/*******************************************************************************
 * Copyright(c) 2012 dongke All rights reserved. / Confidential
 * 类的信息：
 *      1.程序名称：Encryption.cs
 *      2.功能描述：系统各种字符串加密算法类
 * 编辑履历：
 *      作者            日期                版本            修改内容
 *      欧阳涛          2013/07/14          1.00            新建
 *******************************************************************************/

using System;
using System.Security.Cryptography;

namespace Dongke.IBOSS.PRD.Basics.Library
{
    /// <summary>
    /// 系统各种字符串加密算法类
    /// </summary>
    public class Encryption
    {
        #region RSA公钥加密算法
        /// <summary>
        /// RSA算法产生公共密钥和私有密钥
        /// </summary>
        /// <param name="publicKey">公共密钥</param>
        /// <param name="privateKey">私有密钥</param>
        public static void CreateRSAKeys(out string publicKey, out string privateKey)
        {
            System.Security.Cryptography.RSACryptoServiceProvider rsa =
                CreateRSACryptoServiceProvider();

            publicKey = rsa.ToXmlString(false);
            privateKey = rsa.ToXmlString(true);
        }

        public static string EncryptRSA(string value, string publicKey)
        {
            System.Security.Cryptography.RSACryptoServiceProvider rsa =
                CreateRSACryptoServiceProvider();
            rsa.FromXmlString(publicKey);

            byte[] data = System.Text.Encoding.UTF8.GetBytes(value);
            byte[] encryptedData = rsa.Encrypt(data, false);

            return System.Convert.ToBase64String(encryptedData);
        }

        public static string DecryptRSA(string value, string privateKey)
        {
            System.Security.Cryptography.RSACryptoServiceProvider rsa =
                CreateRSACryptoServiceProvider();
            rsa.FromXmlString(privateKey);

            byte[] data = System.Convert.FromBase64String(value);
            byte[] decryptedData = rsa.Decrypt(data, false);

            return System.Text.Encoding.UTF8.GetString(decryptedData);
        }

        protected static RSACryptoServiceProvider CreateRSACryptoServiceProvider()
        {
            System.Security.Cryptography.CspParameters cspParameters =
                new System.Security.Cryptography.CspParameters();
            cspParameters.Flags = System.Security.Cryptography.CspProviderFlags.UseMachineKeyStore;
            return new System.Security.Cryptography.RSACryptoServiceProvider(cspParameters);
        }
        #endregion

        #region DES加密算法
        public static string EncryptDES(string value, string key)
        {
            System.Security.Cryptography.DESCryptoServiceProvider des =
                CreateDESCryptoServiceProvider(key);

            byte[] bytesIn = System.Text.Encoding.UTF8.GetBytes(value);
            System.IO.MemoryStream stream = new System.IO.MemoryStream();
            System.Security.Cryptography.ICryptoTransform desdecrypt =
                des.CreateEncryptor();
            System.Security.Cryptography.CryptoStream cryptStream =
                new System.Security.Cryptography.CryptoStream(stream,
                                                              desdecrypt,
                                                              CryptoStreamMode.Write);
            cryptStream.Write(bytesIn, 0, bytesIn.Length);
            cryptStream.FlushFinalBlock();
            byte[] bytesOut = stream.ToArray();

            cryptStream.Close();
            stream.Close();

            return System.Convert.ToBase64String(bytesOut);
        }

        public static string DecryptDES(string value, string key)
        {
            System.Security.Cryptography.DESCryptoServiceProvider des =
                CreateDESCryptoServiceProvider(key);

            byte[] bytesIn = System.Convert.FromBase64String(value);
            System.IO.MemoryStream stream = new System.IO.MemoryStream(bytesIn);
            System.Security.Cryptography.ICryptoTransform desdecrypt = des.CreateDecryptor();
            System.Security.Cryptography.CryptoStream cryptStream =
                new System.Security.Cryptography.CryptoStream(stream,
                                                              desdecrypt,
                                                              CryptoStreamMode.Read);
            System.IO.StreamReader streamReader =
                new System.IO.StreamReader(cryptStream, System.Text.Encoding.UTF8);
            string result = streamReader.ReadToEnd();

            streamReader.Close();
            cryptStream.Close();
            stream.Close();

            return result;
        }

        protected static DESCryptoServiceProvider CreateDESCryptoServiceProvider(string key)
        {
            System.Security.Cryptography.DESCryptoServiceProvider des =
                new System.Security.Cryptography.DESCryptoServiceProvider();

            byte[] bytesKey = System.Text.Encoding.UTF8.GetBytes(key);
            des.Key = ResizeBytesArray(bytesKey, des.Key.Length);
            des.IV = ResizeBytesArray(bytesKey, des.IV.Length);

            return des;
        }

        protected static byte[] ResizeBytesArray(byte[] bytes, int newSize)
        {
            byte[] newBytes = new byte[newSize];
            if (bytes.Length <= newSize)
            {
                for (int i = 0; i < bytes.Length; i++)
                {
                    newBytes[i] = bytes[i];
                }
            }
            else
            {
                int pos = 0;
                for (int i = 0; i < bytes.Length; i++)
                {
                    newBytes[pos++] ^= bytes[i];
                    if (pos >= newBytes.Length)
                    {
                        pos = 0;
                    }
                }
            }
            return newBytes;
        }
        #endregion

        #region MD5加密算法
        public static string GetMD5String(string value)
        {
            return GetMD5String(System.Text.Encoding.UTF8.GetBytes(value));
        }

        public static string GetMD5String(byte[] value)
        {
            if (value == null)
            {
                return null;
            }

            System.Security.Cryptography.MD5CryptoServiceProvider md5 =
                new System.Security.Cryptography.MD5CryptoServiceProvider();
            byte[] bytes = md5.ComputeHash(value);
            return BitConverter.ToString(bytes).Replace("-", string.Empty);
        }
        #endregion

        #region SHA1加密算法
        public static string GetSHA1String(string value)
        {
            return GetSHA1String(System.Text.Encoding.UTF8.GetBytes(value));
        }

        public static string GetSHA1String(byte[] value)
        {
            if (value == null)
            {
                return null;
            }

            System.Security.Cryptography.SHA1CryptoServiceProvider sha1 =
                new System.Security.Cryptography.SHA1CryptoServiceProvider();
            byte[] bytes = sha1.ComputeHash(value);
            return BitConverter.ToString(bytes).Replace("-", string.Empty);
        }
        #endregion

        #region SHA256加密算法
        public static string GetSHA256String(string value)
        {
            return GetSHA256String(System.Text.Encoding.UTF8.GetBytes(value));
        }

        public static string GetSHA256String(byte[] value)
        {
            if (value == null)
            {
                return null;
            }

            System.Security.Cryptography.SHA256 sha256 =
                new System.Security.Cryptography.SHA256Managed();
            byte[] bytes = sha256.ComputeHash(value);
            return BitConverter.ToString(bytes).Replace("-", string.Empty);
        }
        #endregion
    }
}