cleanup

2025-12-24 12:58:05 +08:00 · 2025-06-03 02:03:16 +02:00
parent 0b8de06a09
commit edcdaf3e35
8 changed files with 172 additions and 138 deletions
--- a/internal/asthelper/asthelper.go
+++ b/internal/asthelper/asthelper.go
@@ -140,6 +140,63 @@ func IndexExprByExpr(xExpr, indexExpr ast.Expr) *ast.IndexExpr {
 	return &ast.IndexExpr{X: xExpr, Index: indexExpr}
 }

+// UnaryExpr creates a unary expression with the given operator and operand
+func UnaryExpr(op token.Token, x ast.Expr) *ast.UnaryExpr {
+	return &ast.UnaryExpr{
+		Op: op,
+		X:  x,
+	}
+}
+
+// StarExpr creates a pointer type expression "*x"
+func StarExpr(x ast.Expr) *ast.StarExpr {
+	return &ast.StarExpr{X: x}
+}
+
+// ArrayType creates an array type expression "[len]eltType"
+func ArrayType(len ast.Expr, eltType ast.Expr) *ast.ArrayType {
+	return &ast.ArrayType{
+		Len: len,
+		Elt: eltType,
+	}
+}
+
+// ByteArrayType creates a byte array type "[len]byte"
+func ByteArrayType(len int64) *ast.ArrayType {
+	lenLit := IntLit(int(len))
+	return ArrayType(lenLit, ast.NewIdent("byte"))
+}
+
+// ByteSliceType creates a byte slice type "[]byte"
+func ByteSliceType() *ast.ArrayType {
+	return &ast.ArrayType{Elt: ast.NewIdent("byte")}
+}
+
+// BinaryExpr creates a binary expression "x op y"
+func BinaryExpr(x ast.Expr, op token.Token, y ast.Expr) *ast.BinaryExpr {
+	return &ast.BinaryExpr{
+		X:  x,
+		Op: op,
+		Y:  y,
+	}
+}
+
+// UintLit returns an ast.BasicLit of kind INT for uint64 values
+func UintLit(value uint64) *ast.BasicLit {
+	return &ast.BasicLit{
+		Kind:  token.INT,
+		Value: fmt.Sprint(value),
+	}
+}
+
+// Field creates a field with names and type for function parameters or struct fields
+func Field(typ ast.Expr, names ...*ast.Ident) *ast.Field {
+	return &ast.Field{
+		Names: names,
+		Type:  typ,
+	}
+}
+
 func ConstToAst(val constant.Value) ast.Expr {
 	switch val.Kind() {
 	case constant.Bool:
--- a/internal/literals/literals.go
+++ b/internal/literals/literals.go
@@ -226,9 +226,10 @@ func withPos(node ast.Node, pos token.Pos) ast.Node {
 func obfuscateString(obfRand *obfRand, data string) *ast.CallExpr {
 	obf := getNextObfuscator(obfRand, len(data))

+	// Generate junk bytes to to prepend and append to the data.
+	// This is to prevent the obfuscated string from being easily fingerprintable.
 	junkBytes := make([]byte, obfRand.Intn(maxStringJunkBytes-minStringJunkBytes)+minStringJunkBytes)
 	obfRand.Read(junkBytes)
-
 	splitIdx := obfRand.Intn(len(junkBytes))

