/
aes.go
106 lines (84 loc) · 2.37 KB
/
aes.go
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package cmd
import (
"crypto/aes"
"crypto/cipher"
"crypto/rand"
"errors"
"fmt"
"golang.org/x/crypto/scrypt"
)
// AesEncryptWithKey uses the give 32-bit key to encrypt plaintext.
func AesEncryptWithKey(aesKey, plaintext []byte) ([]byte, error) {
if len(aesKey) != 32 {
return nil, errors.New("AES key must be 32 bytes")
}
blockCipher, err := aes.NewCipher(aesKey)
if err != nil {
return nil, err
}
gcm, err := cipher.NewGCM(blockCipher)
if err != nil {
return nil, err
}
nonce := make([]byte, gcm.NonceSize())
if _, err = rand.Read(nonce); err != nil {
return nil, err
}
ciphertext := gcm.Seal(nonce, nonce, []byte(plaintext), nil)
return ciphertext, nil
}
// AesDecryptWithKey uses the give 32-bit key to decrypt plaintext.
func AesDecryptWithKey(aesKey, ciphertext []byte) ([]byte, error) {
if len(aesKey) != 32 {
fmt.Printf("aesKey len: %d\n", len(aesKey))
return nil, errors.New("AES key must be 32 bytes")
}
blockCipher, err := aes.NewCipher(aesKey)
if err != nil {
return nil, err
}
gcm, err := cipher.NewGCM(blockCipher)
if err != nil {
return nil, err
}
nonce, ct := ciphertext[:gcm.NonceSize()], ciphertext[gcm.NonceSize():]
plaintext, err := gcm.Open(nil, nonce, ct, nil)
if err != nil {
return nil, err
}
return plaintext, nil
}
// AesEncryptWithPassword uses the give password to generate an aes key and decrypt plaintext.
func AesEncryptWithPassword(password string, plaintext []byte) ([]byte, error) {
key, err := deriveKey(password)
if err != nil {
return nil, err
}
return AesEncryptWithKey(key, plaintext)
}
// AesDecryptWithPassword uses the give password to generate an aes key and encrypt plaintext.
func AesDecryptWithPassword(password string, ciphertext []byte) ([]byte, error) {
key, err := deriveKey(password)
if err != nil {
return nil, err
}
return AesDecryptWithKey(key, ciphertext)
}
func deriveKey(password string) ([]byte, error) {
// including a salt would make it impossible to reliably login from other devices
key, err := scrypt.Key([]byte(password), []byte(""), 1<<20, 8, 1, 32)
if err != nil {
return nil, err
}
return key, nil
}
// NewAesKey generates a new 32-bit key.
func NewAesKey() ([]byte, error) {
key := make([]byte, 32)
if n, err := rand.Read(key); err != nil {
return nil, err
} else if n != 32 {
return nil, errors.New("could not create key at 32 bytes")
}
return key, nil
}