diff --git a/common/crypto/benchmark_test.go b/common/crypto/benchmark_test.go
new file mode 100644
index 00000000..14396b5f
--- /dev/null
+++ b/common/crypto/benchmark_test.go
@@ -0,0 +1,49 @@
+package crypto_test
+
+import (
+	"crypto/cipher"
+	"testing"
+
+	. "github.com/v2ray/v2ray-core/common/crypto"
+)
+
+const benchSize = 1024 * 1024
+
+func benchmarkStream(b *testing.B, c cipher.Stream) {
+	b.SetBytes(benchSize)
+	input := make([]byte, benchSize)
+	output := make([]byte, benchSize)
+	for i := 0; i < b.N; i++ {
+		c.XORKeyStream(output, input)
+	}
+}
+
+func BenchmarkChaCha20(b *testing.B) {
+	key := make([]byte, 32)
+	nonce := make([]byte, 8)
+	c := NewChaCha20Stream(key, nonce)
+	benchmarkStream(b, c)
+}
+
+func BenchmarkChaCha20IETF(b *testing.B) {
+	key := make([]byte, 32)
+	nonce := make([]byte, 12)
+	c := NewChaCha20Stream(key, nonce)
+	benchmarkStream(b, c)
+}
+
+func BenchmarkAESEncryption(b *testing.B) {
+	key := make([]byte, 32)
+	iv := make([]byte, 16)
+	c, _ := NewAesEncryptionStream(key, iv)
+
+	benchmarkStream(b, c)
+}
+
+func BenchmarkAESDecryption(b *testing.B) {
+	key := make([]byte, 32)
+	iv := make([]byte, 16)
+	c, _ := NewAesDecryptionStream(key, iv)
+
+	benchmarkStream(b, c)
+}
diff --git a/common/crypto/chacha20.go b/common/crypto/chacha20.go
new file mode 100644
index 00000000..699a00fa
--- /dev/null
+++ b/common/crypto/chacha20.go
@@ -0,0 +1,11 @@
+package crypto
+
+import (
+	"crypto/cipher"
+
+	"github.com/v2ray/v2ray-core/common/crypto/internal"
+)
+
+func NewChaCha20Stream(key []byte, iv []byte) cipher.Stream {
+	return internal.NewChaCha20Stream(key, iv, 20)
+}
diff --git a/common/crypto/chacha20_test.go b/common/crypto/chacha20_test.go
new file mode 100644
index 00000000..1f16ec95
--- /dev/null
+++ b/common/crypto/chacha20_test.go
@@ -0,0 +1,57 @@
+package crypto_test
+
+import (
+	"encoding/hex"
+	"testing"
+
+	. "github.com/v2ray/v2ray-core/common/crypto"
+	v2testing "github.com/v2ray/v2ray-core/testing"
+	"github.com/v2ray/v2ray-core/testing/assert"
+)
+
+func mustDecodeHex(s string) []byte {
+	b, err := hex.DecodeString(s)
+	if err != nil {
+		panic(err)
+	}
+	return b
+}
+
+func TestChaCha20Stream(t *testing.T) {
+	v2testing.Current(t)
+
+	var cases = []struct {
+		key    []byte
+		iv     []byte
+		output []byte
+	}{
+		{
+			key: mustDecodeHex("0000000000000000000000000000000000000000000000000000000000000000"),
+			iv:  mustDecodeHex("0000000000000000"),
+			output: mustDecodeHex("76b8e0ada0f13d90405d6ae55386bd28bdd219b8a08ded1aa836efcc8b770dc7" +
+				"da41597c5157488d7724e03fb8d84a376a43b8f41518a11cc387b669b2ee6586" +
+				"9f07e7be5551387a98ba977c732d080dcb0f29a048e3656912c6533e32ee7aed" +
+				"29b721769ce64e43d57133b074d839d531ed1f28510afb45ace10a1f4b794d6f"),
+		},
+		{
+			key: mustDecodeHex("5555555555555555555555555555555555555555555555555555555555555555"),
+			iv:  mustDecodeHex("5555555555555555"),
+			output: mustDecodeHex("bea9411aa453c5434a5ae8c92862f564396855a9ea6e22d6d3b50ae1b3663311" +
+				"a4a3606c671d605ce16c3aece8e61ea145c59775017bee2fa6f88afc758069f7" +
+				"e0b8f676e644216f4d2a3422d7fa36c6c4931aca950e9da42788e6d0b6d1cd83" +