 	extKeys := randExtKeys(obfRand.Rand)
@@ -246,7 +247,7 @@ func obfuscateString(obfRand *obfRand, data string) *ast.CallExpr {
 	//	}
 	funcTyp := &ast.FuncType{
 		Params: &ast.FieldList{List: []*ast.Field{{
-			Type: &ast.ArrayType{Elt: ast.NewIdent("byte")},
+			Type: ah.ByteSliceType(),
 		}}},
 		Results: &ast.FieldList{List: []*ast.Field{{
 			Type: ast.NewIdent("string"),
@@ -256,26 +257,23 @@ func obfuscateString(obfRand *obfRand, data string) *ast.CallExpr {
 		Type: &ast.FuncType{
 			Params: &ast.FieldList{List: []*ast.Field{{
 				Names: []*ast.Ident{ast.NewIdent("x")},
-				Type:  &ast.ArrayType{Elt: ast.NewIdent("byte")},
+				Type:  ah.ByteSliceType(),
 			}}},
 			Results: &ast.FieldList{List: []*ast.Field{{
 				Type: ast.NewIdent("string"),
 			}}},
 		},
-		Body: &ast.BlockStmt{List: []ast.Stmt{
-			&ast.ReturnStmt{Results: []ast.Expr{
-				&ast.CallExpr{
-					Fun: ast.NewIdent("string"),
-					Args: []ast.Expr{
-						&ast.SliceExpr{
-							X:    ast.NewIdent("x"),
-							Low:  ah.IntLit(splitIdx),
-							High: ah.IntLit(splitIdx + len(plainData)),
-						},
+		Body: ah.BlockStmt(
+			ah.ReturnStmt(
+				ah.CallExprByName("string",
+					&ast.SliceExpr{
+						X:    ast.NewIdent("x"),
+						Low:  ah.IntLit(splitIdx),
+						High: ah.IntLit(splitIdx + len(plainData)),
 					},
-				},
-			}},
-		}},
+				),
+			),
+		),
 	}
 	block.List = append(block.List, ah.ReturnStmt(ah.CallExpr(obfRand.proxyDispatcher.HideValue(funcVal, funcTyp), ast.NewIdent("data"))))
 	return ah.LambdaCall(params, ast.NewIdent("string"), block, args)
@@ -289,17 +287,14 @@ func obfuscateByteSlice(obfRand *obfRand, isPointer bool, data []byte) *ast.Call
 	params, args := extKeysToParams(obfRand, extKeys)

 	if isPointer {
-		block.List = append(block.List, ah.ReturnStmt(&ast.UnaryExpr{
-			Op: token.AND,
-			X:  ast.NewIdent("data"),
-		}))
-		return ah.LambdaCall(params, &ast.StarExpr{
-			X: &ast.ArrayType{Elt: ast.NewIdent("byte")},
-		}, block, args)
+		block.List = append(block.List, ah.ReturnStmt(
+			ah.UnaryExpr(token.AND, ast.NewIdent("data")),
+		))
+		return ah.LambdaCall(params, ah.StarExpr(ah.ByteSliceType()), block, args)
 	}

 	block.List = append(block.List, ah.ReturnStmt(ast.NewIdent("data")))
-	return ah.LambdaCall(params, &ast.ArrayType{Elt: ast.NewIdent("byte")}, block, args)
+	return ah.LambdaCall(params, ah.ByteSliceType(), block, args)
 }

 func obfuscateByteArray(obfRand *obfRand, isPointer bool, data []byte, length int64) *ast.CallExpr {
@@ -309,10 +304,7 @@ func obfuscateByteArray(obfRand *obfRand, isPointer bool, data []byte, length in
 	block := obf.obfuscate(obfRand.Rand, data, extKeys)
 	params, args := extKeysToParams(obfRand, extKeys)

-	arrayType := &ast.ArrayType{
-		Len: ah.IntLit(int(length)),
-		Elt: ast.NewIdent("byte"),
-	}
+	arrayType := ah.ByteArrayType(length)

 	sliceToArray := []ast.Stmt{
 		&ast.DeclStmt{
@@ -328,26 +320,25 @@ func obfuscateByteArray(obfRand *obfRand, isPointer bool, data []byte, length in
 			Key: ast.NewIdent("i"),
 			Tok: token.DEFINE,
 			X:   ast.NewIdent("data"),
-			Body: &ast.BlockStmt{List: []ast.Stmt{
-				&ast.AssignStmt{
-					Lhs: []ast.Expr{ah.IndexExpr("newdata", ast.NewIdent("i"))},
-					Tok: token.ASSIGN,
-					Rhs: []ast.Expr{ah.IndexExpr("data", ast.NewIdent("i"))},
-				},
-			}},
+			Body: ah.BlockStmt(
+				ah.AssignStmt(
+					ah.IndexExprByExpr(ast.NewIdent("newdata"), ast.NewIdent("i")),
+					ah.IndexExprByExpr(ast.NewIdent("data"), ast.NewIdent("i")),
+				),
+			),
 		},
 	}

 	var retexpr ast.Expr = ast.NewIdent("newdata")
 	if isPointer {
-		retexpr = &ast.UnaryExpr{X: retexpr, Op: token.AND}
+		retexpr = ah.UnaryExpr(token.AND, retexpr)
 	}

 	sliceToArray = append(sliceToArray, ah.ReturnStmt(retexpr))
 	block.List = append(block.List, sliceToArray...)

