using System;
using System.Collections.Generic;
using System.Globalization;
using System.IO;
using System.Security.Cryptography;
using System.Text;

/// <summary>
/// 加解密
/// </summary>
public static class CryptHelper
{
    #region RSA加密

    /// <summary>
    /// 用指定公鑰加密文本
    /// </summary>
    /// <param name="publicKey">公鑰</param>
    /// <param name="input">文本</param>
    /// <returns></returns>
    public static string RsaEncrypt(string publicKey, string input)
    {
        const string sFormat =
            "<RSAKeyValue><Modulus>{0}</Modulus><Exponent>AQAB</Exponent></RSAKeyValue>";
        var provider = new RSACryptoServiceProvider();
        var arrPubKey = Hex2Bytes(publicKey);
        var pkB64 = Convert.ToBase64String(arrPubKey);
        var xmlStr = string.Format(sFormat, pkB64);
        var bytesInput = Encoding.UTF8.GetBytes(input);
        provider.FromXmlString(xmlStr);
        var encryptArray = provider.Encrypt(bytesInput, false);
        var hexStr = BitConverter.ToString(encryptArray).Replace("-", "");
        return hexStr.ToLower();
    }

    #endregion

    #region 公用函數

    /// <summary>
    /// 將字節轉換成16進制數字
    /// </summary>
    /// <param name="bytes">字節數組</param>
    /// <returns></returns>
    public static string Bytes2Hex(byte[] bytes)
    {
        var buffer = new StringBuilder();
        foreach (var t in bytes)
        {
            buffer.AppendFormat("{0:x2}", t);
        }
        return buffer.ToString();
    }

    /// <summary>
    /// 將16進制數組轉換成字節
    /// </summary>
    /// <param name="input">16進制數組</param>
    /// <returns></returns>
    /// <exception cref="ArgumentOutOfRangeException"></exception>
    public static byte[] Hex2Bytes(string input)
    {
        if (string.IsNullOrEmpty(input)) return null;
        var offset = input.Length%2;
        if (offset == 1) input = "0" + input;
        int i;
        var list = new List<byte>();
        for (i = 0; i < input.Length; i += 2)
        {
            var temp = input.Substring(i, 2);
            byte bv;
            var success = byte.TryParse(temp, NumberStyles.HexNumber, null, out bv);
            if (!success) throw new ArgumentOutOfRangeException();
            list.Add(bv);
        }
        return list.ToArray();
    }

    #endregion

    #region SHA1加密

    /// <summary>
    /// SHA1加密 使用缺省密鑰給字符串加密
    /// </summary>
    /// <param name="sourceString"></param>
    /// <returns></returns>
    public static string Sha1Encrypt(string sourceString)
    {
        var data = Encoding.Default.GetBytes(sourceString);
        HashAlgorithm sha = new SHA1CryptoServiceProvider();
        var bytes = sha.ComputeHash(data);
        return BitConverter.ToString(bytes).Replace("-", "");
    }

    #endregion

    #region DES加解密

    /// <summary>
    /// DES加密
    /// </summary>
    /// <param name="pubKey"></param>
    /// <param name="input"></param>
    /// <returns></returns>
    public static string DesEncrypt(string pubKey, string input)
    {
        var des = new DESCryptoServiceProvider();
        var bytes = Encoding.UTF8.GetBytes(input);
        des.Key = Encoding.ASCII.GetBytes(pubKey);
        des.IV = Encoding.ASCII.GetBytes(pubKey);
        using (var ms = new MemoryStream())
        {
            using (var cryptoStream = new CryptoStream(ms, des.CreateEncryptor(), CryptoStreamMode.Write))
            {
                cryptoStream.Write(bytes, 0, bytes.Length);
                cryptoStream.FlushFinalBlock();
            }
            var data = ms.ToArray();
            return BitConverter.ToString(data).Replace("-", "");
        }
    }

    /// <summary>
    /// DES解密
    /// </summary>
    /// <param name="pubKey"></param>
    /// <param name="input"></param>
    /// <returns></returns>
    public static string DesDecrypt(string pubKey, string input)
    {
        var des = new DESCryptoServiceProvider();
        var bytes = Hex2Bytes(input);
        des.Key = Encoding.ASCII.GetBytes(pubKey);
        des.IV = Encoding.ASCII.GetBytes(pubKey);
        using (var ms = new MemoryStream())
        {
            using (var cryptoStream = new CryptoStream(ms, des.CreateDecryptor(), CryptoStreamMode.Write))
            {
                cryptoStream.Write(bytes, 0, bytes.Length);
                cryptoStream.FlushFinalBlock();
            }
            var data = ms.ToArray();
            return Encoding.UTF8.GetString(data);
        }
    }

    #endregion

    #region MD5加密

    /// <summary>
    /// MD5加密
    /// </summary>
    /// <param name="input">輸入</param>
    /// <returns></returns>
    public static string Md5Encrypt(string input)
    {
        MD5 md5 = new MD5CryptoServiceProvider();
        var data = Encoding.UTF8.GetBytes(input);
        var encs = md5.ComputeHash(data);
        return BitConverter.ToString(encs).Replace("-", "");
    }

    #endregion
}