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crypter.go
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crypter.go
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// Copyright 2020 TiKV Project Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package encryption
import (
"crypto/aes"
"crypto/cipher"
"crypto/rand"
"encoding/binary"
"io"
"unsafe"
"github.com/pingcap/kvproto/pkg/encryptionpb"
"github.com/tikv/pd/pkg/errs"
)
const (
ivLengthCTR = 16
ivLengthGCM = 12
)
// CheckEncryptionMethodSupported check whether the encryption method is currently supported.
// This is to handle future extension to encryption methods on kvproto side.
func CheckEncryptionMethodSupported(method encryptionpb.EncryptionMethod) error {
switch method {
case encryptionpb.EncryptionMethod_AES128_CTR:
return nil
case encryptionpb.EncryptionMethod_AES192_CTR:
return nil
case encryptionpb.EncryptionMethod_AES256_CTR:
return nil
default:
name, ok := encryptionpb.EncryptionMethod_name[int32(method)]
if ok {
return errs.ErrEncryptionInvalidMethod.GenWithStackByArgs(name)
}
return errs.ErrEncryptionInvalidMethod.GenWithStackByArgs(int32(method))
}
}
// KeyLength return the encryption key length for supported encryption methods.
func KeyLength(method encryptionpb.EncryptionMethod) (int, error) {
switch method {
case encryptionpb.EncryptionMethod_AES128_CTR:
return 16, nil
case encryptionpb.EncryptionMethod_AES192_CTR:
return 24, nil
case encryptionpb.EncryptionMethod_AES256_CTR:
return 32, nil
default:
name, ok := encryptionpb.EncryptionMethod_name[int32(method)]
if ok {
return 0, errs.ErrEncryptionInvalidMethod.GenWithStackByArgs(name)
}
return 0, errs.ErrEncryptionInvalidMethod.GenWithStackByArgs(int32(method))
}
}
// IvCTR represent IV bytes for CTR mode.
type IvCTR []byte
// IvGCM represent IV bytes for GCM mode.
type IvGCM []byte
func newIV(ivLength int) ([]byte, error) {
iv := make([]byte, ivLength)
n, err := io.ReadFull(rand.Reader, iv)
if err != nil {
return nil, errs.ErrEncryptionGenerateIV.Wrap(err).GenWithStackByArgs()
}
if n != ivLength {
return nil, errs.ErrEncryptionGenerateIV.GenWithStack(
"iv length exepcted %d vs actual %d", ivLength, n)
}
return iv, nil
}
// NewIvCTR randomly generate an IV for CTR mode.
func NewIvCTR() (IvCTR, error) {
return newIV(ivLengthCTR)
}
// NewIvGCM randomly generate an IV for GCM mode.
func NewIvGCM() (IvGCM, error) {
return newIV(ivLengthGCM)
}
// NewDataKey randomly generate a new data key.
func NewDataKey(
method encryptionpb.EncryptionMethod,
creationTime uint64,
) (keyID uint64, key *encryptionpb.DataKey, err error) {
err = CheckEncryptionMethodSupported(method)
if err != nil {
return
}
keyIDBufSize := unsafe.Sizeof(uint64(0))
keyIDBuf := make([]byte, keyIDBufSize)
n, err := io.ReadFull(rand.Reader, keyIDBuf)
if err != nil {
err = errs.ErrEncryptionNewDataKey.Wrap(err).GenWithStack(
"fail to generate data key id")
return
}
if n != int(keyIDBufSize) {
err = errs.ErrEncryptionNewDataKey.GenWithStack(
"no enough random bytes to generate data key id, bytes %d", n)
return
}
keyID = binary.BigEndian.Uint64(keyIDBuf)
keyLength, err := KeyLength(method)
if err != nil {
return
}
keyBuf := make([]byte, keyLength)
n, err = io.ReadFull(rand.Reader, keyBuf)
if err != nil {
err = errs.ErrEncryptionNewDataKey.Wrap(err).GenWithStack(
"fail to generate data key")
return
}
if n != keyLength {
err = errs.ErrEncryptionNewDataKey.GenWithStack(
"no enough random bytes to generate data key, bytes %d", n)
return
}
key = &encryptionpb.DataKey{
Key: keyBuf,
Method: method,
CreationTime: creationTime,
WasExposed: false,
}
return
}
func aesGcmEncryptImpl(
key []byte,
plaintext []byte,
iv IvGCM,
) (ciphertext []byte, err error) {
block, err := aes.NewCipher(key)
if err != nil {
err = errs.ErrEncryptionGCMEncrypt.Wrap(err).GenWithStack("fail to create aes cipher")
return
}
aesgcm, err := cipher.NewGCM(block)
if err != nil {
err = errs.ErrEncryptionGCMEncrypt.Wrap(err).GenWithStack("fail to create aes-gcm cipher")
return
}
ciphertext = aesgcm.Seal(nil, iv, plaintext, nil)
return
}
// AesGcmEncrypt encrypt given plaintext with given key using aes256-gcm.
// The method is used to encrypt data keys.
func AesGcmEncrypt(
key []byte,
plaintext []byte,
) (ciphertext []byte, iv IvGCM, err error) {
iv, err = NewIvGCM()
if err != nil {
return
}
ciphertext, err = aesGcmEncryptImpl(key, plaintext, iv)
return
}
// AesGcmDecrypt decrypt given ciphertext with given key using aes256-gcm.
// The method is used to decrypt data keys.
func AesGcmDecrypt(
key []byte,
ciphertext []byte,
iv IvGCM,
) (plaintext []byte, err error) {
if len(iv) != ivLengthGCM {
err = errs.ErrEncryptionGCMDecrypt.GenWithStack("unexpected gcm iv length %d", len(iv))
return
}
block, err := aes.NewCipher(key)
if err != nil {
err = errs.ErrEncryptionGCMDecrypt.Wrap(err).GenWithStack("fail to create aes cipher")
return
}
aesgcm, err := cipher.NewGCM(block)
if err != nil {
err = errs.ErrEncryptionGCMDecrypt.Wrap(err).GenWithStack("fail to create aes-gcm cipher")
return
}
plaintext, err = aesgcm.Open(nil, iv, ciphertext, nil)
if err != nil {
err = errs.ErrEncryptionGCMDecrypt.Wrap(err).GenWithStack("authentication fail")
return
}
return
}