C#實現AES加密解密

 

AES 

 

AES 高級加密標準（英語：Advanced Encryption Standard，縮寫：AES），在密碼學中又稱Rijndael加密法

Rijndael（讀做rain-dahl）是由美國國家標準與技術協會（NIST）所選的高級加密標準（AES）的候選算法。這個標準用來替代原先的DES，已經被多方分析且廣爲全世界所使用。

Rijndael 算法首先是一個密鑰分組加密的算法，經過置換（permutations ）和替換(substitutions）迭代加密，進過多輪操做造成密文。

AES算是Rijndael算法的一種特殊實現，選的分組爲128bit（16字節），密鑰能夠使用12八、192 和 256bit三種，而Rijndael使用的密鑰和區塊長度能夠是32位的整數倍，以128位爲下限，256比特爲上限。加密過程當中使用的密鑰是由Rijndael密鑰生成方案產生。

AES加密過程是在一個4×4的字節矩陣上運做，這個矩陣又稱爲「狀態（state）」，其初值就是一個明文區塊（矩陣中一個元素大小就是明文區塊中的一個Byte）。（Rijndael加密法因支持更大的區塊，其矩陣行數可視狀況增長）加密時，各輪AES加密循環（除最後一輪外）均包含4個步驟：
AddRoundKey — 矩陣中的每個字節都與該次輪祕鑰（round key）作XOR運算；每一個子密鑰由密鑰生成方案產生。
SubBytes — 經過非線性的替換函數，用查找表的方式把每一個字節替換成對應的字節。
ShiftRows — 將矩陣中的每一個橫列進行循環式移位。
MixColumns — 爲了充分混合矩陣中各個直行的操做。這個步驟使用線性轉換來混合每列的四個字節。

 

 

RijndaelManager代碼實現

 

 

1.  
   using System;
2.  
   using System.Collections.Generic;
3.  
   using System.Text;
4.  
   using System.Security.Cryptography;
5.  
   using System.IO;
6.  
    
7.  
   namespace Csharp
8.  
   {
9.  
   class AESHelper
10.  
    {
11.  
    /// <summary>
12.  
    /// AES加密
13.  
    /// </summary>
14.  
    /// <param name="Data">被加密的明文</param>
15.  
    /// <param name="Key">密鑰</param>
16.  
    /// <param name="Vector">向量</param>
17.  
    /// <returns>密文</returns>
18.  
    public static String AESEncrypt(String Data, String Key, String Vector)
19.  
    {
20.  
    Byte[] plainBytes = Encoding.UTF8.GetBytes(Data);
21.  
     
22.  
    Byte[] bKey = new Byte[ 32];
23.  
    Array.Copy(Encoding.UTF8.GetBytes(Key.PadRight(bKey.Length)), bKey, bKey.Length);
24.  
    Byte[] bVector = new Byte[ 16];
25.  
    Array.Copy(Encoding.UTF8.GetBytes(Vector.PadRight(bVector.Length)), bVector, bVector.Length);
26.  
     
27.  
    Byte[] Cryptograph = null; // 加密後的密文
28.  
     
29.  
    Rijndael Aes = Rijndael.Create();
30.  
    try
31.  
    {
32.  
    // 開闢一塊內存流
33.  
    using (MemoryStream Memory = new MemoryStream())
34.  
    {
35.  
    // 把內存流對象包裝成加密流對象
36.  
    using (CryptoStream Encryptor = new CryptoStream(Memory,
37.  
    Aes.CreateEncryptor(bKey, bVector),
38.  
    CryptoStreamMode.Write))
39.  
    {
40.  
    // 明文數據寫入加密流
41.  
    Encryptor.Write(plainBytes, 0, plainBytes.Length);
42.  
    Encryptor.FlushFinalBlock();
43.  
     
44.  
    Cryptograph = Memory.ToArray();
45.  
    }
46.  
    }
47.  
    }
48.  
    catch
49.  
    {
50.  
    Cryptograph = null;
51.  
    }
52.  
     
53.  
    return Convert.ToBase64String(Cryptograph);
54.  
    }
55.  
     
56.  
    /// <summary>
57.  
    /// AES解密
58.  
    /// </summary>
59.  
    /// <param name="Data">被解密的密文</param>
60.  
    /// <param name="Key">密鑰</param>
61.  
    /// <param name="Vector">向量</param>
62.  
    /// <returns>明文</returns>
63.  
    public static String AESDecrypt(String Data, String Key, String Vector)
64.  
    {
65.  
    Byte[] encryptedBytes = Convert.FromBase64String(Data);
66.  
    Byte[] bKey = new Byte[ 32];
67.  
    Array.Copy(Encoding.UTF8.GetBytes(Key.PadRight(bKey.Length)), bKey, bKey.Length);
68.  
    Byte[] bVector = new Byte[ 16];
69.  
    Array.Copy(Encoding.UTF8.GetBytes(Vector.PadRight(bVector.Length)), bVector, bVector.Length);
70.  
     
