Question

我正在编写一个可公开访问的网络应用程序，其中包含个人用户数据，例如姓名和出生日期，我需要以一种对可能访问原始数据的人来说很难加密的数据数据要解密。我正在使用Fluent NHibernate，mySQL和C＃3.5。

我应该使用哪种方法进行行业标准加密和解密用户信息？加密方法不应该依赖于数据库。
如何告诉nHibernate使用简单属性（如StorageType = StorageType.Encrypted）对某些映射类进行透明加密/解密。我不介意结果数据库表只有一列或两列，或者每个加密字段一列。根据我的发现，我应该从IUserDataType创建自己的数据类型并加密构造函数中的数据。这是对的吗？

Answer 1

在真正的蓝色彼得时尚中，这是我之前创造的这样一个。它依赖于提供者模式来获取加密算法，但您可以将其替换为您想要的任何内容。

这会在域对象中公开一个字符串属性，但会将其作为表示加密表单的二进制文件（字节数组）保留。在我的提供者模式代码中，Encrypt接受一个字符串并返回一个字节数组，而Decrypt则相反。

[Serializable]
public class EncryptedStringType : PrimitiveType
{
    public EncryptedStringType() : this(new BinarySqlType()) {}

    public EncryptedStringType(SqlType sqlType) : base(sqlType) {}

    public override string Name
    {
        get { return "String"; }
    }

    public override Type ReturnedClass
    {
        get { return typeof (string); }
    }

    public override Type PrimitiveClass
    {
        get { return typeof (string); }
    }

    public override object DefaultValue
    {
        get { return null; }
    }

    public override void Set(IDbCommand cmd, object value, int index)
    {
        if (cmd == null) throw new ArgumentNullException("cmd");
        if (value == null)
        {
            ((IDataParameter)cmd.Parameters[index]).Value = null;
        }
        else
        {
            ((IDataParameter)cmd.Parameters[index]).Value = EncryptionManager.Provider.Encrypt((string)value);
        }
    }

    public override object Get(IDataReader rs, int index)
    {
        if (rs == null) throw new ArgumentNullException("rs");
        var encrypted = rs[index] as byte[];
        if (encrypted == null) return null;
        return EncryptionManager.Provider.Decrypt(encrypted);
    }

    public override object Get(IDataReader rs, string name)
    {
        return Get(rs, rs.GetOrdinal(name));
    }

    public override object FromStringValue(string xml)
    {
        if (xml == null)
        {
            return null;
        }

        if (xml.Length % 2 != 0)
        {
            throw new ArgumentException(
                "The string is not a valid xml representation of a binary content.",
                "xml");
        }

        var bytes = new byte[xml.Length / 2];
        for (int i = 0; i < bytes.Length; i++)
        {
            string hexStr = xml.Substring(i * 2, (i + 1) * 2);
            bytes[i] = (byte)(byte.MinValue
                              + byte.Parse(hexStr, NumberStyles.HexNumber, CultureInfo.InvariantCulture));
        }

        return EncryptionManager.Provider.Decrypt(bytes);
    }

    public override string ObjectToSQLString(object value, Dialect dialect)
    {
        var bytes = value as byte[];
        if (bytes == null)
        {
            return "NULL";
        }
        var builder = new StringBuilder();
        for (int i = 0; i < bytes.Length; i++)
        {
            string hexStr = (bytes[i] - byte.MinValue).ToString("x", CultureInfo.InvariantCulture);
            if (hexStr.Length == 1)
            {
                builder.Append('0');
            }
            builder.Append(hexStr);
        }
        return builder.ToString();
    }
}

Answer 2

我会创建一个EncryptionService，使用您想要的任何Key加密字符串。然后我会在你的实体中制作2个属性。 NHibernate与（加密值）交互的一个和您（或其他开发人员）与之交互的另一个将自动加密值。

请参阅：http://kockerbeck.blogspot.com/2009/08/fluent-nhibernate-encrypting-values.html