 	if isPointer {
-		return ah.LambdaCall(params, &ast.StarExpr{X: arrayType}, block, args)
+		return ah.LambdaCall(params, ah.StarExpr(arrayType), block, args)
 	}

 	return ah.LambdaCall(params, arrayType, block, args)
--- a/internal/literals/obfuscators.go
+++ b/internal/literals/obfuscators.go
@@ -15,48 +15,48 @@ import (
 	ah "mvdan.cc/garble/internal/asthelper"
 )

-// extKeyRarity probability of using an external key.
+// externalKeyProbability probability of using an external key.
 // Larger value, greater probability of using an external key.
 // Must be between 0 and 1
-type extKeyRarity float32
+type externalKeyProbability float32

 const (
-	rareRarity   extKeyRarity = 0.4
-	normalRarity extKeyRarity = 0.6
-	commonRarity extKeyRarity = 0.8
+	lowProb    externalKeyProbability = 0.4
+	normalProb externalKeyProbability = 0.6
+	highProb   externalKeyProbability = 0.8
 )

-func (r extKeyRarity) Try(rand *mathrand.Rand) bool {
+func (r externalKeyProbability) Try(rand *mathrand.Rand) bool {
 	return rand.Float32() < float32(r)
 }

-// extKey contains all information about the external key
-type extKey struct {
+// externalKey contains all information about the external key
+type externalKey struct {
 	name, typ string
 	value     uint64
 	bits      int
 	refs      int
 }

-func (k *extKey) Type() *ast.Ident {
+func (k *externalKey) Type() *ast.Ident {
 	return ast.NewIdent(k.typ)
 }

-func (k *extKey) Name() *ast.Ident {
+func (k *externalKey) Name() *ast.Ident {
 	return ast.NewIdent(k.name)
 }

-func (k *extKey) AddRef() {
+func (k *externalKey) AddRef() {
 	k.refs++
 }

-func (k *extKey) IsUsed() bool {
+func (k *externalKey) IsUsed() bool {
 	return k.refs > 0
 }

 // obfuscator takes a byte slice and converts it to a ast.BlockStmt
 type obfuscator interface {
-	obfuscate(obfRand *mathrand.Rand, data []byte, extKeys []*extKey) *ast.BlockStmt
+	obfuscate(obfRand *mathrand.Rand, data []byte, extKeys []*externalKey) *ast.BlockStmt
 }

 var (
@@ -107,20 +107,18 @@ func evalOperator(t token.Token, x, y byte) byte {
 }

 func operatorToReversedBinaryExpr(t token.Token, x, y ast.Expr) *ast.BinaryExpr {
-	expr := &ast.BinaryExpr{X: x, Y: y}
-
+	var op token.Token
 	switch t {
 	case token.XOR:
-		expr.Op = token.XOR
+		op = token.XOR
 	case token.ADD:
-		expr.Op = token.SUB
+		op = token.SUB
 	case token.SUB:
-		expr.Op = token.ADD
+		op = token.ADD
 	default:
 		panic(fmt.Sprintf("unknown operator: %s", t))
 	}
-
-	return expr
+	return ah.BinaryExpr(x, op, y)
 }

 const (
@@ -149,44 +147,38 @@ var extKeyRanges = []struct {
 }

 // randExtKey generates a random external key with a unique name, type, value, and bitnesses
-func randExtKey(obfRand *mathrand.Rand, idx int) *extKey {
-	r := extKeyRanges[obfRand.Intn(len(extKeyRanges))]
-	return &extKey{
+func randExtKey(rand *mathrand.Rand, idx int) *externalKey {
+	r := extKeyRanges[rand.Intn(len(extKeyRanges))]
+	return &externalKey{
 		name:  "garbleExternalKey" + strconv.Itoa(idx),
 		typ:   r.typ,
-		value: obfRand.Uint64() & r.max,
+		value: rand.Uint64() & r.max,
 		bits:  r.bits,
 	}
 }

