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117 lines
2.7 KiB
Go
117 lines
2.7 KiB
Go
// Copyright (c) 2020, The Garble Authors.
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// See LICENSE for licensing information.
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package literals
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import (
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"go/ast"
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"go/token"
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mathrand "math/rand"
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ah "mvdan.cc/garble/internal/asthelper"
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)
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type seed struct{}
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// check that the obfuscator interface is implemented
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var _ obfuscator = seed{}
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func (seed) obfuscate(obfRand *mathrand.Rand, data []byte) *ast.BlockStmt {
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seed := byte(obfRand.Uint32())
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originalSeed := seed
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op := randOperator(obfRand)
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var callExpr *ast.CallExpr
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for i, b := range data {
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encB := evalOperator(op, b, seed)
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seed += encB
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if i == 0 {
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callExpr = ah.CallExpr(ast.NewIdent("fnc"), ah.IntLit(int(encB)))
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continue
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}
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callExpr = ah.CallExpr(callExpr, ah.IntLit(int(encB)))
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}
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return ah.BlockStmt(
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&ast.AssignStmt{
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Lhs: []ast.Expr{ast.NewIdent("seed")},
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Tok: token.DEFINE,
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Rhs: []ast.Expr{ah.CallExpr(ast.NewIdent("byte"), ah.IntLit(int(originalSeed)))},
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},
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&ast.DeclStmt{
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Decl: &ast.GenDecl{
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Tok: token.VAR,
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Specs: []ast.Spec{&ast.ValueSpec{
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Names: []*ast.Ident{ast.NewIdent("data")},
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Type: &ast.ArrayType{Elt: ast.NewIdent("byte")},
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}},
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},
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},
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&ast.DeclStmt{
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Decl: &ast.GenDecl{
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Tok: token.TYPE,
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Specs: []ast.Spec{&ast.TypeSpec{
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Name: ast.NewIdent("decFunc"),
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Type: &ast.FuncType{
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Params: &ast.FieldList{List: []*ast.Field{
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{Type: ast.NewIdent("byte")},
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}},
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Results: &ast.FieldList{List: []*ast.Field{
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{Type: ast.NewIdent("decFunc")},
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}},
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},
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}},
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},
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},
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&ast.DeclStmt{
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Decl: &ast.GenDecl{
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Tok: token.VAR,
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Specs: []ast.Spec{&ast.ValueSpec{
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Names: []*ast.Ident{ast.NewIdent("fnc")},
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Type: ast.NewIdent("decFunc"),
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}},
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},
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},
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&ast.AssignStmt{
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Lhs: []ast.Expr{ast.NewIdent("fnc")},
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Tok: token.ASSIGN,
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Rhs: []ast.Expr{
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&ast.FuncLit{
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Type: &ast.FuncType{
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Params: &ast.FieldList{
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List: []*ast.Field{{
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Names: []*ast.Ident{ast.NewIdent("x")},
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Type: ast.NewIdent("byte"),
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}},
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},
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Results: &ast.FieldList{
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List: []*ast.Field{{
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Type: ast.NewIdent("decFunc"),
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}},
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},
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},
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Body: ah.BlockStmt(
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&ast.AssignStmt{
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Lhs: []ast.Expr{ast.NewIdent("data")},
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Tok: token.ASSIGN,
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Rhs: []ast.Expr{
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ah.CallExpr(ast.NewIdent("append"), ast.NewIdent("data"), operatorToReversedBinaryExpr(op, ast.NewIdent("x"), ast.NewIdent("seed"))),
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},
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},
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&ast.AssignStmt{
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Lhs: []ast.Expr{ast.NewIdent("seed")},
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Tok: token.ADD_ASSIGN,
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Rhs: []ast.Expr{ast.NewIdent("x")},
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},
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ah.ReturnStmt(ast.NewIdent("fnc")),
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),
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},
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},
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},
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ah.ExprStmt(callExpr),
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)
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}
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