前言
对于数据加密和解密每次我都是从网上拷贝一份，无需有太多了解，由于在.net core中对加密和解密目前全部是统一了接口，只是做具体的实现，由于遇到过问题，所以将打算基本了解下其原理，知其然足矣，知其所以然那就达不到了，利用AES加密更加安全，上一篇园友又提出，所以借着这个机会刚好用到加密和解密，同时我也已将项目中DES加密已替换为AES，在这里介绍一下。
AES加密介绍
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，是美国联邦*采用的一种区块加密标准。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。它要求区块大小必须为128位，而密钥长度则可以为128、196、256位。基于此我们来实现.NET Framework版本和.NET Core版本。
在.NET Framework中实现AES加密和解密
AES加密
public static string EncryptText(string input, string key)
{ byte[] bytesToBeEncrypted = Encoding.UTF8.GetBytes(input);
byte[] passwordBytes = Encoding.UTF8.GetBytes(key); passwordBytes = SHA256.Create().ComputeHash(passwordBytes); byte[] bytesEncrypted = AESEncryptBytes(bytesToBeEncrypted, passwordBytes); string result = Convert.ToBase64String(bytesEncrypted); return result;
}
public static byte[] AESEncryptBytes(byte[] bytesToBeEncrypted, byte[] passwordBytes)
{
byte[] encryptedBytes = null; var saltBytes = new byte[] { , , , , , , , ,}; using (var ms = new MemoryStream())
{
using (var AES = new RijndaelManaged())
{
AES.KeySize = ;
AES.BlockSize = ; var key = new Rfc2898DeriveBytes(passwordBytes, saltBytes, );
AES.Key = key.GetBytes();
AES.IV = key.GetBytes(); AES.Mode = CipherMode.CBC; using (var cs = new CryptoStream(ms, AES.CreateEncryptor(),
CryptoStreamMode.Write))
{
cs.Write(bytesToBeEncrypted, , bytesToBeEncrypted.Length);
cs.Close();
} encryptedBytes = ms.ToArray();
}
} return encryptedBytes;
}
上述盐字节必须为至少8个字节，否则报错如下：
AES解密
public static string DecryptText(string input, string key)
{
byte[] bytesToBeDecrypted = Convert.FromBase64String(input); byte[] passwordBytes = Encoding.UTF8.GetBytes(key); passwordBytes = SHA256.Create().ComputeHash(passwordBytes); byte[] bytesDecrypted = AESDecryptBytes(bytesToBeDecrypted, passwordBytes); string result = Encoding.UTF8.GetString(bytesDecrypted); return result;
}
public static byte[] AESDecryptBytes(byte[] bytesToBeDecrypted, byte[] passwordBytes)
{
byte[] decryptedBytes = null; var saltBytes = new byte[] { , , , , , , , ,}; using (var ms = new MemoryStream())
{
using (var AES = new RijndaelManaged())
{
AES.KeySize = ;
AES.BlockSize = ; var key = new Rfc2898DeriveBytes(passwordBytes, saltBytes, );
AES.Key = key.GetBytes();
AES.IV = key.GetBytes(); AES.Mode = CipherMode.CBC; using (var cs = new CryptoStream(ms, AES.CreateDecryptor(), CryptoStreamMode.Write))
{
cs.Write(bytesToBeDecrypted, , bytesToBeDecrypted.Length);
cs.Close();
} decryptedBytes = ms.ToArray();
}
} return decryptedBytes;
}
测试如下：
var encrptText = "Jeffcky";
var key = Guid.NewGuid().ToString("N");
Console.WriteLine("加密前内容：" + encrptText);
var input = EncryptText(encrptText,key);
Console.WriteLine("加密后字符串为：" + input);
var text = DecryptText(input, key);
Console.WriteLine("解密后内容：" + text);
上述利用 RijndaelManaged 来实例化AES，最终该类继承自 SymmetricAlgorithm 对称算法类。通过我们实例化一个 Rfc2898DeriveBytes 来对密钥密钥和盐循环迭代1000次从而实现加密，同理解密反向操作。
在.NET Core中实现AES加密和解密
在.NET Core中对于对称加密统一接口不再利用不同类而实现，对于非对称加密当然和对称加密接口就不同了，创建起来格外方便，不再是实例化对应的类，如下
//对称加密
var aes = Aes.Create();
var tripleDES = TripleDES.Create(); //非对称加密
var rsa = RSA.Create();
由下可以看出直接定义了一个静态方法来创建加密
public abstract class Aes : SymmetricAlgorithm
{
protected Aes(); public override KeySizes[] LegalBlockSizes { get; }
public override KeySizes[] LegalKeySizes { get; } public static Aes Create();
}
public abstract class RSA : AsymmetricAlgorithm
{
protected RSA(); public static RSA Create();
...
}
当然命名空间依然是 System.Security.Cryptography 。我们直接看实现。
AES加密
public static string AESEncrypt(string input, string key)
{
var encryptKey = Encoding.UTF8.GetBytes(key); using (var aesAlg = Aes.Create())
{
using (var encryptor = aesAlg.CreateEncryptor(encryptKey, aesAlg.IV))
{
using (var msEncrypt = new MemoryStream())
{
using (var csEncrypt = new CryptoStream(msEncrypt, encryptor,
CryptoStreamMode.Write)) using (var swEncrypt = new StreamWriter(csEncrypt))
{
swEncrypt.Write(input);
} var iv = aesAlg.IV; var decryptedContent = msEncrypt.ToArray(); var result = new byte[iv.Length + decryptedContent.Length]; Buffer.BlockCopy(iv, , result, , iv.Length);
Buffer.BlockCopy(decryptedContent, , result,
iv.Length, decryptedContent.Length); return Convert.ToBase64String(result);
}
}
}
}
AES解密（修改：2019-11-13）
public static string AESDecrypt(string input, string key)
{
var fullCipher = Convert.FromBase64String(input); var iv = new byte[];
var cipher = new byte[fullCipher.Length-iv.Length]; Buffer.BlockCopy(fullCipher, , iv, , iv.Length);
Buffer.BlockCopy(fullCipher, iv.Length, cipher, , fullCipher.Length- iv.Length);
var decryptKey = Encoding.UTF8.GetBytes(key); using (var aesAlg = Aes.Create())
{
using (var decryptor = aesAlg.CreateDecryptor(decryptKey, iv))
{
string result;
using (var msDecrypt = new MemoryStream(cipher))
{
using (var csDecrypt = new CryptoStream(msDecrypt,
decryptor, CryptoStreamMode.Read))
{
using (var srDecrypt = new StreamReader(csDecrypt))
{
result = srDecrypt.ReadToEnd();
}
}
} return result;
}
}
}
测试如下：
var key = Guid.NewGuid().ToString("N");
var name = "Jeffcky";
Console.WriteLine($"加密字符串为{name}");
var encryptStr = AESEncrypt(name, key);
Console.WriteLine($"加密后结果为：{encryptStr}");
var decryptStr = AESDecrypt(encryptStr, key);
Console.WriteLine($"解密后字符串为{decryptStr}");
总结
在.NET Core中实现对称加密和非对称加密无论是实现还是创建都更加简洁，之前也并未去具体了解加密和解密相关内容，借此机会稍微了解下对应的加密所以花了一点时间。对于AES加密还没怎么具体去了解内部原理，只是参照了一点资料，以此作为备忘录，目前.NET Core仅支持AES、TripleDES、RSA。希望对在.NET Core项目中需要实现加密的童鞋提供一点帮助。接下来有时间我们继续巩固下线程基础知识，敬请期待，待我学习完毕再来更新博客和大家一起分享。