-func randExtKeys(obfRand *mathrand.Rand) []*extKey {
-	count := minExtKeyCount + obfRand.Intn(maxExtKeyCount-minExtKeyCount)
-	keys := make([]*extKey, count)
+func randExtKeys(rand *mathrand.Rand) []*externalKey {
+	count := minExtKeyCount + rand.Intn(maxExtKeyCount-minExtKeyCount)
+	keys := make([]*externalKey, count)
 	for i := 0; i < count; i++ {
-		keys[i] = randExtKey(obfRand, i)
+		keys[i] = randExtKey(rand, i)
 	}
 	return keys
 }

 // extKeysToParams converts a list of extKeys into a parameter list and argument expressions for function calls.
 // It ensures unused keys have placeholder names and sometimes use proxyDispatcher.HideValue for key values
-func extKeysToParams(objRand *obfRand, keys []*extKey) (params *ast.FieldList, args []ast.Expr) {
+func extKeysToParams(objRand *obfRand, keys []*externalKey) (params *ast.FieldList, args []ast.Expr) {
 	params = &ast.FieldList{}
 	for _, key := range keys {
 		name := key.Name()
 		if !key.IsUsed() {
 			name.Name = "_"
 		}
-		params.List = append(params.List, &ast.Field{
-			Names: []*ast.Ident{name},
-			Type:  key.Type(),
-		})
+		params.List = append(params.List, ah.Field(key.Type(), name))

-		var extKeyExpr ast.Expr = &ast.BasicLit{
-			Kind:  token.INT,
-			Value: fmt.Sprint(key.value),
-		}
-		if rareRarity.Try(objRand.Rand) {
+		var extKeyExpr ast.Expr = ah.UintLit(key.value)
+		if lowProb.Try(objRand.Rand) {
 			extKeyExpr = objRand.proxyDispatcher.HideValue(extKeyExpr, ast.NewIdent(key.typ))
 		}
 		args = append(args, extKeyExpr)
@@ -196,15 +188,11 @@ func extKeysToParams(objRand *obfRand, keys []*extKey) (params *ast.FieldList, a

 // extKeyToExpr converts an external key into an AST expression like:
 //
-// uint8(key >> b)
-func extKeyToExpr(key *extKey, b int) ast.Expr {
+//	uint8(key >> b)
+func (key *externalKey) ToExpr(b int) ast.Expr {
 	var x ast.Expr = key.Name()
 	if b > 0 {
-		x = &ast.BinaryExpr{
-			X:  x,
-			Op: token.SHR,
-			Y:  ah.IntLit(b * 8),
-		}
+		x = ah.BinaryExpr(x, token.SHR, ah.IntLit(b*8))
 	}
 	if key.typ != "uint8" {
 		x = ah.CallExprByName("byte", x)
@@ -219,26 +207,23 @@ func extKeyToExpr(key *extKey, b int) ast.Expr {
 //		data[<index>] = data[<index>] <random operator> byte(<external key> >> <random shift>) // repeated random times
 //		return data
 //	}()
-func dataToByteSliceWithExtKeys(obfRand *mathrand.Rand, data []byte, extKeys []*extKey) ast.Expr {
-	extKeyOpCount := minByteSliceExtKeyOps + obfRand.Intn(maxByteSliceExtKeyOps-minByteSliceExtKeyOps)
+func dataToByteSliceWithExtKeys(rand *mathrand.Rand, data []byte, extKeys []*externalKey) ast.Expr {
+	extKeyOpCount := minByteSliceExtKeyOps + rand.Intn(maxByteSliceExtKeyOps-minByteSliceExtKeyOps)

 	var stmts []ast.Stmt
 	for i := 0; i < extKeyOpCount; i++ {
-		key := extKeys[obfRand.Intn(len(extKeys))]
+		key := extKeys[rand.Intn(len(extKeys))]
 		key.AddRef()

