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87 lines
1.8 KiB
Go
87 lines
1.8 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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"fmt"
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"go/ast"
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"go/token"
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mathrand "math/rand"
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)
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// obfuscator takes a byte slice and converts it to a ast.BlockStmt
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type obfuscator interface {
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obfuscate(data []byte) *ast.BlockStmt
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}
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var (
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// obfuscators contains all types which implement the obfuscator Interface
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obfuscators = []obfuscator{
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simple{},
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swap{},
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split{},
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shuffle{},
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seed{},
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}
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)
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// If math/rand.Seed() is not called, the generator behaves as if seeded by rand.Seed(1),
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// so the generator is deterministic.
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// genRandBytes return a random []byte with the length of size.
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func genRandBytes(buffer []byte) {
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if _, err := mathrand.Read(buffer); err != nil {
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panic(fmt.Sprintf("couldn't generate random key: %v", err))
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}
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}
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func genRandByte() byte {
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bytes := make([]byte, 1)
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genRandBytes(bytes)
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return bytes[0]
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}
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func genRandIntSlice(max, count int) []int {
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indexes := make([]int, count)
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for i := 0; i < count; i++ {
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indexes[i] = mathrand.Intn(max)
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}
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return indexes
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}
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func randOperator() token.Token {
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operatorTokens := [...]token.Token{token.XOR, token.ADD, token.SUB}
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return operatorTokens[mathrand.Intn(len(operatorTokens))]
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}
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func evalOperator(t token.Token, x, y byte) byte {
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switch t {
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case token.XOR:
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return x ^ y
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case token.ADD:
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return x + y
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case token.SUB:
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return x - y
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default:
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panic(fmt.Sprintf("unknown operator: %s", t))
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}
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}
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func operatorToReversedBinaryExpr(t token.Token, x, y ast.Expr) *ast.BinaryExpr {
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expr := &ast.BinaryExpr{X: x, Y: y}
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switch t {
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case token.XOR:
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expr.Op = token.XOR
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case token.ADD:
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expr.Op = token.SUB
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case token.SUB:
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expr.Op = token.ADD
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default:
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panic(fmt.Sprintf("unknown operator: %s", t))
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}
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return expr
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}
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