harness-drone/store/shared/encrypt/aesgcm.go

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// Copyright 2019 Drone IO, Inc.
//
// 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.
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package encrypt
import (
"crypto/cipher"
"crypto/rand"
"errors"
"io"
)
// Aesgcm provides an encryper that uses the aesgcm encryption
// alogirthm.
type Aesgcm struct {
block cipher.Block
Compat bool
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}
// Encrypt encrypts the plaintext using aesgcm.
func (e *Aesgcm) Encrypt(plaintext string) ([]byte, error) {
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gcm, err := cipher.NewGCM(e.block)
if err != nil {
return nil, err
}
nonce := make([]byte, gcm.NonceSize())
_, err = io.ReadFull(rand.Reader, nonce)
if err != nil {
return nil, err
}
return gcm.Seal(nonce, nonce, []byte(plaintext), nil), nil
}
// Decrypt decrypts the ciphertext using aesgcm.
func (e *Aesgcm) Decrypt(ciphertext []byte) (string, error) {
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gcm, err := cipher.NewGCM(e.block)
if err != nil {
return "", err
}
if len(ciphertext) < gcm.NonceSize() {
// if the decryption utility is running in compatibility
// mode, it will return the ciphertext as plain text if
// decryption fails. This should be used when running the
// database in mixed-mode, where there is a mix of encrypted
// and unecrypted content.
if e.Compat {
return string(ciphertext), nil
}
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return "", errors.New("malformed ciphertext")
}
plaintext, err := gcm.Open(nil,
ciphertext[:gcm.NonceSize()],
ciphertext[gcm.NonceSize():],
nil,
)
// if the decryption utility is running in compatibility
// mode, it will return the ciphertext as plain text if
// decryption fails. This should be used when running the
// database in mixed-mode, where there is a mix of encrypted
// and unecrypted content.
if err != nil && e.Compat {
return string(ciphertext), nil
}
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return string(plaintext), err
}