Clash.Meta/transport/shadowsocks/shadowaead/cipher.go

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Go
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package shadowaead
import (
"crypto/aes"
"crypto/cipher"
"crypto/sha1"
"io"
"strconv"
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"github.com/metacubex/chacha"
"gitlab.com/go-extension/aes-ccm"
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"golang.org/x/crypto/chacha20poly1305"
"golang.org/x/crypto/hkdf"
)
type Cipher interface {
KeySize() int
SaltSize() int
Encrypter(salt []byte) (cipher.AEAD, error)
Decrypter(salt []byte) (cipher.AEAD, error)
}
type KeySizeError int
func (e KeySizeError) Error() string {
return "key size error: need " + strconv.Itoa(int(e)) + " bytes"
}
func hkdfSHA1(secret, salt, info, outkey []byte) {
r := hkdf.New(sha1.New, secret, salt, info)
if _, err := io.ReadFull(r, outkey); err != nil {
panic(err) // should never happen
}
}
type metaCipher struct {
psk []byte
makeAEAD func(key []byte) (cipher.AEAD, error)
}
func (a *metaCipher) KeySize() int { return len(a.psk) }
func (a *metaCipher) SaltSize() int {
if ks := a.KeySize(); ks > 16 {
return ks
}
return 16
}
func (a *metaCipher) Encrypter(salt []byte) (cipher.AEAD, error) {
subkey := make([]byte, a.KeySize())
hkdfSHA1(a.psk, salt, []byte("ss-subkey"), subkey)
return a.makeAEAD(subkey)
}
func (a *metaCipher) Decrypter(salt []byte) (cipher.AEAD, error) {
subkey := make([]byte, a.KeySize())
hkdfSHA1(a.psk, salt, []byte("ss-subkey"), subkey)
return a.makeAEAD(subkey)
}
func aesGCM(key []byte) (cipher.AEAD, error) {
blk, err := aes.NewCipher(key)
if err != nil {
return nil, err
}
return cipher.NewGCM(blk)
}
// AESGCM creates a new Cipher with a pre-shared key. len(psk) must be
// one of 16, 24, or 32 to select AES-128/196/256-GCM.
func AESGCM(psk []byte) (Cipher, error) {
switch l := len(psk); l {
case 16, 24, 32: // AES 128/196/256
default:
return nil, aes.KeySizeError(l)
}
return &metaCipher{psk: psk, makeAEAD: aesGCM}, nil
}
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func aesCCM(key []byte) (cipher.AEAD, error) {
blk, err := aes.NewCipher(key)
if err != nil {
return nil, err
}
return ccm.NewCCM(blk)
}
// AESCCM creates a new Cipher with a pre-shared key. len(psk) must be
// one of 16, 24, or 32 to select AES-128/196/256-GCM.
func AESCCM(psk []byte) (Cipher, error) {
switch l := len(psk); l {
case 16, 24, 32: // AES 128/196/256
default:
return nil, aes.KeySizeError(l)
}
return &metaCipher{psk: psk, makeAEAD: aesCCM}, nil
}
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// Chacha20Poly1305 creates a new Cipher with a pre-shared key. len(psk)
// must be 32.
func Chacha20Poly1305(psk []byte) (Cipher, error) {
if len(psk) != chacha20poly1305.KeySize {
return nil, KeySizeError(chacha20poly1305.KeySize)
}
return &metaCipher{psk: psk, makeAEAD: chacha20poly1305.New}, nil
}
// XChacha20Poly1305 creates a new Cipher with a pre-shared key. len(psk)
// must be 32.
func XChacha20Poly1305(psk []byte) (Cipher, error) {
if len(psk) != chacha20poly1305.KeySize {
return nil, KeySizeError(chacha20poly1305.KeySize)
}
return &metaCipher{psk: psk, makeAEAD: chacha20poly1305.NewX}, nil
}
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// Chacha8Poly1305 creates a new Cipher with a pre-shared key. len(psk)
// must be 32.
func Chacha8Poly1305(psk []byte) (Cipher, error) {
if len(psk) != chacha.KeySize {
return nil, KeySizeError(chacha.KeySize)
}
return &metaCipher{psk: psk, makeAEAD: chacha.NewChaCha8IETFPoly1305}, nil
}
// XChacha8Poly1305 creates a new Cipher with a pre-shared key. len(psk)
// must be 32.
func XChacha8Poly1305(psk []byte) (Cipher, error) {
if len(psk) != chacha.KeySize {
return nil, KeySizeError(chacha.KeySize)
}
return &metaCipher{psk: psk, makeAEAD: chacha.NewXChaCha20IETFPoly1305}, nil
}