-		idx, op, b := obfRand.Intn(len(data)), randOperator(obfRand), obfRand.Intn(key.bits/8)
+		idx, op, b := rand.Intn(len(data)), randOperator(rand), rand.Intn(key.bits/8)
 		data[idx] = evalOperator(op, data[idx], byte(key.value>>(b*8)))
-		stmts = append(stmts, &ast.AssignStmt{
-			Lhs: []ast.Expr{ah.IndexExpr("data", ah.IntLit(idx))},
-			Tok: token.ASSIGN,
-			Rhs: []ast.Expr{
-				operatorToReversedBinaryExpr(op,
-					ah.IndexExpr("data", ah.IntLit(idx)),
-					extKeyToExpr(key, b),
-				),
-			},
-		})
+		stmts = append(stmts, ah.AssignStmt(
+			ah.IndexExpr("data", ah.IntLit(idx)),
+			operatorToReversedBinaryExpr(op,
+				ah.IndexExpr("data", ah.IntLit(idx)),
+				key.ToExpr(b),
+			),
+		))
 	}

 	// External keys can be applied several times to the same array element,
@@ -246,26 +231,26 @@ func dataToByteSliceWithExtKeys(obfRand *mathrand.Rand, data []byte, extKeys []*
 	slices.Reverse(stmts)

 	stmts = append([]ast.Stmt{ah.AssignDefineStmt(ast.NewIdent("data"), ah.DataToByteSlice(data))}, append(stmts, ah.ReturnStmt(ast.NewIdent("data")))...)
-	return ah.LambdaCall(nil, &ast.ArrayType{Elt: ast.NewIdent("byte")}, ah.BlockStmt(stmts...), nil)
+	return ah.LambdaCall(nil, ah.ByteSliceType(), ah.BlockStmt(stmts...), nil)
 }

 // dataToByteSliceWithExtKeys scramble and turns a byte into an AST expression like:
 //
 //	byte(<obfuscated value>) <random operator> byte(<external key> >> <random shift>)
-func byteLitWithExtKey(obfRand *mathrand.Rand, val byte, extKeys []*extKey, rarity extKeyRarity) ast.Expr {
-	if !rarity.Try(obfRand) {
+func byteLitWithExtKey(rand *mathrand.Rand, val byte, extKeys []*externalKey, extKeyProb externalKeyProbability) ast.Expr {
+	if !extKeyProb.Try(rand) {
 		return ah.IntLit(int(val))
 	}

-	key := extKeys[obfRand.Intn(len(extKeys))]
+	key := extKeys[rand.Intn(len(extKeys))]
 	key.AddRef()

-	op, b := randOperator(obfRand), obfRand.Intn(key.bits/8)
+	op, b := randOperator(rand), rand.Intn(key.bits/8)
 	newVal := evalOperator(op, val, byte(key.value>>(b*8)))

 	return operatorToReversedBinaryExpr(op,
 		ah.CallExprByName("byte", ah.IntLit(int(newVal))),
-		extKeyToExpr(key, b),
+		key.ToExpr(b),
 	)
 }

--- a/internal/literals/seed.go
+++ b/internal/literals/seed.go
@@ -16,7 +16,7 @@ type seed struct{}
 // check that the obfuscator interface is implemented
 var _ obfuscator = seed{}

-func (seed) obfuscate(obfRand *mathrand.Rand, data []byte, extKeys []*extKey) *ast.BlockStmt {
+func (seed) obfuscate(obfRand *mathrand.Rand, data []byte, extKeys []*externalKey) *ast.BlockStmt {
 	seed := byte(obfRand.Uint32())
 	originalSeed := seed

@@ -27,18 +27,18 @@ func (seed) obfuscate(obfRand *mathrand.Rand, data []byte, extKeys []*extKey) *a
 		seed += encB

 		if i == 0 {
-			callExpr = ah.CallExpr(ast.NewIdent("fnc"), byteLitWithExtKey(obfRand, encB, extKeys, commonRarity))
+			callExpr = ah.CallExpr(ast.NewIdent("fnc"), byteLitWithExtKey(obfRand, encB, extKeys, highProb))
 			continue
 		}

