63 lines
1.2 KiB
Go
63 lines
1.2 KiB
Go
|
package encrypt
|
||
|
|
|
||
|
|
import (
|
||
|
|
"crypto/aes"
|
||
|
|
"crypto/cipher"
|
||
|
|
"crypto/rand"
|
||
|
|
"errors"
|
||
|
|
"io"
|
||
|
|
)
|
||
|
|
|
||
|
|
var tooShort = errors.New("Too Short")
|
||
|
|
|
||
|
|
type Message struct {
|
||
|
|
Data []byte
|
||
|
|
}
|
||
|
|
|
||
|
|
// NOTE: should use only 32 byte key
|
||
|
|
// key can be derived via hkdf package
|
||
|
|
func Encrypt(plaintext, key []byte) (*Message, error) {
|
||
|
|
block, err := aes.NewCipher(key)
|
||
|
|
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(nil, nonce, plaintext, nil)
|
||
|
|
return &Message{
|
||
|
|
Data: append(nonce, ciphertext...),
|
||
|
|
}, nil
|
||
|
|
}
|
||
|
|
|
||
|
|
// NOTE: should use only 32 byte key
|
||
|
|
// key can be derived via hkdf package
|
||
|
|
func Decrypt(ciphertext, key []byte) (*Message, error) {
|
||
|
|
block, err := aes.NewCipher(key)
|
||
|
|
if err != nil {
|
||
|
|
return nil, err
|
||
|
|
}
|
||
|
|
gcm, err := cipher.NewGCM(block)
|
||
|
|
if err != nil {
|
||
|
|
return nil, err
|
||
|
|
}
|
||
|
|
nonceSize := gcm.NonceSize()
|
||
|
|
if len(ciphertext) < nonceSize {
|
||
|
|
return nil, tooShort
|
||
|
|
}
|
||
|
|
nonce, ciphertext := ciphertext[:nonceSize], ciphertext[nonceSize:]
|
||
|
|
plaintext, err := gcm.Open(nil, nonce, ciphertext, nil)
|
||
|
|
if err != nil {
|
||
|
|
return nil, err
|
||
|
|
}
|
||
|
|
return &Message{
|
||
|
|
Data: plaintext,
|
||
|
|
}, nil
|
||
|
|
}
|