C#实现AES(Rijndael算法)加密解密
AES
AES 高级加密标准（英语：Advanced Encryption Standard，缩写：AES），在密码学中又称Rijndael加密法
Rijndael（读作rain-dahl）是由美国国家标准与技术协会（NIST）所选的高级加密标准（AES）的候选算法。这个标准用来替代原先的DES，已经被多方分析且广为全世界所使用。
Rijndael 算法首先是一个密钥分组加密的算法，通过置换（permutations ）和替换(substitutions）迭代加密，进过多轮操作形成密文。
AES算是Rijndael算法的一种特殊实现，选的分组为128bit（16字节），密钥可以使用128、192 和 256bit三种，而Rijndael使用的密钥和区块长度可以是32位的整数倍，以128位为下限，256比特为上限。加密过程中使用的密钥是由Rijndael密钥生成方案产生。
AES加密过程是在一个4×4的字节矩阵上运作，这个矩阵又称为“状态（state）”，其初值就是一个明文区块（矩阵中一个元素大小就是明文区块中的一个Byte）。（Rijndael加密法因支持更大的区块，其矩阵行数可视情况增加）加密时，各轮AES加密循环（除最后一轮外）均包含4个步骤：
AddRoundKey — 矩阵中的每一个字节都与该次轮秘钥（round key）做XOR运算；每个子密钥由密钥生成方案产生。
SubBytes — 通过非线性的替换函数，用查找表的方式把每个字节替换成对应的字节。
ShiftRows — 将矩阵中的每个横列进行循环式移位。
MixColumns — 为了充分混合矩阵中各个直行的操作。这个步骤使用线性转换来混合每列的四个字节。
RijndaelManager代码实现
using System;
using System.Collections.Generic;
using System.Text;
using System.Security.Cryptography;
using System.IO;
namespace Csharp
{
class AESHelper
{
///
/// AES加密
///
/// 被加密的明文
/// 密钥
/// 向量
/// 密文
public static String AESEncrypt(String Data, String Key, String Vector)
{
Byte[] plainBytes = Encoding.UTF8.GetBytes(Data);
Byte[] bKey = new Byte[32];
Array.Copy(Encoding.UTF8.GetBytes(Key.PadRight(bKey.Length)), bKey, bKey.Length);
Byte[] bVector = new Byte[16];
Array.Copy(Encoding.UTF8.GetBytes(Vector.PadRight(bVector.Length)), bVector, bVector.Length);
Byte[] Cryptograph = null; // 加密后的密文
Rijndael Aes = Rijndael.Create();
try
{
// 开辟一块内存流
using (MemoryStream Memory = new MemoryStream())
{
// 把内存流对象包装成加密流对象
using (CryptoStream Encryptor = new CryptoStream(Memory,
Aes.CreateEncryptor(bKey, bVector),
CryptoStreamMode.Write))
{
// 明文数据写入加密流
Encryptor.Write(plainBytes, 0, plainBytes.Length);
Encryptor.FlushFinalBlock();
Cryptograph = Memory.ToArray();
}
}
}
catch
{
Cryptograph = null;
}
return Convert.ToBase64String(Cryptograph);
}
///
/// AES解密
///
/// 被解密的密文
/// 密钥
/// 向量
/// 明文
public static String AESDecrypt(String Data, String Key, String Vector)
{
Byte[] encryptedBytes = Convert.FromBase64String(Data);
Byte[] bKey = new Byte[32];
Array.Copy(Encoding.UTF8.GetBytes(Key.PadRight(bKey.Length)), bKey, bKey.Length);
Byte[] bVector = new Byte[16];
Array.Copy(Encoding.UTF8.GetBytes(Vector.PadRight(bVector.Length)), bVector, bVector.Length);
Byte[] original = null; // 解密后的明文
Rijndael Aes = Rijndael.Create();
try
{
// 开辟一块内存流，存储密文
using (MemoryStream Memory = new MemoryStream(encryptedBytes))
{
// 把内存流对象包装成加密流对象
using (CryptoStream Decryptor = new CryptoStream(Memory,
Aes.CreateDecryptor(bKey, bVector),
CryptoStreamMode.Read))
{
// 明文存储区
using (MemoryStream originalMemory = new MemoryStream())
{
Byte[] Buffer = new Byte[1024];
Int32 readBytes = 0;
while ((readBytes = Decryptor.Read(Buffer, 0, Buffer.Length)) > 0)
{
originalMemory.Write(Buffer, 0, readBytes);
}
original = originalMemory.ToArray();
}
}
}
}
catch
{
original = null;
}
return Encoding.UTF8.GetString(original);
}
///
/// AES加密(无向量)
///
/// 被加密的明文
/// 密钥
/// 密文
public static string AESEncrypt(String Data, String Key)
{
MemoryStream mStream = new MemoryStream();
RijndaelManaged aes = new RijndaelManaged();
byte[] plainBytes = Encoding.UTF8.GetBytes(Data);
Byte[] bKey = new Byte[32];
Array.Copy(Encoding.UTF8.GetBytes(Key.PadRight(bKey.Length)), bKey, bKey.Length);
aes.Mode = CipherMode.ECB;
aes.Padding = PaddingMode.PKCS7;
aes.KeySize = 128;
//aes.Key = _key;
aes.Key = bKey;
//aes.IV = _iV;
CryptoStream cryptoStream = new CryptoStream(mStream, aes.CreateEncryptor(), CryptoStreamMode.Write);
try
{
cryptoStream.Write(plainBytes, 0, plainBytes.Length);
cryptoStream.FlushFinalBlock();
return Convert.ToBase64String(mStream.ToArray());
}
finally
{
cryptoStream.Close();
mStream.Close();
aes.Clear();
}
}
///
/// AES解密(无向量)
///
/// 被加密的明文
/// 密钥
/// 明文
public static string AESDecrypt(String Data, String Key)
{
Byte[] encryptedBytes = Convert.FromBase64String(Data);