+				"8ef652e97b145b14871eae6c6804c7004db5ac2fce4c68c726d004b10fcaba86"),
+		},
+		{
+			key:    mustDecodeHex("0000000000000000000000000000000000000000000000000000000000000000"),
+			iv:     mustDecodeHex("000000000000000000000000"),
+			output: mustDecodeHex("76b8e0ada0f13d90405d6ae55386bd28bdd219b8a08ded1aa836efcc8b770dc7da41597c5157488d7724e03fb8d84a376a43b8f41518a11cc387b669b2ee6586"),
+		},
+	}
+	for _, c := range cases {
+		s := NewChaCha20Stream(c.key, c.iv)
+		input := make([]byte, len(c.output))
+		actualOutout := make([]byte, len(c.output))
+		s.XORKeyStream(actualOutout, input)
+		assert.Bytes(c.output).Equals(actualOutout)
+	}
+}
diff --git a/common/crypto/internal/chacha.go b/common/crypto/internal/chacha.go
new file mode 100644
index 00000000..7624248f
--- /dev/null
+++ b/common/crypto/internal/chacha.go
@@ -0,0 +1,85 @@
+package internal
+
+//go:generate go run chacha_core_gen.go
+
+import (
+	"encoding/binary"
+)
+
+const (
+	wordSize  = 4                    // the size of ChaCha20's words
+	stateSize = 16                   // the size of ChaCha20's state, in words
+	blockSize = stateSize * wordSize // the size of ChaCha20's block, in bytes
+)
+
+type ChaCha20Stream struct {
+	state  [stateSize]uint32 // the state as an array of 16 32-bit words
+	block  [blockSize]byte   // the keystream as an array of 64 bytes
+	offset int               // the offset of used bytes in block
+	rounds int
+}
+
+func NewChaCha20Stream(key []byte, nonce []byte, rounds int) *ChaCha20Stream {
+	s := new(ChaCha20Stream)
+	// the magic constants for 256-bit keys
+	s.state[0] = 0x61707865
+	s.state[1] = 0x3320646e
+	s.state[2] = 0x79622d32
+	s.state[3] = 0x6b206574
+
+	for i := 0; i < 8; i++ {
+		s.state[i+4] = binary.LittleEndian.Uint32(key[i*4 : i*4+4])
+	}
+
+	switch len(nonce) {
+	case 8:
+		s.state[14] = binary.LittleEndian.Uint32(nonce[0:])
+		s.state[15] = binary.LittleEndian.Uint32(nonce[4:])
+	case 12:
+		s.state[13] = binary.LittleEndian.Uint32(nonce[0:4])
+		s.state[14] = binary.LittleEndian.Uint32(nonce[4:8])
+		s.state[15] = binary.LittleEndian.Uint32(nonce[8:12])
+	default:
+		panic("bad nonce length")
+	}
+
+	s.rounds = rounds
+	s.advance()
+	return s
+}
+
+func (s *ChaCha20Stream) XORKeyStream(dst, src []byte) {
+	// Stride over the input in 64-byte blocks, minus the amount of keystream
+	// previously used. This will produce best results when processing blocks
+	// of a size evenly divisible by 64.
+	i := 0
+	max := len(src)
+	for i < max {
+		gap := blockSize - s.offset
+
+		limit := i + gap
+		if limit > max {
+			limit = max
+		}
+
+		o := s.offset
+		for j := i; j < limit; j++ {
+			dst[j] = src[j] ^ s.block[o]
+			o++
+		}
+
+		i += gap
+		s.offset = o
+
+		if o == blockSize {
+			s.advance()
+		}
+	}
+}
+
+func (s *ChaCha20Stream) advance() {
+	ChaCha20Block(&s.state, s.block[:], s.rounds)
+
+	s.offset = 0
+	s.state[12]++
+}
diff --git a/common/crypto/internal/chacha_core.go b/common/crypto/internal/chacha_core.go
new file mode 100644
index 00000000..ede94d89
--- /dev/null
+++ b/common/crypto/internal/chacha_core.go
@@ -0,0 +1,126 @@
+// GENERATED CODE. DO NOT MODIFY!
