AES:是高级加密标准,在密码学中又称Rijndael加密法,是美国联邦政府采用的一种区块加密标准。这个标准主要是代替原先的DES,以及被多方分析且广为全世界所使用。
AES加密数据块分组长度必须是128比特,密钥长度可以使128比特,192比特,256比特中的任意一个(如果数据块及密钥 长度不足时,会补齐)。AES加密有很多轮的重复和变换。大致的步骤是:1、密钥的扩展(KeyExpansion),2、初始轮(InitialRound),3.重复轮(Rounds),每一轮又包括:SubBytes、ShiftRows、MixColumns、AddRoundKey,4、最终轮(FinalRound),最终轮没有MixColumns。
以下展示一个小小的案例,参考学习:
//默认密钥向量
private static byte[] _Aeskey = { 0x12, 0x34, 0x56, 0x78, 0x90, 0xAB, 0xCD, 0xEF, 0x12, 0x34, 0x56, 0x78, 0x90, 0xAB, 0xCD, 0xEF };
/// <summary>
/// AES加密,返回Base64编码后的字符
/// </summary>
/// <param name="plainText">明文字符串</param>
/// <param name="strKey">密钥</param>
/// <returns>返回加密后的Base64编码字符串</returns>
public static string EncryptAES(string plainText, string strKey="123456")
{
byte[] byteArray = Encoding.UTF8.GetBytes(plainText);
Byte[] bKey = new Byte[32];
Array.Copy(Encoding.UTF8.GetBytes(strKey.PadRight(bKey.Length)), bKey, bKey.Length);
RijndaelManaged rDel = new RijndaelManaged();
// rDel.Key = Encoding.UTF8.GetBytes(strKey);
rDel.Key = bKey;
rDel.IV = _Aeskey;
rDel.BlockSize = 128;
rDel.Mode = CipherMode.ECB;//设置为ECB
rDel.Padding = PaddingMode.PKCS7;//设置为PKCS7,否则解密后字符串结尾会出现多余字符
ICryptoTransform cTransform = rDel.CreateEncryptor();
var s = cTransform.TransformFinalBlock(byteArray, 0, byteArray.Length);
var encrypt = Convert.ToBase64String(s);
rDel.Clear();
return encrypt;
}
/// <summary>
/// AES解密,返回解密后的字符串
/// </summary>
/// <param name="cipherText">Base64编码的密文</param>
/// <param name="strKey">密钥</param>
/// <returns>返回解密后的字符串</returns>
public static string DecryptAES(string cipherText, string strKey="123456")
{
byte[] byteArray = Convert.FromBase64String(cipherText);
Byte[] bKey = new Byte[32];
Array.Copy(Encoding.UTF8.GetBytes(strKey.PadRight(bKey.Length)), bKey, bKey.Length);
RijndaelManaged rDel = new RijndaelManaged();
rDel.Key = bKey;
rDel.IV = _Aeskey;
rDel.BlockSize = 128;
rDel.Mode = CipherMode.ECB;//必须设置为ECB,要与加密的模式一致
rDel.Padding = PaddingMode.PKCS7;//必须设置为PKCS7,要与加密的模式一致
ICryptoTransform cTransform = rDel.CreateDecryptor();
var s = cTransform.TransformFinalBlock(byteArray, 0, byteArray.Length);
var decrypt = Encoding.UTF8.GetString(s);
rDel.Clear();
return decrypt;
}