-		callExpr = ah.CallExpr(callExpr, byteLitWithExtKey(obfRand, encB, extKeys, rareRarity))
+		callExpr = ah.CallExpr(callExpr, byteLitWithExtKey(obfRand, encB, extKeys, lowProb))
 	}

 	return ah.BlockStmt(
 		&ast.AssignStmt{
 			Lhs: []ast.Expr{ast.NewIdent("seed")},
 			Tok: token.DEFINE,
-			Rhs: []ast.Expr{ah.CallExprByName("byte", byteLitWithExtKey(obfRand, originalSeed, extKeys, commonRarity))},
+			Rhs: []ast.Expr{ah.CallExprByName("byte", byteLitWithExtKey(obfRand, originalSeed, extKeys, highProb))},
 		},
 		&ast.DeclStmt{
 			Decl: &ast.GenDecl{
--- a/internal/literals/shuffle.go
+++ b/internal/literals/shuffle.go
@@ -16,9 +16,9 @@ type shuffle struct{}
 // check that the obfuscator interface is implemented
 var _ obfuscator = shuffle{}

-func (shuffle) obfuscate(obfRand *mathrand.Rand, data []byte, extKeys []*extKey) *ast.BlockStmt {
+func (shuffle) obfuscate(rand *mathrand.Rand, data []byte, extKeys []*externalKey) *ast.BlockStmt {
 	key := make([]byte, len(data))
-	obfRand.Read(key)
+	rand.Read(key)

 	const (
 		minIdxKeySize = 2
@@ -26,7 +26,7 @@ func (shuffle) obfuscate(obfRand *mathrand.Rand, data []byte, extKeys []*extKey)
 	)

 	idxKeySize := minIdxKeySize
-	if tmp := obfRand.Intn(len(data)); tmp > idxKeySize {
+	if tmp := rand.Intn(len(data)); tmp > idxKeySize {
 		idxKeySize = tmp
 	}
 	if idxKeySize > maxIdxKeySize {
@@ -34,19 +34,19 @@ func (shuffle) obfuscate(obfRand *mathrand.Rand, data []byte, extKeys []*extKey)
 	}

 	idxKey := make([]byte, idxKeySize)
-	obfRand.Read(idxKey)
+	rand.Read(idxKey)

 	fullData := make([]byte, len(data)+len(key))
 	operators := make([]token.Token, len(fullData))
 	for i := range operators {
-		operators[i] = randOperator(obfRand)
+		operators[i] = randOperator(rand)
 	}

 	for i, b := range key {
 		fullData[i], fullData[i+len(data)] = evalOperator(operators[i], data[i], b), b
 	}

-	shuffledIdxs := obfRand.Perm(len(fullData))
+	shuffledIdxs := rand.Perm(len(fullData))

 	shuffledFullData := make([]byte, len(fullData))
 	for i, b := range fullData {
@@ -55,7 +55,7 @@ func (shuffle) obfuscate(obfRand *mathrand.Rand, data []byte, extKeys []*extKey)

 	args := []ast.Expr{ast.NewIdent("data")}
 	for i := range data {
-		keyIdx := obfRand.Intn(idxKeySize)
+		keyIdx := rand.Intn(idxKeySize)
 		k := int(idxKey[keyIdx])

 		args = append(args, operatorToReversedBinaryExpr(
@@ -69,12 +69,12 @@ func (shuffle) obfuscate(obfRand *mathrand.Rand, data []byte, extKeys []*extKey)
 		&ast.AssignStmt{
 			Lhs: []ast.Expr{ast.NewIdent("fullData")},
 			Tok: token.DEFINE,
-			Rhs: []ast.Expr{dataToByteSliceWithExtKeys(obfRand, shuffledFullData, extKeys)},
+			Rhs: []ast.Expr{dataToByteSliceWithExtKeys(rand, shuffledFullData, extKeys)},
 		},
 		&ast.AssignStmt{
 			Lhs: []ast.Expr{ast.NewIdent("idxKey")},
 			Tok: token.DEFINE,
-			Rhs: []ast.Expr{dataToByteSliceWithExtKeys(obfRand, idxKey, extKeys)},
+			Rhs: []ast.Expr{dataToByteSliceWithExtKeys(rand, idxKey, extKeys)},
 		},
 		&ast.AssignStmt{
 			Lhs: []ast.Expr{ast.NewIdent("data")},
--- a/internal/literals/simple.go
+++ b/internal/literals/simple.go
@@ -7,6 +7,7 @@ import (
 	"go/ast"
 	"go/token"
 	mathrand "math/rand"
+
 	ah "mvdan.cc/garble/internal/asthelper"
 )

