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package security
import (
"crypto/aes"
"crypto/cipher"
"crypto/rand"
"errors"
"golang.org/x/crypto/scrypt"
)
var EncryptionError = errors.New("could not encrypt the given content")
func Encrypt(key, data string) (string, error) {
// initialize aes block cipher with given key
blockCipher, err := aes.NewCipher([]byte(key))
if err != nil {
return "", err
}
// wrap block cipher with Galois Counter Mode and standard nonce length
gcm, err := cipher.NewGCM(blockCipher)
if err != nil {
return "", err
}
// generate nonce (number once used) unique to the given key
nonce := make([]byte, gcm.NonceSize())
if _, err = rand.Read(nonce); err != nil {
return "", err
}
// seal nonce with data to use during decryption
cipherText := gcm.Seal(nonce, nonce, []byte(data), nil)
return string(cipherText), nil
}
func Decrypt(key, data string) (string, error) {
// similar to encrypt, create cipher and wrap with GCM
blockCipher, err := aes.NewCipher([]byte(key))
if err != nil {
return "", err
}
gcm, err := cipher.NewGCM(blockCipher)
if err != nil {
return "", err
}
// extract the nonce from the data
nonce, cipherText := data[:gcm.NonceSize()], data[gcm.NonceSize():]
// use nonce to decrypt the data
plaintext, err := gcm.Open(nil, []byte(nonce), []byte(cipherText), nil)
if err != nil {
return "", err
}
return string(plaintext), nil
}
const keyBytes = 16
const iterations = 16384
const relativeMemoryCost = 8
const relativeCPUCost = 1
func DeriveKey(password string, salt []byte) (string, []byte, error) {
if salt == nil {
salt = make([]byte, keyBytes)
if _, err := rand.Read(salt); err != nil {
return "", nil, err
}
}
key, err := scrypt.Key([]byte(password), salt, iterations, relativeMemoryCost, relativeCPUCost, keyBytes)
if err != nil {
return "", nil, err
}
return string(key), salt, nil
}
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