83 lines
2.1 KiB
Go
83 lines
2.1 KiB
Go
package handshake
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import (
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"crypto/aes"
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"crypto/cipher"
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"crypto/rand"
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"crypto/sha256"
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"fmt"
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"io"
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"golang.org/x/crypto/hkdf"
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)
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// TokenProtectorKey is the key used to encrypt both Retry and session resumption tokens.
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type TokenProtectorKey [32]byte
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// TokenProtector is used to create and verify a token
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type tokenProtector interface {
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// NewToken creates a new token
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NewToken([]byte) ([]byte, error)
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// DecodeToken decodes a token
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DecodeToken([]byte) ([]byte, error)
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}
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const tokenNonceSize = 32
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// tokenProtector is used to create and verify a token
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type tokenProtectorImpl struct {
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key TokenProtectorKey
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}
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// newTokenProtector creates a source for source address tokens
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func newTokenProtector(key TokenProtectorKey) tokenProtector {
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return &tokenProtectorImpl{key: key}
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}
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// NewToken encodes data into a new token.
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func (s *tokenProtectorImpl) NewToken(data []byte) ([]byte, error) {
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var nonce [tokenNonceSize]byte
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if _, err := rand.Read(nonce[:]); err != nil {
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return nil, err
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}
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aead, aeadNonce, err := s.createAEAD(nonce[:])
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if err != nil {
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return nil, err
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}
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return append(nonce[:], aead.Seal(nil, aeadNonce, data, nil)...), nil
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}
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// DecodeToken decodes a token.
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func (s *tokenProtectorImpl) DecodeToken(p []byte) ([]byte, error) {
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if len(p) < tokenNonceSize {
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return nil, fmt.Errorf("token too short: %d", len(p))
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}
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nonce := p[:tokenNonceSize]
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aead, aeadNonce, err := s.createAEAD(nonce)
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if err != nil {
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return nil, err
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}
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return aead.Open(nil, aeadNonce, p[tokenNonceSize:], nil)
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}
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func (s *tokenProtectorImpl) createAEAD(nonce []byte) (cipher.AEAD, []byte, error) {
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h := hkdf.New(sha256.New, s.key[:], nonce, []byte("quic-go token source"))
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key := make([]byte, 32) // use a 32 byte key, in order to select AES-256
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if _, err := io.ReadFull(h, key); err != nil {
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return nil, nil, err
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}
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aeadNonce := make([]byte, 12)
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if _, err := io.ReadFull(h, aeadNonce); err != nil {
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return nil, nil, err
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}
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c, err := aes.NewCipher(key)
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if err != nil {
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return nil, nil, err
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}
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aead, err := cipher.NewGCM(c)
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if err != nil {
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return nil, nil, err
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}
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return aead, aeadNonce, nil
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}
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