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，是美国联邦政府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[9] { 13, 34, 27, 67, 189, 255, 104, 219 ,122}; using (var ms = new MemoryStream()) { using (var AES = new RijndaelManaged()) { AES.KeySize = 256; AES.BlockSize = 128; var key = new Rfc2898DeriveBytes(passwordBytes, saltBytes, 1000); AES.Key = key.GetBytes(32); AES.IV = key.GetBytes(16); AES.Mode = CipherMode.CBC; using (var cs = new CryptoStream(ms, AES.CreateEncryptor(), CryptoStreamMode.Write)) { cs.Write(bytesToBeEncrypted, 0, 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[9] { 13, 34, 27, 67, 189, 255, 104, 219 ,122}; using (var ms = new MemoryStream()) { using (var AES = new RijndaelManaged()) { AES.KeySize = 256; AES.BlockSize = 128; var key = new Rfc2898DeriveBytes(passwordBytes, saltBytes, 1000); AES.Key = key.GetBytes(32); AES.IV = key.GetBytes(16); AES.Mode = CipherMode.CBC; using (var cs = new CryptoStream(ms, AES.CreateDecryptor(), CryptoStreamMode.Write)) { cs.Write(bytesToBeDecrypted, 0, 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, 0, result, 0, iv.Length); Buffer.BlockCopy(decryptedContent, 0, result, iv.Length, decryptedContent.Length); return Convert.ToBase64String(result); } } } }
AES解密
public static string AESDecrypt(string input, string key) { var fullCipher = Convert.FromBase64String(input); var iv = new byte[16]; var cipher = new byte[16]; Buffer.BlockCopy(fullCipher, 0, iv, 0, iv.Length); Buffer.BlockCopy(fullCipher, iv.Length, cipher, 0, 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。