71.  
    Byte[] original = null; // 解密後的明文
72.  
     
73.  
    Rijndael Aes = Rijndael.Create();
74.  
    try
75.  
    {
76.  
    // 開闢一塊內存流，存儲密文
77.  
    using (MemoryStream Memory = new MemoryStream(encryptedBytes))
78.  
    {
79.  
    // 把內存流對象包裝成加密流對象
80.  
    using (CryptoStream Decryptor = new CryptoStream(Memory,
81.  
    Aes.CreateDecryptor(bKey, bVector),
82.  
    CryptoStreamMode.Read))
83.  
    {
84.  
    // 明文存儲區
85.  
    using (MemoryStream originalMemory = new MemoryStream())
86.  
    {
87.  
    Byte[] Buffer = new Byte[ 1024];
88.  
    Int32 readBytes = 0;
89.  
    while ((readBytes = Decryptor.Read(Buffer, 0, Buffer.Length)) > 0)
90.  
    {
91.  
    originalMemory.Write(Buffer, 0, readBytes);
92.  
    }
93.  
     
94.  
    original = originalMemory.ToArray();
95.  
    }
96.  
    }
97.  
    }
98.  
    }
99.  
    catch
100.  
     {
101.  
     original = null;
102.  
     }
103.  
     return Encoding.UTF8.GetString(original);
104.  
     }
105.  
      
106.  
      
107.  
      
108.  
     /// <summary>
109.  
     /// AES加密(無向量)
110.  
     /// </summary>
111.  
     /// <param name="plainBytes">被加密的明文</param>
112.  
     /// <param name="key">密鑰</param>
113.  
     /// <returns>密文</returns>
114.  
     public static string AESEncrypt(String Data, String Key)
115.  
     {
116.  
     MemoryStream mStream = new MemoryStream();
117.  
     RijndaelManaged aes = new RijndaelManaged();
118.  
      
119.  
     byte[] plainBytes = Encoding.UTF8.GetBytes(Data);
120.  
     Byte[] bKey = new Byte[ 32];
121.  
     Array.Copy(Encoding.UTF8.GetBytes(Key.PadRight(bKey.Length)), bKey, bKey.Length);
122.  
      
123.  
     aes.Mode = CipherMode.ECB;
124.  
     aes.Padding = PaddingMode.PKCS7;
125.  
     aes.KeySize = 128;
126.  
     //aes.Key = _key;
127.  
     aes.Key = bKey;
128.  
     //aes.IV = _iV;
129.  
     CryptoStream cryptoStream = new CryptoStream(mStream, aes.CreateEncryptor(), CryptoStreamMode.Write);
130.  
     try
131.  
     {
132.  
     cryptoStream.Write(plainBytes, 0, plainBytes.Length);
133.  
     cryptoStream.FlushFinalBlock();
134.  
     return Convert.ToBase64String(mStream.ToArray());
135.  
     }
136.  
     finally
137.  
     {
138.  
     cryptoStream.Close();
139.  
     mStream.Close();
140.  
     aes.Clear();
141.  
     }
142.  
     }
143.  
      
144.  
      
145.  
     /// <summary>
146.  
     /// AES解密(無向量)
147.  
     /// </summary>
148.  
     /// <param name="encryptedBytes">被加密的明文</param>
149.  
     /// <param name="key">密鑰</param>
150.  
     /// <returns>明文</returns>
151.  
     public static string AESDecrypt(String Data, String Key)
152.  
     {
153.  
     Byte[] encryptedBytes = Convert.FromBase64String(Data);
154.  
     Byte[] bKey = new Byte[ 32];
155.  
     Array.Copy(Encoding.UTF8.GetBytes(Key.PadRight(bKey.Length)), bKey, bKey.Length);
156.  
      
157.  
     MemoryStream mStream = new MemoryStream(encryptedBytes);
158.  
     //mStream.Write( encryptedBytes, 0, encryptedBytes.Length );
159.  
     //mStream.Seek( 0, SeekOrigin.Begin );
160.  
     RijndaelManaged aes = new RijndaelManaged();
161.  
     aes.Mode = CipherMode.ECB;
162.  
     aes.Padding = PaddingMode.PKCS7;
163.  
     aes.KeySize = 128;
164.  
     aes.Key = bKey;
165.  
     //aes.IV = _iV;
166.  
     CryptoStream cryptoStream = new CryptoStream(mStream, aes.CreateDecryptor(), CryptoStreamMode.Read);
167.  
     try
168.  
     {
169.  
     byte[] tmp = new byte[encryptedBytes.Length + 32];
170.  
     int len = cryptoStream.Read(tmp, 0, encryptedBytes.Length + 32);
171.  
     byte[] ret = new byte[len];
172.  
     Array.Copy(tmp, 0, ret, 0, len);
173.  
     return Encoding.UTF8.GetString(ret);
174.  
     }
175.  
     finally
176.  
     {
177.  
     cryptoStream.Close();
178.  
     mStream.Close();
179.  
     aes.Clear();
180.  
     }
181.  
     }
182.  
     }
183.  
     }

 

AesManager代碼實現

 

1.  
   using System;
2.  
   using System.IO;
3.  
   using System.Security.Cryptography;
4.  
    