Byte[] bKey = new Byte[32];
Array.Copy(Encoding.UTF8.GetBytes(Key.PadRight(bKey.Length)), bKey, bKey.Length);
MemoryStream mStream = new MemoryStream(encryptedBytes);
//mStream.Write( encryptedBytes, 0, encryptedBytes.Length );
//mStream.Seek( 0, SeekOrigin.Begin );
RijndaelManaged aes = new RijndaelManaged();
aes.Mode = CipherMode.ECB;
aes.Padding = PaddingMode.PKCS7;
aes.KeySize = 128;
aes.Key = bKey;
//aes.IV = _iV;
CryptoStream cryptoStream = new CryptoStream(mStream, aes.CreateDecryptor(), CryptoStreamMode.Read);
try
{
byte[] tmp = new byte[encryptedBytes.Length + 32];
int len = cryptoStream.Read(tmp, 0, encryptedBytes.Length + 32);
byte[] ret = new byte[len];
Array.Copy(tmp, 0, ret, 0, len);
return Encoding.UTF8.GetString(ret);
}
finally
{
cryptoStream.Close();
mStream.Close();
aes.Clear();
}
}
}
} AesManager代码实现
using System;
using System.IO;
using System.Security.Cryptography;
namespace Aes_Example
{
class AesExample
{
public static void Main()
{
try
{
string original = "Here is some data to encrypt!";
// Create a new instance of the AesManaged
// class. This generates a new key and initialization
// vector (IV).
using (AesManaged myAes = new AesManaged())
{
// Encrypt the string to an array of bytes.
byte[] encrypted = EncryptStringToBytes_Aes(original, myAes.Key, myAes.IV);
// Decrypt the bytes to a string.
string roundtrip = DecryptStringFromBytes_Aes(encrypted, myAes.Key, myAes.IV);
//Display the original data and the decrypted data.
Console.WriteLine("Original: {0}", original);
Console.WriteLine("Round Trip: {0}", roundtrip);
}
}
catch (Exception e)
{
Console.WriteLine("Error: {0}", e.Message);
}
}
static byte[] EncryptStringToBytes_Aes(string plainText, byte[] Key, byte[] IV)
{
// Check arguments.
if (plainText == null || plainText.Length <= 0)
throw new ArgumentNullException("plainText");
if (Key == null || Key.Length <= 0)
throw new ArgumentNullException("Key");
if (IV == null || IV.Length <= 0)
throw new ArgumentNullException("IV");
byte[] encrypted;
// Create an AesManaged object
// with the specified key and IV.
using (AesManaged aesAlg = new AesManaged())
{
aesAlg.Key = Key;
aesAlg.IV = IV;
// Create a decrytor to perform the stream transform.
ICryptoTransform encryptor = aesAlg.CreateEncryptor(aesAlg.Key, aesAlg.IV);
// Create the streams used for encryption.
using (MemoryStream msEncrypt = new MemoryStream())
{
using (CryptoStream csEncrypt = new CryptoStream(msEncrypt, encryptor, CryptoStreamMode.Write))
{
using (StreamWriter swEncrypt = new StreamWriter(csEncrypt))
{
//Write all data to the stream.
swEncrypt.Write(plainText);
}
encrypted = msEncrypt.ToArray();
}
}
}
// Return the encrypted bytes from the memory stream.
return encrypted;
}
static string DecryptStringFromBytes_Aes(byte[] cipherText, byte[] Key, byte[] IV)
{
// Check arguments.
if (cipherText == null || cipherText.Length <= 0)
throw new ArgumentNullException("cipherText");
if (Key == null || Key.Length <= 0)
throw new ArgumentNullException("Key");
if (IV == null || IV.Length <= 0)
throw new ArgumentNullException("IV");
// Declare the string used to hold
// the decrypted text.
string plaintext = null;
// Create an AesManaged object
// with the specified key and IV.
using (AesManaged aesAlg = new AesManaged())
{
aesAlg.Key = Key;
aesAlg.IV = IV;
// Create a decrytor to perform the stream transform.
ICryptoTransform decryptor = aesAlg.CreateDecryptor(aesAlg.Key, aesAlg.IV);
// Create the streams used for decryption.
using (MemoryStream msDecrypt = new MemoryStream(cipherText))
{
using (CryptoStream csDecrypt = new CryptoStream(msDecrypt, decryptor, CryptoStreamMode.Read))
{
using (StreamReader srDecrypt = new StreamReader(csDecrypt))
{
// Read the decrypted bytes from the decrypting stream
// and place them in a string.
plaintext = srDecrypt.ReadToEnd();
}
}
}
}
return plaintext;
}
}
}