlock = new BasicBlock();
deadCodeBasicBlock.startIdx = 0;
deadCodeBasicBlock.endIdx = 0;
// set the dead code basic block as "not taken" target for the conditional branch of the checking basic block
deadCodeBasicBlock.entryBranches.Add(stateChangeExitBranch);
stateChangeExitBranch.notTakenTarget = deadCodeBasicBlock; // TODO at the moment always the not taken branch of the switch statement is the dead code basic block
// generate dead code for the dead code basic block
GraphTransformerDeadCodeBasicBlock deadCodeMetadata = new GraphTransformerDeadCodeBasicBlock();
deadCodeBasicBlock.transformationMetadata.Add(deadCodeMetadata);
outStateChangeBasicBlock = stateChangeBasicBlock;
outStateChangeExitBranch = stateChangeExitBranch;
}