5.  
   namespace Aes_Example
6.  
   {
7.  
   class AesExample
8.  
   {
9.  
   public static void Main()
10.  
    {
11.  
    try
12.  
    {
13.  
    string original = "Here is some data to encrypt!";
14.  
     
15.  
    // Create a new instance of the AesManaged
16.  
    // class. This generates a new key and initialization
17.  
    // vector (IV).
18.  
    using (AesManaged myAes = new AesManaged())
19.  
    {
20.  
    // Encrypt the string to an array of bytes.
21.  
    byte[] encrypted = EncryptStringToBytes_Aes(original, myAes.Key, myAes.IV);
22.  
     
23.  
    // Decrypt the bytes to a string.
24.  
    string roundtrip = DecryptStringFromBytes_Aes(encrypted, myAes.Key, myAes.IV);
25.  
     
26.  
    //Display the original data and the decrypted data.
27.  
    Console.WriteLine( "Original: {0}", original);
28.  
    Console.WriteLine( "Round Trip: {0}", roundtrip);
29.  
    }
30.  
     
31.  
    }
32.  
    catch (Exception e)
33.  
    {
34.  
    Console.WriteLine( "Error: {0}", e.Message);
35.  
    }
36.  
    }
37.  
    static byte[] EncryptStringToBytes_Aes(string plainText, byte[] Key, byte[] IV)
38.  
    {
39.  
    // Check arguments.
40.  
    if (plainText == null || plainText.Length <= 0)
41.  
    throw new ArgumentNullException( "plainText");
42.  
    if (Key == null || Key.Length <= 0)
43.  
    throw new ArgumentNullException( "Key");
44.  
    if (IV == null || IV.Length <= 0)
45.  
    throw new ArgumentNullException( "IV");
46.  
    byte[] encrypted;
47.  
    // Create an AesManaged object
48.  
    // with the specified key and IV.
49.  
    using (AesManaged aesAlg = new AesManaged())
50.  
    {
51.  
    aesAlg.Key = Key;
52.  
    aesAlg.IV = IV;
53.  
     
54.  
    // Create a decrytor to perform the stream transform.
55.  
    ICryptoTransform encryptor = aesAlg.CreateEncryptor(aesAlg.Key, aesAlg.IV);
56.  
     
57.  
    // Create the streams used for encryption.
58.  
    using (MemoryStream msEncrypt = new MemoryStream())
59.  
    {
60.  
    using (CryptoStream csEncrypt = new CryptoStream(msEncrypt, encryptor, CryptoStreamMode.Write))
61.  
    {
62.  
    using (StreamWriter swEncrypt = new StreamWriter(csEncrypt))
63.  
    {
64.  
     
65.  
    //Write all data to the stream.
66.  
    swEncrypt.Write(plainText);
67.  
    }
68.  
    encrypted = msEncrypt.ToArray();
69.  
    }
70.  
    }
71.  
    }
72.  
     
73.  
     
74.  
    // Return the encrypted bytes from the memory stream.
75.  
    return encrypted;
76.  
     
77.  
    }
78.  
     
79.  
    static string DecryptStringFromBytes_Aes(byte[] cipherText, byte[] Key, byte[] IV)
80.  
    {
81.  
    // Check arguments.
82.  
    if (cipherText == null || cipherText.Length <= 0)
83.  
    throw new ArgumentNullException( "cipherText");
84.  
    if (Key == null || Key.Length <= 0)
85.  
    throw new ArgumentNullException( "Key");
86.  
    if (IV == null || IV.Length <= 0)
87.  
    throw new ArgumentNullException( "IV");
88.  
     
89.  
    // Declare the string used to hold
90.  
    // the decrypted text.
91.  
    string plaintext = null;
92.  
     
93.  
    // Create an AesManaged object
94.  
    // with the specified key and IV.
95.  
    using (AesManaged aesAlg = new AesManaged())
96.  
    {
97.  
    aesAlg.Key = Key;
98.  
    aesAlg.IV = IV;
99.  
     
100.  
     // Create a decrytor to perform the stream transform.
101.  
     ICryptoTransform decryptor = aesAlg.CreateDecryptor(aesAlg.Key, aesAlg.IV);
102.  
      
103.  
     // Create the streams used for decryption.
104.  
     using (MemoryStream msDecrypt = new MemoryStream(cipherText))
105.  
     {
106.  
     using (CryptoStream csDecrypt = new CryptoStream(msDecrypt, decryptor, CryptoStreamMode.Read))
107.  
     {
108.  
     using (StreamReader srDecrypt = new StreamReader(csDecrypt))
109.  
     {
110.  
      
111.  
     // Read the decrypted bytes from the decrypting stream
112.  
     // and place them in a string.
113.  
     plaintext = srDecrypt.ReadToEnd();
114.  
     }
115.  
     }
116.  
     }
117.  
      
118.  
     }
119.  
      
120.  
     return plaintext;
121.  
     }
122.  
     }
123.  
     }