885c170a64
This commit introduces a new package `pkg/kms`. It contains basic types and functions to interact with various KMS implementations. This commit also moves KMS-related code from `cmd/crypto` to `pkg/kms`. Now, it is possible to implement a KMS-based config data encryption in the `pkg/config` package.
139 lines
3.5 KiB
Go
139 lines
3.5 KiB
Go
// MinIO Cloud Storage, (C) 2021 MinIO, Inc.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package config
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import (
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"bytes"
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"crypto/rand"
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"encoding/binary"
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"encoding/json"
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"errors"
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"fmt"
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"io"
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"github.com/minio/minio/pkg/kms"
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"github.com/secure-io/sio-go"
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"github.com/secure-io/sio-go/sioutil"
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)
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// Encrypt encrypts the plaintext with a key managed by KMS.
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// The context is bound to the returned ciphertext.
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//
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// The same context must be provided when decrypting the
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// ciphertext.
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func Encrypt(KMS kms.KMS, plaintext io.Reader, context kms.Context) (io.Reader, error) {
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var algorithm = sio.AES_256_GCM
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if !sioutil.NativeAES() {
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algorithm = sio.ChaCha20Poly1305
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}
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key, err := KMS.GenerateKey("", context)
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if err != nil {
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return nil, err
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}
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stream, err := algorithm.Stream(key.Plaintext)
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if err != nil {
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return nil, err
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}
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nonce := make([]byte, stream.NonceSize())
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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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const (
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MaxMetadataSize = 1 << 20 // max. size of the metadata
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Version = 1
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)
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var (
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header [5]byte
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buffer bytes.Buffer
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)
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metadata, err := json.Marshal(encryptedObject{
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KeyID: key.KeyID,
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KMSKey: key.Ciphertext,
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Algorithm: algorithm,
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Nonce: nonce,
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})
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if err != nil {
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return nil, err
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}
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if len(metadata) > MaxMetadataSize {
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return nil, errors.New("config: encryption metadata is too large")
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}
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header[0] = Version
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binary.LittleEndian.PutUint32(header[1:], uint32(len(metadata)))
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buffer.Write(header[:])
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buffer.Write(metadata)
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return io.MultiReader(
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&buffer,
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stream.EncryptReader(plaintext, nonce, nil),
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), nil
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}
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// Decrypt decrypts the ciphertext using a key managed by the KMS.
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// The same context that have been used during encryption must be
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// provided.
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func Decrypt(KMS kms.KMS, ciphertext io.Reader, context kms.Context) (io.Reader, error) {
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const (
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MaxMetadataSize = 1 << 20 // max. size of the metadata
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Version = 1
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)
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var header [5]byte
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if _, err := io.ReadFull(ciphertext, header[:]); err != nil {
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return nil, err
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}
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if header[0] != Version {
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return nil, fmt.Errorf("config: unknown ciphertext version %d", header[0])
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}
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size := binary.LittleEndian.Uint32(header[1:])
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if size > MaxMetadataSize {
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return nil, errors.New("config: encryption metadata is too large")
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}
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var (
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metadataBuffer = make([]byte, size)
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metadata encryptedObject
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)
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if _, err := io.ReadFull(ciphertext, metadataBuffer); err != nil {
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return nil, err
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}
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if err := json.Unmarshal(metadataBuffer, &metadata); err != nil {
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return nil, err
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}
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key, err := KMS.DecryptKey(metadata.KeyID, metadata.KMSKey, context)
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if err != nil {
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return nil, err
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}
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stream, err := metadata.Algorithm.Stream(key)
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if err != nil {
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return nil, err
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}
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if stream.NonceSize() != len(metadata.Nonce) {
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return nil, sio.NotAuthentic
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}
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return stream.DecryptReader(ciphertext, metadata.Nonce, nil), nil
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}
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type encryptedObject struct {
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KeyID string `json:"keyid"`
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KMSKey []byte `json:"kmskey"`
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Algorithm sio.Algorithm `json:"algorithm"`
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Nonce []byte `json:"nonce"`
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}
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