+package internal
+
+import "encoding/binary"
+
+
+func ChaCha20Block(s *[16]uint32, out []byte, rounds int) {
+  var x0,x1,x2,x3,x4,x5,x6,x7,x8,x9,x10,x11,x12,x13,x14,x15 = s[0],s[1],s[2],s[3],s[4],s[5],s[6],s[7],s[8],s[9],s[10],s[11],s[12],s[13],s[14],s[15]
+	for i := 0; i < rounds; i+=2 {
+    var x uint32
+    
+x0+=x4
+x=x12^x0
+x12=(x << 16) | (x >> (32 - 16))
+x8+=x12
+x=x4^x8
+x4=(x << 12) | (x >> (32 - 12))
+x0+=x4
+x=x12^x0
+x12=(x << 8) | (x >> (32 - 8))
+x8+=x12
+x=x4^x8
+x4=(x << 7) | (x >> (32 - 7))
+x1+=x5
+x=x13^x1
+x13=(x << 16) | (x >> (32 - 16))
+x9+=x13
+x=x5^x9
+x5=(x << 12) | (x >> (32 - 12))
+x1+=x5
+x=x13^x1
+x13=(x << 8) | (x >> (32 - 8))
+x9+=x13
+x=x5^x9
+x5=(x << 7) | (x >> (32 - 7))
+x2+=x6
+x=x14^x2
+x14=(x << 16) | (x >> (32 - 16))
+x10+=x14
+x=x6^x10
+x6=(x << 12) | (x >> (32 - 12))
+x2+=x6
+x=x14^x2
+x14=(x << 8) | (x >> (32 - 8))
+x10+=x14
+x=x6^x10
+x6=(x << 7) | (x >> (32 - 7))
+x3+=x7
+x=x15^x3
+x15=(x << 16) | (x >> (32 - 16))
+x11+=x15
+x=x7^x11
+x7=(x << 12) | (x >> (32 - 12))
+x3+=x7
+x=x15^x3
+x15=(x << 8) | (x >> (32 - 8))
+x11+=x15
+x=x7^x11
+x7=(x << 7) | (x >> (32 - 7))
+x0+=x5
+x=x15^x0
+x15=(x << 16) | (x >> (32 - 16))
+x10+=x15
+x=x5^x10
+x5=(x << 12) | (x >> (32 - 12))
+x0+=x5
+x=x15^x0
+x15=(x << 8) | (x >> (32 - 8))
+x10+=x15
+x=x5^x10
+x5=(x << 7) | (x >> (32 - 7))
+x1+=x6
+x=x12^x1
+x12=(x << 16) | (x >> (32 - 16))
+x11+=x12
+x=x6^x11
+x6=(x << 12) | (x >> (32 - 12))
+x1+=x6
+x=x12^x1
+x12=(x << 8) | (x >> (32 - 8))
+x11+=x12
+x=x6^x11
+x6=(x << 7) | (x >> (32 - 7))
+x2+=x7
+x=x13^x2
+x13=(x << 16) | (x >> (32 - 16))
+x8+=x13
+x=x7^x8
+x7=(x << 12) | (x >> (32 - 12))
+x2+=x7
+x=x13^x2
+x13=(x << 8) | (x >> (32 - 8))
+x8+=x13
+x=x7^x8
+x7=(x << 7) | (x >> (32 - 7))
+x3+=x4
+x=x14^x3
+x14=(x << 16) | (x >> (32 - 16))
+x9+=x14
+x=x4^x9
+x4=(x << 12) | (x >> (32 - 12))
+x3+=x4
+x=x14^x3
+x14=(x << 8) | (x >> (32 - 8))
+x9+=x14
+x=x4^x9
+x4=(x << 7) | (x >> (32 - 7))
+}
+binary.LittleEndian.PutUint32(out[0:4], s[0]+x0)
+binary.LittleEndian.PutUint32(out[4:8], s[1]+x1)
+binary.LittleEndian.PutUint32(out[8:12], s[2]+x2)
+binary.LittleEndian.PutUint32(out[12:16], s[3]+x3)
+binary.LittleEndian.PutUint32(out[16:20], s[4]+x4)
+binary.LittleEndian.PutUint32(out[20:24], s[5]+x5)
+binary.LittleEndian.PutUint32(out[24:28], s[6]+x6)
+binary.LittleEndian.PutUint32(out[28:32], s[7]+x7)
+binary.LittleEndian.PutUint32(out[32:36], s[8]+x8)
+binary.LittleEndian.PutUint32(out[36:40], s[9]+x9)
