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