C# RSA Base64 加密解密

public static class RSAHelper
{
/// <summary>
/// RSA的容器 可以解密的源字符串长度为 DWKEYSIZE/8-11
/// </summary>
public const int DWKEYSIZE = 1024;

/// <summary>
/// RSA加密的密匙结构 公钥和私匙
/// </summary>
public struct RSAKey
{

public string PublicKey { get; set; }
public string PrivateKey { get; set; }
}

#region 得到RSA的解谜的密匙对
/// <summary>
/// 得到RSA的解谜的密匙对
/// </summary>
/// <returns></returns>
public static RSAKey GetRASKey()
{
RSACryptoServiceProvider.UseMachineKeyStore = true;
//声明一个指定大小的RSA容器
RSACryptoServiceProvider rsaProvider = new RSACryptoServiceProvider(DWKEYSIZE);
//取得RSA容易里的各种参数
RSAParameters p = rsaProvider.ExportParameters(true);

return new RSAKey()
{
PublicKey = ComponentKey(p.Exponent, p.Modulus),
PrivateKey = ComponentKey(p.D, p.Modulus)
};
}
#endregion

#region 检查明文的有效性 DWKEYSIZE/8-11 长度之内为有效 中英文都算一个字符
/// <summary>
/// 检查明文的有效性 DWKEYSIZE/8-11 长度之内为有效 中英文都算一个字符
/// </summary>
/// <param name="source"></param>
/// <returns></returns>
public static bool CheckSourceValidate(string source)
{
return (DWKEYSIZE / 8 - 11) >= source.Length;
}
#endregion

#region 组合解析密匙
/// <summary>
/// 组合成密匙字符串
/// </summary>
/// <param name="b1"></param>
/// <param name="b2"></param>
/// <returns></returns>
private static string ComponentKey(byte[] b1, byte[] b2)
{
List<byte> list = new List<byte>();
//在前端加上第一个数组的长度值 这样今后可以根据这个值分别取出来两个数组
list.Add((byte)b1.Length);
list.AddRange(b1);
list.AddRange(b2);
byte[] b = list.ToArray<byte>();
return Convert.ToBase64String(b);
}

/// <summary>
/// 解析密匙
/// </summary>
/// <param name="key">密匙</param>
/// <param name="b1">RSA的相应参数1</param>
/// <param name="b2">RSA的相应参数2</param>
private static void ResolveKey(string key, out byte[] b1, out byte[] b2)
{
//从base64字符串 解析成原来的字节数组
byte[] b = Convert.FromBase64String(key);
//初始化参数的数组长度
b1 = new byte[b[0]];
b2 = new byte[b.Length - b[0] - 1];
//将相应位置是值放进相应的数组
for (int n = 1, i = 0, j = 0; n < b.Length; n++)
{
if (n <= b[0])
{
b1[i++] = b[n];
}
else
{
b2[j++] = b[n];
}
}
}
#endregion

#region 字符串加密解密 公开方法
/// <summary>
/// 字符串加密
/// </summary>
/// <param name="source">源字符串 明文</param>
/// <param name="key">密匙</param>
/// <returns>加密遇到错误将会返回原字符串</returns>
public static string EncryptString(string source, string key)
{
string encryptString = string.Empty;
byte[] d;
byte[] n;
try
{
if (!CheckSourceValidate(source))
{
throw new Exception("source string too long");
}
//解析这个密钥
ResolveKey(key, out d, out n);
BigInteger biN = new BigInteger(n);
BigInteger biD = new BigInteger(d);
encryptString = EncryptString(source, biD, biN);
}
catch
{
encryptString = source;
}
return encryptString;
}

/// <summary>
/// 字符串解密
/// </summary>
/// <param name="encryptString">密文</param>
/// <param name="key">密钥</param>
/// <returns>遇到解密失败将会返回原字符串</returns>
public static string DecryptString(string encryptString, string key)
{
string source = string.Empty;
byte[] e;
byte[] n;
try
{
//解析这个密钥
ResolveKey(key, out e, out n);
BigInteger biE = new BigInteger(e);
BigInteger biN = new BigInteger(n);
source = DecryptString(encryptString, biE, biN);
}
catch
{
source = encryptString;
}
return source;
}
#endregion

#region 字符串加密解密 私有 实现加解密的实现方法
/// <summary>
/// 用指定的密匙加密
/// </summary>
/// <param name="source">明文</param>
/// <param name="d">可以是RSACryptoServiceProvider生成的D</param>
/// <param name="n">可以是RSACryptoServiceProvider生成的Modulus</param>
/// <returns>返回密文</returns>
private static string EncryptString(string source, BigInteger d, BigInteger n)
{
int len = source.Length;
int len1 = 0;
int blockLen = 0;
if ((len % 128) == 0)
len1 = len / 128;
else
len1 = len / 128 + 1;
string block = "";
StringBuilder result = new StringBuilder();
for (int i = 0; i < len1; i++)
{
if (len >= 128)
blockLen = 128;
else
blockLen = len;
block = source.Substring(i * 128, blockLen);
byte[] oText = System.Text.Encoding.Default.GetBytes(block);
BigInteger biText = new BigInteger(oText);
BigInteger biEnText = biText.modPow(d, n);
string temp = biEnText.ToHexString();
result.Append(temp).Append("@");
len -= blockLen;
}
return result.ToString().TrimEnd('@');
}

/// <summary>
/// 用指定的密匙加密
/// </summary>
/// <param name="source">密文</param>
/// <param name="e">可以是RSACryptoServiceProvider生成的Exponent</param>
/// <param name="n">可以是RSACryptoServiceProvider生成的Modulus</param>
/// <returns>返回明文</returns>
private static string DecryptString(string encryptString, BigInteger e, BigInteger n)
{
StringBuilder result = new StringBuilder();
string[] strarr1 = encryptString.Split(new char[] { '@' }, StringSplitOptions.RemoveEmptyEntries);
for (int i = 0; i < strarr1.Length; i++)
{
string block = strarr1[i];
BigInteger biText = new BigInteger(block, 16);
BigInteger biEnText = biText.modPow(e, n);
string temp = System.Text.Encoding.Default.GetString(biEnText.getBytes());
result.Append(temp);
}
return result.ToString();
}
#endregion
}