/// <summary>
/// Base64加密
/// </summary>
/// <param name="Message"></param>
/// <returns></returns>
public string Base64Code(string Message)
{
char[] Base64Code = new char[]{'A','B','C','D','E','F','G','H','I','J','K','L','M','N','O','P','Q','R','S','T',
'U','V','W','X','Y','Z','a','b','c','d','e','f','g','h','i','j','k','l','m','n',
'o','p','q','r','s','t','u','v','w','x','y','z','0','1','2','3','4','5','6','7',
'8','9','+','/','='};
byte empty = (byte)0;
System.Collections.ArrayList byteMessage = new System.Collections.ArrayList(System.Text.Encoding.Default.GetBytes(Message));
System.Text.StringBuilder outmessage;
int messageLen = byteMessage.Count;
//将字符分成3个字节一组，如果不足，则以0补齐
int page = messageLen / 3;
int use = 0;
if ((use = messageLen % 3) > 0)
{
for (int i = 0; i < 3 - use; i++)
byteMessage.Add(empty);
page++;
}
//将3个字节的每组字符转换成4个字节一组的。3个一组，一组一组变成4个字节一组
//方法是：转换成ASCII码，按顺序排列24 位数据，再把这24位数据分成4组，即每组6位。再在每组的的最高位前补两个0凑足一个字节。
outmessage = new System.Text.StringBuilder(page * 4);
for (int i = 0; i < page; i++)
{
//取一组3个字节的组
byte[] instr = new byte[3];
instr[0] = (byte)byteMessage[i * 3];
instr[1] = (byte)byteMessage[i * 3 + 1];
instr[2] = (byte)byteMessage[i * 3 + 2];
//六个位为一组，补0变成4个字节
int[] outstr = new int[4];
//第一个输出字节：取第一输入字节的前6位，并且在高位补0，使其变成8位（一个字节）
outstr[0] = instr[0] >> 2;
//第二个输出字节：取第一输入字节的后2位和第二个输入字节的前4位（共6位），并且在高位补0，使其变成8位（一个字节）
outstr[1] = ((instr[0] & 0x03) << 4) ^ (instr[1] >> 4);
//第三个输出字节：取第二输入字节的后4位和第三个输入字节的前2位（共6位），并且在高位补0，使其变成8位（一个字节）
if (!instr[1].Equals(empty))
outstr[2] = ((instr[1] & 0x0f) << 2) ^ (instr[2] >> 6);
else
outstr[2] = 64;
//第四个输出字节：取第三输入字节的后6位，并且在高位补0，使其变成8位（一个字节）
if (!instr[2].Equals(empty))
outstr[3] = (instr[2] & 0x3f);
else
outstr[3] = 64;
outmessage.Append(Base64Code[outstr[0]]);
outmessage.Append(Base64Code[outstr[1]]);
outmessage.Append(Base64Code[outstr[2]]);
outmessage.Append(Base64Code[outstr[3]]);
}
return outmessage.ToString();
}
/// <summary>
/// Base64解密
/// </summary>
/// <param name="Message"></param>
/// <returns></returns>
public string Base64Decode(string Message)
{
if ((Message.Length % 4) != 0)
{
throw new ArgumentException("不是正确的BASE64编码，请检查。", "Message");
}
if (!System.Text.RegularExpressions.Regex.IsMatch(Message, "^[A-Z0-9/+=]*$", System.Text.RegularExpressions.RegexOptions.IgnoreCase))
{
throw new ArgumentException("包含不正确的BASE64编码，请检查。", "Message");
}
string Base64Code = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";
int page = Message.Length / 4;
System.Collections.ArrayList outMessage = new System.Collections.ArrayList(page * 3);
char[] message = Message.ToCharArray();
for (int i = 0; i < page; i++)
{
byte[] instr = new byte[4];
instr[0] = (byte)Base64Code.IndexOf(message[i * 4]);
instr[1] = (byte)Base64Code.IndexOf(message[i * 4 + 1]);
instr[2] = (byte)Base64Code.IndexOf(message[i * 4 + 2]);
instr[3] = (byte)Base64Code.IndexOf(message[i * 4 + 3]);
byte[] outstr = new byte[3];
outstr[0] = (byte)((instr[0] << 2) ^ ((instr[1] & 0x30) >> 4));
if (instr[2] != 64)
{
outstr[1] = (byte)((instr[1] << 4) ^ ((instr[2] & 0x3c) >> 2));
}
else
{
outstr[2] = 0;
}
if (instr[3] != 64)
{
outstr[2] = (byte)((instr[2] << 6) ^ instr[3]);
}
else
{
outstr[2] = 0;
}
outMessage.Add(outstr[0]);
if (outstr[1] != 0)
outMessage.Add(outstr[1]);
if (outstr[2] != 0)
outMessage.Add(outstr[2]);
}
byte[] outbyte = (byte[])outMessage.ToArray(Type.GetType("System.Byte"));
return System.Text.Encoding.Default.GetString(outbyte);
}
方法二：直接使用.NET中的的库类函数
/// <summary>
/// Base64加密
/// </summary>
/// <param name="Message"></param>
/// <returns></returns>
public string Base64Code(string Message)
{
byte[] bytes = Encoding.Default.GetBytes(Message);
return Convert.ToBase64String(bytes);
}
/// <summary>
/// Base64解密
/// </summary>
/// <param name="Message"></param>
/// <returns></returns>
public string Base64Decode(string Message)
{
byte[] bytes = Convert.FromBase64String(Message);
return Encoding.Default.GetString(bytes);
}