package encoding import ( "crypto/md5" "encoding/binary" "hash/fnv" "github.com/xtls/xray-core/common" "golang.org/x/crypto/sha3" ) // Authenticate authenticates a byte array using Fnv hash. func Authenticate(b []byte) uint32 { fnv1hash := fnv.New32a() common.Must2(fnv1hash.Write(b)) return fnv1hash.Sum32() } type NoOpAuthenticator struct{} func (NoOpAuthenticator) NonceSize() int { return 0 } func (NoOpAuthenticator) Overhead() int { return 0 } // Seal implements AEAD.Seal(). func (NoOpAuthenticator) Seal(dst, nonce, plaintext, additionalData []byte) []byte { return append(dst[:0], plaintext...) } // Open implements AEAD.Open(). func (NoOpAuthenticator) Open(dst, nonce, ciphertext, additionalData []byte) ([]byte, error) { return append(dst[:0], ciphertext...), nil } // FnvAuthenticator is an AEAD based on Fnv hash. type FnvAuthenticator struct { } // NonceSize implements AEAD.NonceSize(). func (*FnvAuthenticator) NonceSize() int { return 0 } // Overhead impelements AEAD.Overhead(). func (*FnvAuthenticator) Overhead() int { return 4 } // Seal implements AEAD.Seal(). func (*FnvAuthenticator) Seal(dst, nonce, plaintext, additionalData []byte) []byte { dst = append(dst, 0, 0, 0, 0) binary.BigEndian.PutUint32(dst, Authenticate(plaintext)) return append(dst, plaintext...) } // Open implements AEAD.Open(). func (*FnvAuthenticator) Open(dst, nonce, ciphertext, additionalData []byte) ([]byte, error) { if binary.BigEndian.Uint32(ciphertext[:4]) != Authenticate(ciphertext[4:]) { return dst, newError("invalid authentication") } return append(dst, ciphertext[4:]...), nil } // GenerateChacha20Poly1305Key generates a 32-byte key from a given 16-byte array. func GenerateChacha20Poly1305Key(b []byte) []byte { key := make([]byte, 32) t := md5.Sum(b) copy(key, t[:]) t = md5.Sum(key[:16]) copy(key[16:], t[:]) return key } type ShakeSizeParser struct { shake sha3.ShakeHash buffer [2]byte } func NewShakeSizeParser(nonce []byte) *ShakeSizeParser { shake := sha3.NewShake128() common.Must2(shake.Write(nonce)) return &ShakeSizeParser{ shake: shake, } } func (*ShakeSizeParser) SizeBytes() int32 { return 2 } func (s *ShakeSizeParser) next() uint16 { common.Must2(s.shake.Read(s.buffer[:])) return binary.BigEndian.Uint16(s.buffer[:]) } func (s *ShakeSizeParser) Decode(b []byte) (uint16, error) { mask := s.next() size := binary.BigEndian.Uint16(b) return mask ^ size, nil } func (s *ShakeSizeParser) Encode(size uint16, b []byte) []byte { mask := s.next() binary.BigEndian.PutUint16(b, mask^size) return b[:2] } func (s *ShakeSizeParser) NextPaddingLen() uint16 { return s.next() % 64 } func (s *ShakeSizeParser) MaxPaddingLen() uint16 { return 64 }