@@ -15,11 +16,11 @@ type simple struct{}
 // check that the obfuscator interface is implemented
 var _ obfuscator = simple{}

-func (simple) obfuscate(obfRand *mathrand.Rand, data []byte, extKeys []*extKey) *ast.BlockStmt {
+func (simple) obfuscate(rand *mathrand.Rand, data []byte, extKeys []*externalKey) *ast.BlockStmt {
 	key := make([]byte, len(data))
-	obfRand.Read(key)
+	rand.Read(key)

-	op := randOperator(obfRand)
+	op := randOperator(rand)
 	for i, b := range key {
 		data[i] = evalOperator(op, data[i], b)
 	}
@@ -28,12 +29,12 @@ func (simple) obfuscate(obfRand *mathrand.Rand, data []byte, extKeys []*extKey)
 		&ast.AssignStmt{
 			Lhs: []ast.Expr{ast.NewIdent("key")},
 			Tok: token.DEFINE,
-			Rhs: []ast.Expr{dataToByteSliceWithExtKeys(obfRand, key, extKeys)},
+			Rhs: []ast.Expr{dataToByteSliceWithExtKeys(rand, key, extKeys)},
 		},
 		&ast.AssignStmt{
 			Lhs: []ast.Expr{ast.NewIdent("data")},
 			Tok: token.DEFINE,
-			Rhs: []ast.Expr{dataToByteSliceWithExtKeys(obfRand, data, extKeys)},
+			Rhs: []ast.Expr{dataToByteSliceWithExtKeys(rand, data, extKeys)},
 		},
 		&ast.RangeStmt{
 			Key:   ast.NewIdent("i"),
--- a/internal/literals/split.go
+++ b/internal/literals/split.go
@@ -66,33 +66,33 @@ func encryptChunks(chunks [][]byte, op token.Token, key byte) {
 	}
 }

-func (split) obfuscate(obfRand *mathrand.Rand, data []byte, extKeys []*extKey) *ast.BlockStmt {
+func (split) obfuscate(rand *mathrand.Rand, data []byte, extKeys []*externalKey) *ast.BlockStmt {
 	var chunks [][]byte
 	// Short arrays should be divided into single-byte fragments
 	if len(data)/maxChunkSize < minCaseCount {
 		chunks = splitIntoOneByteChunks(data)
 	} else {
-		chunks = splitIntoRandomChunks(obfRand, data)
+		chunks = splitIntoRandomChunks(rand, data)
 	}

 	// Generate indexes for cases chunk count + 1 decrypt case + 1 exit case
-	indexes := obfRand.Perm(len(chunks) + 2)
+	indexes := rand.Perm(len(chunks) + 2)

-	decryptKeyInitial := byte(obfRand.Uint32())
+	decryptKeyInitial := byte(rand.Uint32())
 	decryptKey := decryptKeyInitial
 	// Calculate decrypt key based on indexes and position. Ignore exit index
 	for i, index := range indexes[:len(indexes)-1] {
 		decryptKey ^= byte(index * i)
 	}

-	op := randOperator(obfRand)
+	op := randOperator(rand)
 	encryptChunks(chunks, op, decryptKey)

 	decryptIndex := indexes[len(indexes)-2]
 	exitIndex := indexes[len(indexes)-1]
 	switchCases := []ast.Stmt{&ast.CaseClause{
 		List: []ast.Expr{ah.IntLit(decryptIndex)},
-		Body: shuffleStmts(obfRand,
+		Body: shuffleStmts(rand,
 			&ast.AssignStmt{
 				Lhs: []ast.Expr{ast.NewIdent("i")},
 				Tok: token.ASSIGN,
@@ -131,15 +131,15 @@ func (split) obfuscate(obfRand *mathrand.Rand, data []byte, extKeys []*extKey) *
 		}

