session for go-chi
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// Copyright 2019 The Gitea Authors. All rights reserved.
// Use of this source code is governed by a MIT-style
// license that can be found in the LICENSE file.
package session
import (
"crypto/aes"
"crypto/cipher"
"crypto/rand"
"crypto/sha256"
"encoding/base64"
"errors"
"io"
)
// NewSecret creates a new secret
func NewSecret() (string, error) {
return NewSecretWithLength(32)
}
// NewSecretWithLength creates a new secret for a given length
func NewSecretWithLength(length int64) (string, error) {
return randomString(length)
}
func randomBytes(len int64) ([]byte, error) {
b := make([]byte, len)
if _, err := rand.Read(b); err != nil {
return nil, err
}
return b, nil
}
func randomString(len int64) (string, error) {
b, err := randomBytes(len)
return base64.URLEncoding.EncodeToString(b), err
}
// AesEncrypt encrypts text and given key with AES.
func AesEncrypt(key, text []byte) ([]byte, error) {
block, err := aes.NewCipher(key)
if err != nil {
return nil, err
}
b := base64.StdEncoding.EncodeToString(text)
ciphertext := make([]byte, aes.BlockSize+len(b))
iv := ciphertext[:aes.BlockSize]
if _, err := io.ReadFull(rand.Reader, iv); err != nil {
return nil, err
}
cfb := cipher.NewCFBEncrypter(block, iv)
cfb.XORKeyStream(ciphertext[aes.BlockSize:], []byte(b))
return ciphertext, nil
}
// AesDecrypt decrypts text and given key with AES.
func AesDecrypt(key, text []byte) ([]byte, error) {
block, err := aes.NewCipher(key)
if err != nil {
return nil, err
}
if len(text) < aes.BlockSize {
return nil, errors.New("ciphertext too short")
}
iv := text[:aes.BlockSize]
text = text[aes.BlockSize:]
cfb := cipher.NewCFBDecrypter(block, iv)
cfb.XORKeyStream(text, text)
data, err := base64.StdEncoding.DecodeString(string(text))
if err != nil {
return nil, err
}
return data, nil
}
// EncryptSecret encrypts a string with given key into a hex string
func EncryptSecret(key string, str string) (string, error) {
keyHash := sha256.Sum256([]byte(key))
plaintext := []byte(str)
ciphertext, err := AesEncrypt(keyHash[:], plaintext)
if err != nil {
return "", err
}
return base64.StdEncoding.EncodeToString(ciphertext), nil
}
// DecryptSecret decrypts a previously encrypted hex string
func DecryptSecret(key string, cipherhex string) (string, error) {
keyHash := sha256.Sum256([]byte(key))
ciphertext, err := base64.StdEncoding.DecodeString(cipherhex)
if err != nil {
return "", err
}
plaintext, err := AesDecrypt(keyHash[:], ciphertext)
if err != nil {
return "", err
}
return string(plaintext), nil
}