// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package rc4

import (
	"bytes"
	"fmt"
	"testing"
)

type rc4Test struct {
	key, keystream []byte
}

var golden = []rc4Test{
	// Test vectors from the original cypherpunk posting of ARC4:
	//   https://groups.google.com/group/sci.crypt/msg/10a300c9d21afca0?pli=1
	{
		[]byte{0x01, 0x23, 0x45, 0x67, 0x89, 0xab, 0xcd, 0xef},
		[]byte{0x74, 0x94, 0xc2, 0xe7, 0x10, 0x4b, 0x08, 0x79},
	},
	{
		[]byte{0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00},
		[]byte{0xde, 0x18, 0x89, 0x41, 0xa3, 0x37, 0x5d, 0x3a},
	},
	{
		[]byte{0xef, 0x01, 0x23, 0x45},
		[]byte{0xd6, 0xa1, 0x41, 0xa7, 0xec, 0x3c, 0x38, 0xdf, 0xbd, 0x61},
	},

	// Test vectors from the Wikipedia page: https://en.wikipedia.org/wiki/RC4
	{
		[]byte{0x4b, 0x65, 0x79},
		[]byte{0xeb, 0x9f, 0x77, 0x81, 0xb7, 0x34, 0xca, 0x72, 0xa7, 0x19},
	},
	{
		[]byte{0x57, 0x69, 0x6b, 0x69},
		[]byte{0x60, 0x44, 0xdb, 0x6d, 0x41, 0xb7},
	},
	{
		[]byte{0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00},
		[]byte{
			0xde, 0x18, 0x89, 0x41, 0xa3, 0x37, 0x5d, 0x3a,
			0x8a, 0x06, 0x1e, 0x67, 0x57, 0x6e, 0x92, 0x6d,
			0xc7, 0x1a, 0x7f, 0xa3, 0xf0, 0xcc, 0xeb, 0x97,
			0x45, 0x2b, 0x4d, 0x32, 0x27, 0x96, 0x5f, 0x9e,
			0xa8, 0xcc, 0x75, 0x07, 0x6d, 0x9f, 0xb9, 0xc5,
			0x41, 0x7a, 0xa5, 0xcb, 0x30, 0xfc, 0x22, 0x19,
			0x8b, 0x34, 0x98, 0x2d, 0xbb, 0x62, 0x9e, 0xc0,
			0x4b, 0x4f, 0x8b, 0x05, 0xa0, 0x71, 0x08, 0x50,
			0x92, 0xa0, 0xc3, 0x58, 0x4a, 0x48, 0xe4, 0xa3,
			0x0a, 0x39, 0x7b, 0x8a, 0xcd, 0x1d, 0x00, 0x9e,
			0xc8, 0x7d, 0x68, 0x11, 0xf2, 0x2c, 0xf4, 0x9c,
			0xa3, 0xe5, 0x93, 0x54, 0xb9, 0x45, 0x15, 0x35,
			0xa2, 0x18, 0x7a, 0x86, 0x42, 0x6c, 0xca, 0x7d,
			0x5e, 0x82, 0x3e, 0xba, 0x00, 0x44, 0x12, 0x67,
			0x12, 0x57, 0xb8, 0xd8, 0x60, 0xae, 0x4c, 0xbd,
			0x4c, 0x49, 0x06, 0xbb, 0xc5, 0x35, 0xef, 0xe1,
			0x58, 0x7f, 0x08, 0xdb, 0x33, 0x95, 0x5c, 0xdb,
			0xcb, 0xad, 0x9b, 0x10, 0xf5, 0x3f, 0xc4, 0xe5,
			0x2c, 0x59, 0x15, 0x65, 0x51, 0x84, 0x87, 0xfe,
			0x08, 0x4d, 0x0e, 0x3f, 0x03, 0xde, 0xbc, 0xc9,
			0xda, 0x1c, 0xe9, 0x0d, 0x08, 0x5c, 0x2d, 0x8a,
			0x19, 0xd8, 0x37, 0x30, 0x86, 0x16, 0x36, 0x92,
			0x14, 0x2b, 0xd8, 0xfc, 0x5d, 0x7a, 0x73, 0x49,
			0x6a, 0x8e, 0x59, 0xee, 0x7e, 0xcf, 0x6b, 0x94,
			0x06, 0x63, 0xf4, 0xa6, 0xbe, 0xe6, 0x5b, 0xd2,
			0xc8, 0x5c, 0x46, 0x98, 0x6c, 0x1b, 0xef, 0x34,
			0x90, 0xd3, 0x7b, 0x38, 0xda, 0x85, 0xd3, 0x2e,
			0x97, 0x39, 0xcb, 0x23, 0x4a, 0x2b, 0xe7, 0x40,
		},
	},
}

func testEncrypt(t *testing.T, desc string, c *Cipher, src, expect []byte) {
	dst := make([]byte, len(src))
	c.XORKeyStream(dst, src)
	for i, v := range dst {
		if v != expect[i] {
			t.Fatalf("%s: mismatch at byte %d:\nhave %x\nwant %x", desc, i, dst, expect)
		}
	}
}

func TestGolden(t *testing.T) {
	for gi, g := range golden {
		data := make([]byte, len(g.keystream))
		for i := range data {
			data[i] = byte(i)
		}

		expect := make([]byte, len(g.keystream))
		for i := range expect {
			expect[i] = byte(i) ^ g.keystream[i]
		}

		for size := 1; size <= len(g.keystream); size++ {
			c, err := NewCipher(g.key)
			if err != nil {
				t.Fatalf("#%d: NewCipher: %v", gi, err)
			}

			off := 0
			for off < len(g.keystream) {
				n := len(g.keystream) - off
				if n > size {
					n = size
				}
				desc := fmt.Sprintf("#%d@[%d:%d]", gi, off, off+n)
				testEncrypt(t, desc, c, data[off:off+n], expect[off:off+n])
				off += n
			}
		}
	}
}

func TestBlock(t *testing.T) {
	testBlock(t, (*Cipher).XORKeyStream)
}

// Test the pure Go version.
// Because we have assembly for amd64, 386, and arm, this prevents
// bitrot of the reference implementations.
func TestBlockGeneric(t *testing.T) {
	testBlock(t, (*Cipher).xorKeyStreamGeneric)
}

func testBlock(t *testing.T, xor func(c *Cipher, dst, src []byte)) {
	c1a, _ := NewCipher(golden[0].key)
	c1b, _ := NewCipher(golden[1].key)
	data1 := make([]byte, 1<<20)
	for i := range data1 {
		xor(c1a, data1[i:i+1], data1[i:i+1])
		xor(c1b, data1[i:i+1], data1[i:i+1])
	}

	c2a, _ := NewCipher(golden[0].key)
	c2b, _ := NewCipher(golden[1].key)
	data2 := make([]byte, 1<<20)
	xor(c2a, data2, data2)
	xor(c2b, data2, data2)

	if !bytes.Equal(data1, data2) {
		t.Fatalf("bad block")
	}
}

func benchmark(b *testing.B, size int64) {
	buf := make([]byte, size)
	c, err := NewCipher(golden[0].key)
	if err != nil {
		panic(err)
	}
	b.SetBytes(size)

	for i := 0; i < b.N; i++ {
		c.XORKeyStream(buf, buf)
	}
}

func BenchmarkRC4_128(b *testing.B) {
	benchmark(b, 128)
}

func BenchmarkRC4_1K(b *testing.B) {
	benchmark(b, 1024)
}

func BenchmarkRC4_8K(b *testing.B) {
	benchmark(b, 8096)
}