github.com/bhojpur/cache@v0.0.4/pkg/file/crypto/aes.go (about)

     1  package crypto
     2  
     3  // Copyright (c) 2018 Bhojpur Consulting Private Limited, India. All rights reserved.
     4  
     5  // Permission is hereby granted, free of charge, to any person obtaining a copy
     6  // of this software and associated documentation files (the "Software"), to deal
     7  // in the Software without restriction, including without limitation the rights
     8  // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
     9  // copies of the Software, and to permit persons to whom the Software is
    10  // furnished to do so, subject to the following conditions:
    11  
    12  // The above copyright notice and this permission notice shall be included in
    13  // all copies or substantial portions of the Software.
    14  
    15  // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
    16  // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
    17  // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
    18  // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
    19  // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
    20  // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
    21  // THE SOFTWARE.
    22  
    23  import (
    24  	"bytes"
    25  	"crypto/aes"
    26  	"crypto/cipher"
    27  	"crypto/sha256"
    28  	"errors"
    29  )
    30  
    31  // AesEncrypt
    32  type AesEncrypt struct {
    33  	Key string
    34  }
    35  
    36  const prefix = "crypto"
    37  
    38  func (a *AesEncrypt) getKey() []byte {
    39  	strKey := []byte(a.Key)
    40  	var h = sha256.New()
    41  	h.Write([]byte(prefix))
    42  	h.Write(strKey)
    43  	return h.Sum(nil)
    44  }
    45  
    46  // Encrypt
    47  func (a *AesEncrypt) Encrypt(strMesg []byte) ([]byte, error) {
    48  	key := a.getKey()
    49  	var iv = []byte(key)[:aes.BlockSize]
    50  	msg := []byte("prefix")
    51  	msg = append(msg, strMesg...)
    52  	encrypted := make([]byte, len(msg))
    53  	aesBlockEncrypter, err := aes.NewCipher(key)
    54  	if err != nil {
    55  		return nil, err
    56  	}
    57  	aesEncrypter := cipher.NewCFBEncrypter(aesBlockEncrypter, iv)
    58  	aesEncrypter.XORKeyStream(encrypted, msg)
    59  	return encrypted, nil
    60  }
    61  
    62  // Decrypt
    63  func (a *AesEncrypt) Decrypt(src []byte) (strDesc []byte, err error) {
    64  	defer func() {
    65  		if e := recover(); e != nil {
    66  			err = e.(error)
    67  		}
    68  	}()
    69  	key := a.getKey()
    70  	var iv = []byte(key)[:aes.BlockSize]
    71  	decrypted := make([]byte, len(src))
    72  	var aesBlockDecrypter cipher.Block
    73  	aesBlockDecrypter, err = aes.NewCipher([]byte(key))
    74  	if err != nil {
    75  		return nil, err
    76  	}
    77  	aesDecrypter := cipher.NewCFBDecrypter(aesBlockDecrypter, iv)
    78  	aesDecrypter.XORKeyStream(decrypted, src)
    79  	pre := []byte("prefix")
    80  	if bytes.Compare(pre, decrypted[:len(pre)]) != 0 {
    81  		return nil, errors.New("error password")
    82  	}
    83  	return decrypted[len(pre):], nil
    84  }