route/vendor/github.com/lucas-clemente/quic-go/internal/crypto/aesgcm12_aead.go

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2018-01-03 19:19:49 +00:00
package crypto
import (
"crypto/cipher"
"encoding/binary"
"errors"
"github.com/lucas-clemente/aes12"
"github.com/lucas-clemente/quic-go/internal/protocol"
)
type aeadAESGCM12 struct {
otherIV []byte
myIV []byte
encrypter cipher.AEAD
decrypter cipher.AEAD
}
var _ AEAD = &aeadAESGCM12{}
// NewAEADAESGCM12 creates a AEAD using AES-GCM with 12 bytes tag size
//
// AES-GCM support is a bit hacky, since the go stdlib does not support 12 byte
// tag size, and couples the cipher and aes packages closely.
// See https://github.com/lucas-clemente/aes12.
func NewAEADAESGCM12(otherKey []byte, myKey []byte, otherIV []byte, myIV []byte) (AEAD, error) {
if len(myKey) != 16 || len(otherKey) != 16 || len(myIV) != 4 || len(otherIV) != 4 {
return nil, errors.New("AES-GCM: expected 16-byte keys and 4-byte IVs")
}
encrypterCipher, err := aes12.NewCipher(myKey)
if err != nil {
return nil, err
}
encrypter, err := aes12.NewGCM(encrypterCipher)
if err != nil {
return nil, err
}
decrypterCipher, err := aes12.NewCipher(otherKey)
if err != nil {
return nil, err
}
decrypter, err := aes12.NewGCM(decrypterCipher)
if err != nil {
return nil, err
}
return &aeadAESGCM12{
otherIV: otherIV,
myIV: myIV,
encrypter: encrypter,
decrypter: decrypter,
}, nil
}
func (aead *aeadAESGCM12) Open(dst, src []byte, packetNumber protocol.PacketNumber, associatedData []byte) ([]byte, error) {
return aead.decrypter.Open(dst, aead.makeNonce(aead.otherIV, packetNumber), src, associatedData)
}
func (aead *aeadAESGCM12) Seal(dst, src []byte, packetNumber protocol.PacketNumber, associatedData []byte) []byte {
return aead.encrypter.Seal(dst, aead.makeNonce(aead.myIV, packetNumber), src, associatedData)
}
func (aead *aeadAESGCM12) makeNonce(iv []byte, packetNumber protocol.PacketNumber) []byte {
res := make([]byte, 12)
copy(res[0:4], iv)
binary.LittleEndian.PutUint64(res[4:12], uint64(packetNumber))
return res
}
func (aead *aeadAESGCM12) Overhead() int {
return aead.encrypter.Overhead()
}