 		if len(chunk) != 1 {
-			appendCallExpr.Args = append(appendCallExpr.Args, dataToByteSliceWithExtKeys(obfRand, chunk, extKeys))
+			appendCallExpr.Args = append(appendCallExpr.Args, dataToByteSliceWithExtKeys(rand, chunk, extKeys))
 			appendCallExpr.Ellipsis = 1
 		} else {
-			appendCallExpr.Args = append(appendCallExpr.Args, byteLitWithExtKey(obfRand, chunk[0], extKeys, rareRarity))
+			appendCallExpr.Args = append(appendCallExpr.Args, byteLitWithExtKey(rand, chunk[0], extKeys, lowProb))
 		}

 		switchCases = append(switchCases, &ast.CaseClause{
 			List: []ast.Expr{ah.IntLit(index)},
-			Body: shuffleStmts(obfRand,
+			Body: shuffleStmts(rand,
 				&ast.AssignStmt{
 					Lhs: []ast.Expr{ast.NewIdent("i")},
 					Tok: token.ASSIGN,
@@ -168,7 +168,7 @@ func (split) obfuscate(obfRand *mathrand.Rand, data []byte, extKeys []*extKey) *
 		&ast.AssignStmt{
 			Lhs: []ast.Expr{ast.NewIdent("decryptKey")},
 			Tok: token.DEFINE,
-			Rhs: []ast.Expr{ah.CallExprByName("int", byteLitWithExtKey(obfRand, decryptKeyInitial, extKeys, normalRarity))},
+			Rhs: []ast.Expr{ah.CallExprByName("int", byteLitWithExtKey(rand, decryptKeyInitial, extKeys, normalProb))},
 		},
 		&ast.ForStmt{
 			Init: &ast.AssignStmt{
@@ -199,7 +199,7 @@ func (split) obfuscate(obfRand *mathrand.Rand, data []byte, extKeys []*extKey) *
 				},
 				&ast.SwitchStmt{
 					Tag:  ast.NewIdent("i"),
-					Body: ah.BlockStmt(shuffleStmts(obfRand, switchCases...)...),
+					Body: ah.BlockStmt(shuffleStmts(rand, switchCases...)...),
 				}),
 		},
 	)
--- a/internal/literals/swap.go
+++ b/internal/literals/swap.go
@@ -58,13 +58,13 @@ func generateSwapCount(obfRand *mathrand.Rand, dataLen int) int {
 	return swapCount
 }

-func (swap) obfuscate(obfRand *mathrand.Rand, data []byte, extKeys []*extKey) *ast.BlockStmt {
-	swapCount := generateSwapCount(obfRand, len(data))
-	shiftKey := byte(obfRand.Uint32())
+func (swap) obfuscate(rand *mathrand.Rand, data []byte, extKeys []*externalKey) *ast.BlockStmt {
+	swapCount := generateSwapCount(rand, len(data))
+	shiftKey := byte(rand.Uint32())

-	op := randOperator(obfRand)
+	op := randOperator(rand)

-	positions := genRandIntSlice(obfRand, len(data), swapCount)
+	positions := genRandIntSlice(rand, len(data), swapCount)
 	for i := len(positions) - 2; i >= 0; i -= 2 {
 		// Generate local key for xor based on random key and byte position
 		localKey := byte(i) + byte(positions[i]^positions[i+1]) + shiftKey
@@ -76,7 +76,7 @@ func (swap) obfuscate(obfRand *mathrand.Rand, data []byte, extKeys []*extKey) *a
 		&ast.AssignStmt{
 			Lhs: []ast.Expr{ast.NewIdent("data")},
 			Tok: token.DEFINE,
-			Rhs: []ast.Expr{dataToByteSliceWithExtKeys(obfRand, data, extKeys)},
+			Rhs: []ast.Expr{dataToByteSliceWithExtKeys(rand, data, extKeys)},
 		},
 		&ast.AssignStmt{
 			Lhs: []ast.Expr{ast.NewIdent("positions")},
@@ -118,7 +118,7 @@ func (swap) obfuscate(obfRand *mathrand.Rand, data []byte, extKeys []*extKey) *a
 							}),
 						},
 						Op: token.ADD,
-						Y:  byteLitWithExtKey(obfRand, shiftKey, extKeys, commonRarity),
+						Y:  byteLitWithExtKey(rand, shiftKey, extKeys, highProb),
 					}},
 				},
 				&ast.AssignStmt{