/
crypt.go
169 lines (140 loc) · 4.22 KB
/
crypt.go
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package protoutil
import (
"fmt"
"sync"
"time"
"google.golang.org/protobuf/encoding/protojson"
"google.golang.org/protobuf/proto"
"google.golang.org/protobuf/types/known/anypb"
"github.com/pomerium/pomerium/pkg/cryptutil"
cryptpb "github.com/pomerium/pomerium/pkg/grpc/crypt"
)
// An Encryptor encrypts protobuf messages using a key encryption key and periodically rotated
// generated data encryption keys.
type Encryptor struct {
kek *cryptutil.PublicKeyEncryptionKey
rotateEvery time.Duration
sync.RWMutex
nextRotate time.Time
dek *cryptutil.DataEncryptionKey
encryptedDEK []byte
}
// NewEncryptor returns a new protobuf Encryptor.
func NewEncryptor(kek *cryptutil.PublicKeyEncryptionKey) *Encryptor {
return &Encryptor{
kek: kek,
rotateEvery: time.Hour,
}
}
func (enc *Encryptor) getDataEncryptionKey() (*cryptutil.DataEncryptionKey, []byte, error) {
// double-checked locking
// first time we do a read only lookup
enc.RLock()
dek, encryptedDEK, err := enc.getDataEncryptionKeyLocked(true)
enc.RUnlock()
if err != nil {
return nil, nil, err
} else if dek != nil {
return dek, encryptedDEK, nil
}
// second time we do a read/write lookup
enc.Lock()
dek, encryptedDEK, err = enc.getDataEncryptionKeyLocked(false)
enc.Unlock()
return dek, encryptedDEK, err
}
func (enc *Encryptor) getDataEncryptionKeyLocked(readOnly bool) (*cryptutil.DataEncryptionKey, []byte, error) {
needsNewKey := enc.dek == nil || time.Now().After(enc.nextRotate)
if !needsNewKey {
return enc.dek, enc.encryptedDEK, nil
}
if readOnly {
return nil, nil, nil
}
// generate a new data encryption key
dek, err := cryptutil.GenerateDataEncryptionKey()
if err != nil {
return nil, nil, err
}
// seal the data encryption key using the key encryption key
encryptedDEK, err := enc.kek.EncryptDataEncryptionKey(dek)
if err != nil {
return nil, nil, err
}
enc.dek = dek
enc.encryptedDEK = encryptedDEK
enc.nextRotate = time.Now().Add(enc.rotateEvery)
return enc.dek, enc.encryptedDEK, nil
}
// Encrypt encrypts a protobuf message.
func (enc *Encryptor) Encrypt(msg proto.Message) (*cryptpb.SealedMessage, error) {
// get the data encryption key
dek, encryptedDEK, err := enc.getDataEncryptionKey()
if err != nil {
return nil, err
}
plaintext, err := protojson.Marshal(msg)
if err != nil {
return nil, err
}
ciphertext := dek.Encrypt(plaintext)
return &cryptpb.SealedMessage{
KeyId: enc.kek.ID(),
DataEncryptionKey: encryptedDEK,
MessageType: GetTypeURL(msg),
EncryptedMessage: ciphertext,
}, nil
}
// A Decryptor decrypts encrypted protobuf messages.
type Decryptor struct {
keySource cryptutil.KeyEncryptionKeySource
dekCache *cryptutil.DataEncryptionKeyCache
}
// NewDecryptor creates a new decryptor.
func NewDecryptor(keySource cryptutil.KeyEncryptionKeySource) *Decryptor {
return &Decryptor{
keySource: keySource,
dekCache: cryptutil.NewDataEncryptionKeyCache(),
}
}
func (dec *Decryptor) getDataEncryptionKey(keyEncryptionKeyID string, encryptedDEK []byte) (*cryptutil.DataEncryptionKey, error) {
// return a dek if its already cached
dek, ok := dec.dekCache.Get(encryptedDEK)
if ok {
return dek, nil
}
// look up the kek used for this dek
kek, err := dec.keySource.GetKeyEncryptionKey(keyEncryptionKeyID)
if err != nil {
return nil, fmt.Errorf("protoutil: error getting key-encryption-key (%s): %w",
keyEncryptionKeyID, err)
}
// decrypt the dek via the private kek
dek, err = kek.DecryptDataEncryptionKey(encryptedDEK)
if err != nil {
return nil, fmt.Errorf("protoutil: error decrypting data-encryption-key: %w", err)
}
// cache it for next time
dec.dekCache.Put(encryptedDEK, dek)
return dek, nil
}
// Decrypt decrypts an encrypted protobuf message.
func (dec *Decryptor) Decrypt(src *cryptpb.SealedMessage) (proto.Message, error) {
dek, err := dec.getDataEncryptionKey(src.GetKeyId(), src.GetDataEncryptionKey())
if err != nil {
return nil, err
}
plaintext, err := dek.Decrypt(src.GetEncryptedMessage())
if err != nil {
return nil, err
}
msg, err := (&anypb.Any{TypeUrl: src.GetMessageType()}).UnmarshalNew()
if err != nil {
return nil, err
}
err = protojson.Unmarshal(plaintext, msg)
if err != nil {
return nil, err
}
return msg, nil
}