高级加密标准(AES,Advanced Encryption Standard)为最常见的对称加密算法(微信小程序加密传输就是用这个加密算法的)。对称加密算法也就是加密和解密用相同的密钥，具体的加密流程如下图：（原理：转自https://blog.csdn.net/qq_28205153/article/details/55798628）
代码实例如下：
using System;
using System.Text;
using System.Security.Cryptography;
using System.IO;
namespace Common.Helper.Crypto
{
/// <summary>
/// AES加密解密
/// </summary>
public static class AesCrypto
{
//对称加密和分组加密中的四种模式(ECB、CBC、CFB、OFB),这三种的区别，主要来自于密钥的长度，16位密钥=128位，24位密钥=192位，32位密钥=256位。
//更多参考：http://www.cnblogs.com/happyhippy/archive/2006/12/23/601353.html
/// <summary>
/// 检验密钥是否有效长度【16|24|32】
/// </summary>
/// <param name="key">密钥</param>
/// <returns>bool</returns>
private static bool CheckKey(string key)
{
if (string.IsNullOrWhiteSpace(key))
return false;
if (16.Equals(key.Length) || 24.Equals(key.Length) || 32.Equals(key.Length))
return true;
else
return false;
}
/// <summary>
/// 检验向量是否有效长度【16】
/// </summary>
/// <param name="iv">向量</param>
/// <returns>bool</returns>
private static bool CheckIv(string iv)
{
if (string.IsNullOrWhiteSpace(iv))
return false;
if (16.Equals(iv.Length))
return true;
else
return false;
}
#region 参数是string类型的
/// <summary>
/// 加密 参数：string
/// </summary>
/// <param name="palinData">明文</param>
/// <param name="key">密钥</param>
/// <param name="iv">向量</param>
/// <param name="encodingType">编码方式</param>
/// <returns>string：密文</returns>
public static string Encrypt(string palinData, string key, string iv, EncodingStrOrByte.EncodingType encodingType = EncodingStrOrByte.EncodingType.UTF8)
{
if (string.IsNullOrWhiteSpace(palinData)) return null;
if (!(CheckKey(key) && CheckIv(iv))) return palinData;
byte[] toEncryptArray = EncodingStrOrByte.GetBytes(palinData, encodingType);
var rm = new RijndaelManaged
{
IV = EncodingStrOrByte.GetBytes(iv, encodingType),
Key = EncodingStrOrByte.GetBytes(key, encodingType),
Mode = CipherMode.ECB,
Padding = PaddingMode.PKCS7
};
ICryptoTransform cTransform = rm.CreateEncryptor();
byte[] resultArray = cTransform.TransformFinalBlock(toEncryptArray, 0, toEncryptArray.Length);
return Convert.ToBase64String(resultArray, 0, resultArray.Length);
}
/// <summary>
/// 解密 参数：string
/// </summary>
/// <param name="encryptedData">密文</param>
/// <param name="key">密钥</param>
/// <param name="iv">向量</param>
/// <param name="encodingType">编码方式</param>
/// <returns>string：明文</returns>
public static string Decrypt(string encryptedData, string key, string iv, EncodingStrOrByte.EncodingType encodingType = EncodingStrOrByte.EncodingType.UTF8)
{
if (string.IsNullOrWhiteSpace(encryptedData)) return null;
if (!(CheckKey(key) && CheckIv(iv))) return encryptedData;
byte[] toEncryptArray = Convert.FromBase64String(encryptedData);
var rm = new RijndaelManaged
{
IV = EncodingStrOrByte.GetBytes(iv, encodingType),
Key = EncodingStrOrByte.GetBytes(key, encodingType),
Mode = CipherMode.ECB,
Padding = PaddingMode.PKCS7
};
ICryptoTransform cTransform = rm.CreateDecryptor();
byte[] resultArray = cTransform.TransformFinalBlock(toEncryptArray, 0, toEncryptArray.Length);
return Encoding.UTF8.GetString(resultArray);
}
#endregion
#region 参数是byte[]类型的
/// <summary>
/// 加密 参数：byte[]
/// </summary>
/// <param name="palinData">明文</param>
/// <param name="key">密钥</param>
/// <param name="iv">向量</param>
/// <returns>密文</returns>
public static byte[] Encrypt(byte[] palinData, string key, string iv, EncodingStrOrByte.EncodingType encodingType = EncodingStrOrByte.EncodingType.UTF8)
{
if (palinData == null) return null;
if (!(CheckKey(key) && CheckIv(iv))) return palinData;
byte[] bKey = new byte[32];
Array.Copy(EncodingStrOrByte.GetBytes(key.PadRight(bKey.Length), encodingType), bKey, bKey.Length);
byte[] bVector = new byte[16];
Array.Copy(EncodingStrOrByte.GetBytes(iv.PadRight(bVector.Length), encodingType), bVector, bVector.Length);
byte[] cryptograph = null; // 加密后的密文
Rijndael Aes = Rijndael.Create();
// 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(palinData, 0, palinData.Length);
Encryptor.FlushFinalBlock();
cryptograph = Memory.ToArray();
}
}
return cryptograph;
}
/// <summary>
/// 解密 参数：byte[]
/// </summary>
/// <param name="encryptedData">被解密的密文</param>
/// <param name="key">密钥</param>
/// <param name="iv">向量</param>
/// <returns>明文</returns>
public static byte[] Decrypt(byte[] encryptedData, string key, string iv, EncodingStrOrByte.EncodingType encodingType = EncodingStrOrByte.EncodingType.UTF8)
{
if (encryptedData == null) return null;
if (!(CheckKey(key) && CheckIv(iv))) return encryptedData;
byte[] bKey = new byte[32];
Array.Copy(EncodingStrOrByte.GetBytes(key.PadRight(bKey.Length), encodingType), bKey, bKey.Length);
byte[] bVector = new byte[16];
Array.Copy(EncodingStrOrByte.GetBytes(iv.PadRight(bVector.Length), encodingType), bVector, bVector.Length);
byte[] original = null; // 解密后的明文
Rijndael Aes = Rijndael.Create();
// 开辟一块内存流，存储密文
using (MemoryStream Memory = new MemoryStream(encryptedData))
{
// 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];
int readBytes = 0;
while ((readBytes = Decryptor.Read(Buffer, 0, Buffer.Length)) > 0)
{
originalMemory.Write(Buffer, 0, readBytes);
}
original = originalMemory.ToArray();
}
}
}
return original;
}
#endregion
}
}