下面是一个示例EncryptionService，User实体和UserMap。

public class User
{
   private readonly EncryptionService _encryptionService =
                   new EncryptionService();
   public virtual int Id { get; set; }
   public virtual DateTime? DateOfBirth
   {
     get
     {
       return _encryptionService.DecryptObject<DateTime?>(DateOfBirthEncrypted);
     }
     set
     {
       DateOfBirthEncrypted= _encryptionService.EncryptString(value.Value
                                   .ToString("yyyy-MM-dd HH:mm:ss"));
     }
   }
   [Obsolete("Use the 'DateOfBirth' property -- this property is only to be used by NHibernate")]
   public virtual string DateOfBirthEncrypted { get; set; }
}


public sealed class UserMap : ClassMap<User>
{
  public UserMap()
  {
    WithTable("dbo.[User]");
    Id(x => x.Id, "[ID]");
    Map(x => x.DateOfBirthEncrypted, "DOB");
  }
}

加密服务：

using System;
using System.IO;
using System.Security.Cryptography;
using System.Text;

namespace Services
{
    public class EncryptionService : IEncryptionService 
    {
        /// <summary>
        /// Decrypts a string 
        /// </summary>
        /// <param name="encryptedString"></param>
        /// <returns></returns>
        public String DecryptString(string encryptedString)
        {
            if (String.IsNullOrEmpty(encryptedString)) return String.Empty;

            try
            {
                using (TripleDESCryptoServiceProvider cypher = new TripleDESCryptoServiceProvider())
                {
                    PasswordDeriveBytes pdb = new PasswordDeriveBytes("ENTERAKEYHERE", new byte[0]);
                    cypher.Key = pdb.GetBytes(16);
                    cypher.IV = pdb.GetBytes(8);

                    using (MemoryStream ms = new MemoryStream())
                    {
                        using (CryptoStream cs = new CryptoStream(ms, cypher.CreateDecryptor(), CryptoStreamMode.Write))
                        {
                            byte[] data = Convert.FromBase64String(encryptedString);
                            cs.Write(data, 0, data.Length);
                            cs.Close();

                            return Encoding.Unicode.GetString(ms.ToArray());
                        }
                    }
                }
            }
            catch
            {
                return String.Empty;
            }
        }

        /// <summary>
        /// Encrypts a string
        /// </summary>
        /// <param name="decryptedString"
        /// <returns></returns>
        public String EncryptString(string decryptedString)
        {
            if (String.IsNullOrEmpty(decryptedString)) return String.Empty;

            using (TripleDESCryptoServiceProvider cypher = new TripleDESCryptoServiceProvider())
            {
                PasswordDeriveBytes pdb = new PasswordDeriveBytes("ENTERAKEYHERE", new byte[0]);

                cypher.Key = pdb.GetBytes(16);
                cypher.IV = pdb.GetBytes(8);

                using (MemoryStream ms = new MemoryStream())
                {
                    using (CryptoStream cs = new CryptoStream(ms, cypher.CreateEncryptor(), CryptoStreamMode.Write))
                    {
                        byte[] data = Encoding.Unicode.GetBytes(decryptedString);

                        cs.Write(data, 0, data.Length);
                        cs.Close();

                        return Convert.ToBase64String(ms.ToArray());
                    }
                }
            }
        }

        /// <summary>
        /// Decrypts a given value as type of T, if unsuccessful the defaultValue is used
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="value"></param>
        /// <param name="defaultValue"></param>
        /// <returns></returns>
        public T DecryptObject<T>(object value, T defaultValue)
        {
            if (value == null) return defaultValue;

            try
            {
            Type conversionType = typeof(T);

            // Some trickery for Nullable Types
            if (conversionType.IsGenericType && conversionType.GetGenericTypeDefinition().Equals(typeof(Nullable<>)))
            {
                conversionType = new NullableConverter(conversionType).UnderlyingType;
            }

            return (T)Convert.ChangeType(DecryptString(Convert.ToString(value)), conversionType);
            }
            catch 
            {
                // Do nothing
            }

            return defaultValue;
        }
    }
}

使用NHibernate加密和解密数据

2 个答案: