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aes.go
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aes.go
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// Copyright 2023 Linka Cloud All rights reserved.
//
// 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 aes
import (
"crypto/aes"
"crypto/cipher"
"crypto/rand"
"errors"
"io"
)
type data interface {
string | []byte
}
func toBytes[T data](d T) []byte {
switch d := any(d).(type) {
case string:
return []byte(d)
case []byte:
return d
default:
panic("unexpected data type")
}
}
func Encrypt[T, U data](key T, content U) ([]byte, error) {
if len(key) != 32 {
return nil, errors.New("key must be 32 bytes")
}
kb, cb := toBytes(key), toBytes(content)
// Create a new Cipher Block from the key
block, err := aes.NewCipher(kb[:])
if err != nil {
return nil, err
}
// Create a new GCM - https://en.wikipedia.org/wiki/Galois/Counter_Mode
// https://golang.org/pkg/crypto/cipher/#NewGCM
aesGCM, err := cipher.NewGCM(block)
if err != nil {
return nil, err
}
// Create a nonce. Nonce should be from GCM
nonce := make([]byte, aesGCM.NonceSize())
if _, err = io.ReadFull(rand.Reader, nonce); err != nil {
return nil, err
}
// Encrypt the data using aesGCM.Seal
// Since we don't want to save the nonce somewhere else in this case, we add it as a prefix to the encrypted data. The first nonce argument in Seal is the prefix.
return aesGCM.Seal(nonce, nonce, cb, nil), nil
}
func Decrypt[T, U data](key T, enc U) ([]byte, error) {
if len(key) != 32 {
return nil, errors.New("key must be 32 bytes")
}
kb, encb := toBytes(key), toBytes(enc)
// Create a new Cipher Block from the key
block, err := aes.NewCipher(kb[:])
if err != nil {
return nil, err
}
// Create a new GCM
aesGCM, err := cipher.NewGCM(block)
if err != nil {
return nil, err
}
// Get the nonce size
nonceSize := aesGCM.NonceSize()
// Extract the nonce from the encrypted data
nonce, ciphertext := encb[:nonceSize], encb[nonceSize:]
// Decrypt the data
return aesGCM.Open(nil, nonce, ciphertext, nil)
}