+binary.LittleEndian.PutUint32(out[40:44], s[10]+x10)
+binary.LittleEndian.PutUint32(out[44:48], s[11]+x11)
+binary.LittleEndian.PutUint32(out[48:52], s[12]+x12)
+binary.LittleEndian.PutUint32(out[52:56], s[13]+x13)
+binary.LittleEndian.PutUint32(out[56:60], s[14]+x14)
+binary.LittleEndian.PutUint32(out[60:64], s[15]+x15)
+}
+
diff --git a/common/crypto/internal/chacha_core_gen.go b/common/crypto/internal/chacha_core_gen.go
new file mode 100644
index 00000000..b49a63ab
--- /dev/null
+++ b/common/crypto/internal/chacha_core_gen.go
@@ -0,0 +1,70 @@
+// +build generate
+
+package main
+
+import (
+	"fmt"
+	"log"
+	"os"
+)
+
+func writeQuarterRound(file *os.File, a, b, c, d int) {
+	add := "x%d+=x%d\n"
+	xor := "x=x%d^x%d\n"
+	rotate := "x%d=(x << %d) | (x >> (32 - %d))\n"
+
+	fmt.Fprintf(file, add, a, b)
+	fmt.Fprintf(file, xor, d, a)
+	fmt.Fprintf(file, rotate, d, 16, 16)
+
+	fmt.Fprintf(file, add, c, d)
+	fmt.Fprintf(file, xor, b, c)
+	fmt.Fprintf(file, rotate, b, 12, 12)
+
+	fmt.Fprintf(file, add, a, b)
+	fmt.Fprintf(file, xor, d, a)
+	fmt.Fprintf(file, rotate, d, 8, 8)
+
+	fmt.Fprintf(file, add, c, d)
+	fmt.Fprintf(file, xor, b, c)
+	fmt.Fprintf(file, rotate, b, 7, 7)
+}
+
+func writeChacha20Block(file *os.File) {
+	fmt.Fprintln(file, `
+func ChaCha20Block(s *[16]uint32, out []byte, rounds int) {
+  var x0,x1,x2,x3,x4,x5,x6,x7,x8,x9,x10,x11,x12,x13,x14,x15 = s[0],s[1],s[2],s[3],s[4],s[5],s[6],s[7],s[8],s[9],s[10],s[11],s[12],s[13],s[14],s[15]
+	for i := 0; i < rounds; i+=2 {
+    var x uint32
+    `)
+
+	writeQuarterRound(file, 0, 4, 8, 12)
+	writeQuarterRound(file, 1, 5, 9, 13)
+	writeQuarterRound(file, 2, 6, 10, 14)
+	writeQuarterRound(file, 3, 7, 11, 15)
+	writeQuarterRound(file, 0, 5, 10, 15)
+	writeQuarterRound(file, 1, 6, 11, 12)
+	writeQuarterRound(file, 2, 7, 8, 13)
+	writeQuarterRound(file, 3, 4, 9, 14)
+	fmt.Fprintln(file, "}")
+	for i := 0; i < 16; i++ {
+		fmt.Fprintf(file, "binary.LittleEndian.PutUint32(out[%d:%d], s[%d]+x%d)\n", i*4, i*4+4, i, i)
+	}
+	fmt.Fprintln(file, "}")
+	fmt.Fprintln(file)
+}
+
+func main() {
+	file, err := os.OpenFile("chacha_core.go", os.O_WRONLY|os.O_TRUNC|os.O_CREATE, 0644)
+	if err != nil {
+		log.Fatalf("Failed to generate chacha_core.go: %v", err)
+	}
+	defer file.Close()
+
+	fmt.Fprintln(file, "// GENERATED CODE. DO NOT MODIFY!")
+	fmt.Fprintln(file, "package internal")
+	fmt.Fprintln(file)
+	fmt.Fprintln(file, "import \"encoding/binary\"")
+	fmt.Fprintln(file)
+	writeChacha20Block(file)
+}