feature: randomize compressor library-seed hash constants per run (#69)

The rolling hash that derives each embedded library's decryption seed
from its name used fixed constants 0x6fff61 (init) and 0x5e3f1f
(multiplier) in both PackModules and the injected runtime Resolve method
— another de4dot signature.

Generate a random init and a random odd multiplier per pack, use them in
PackModules, and rewrite the literals in the runtime Resolve IL so the
seed derivation stays in sync. Validated by CompressorWithResx.Test,
whose 'de' satellite assembly is resolved+decrypted through this exact
path at runtime (asserts 'Test (deutsch)' across all 12 cases).

Author: RandomCrocodile

Confuser.Protections/Compress/Compressor.cs

@@ -160,9 +160,9 @@ void PackModules(ConfuserContext context, CompressorContext compCtx, ModuleDef s
 				for (int i = 0; i < name.Length; i++)
 					name[i] *= key[i + 4];
 
-				uint state = 0x6fff61;
+				uint state = compCtx.LcgInit;
 				foreach (byte chr in name)
-					state = state * 0x5e3f1f + chr;
+					state = state * compCtx.LcgMultiplier + chr;
 				byte[] encrypted = compCtx.Encrypt(comp, entry.Value, state, progress => {
 					progress = (progress + moduleIndex) / modules.Count;
 					context.ProgressReporter.Progress((int)(progress * 10000), 10000);
@@ -247,6 +247,12 @@ void InjectStub(ConfuserContext context, CompressorContext compCtx, ProtectionPa
 			// the runtime Decrypt method below so encrypt/decrypt stay in sync.
 			compCtx.Feedback = random.NextUInt32();
 
+			// Randomize the rolling-hash used to derive each library's seed from its name
+			// (baked-in 0x6fff61 / 0x5e3f1f). The multiplier is kept odd for good distribution.
+			// The same values are injected into the runtime Resolve method below.
+			compCtx.LcgInit = random.NextUInt32();
+			compCtx.LcgMultiplier = random.NextUInt32() | 1;
+
 			uint seed = random.NextUInt32();
 			compCtx.OriginModule = context.OutputModules[compCtx.ModuleIndex];
 
@@ -295,6 +301,18 @@ void InjectStub(ConfuserContext context, CompressorContext compCtx, ProtectionPa
 			foreach (Instruction instr in instrs)
 				decrypter.Body.Instructions.Add(instr);
 
+			// Resolve — sync the runtime rolling-hash constants with the values used when
+			// deriving each library's seed from its name (see PackModules).
+			MethodDef resolver = defs.OfType<MethodDef>().Single(method => method.Name == "Resolve");
+			foreach (Instruction instr in resolver.Body.Instructions) {
+				if (instr.OpCode != OpCodes.Ldc_I4)
+					continue;
+				if ((int)instr.Operand == 0x6fff61)
+					instr.Operand = (int)compCtx.LcgInit;
+				else if ((int)instr.Operand == 0x5e3f1f)
+					instr.Operand = (int)compCtx.LcgMultiplier;
+			}
+
 			// Pack modules
 			PackModules(context, compCtx, stubModule, comp, random);
 		}

Confuser.Protections/Compress/CompressorContext.cs

@@ -20,6 +20,8 @@ internal class CompressorContext {
 		public ModuleDef OriginModuleDef;
 		public bool CompatMode;
 		public uint Feedback;
+		public uint LcgInit;
+		public uint LcgMultiplier;
 
 		public byte[] Encrypt(ICompressionService compress, byte[] data, uint seed, Action<double> progressFunc) {
 			data = (byte[])data.Clone();