tricrypt/tlep/encrypt/aes.go

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2024-06-04 18:19:11 +02:00
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
}