/
aes.go
89 lines (72 loc) · 2.14 KB
/
aes.go
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package main
import (
"crypto/aes"
"crypto/cipher"
"crypto/rand"
"crypto/sha1"
"encoding/base64"
"errors"
"fmt"
"io"
"golang.org/x/crypto/pbkdf2"
)
const (
keyLen = 32
saltBytes = 32
iter = 4096
)
// aesCryp implements cipher
type aesCryp struct{}
// generate key for AES
func (a *aesCryp) keyGen(pass []byte) (key []byte, salt []byte, err error) {
salt = make([]byte, saltBytes)
_, err = io.ReadFull(rand.Reader, salt)
if err != nil {
return nil, nil, err
}
key = pbkdf2.Key(pass, salt, iter, keyLen, sha1.New)
return key, salt, nil
}
// generate key with salt for AES
func (a *aesCryp) keyGenWithSalt(pass []byte, salt []byte) (key []byte) {
return pbkdf2.Key(pass, salt, iter, keyLen, sha1.New)
}
// encrypt string to base64 crypto using AES
func (a *aesCryp) encrypt(key, text []byte) (string, error) {
// key := []byte(keyText)
plaintext := text
block, err := aes.NewCipher(key)
if err != nil {
return "", err
}
// The IV needs to be unique, but not secure. Therefore it's common to
// include it at the beginning of the ciphertext.
ciphertext := make([]byte, aes.BlockSize+len(plaintext))
iv := ciphertext[:aes.BlockSize]
if _, err := io.ReadFull(rand.Reader, iv); err != nil {
return "", err
}
stream := cipher.NewCFBEncrypter(block, iv)
stream.XORKeyStream(ciphertext[aes.BlockSize:], plaintext)
// convert to base64
return base64.URLEncoding.EncodeToString(ciphertext), nil
}
// decrypt from base64 to decrypted string
func (a *aesCryp) decrypt(key []byte, cryptoText string) (string, error) {
ciphertext, _ := base64.URLEncoding.DecodeString(cryptoText)
block, err := aes.NewCipher(key)
if err != nil {
return "", err
}
// The IV needs to be unique, but not secure. Therefore it's common to
// include it at the beginning of the ciphertext.
if len(ciphertext) < aes.BlockSize {
return "", errors.New("cipher to short")
}
iv := ciphertext[:aes.BlockSize]
ciphertext = ciphertext[aes.BlockSize:]
stream := cipher.NewCFBDecrypter(block, iv)
// XORKeyStream can work in-place if the two arguments are the same.
stream.XORKeyStream(ciphertext, ciphertext)
return fmt.Sprintf("%s", ciphertext), nil
}