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@proteye
Created August 31, 2018 10:27
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package aeslib
import (
"bytes"
"crypto/aes"
"crypto/cipher"
"crypto/rand"
"crypto/sha256"
"encoding/base64"
"errors"
"io"
"strings"
"golang.org/x/crypto/pbkdf2"
)
const BlockSize = 32
func deriveKey(passphrase string, salt []byte) []byte {
// http://www.ietf.org/rfc/rfc2898.txt
if salt == nil {
salt = make([]byte, 8)
// rand.Read(salt)
}
return pbkdf2.Key([]byte(passphrase), salt, 1000, BlockSize, sha256.New)
}
func addBase64Padding(value string) string {
m := len(value) % 4
if m != 0 {
value += strings.Repeat("=", 4-m)
}
return value
}
func removeBase64Padding(value string) string {
return strings.Replace(value, "=", "", -1)
}
func Pad(src []byte) []byte {
padding := aes.BlockSize - len(src)%aes.BlockSize
padtext := bytes.Repeat([]byte{byte(padding)}, padding)
return append(src, padtext...)
}
func Unpad(src []byte) ([]byte, error) {
length := len(src)
unpadding := int(src[length-1])
if unpadding > length {
return nil, errors.New("unpad error. This could happen when incorrect encryption key is used")
}
return src[:(length - unpadding)], nil
}
func encrypt(key []byte, text string) (string, error) {
block, err := aes.NewCipher(key)
if err != nil {
return "", err
}
msg := Pad([]byte(text))
ciphertext := make([]byte, aes.BlockSize+len(msg))
iv := ciphertext[:aes.BlockSize]
if _, err := io.ReadFull(rand.Reader, iv); err != nil {
return "", err
}
cfb := cipher.NewCFBEncrypter(block, iv)
cfb.XORKeyStream(ciphertext[aes.BlockSize:], []byte(msg))
finalMsg := removeBase64Padding(base64.URLEncoding.EncodeToString(ciphertext))
return finalMsg, nil
}
func decrypt(key []byte, text string) (string, error) {
block, err := aes.NewCipher(key)
if err != nil {
return "", err
}
decodedMsg, err := base64.URLEncoding.DecodeString(addBase64Padding(text))
if err != nil {
return "", err
}
if (len(decodedMsg) % aes.BlockSize) != 0 {
return "", errors.New("blocksize must be multipe of decoded message length")
}
iv := decodedMsg[:aes.BlockSize]
msg := decodedMsg[aes.BlockSize:]
cfb := cipher.NewCFBDecrypter(block, iv)
cfb.XORKeyStream(msg, msg)
unpadMsg, err := Unpad(msg)
if err != nil {
return "", err
}
return string(unpadMsg), nil
}
func Encrypt(password string, plaintext string) string {
key := deriveKey(password, nil)
encryptMsg, _ := encrypt(key, plaintext)
return encryptMsg
}
func Decrypt(password string, cipher string) string {
key := deriveKey(password, nil)
msg, _ := decrypt(key, cipher)
return msg
}
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