假设有User表

public class User : Entity<int>
{public int Id { get; set; }public string UserName { get; set; }public string Name { get; set; }public string IdentificationNumber { get; set; }
}

其中有身份证号码IdentificationNumber列，需要加密存储，该如何实现？

创建一个值转换器，继承ValueConverter<TModel, string>类型。其中泛型TModel为实体中属性的类型。

转换器将实体中属性类型，通过AES加密算法，转换为Base64编码字符串类型，存储到数据库中。当从数据库中读取数据时，再通过AES解密算法，将Base64编码字符串类型转换为实体中属性类型。

若实体类型为byte[]，则不需要转换为Base64编码字符串类型，直接对二进制数据进行加密和解密。此转换器可以用于加密存储图片、文件等二进制数据。

AES加密算法是一种对称加密算法，加密和解密使用相同的密钥。在加密和解密时，需要指定密钥、初始向量、盐值等参数。在转换器中，将这些参数设置为静态属性，方便在使用时，进行修改。

代码如下：

public class EncryptionConverter<TModel> : ValueConverter<TModel, string>
{public const int DefaultKeysize = 256;public static string DefaultPassPhrase { get; set; }public static byte[] DefaultInitVectorBytes { get; set; }public static byte[] DefaultSalt { get; set; }public EncryptionConverter(): base(x => Encrypt(x),x => Decrypt(x)){DefaultPassPhrase = "gsKnGZ041HLL4IM8";DefaultInitVectorBytes = Encoding.ASCII.GetBytes("jkE49230Tf093b42");DefaultSalt = Encoding.ASCII.GetBytes("hgt!16kl");}private static string Encrypt(TModel input){try{byte[] inputData = input switch{string => Encoding.UTF8.GetBytes(input.ToString()),byte[] => input as byte[],_ => null,};using (var password = new Rfc2898DeriveBytes(DefaultPassPhrase, DefaultSalt)){var keyBytes = password.GetBytes(DefaultKeysize / 8);using (var symmetricKey = Aes.Create()){symmetricKey.Mode = CipherMode.CBC;using (var encryptor = symmetricKey.CreateEncryptor(keyBytes, DefaultInitVectorBytes)){using (var memoryStream = new MemoryStream()){using (var cryptoStream = new CryptoStream(memoryStream, encryptor, CryptoStreamMode.Write)){cryptoStream.Write(inputData, 0, inputData.Length);cryptoStream.FlushFinalBlock();var cipherTextBytes = memoryStream.ToArray();var rawString = Convert.ToBase64String(cipherTextBytes);return rawString;}}}}}}catch (Exception ex){              LogHelper.LogException(ex);return input.ToString();              }}private static TModel Decrypt(string input){try{var cipherTextBytes = Convert.FromBase64String(input);using (var password = new Rfc2898DeriveBytes(DefaultPassPhrase, DefaultSalt)){var keyBytes = password.GetBytes(DefaultKeysize / 8);using (var symmetricKey = Aes.Create()){symmetricKey.Mode = CipherMode.CBC;using (var decryptor = symmetricKey.CreateDecryptor(keyBytes, DefaultInitVectorBytes)){using (var memoryStream = new MemoryStream(cipherTextBytes)){using (var cryptoStream = new CryptoStream(memoryStream, decryptor, CryptoStreamMode.Read)){var plainTextBytes = new byte[cipherTextBytes.Length];int totalDecryptedByteCount = 0;while (totalDecryptedByteCount < plainTextBytes.Length){var decryptedByteCount = cryptoStream.Read(plainTextBytes,totalDecryptedByteCount,plainTextBytes.Length - totalDecryptedByteCount);if (decryptedByteCount == 0){break;}totalDecryptedByteCount += decryptedByteCount;}byte[] outputData = null;if (typeof(TModel) == typeof(string)){var outputData = Encoding.UTF8.GetString(plainTextBytes, 0, totalDecryptedByteCount);return (TModel)Convert.ChangeType(outputData, typeof(TModel));}else if (typeof(TModel) == typeof(byte[])){var outputData = plainTextBytes as byte[];return (TModel)Convert.ChangeType(outputData, typeof(TModel));};return default; }}}}}}catch (Exception ex){// 记录异常// LogHelper.LogException(ex);return (TModel)Convert.ChangeType(input, typeof(TModel));}}
}

在DbContext中，重写OnModelCreating方法，为User表的IdentificationNumber列，添加值转换器。

protected override void OnModelCreating(ModelBuilder modelBuilder)
{base.OnModelCreating(modelBuilder);modelBuilder.Entity<User>().Property(c => c.IdentificationNumber).HasConversion<EncryptionConverter<string>>();
}

再次调用Add方法插入数据时，可以看到IdentificationNumber列已被加密了