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encrypt.go
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encrypt.go
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// Copyright The OpenTelemetry 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 credentials
import (
"crypto/aes"
"crypto/cipher"
"crypto/md5"
"crypto/rand"
"crypto/sha256"
"encoding/hex"
"fmt"
"io"
)
func _getDeprecatedHasher() Hasher {
return md5.New()
}
func _getHasher() Hasher {
return sha256.New()
}
const (
filenamePrefix = "filename"
encryptionKeyPrefix = "encryption"
)
type Hasher interface {
Write(p []byte) (n int, err error)
Sum(b []byte) []byte
}
func hashWith(hasher Hasher, key []byte) (string, error) {
if _, err := hasher.Write(key); err != nil {
return "", err
}
return hex.EncodeToString(hasher.Sum(nil)), nil
}
// HashKeyToFilename creates a filename using the default hasher and provided key
// as input. It returns this filename and an error.
func HashKeyToFilename(key string) (string, error) {
return HashKeyToFilenameWith(_getHasher(), key)
}
// HashKeyToFilenameWith creates a filename using the provided key as input and
// using the provided hasher.
func HashKeyToFilenameWith(hasher Hasher, key string) (string, error) {
return hashWith(hasher, []byte(filenamePrefix+key))
}
// HashKeyToEncryptionKey creates an encryption key using a default hasher.
// It returns the created key and an error.
func HashKeyToEncryptionKey(key string) ([]byte, error) {
return HashKeyToEncryptionKeyWith(_getHasher(), key)
}
// HashKeyToEncryptionKeyWith creates a 32 bytes long key from the provided
// key using the provided hasher.
func HashKeyToEncryptionKeyWith(hasher Hasher, key string) ([]byte, error) {
h, err := hashWith(hasher, []byte(encryptionKeyPrefix+key))
if err != nil {
return nil, err
}
b := []byte(h)
return b[:32], nil
}
// encrypt encrypts provided byte slice with AES using the encryption key.
func encrypt(data []byte, encryptionKey []byte) ([]byte, error) {
f := func(hasher Hasher, data []byte, encryptionKey []byte) ([]byte, error) {
block, err := aes.NewCipher(encryptionKey)
if err != nil {
return nil, err
}
gcm, err := cipher.NewGCM(block)
if err != nil {
return nil, err
}
nonce := make([]byte, gcm.NonceSize())
if _, err = io.ReadFull(rand.Reader, nonce); err != nil {
return nil, err
}
ciphertext := gcm.Seal(nonce, nonce, data, nil)
return ciphertext, nil
}
if ret, err := f(_getHasher(), data, encryptionKey); err == nil {
return ret, nil
}
ret, err := f(_getDeprecatedHasher(), data, encryptionKey)
if err == nil {
return ret, nil
}
return nil, err
}
// decrypt decrypts provided byte slice with AES using the encryptionKey.
func decrypt(data []byte, encryptionKey []byte) ([]byte, error) {
f := func(hasher Hasher, data []byte, encryptionKey []byte) ([]byte, error) {
block, err := aes.NewCipher(encryptionKey)
if err != nil {
return nil, fmt.Errorf("unable tocreate new aes cipher: %w", err)
}
gcm, err := cipher.NewGCM(block)
if err != nil {
return nil, fmt.Errorf("unable to create new cipher gcm: %w", err)
}
nonceSize := gcm.NonceSize()
if nonceSize > len(data) {
return nil, fmt.Errorf("unable to decrypt credentials")
}
nonce, ciphertext := data[:nonceSize], data[nonceSize:]
plaintext, err := gcm.Open(nil, nonce, ciphertext, nil)
if err != nil {
return nil, fmt.Errorf("unable to decrypt: %w", err)
}
return plaintext, nil
}
if ret, err := f(_getHasher(), data, encryptionKey); err == nil {
return ret, nil
}
ret, err := f(_getDeprecatedHasher(), data, encryptionKey)
if err == nil {
return ret, nil
}
return nil, err
}