forked from quic-go/quic-go
74 lines
1.8 KiB
Go
74 lines
1.8 KiB
Go
package crypto
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import (
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"bytes"
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"crypto/aes"
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"crypto/cipher"
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"encoding/binary"
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"errors"
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"io"
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"io/ioutil"
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"github.com/lucas-clemente/quic-go/protocol"
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)
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type aeadAESGCM 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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// NewAEADAESGCM creates a AEAD using AES-GCM
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func NewAEADAESGCM(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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encCipher, err := aes.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 := cipher.NewGCM(encCipher)
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if err != nil {
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return nil, err
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}
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decCipher, err := aes.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 := cipher.NewGCM(decCipher)
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if err != nil {
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return nil, err
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}
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return &aeadAESGCM{
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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 *aeadAESGCM) Open(packetNumber protocol.PacketNumber, associatedData []byte, r io.Reader) (*bytes.Reader, error) {
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ciphertext, err := ioutil.ReadAll(r)
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if err != nil {
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return nil, err
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}
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plaintext, err := aead.decrypter.Open(nil, makeNonce(aead.otherIV, packetNumber), ciphertext, associatedData)
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if err != nil {
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return nil, err
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}
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return bytes.NewReader(plaintext), nil
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}
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func (aead *aeadAESGCM) Seal(packetNumber protocol.PacketNumber, b *bytes.Buffer, associatedData []byte, plaintext []byte) {
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ciphertext := aead.encrypter.Seal(nil, makeNonce(aead.myIV, packetNumber), plaintext, associatedData)
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b.Write(ciphertext)
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}
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func 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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