RSA加密算法是一種非對稱加密算法。在公鑰加密標準和電子商業中RSA被廣泛使用。RSA是1977年由羅納德•李維斯特（Ron Rivest）、阿迪•薩莫爾（Adi Shamir）和倫納德•阿德曼（Leonard Adleman）一起提出的。當時他們三人都在麻省理工學院工作。RSA就是他們三人姓氏開頭字母拼在一起組成的。.Net的推出，我們能夠利用.Net Framework中的類提供的加密服務來保證數據安全。目前應用較爲廣泛的加密方法是使用RSA算法進行加密。在.Net Framework中與RSA加密算法相關的類主要有兩個：RSA 類和RSACryptoServiceProvider 類。按照MSDN的說法RSA 類是“表示 RSA 算法的所有實現均從中繼承的基類”，而RSACryptoServiceProvider 類是“使用加密服務提供程序 (CSP) 提供的 RSA 算法的實現執行不對稱加密和解密”。另外，“表示 RSA 算法的標準參數”的RSAParameters 結構也是很重要的，它保存了RSA算法的參數。
這是本人剛剛寫的RSA加密與解密、數字簽名與驗證數字簽名的一個簡單例子
希望對初學者能起到一定作用
class RSAEncode
{
public RSACryptoServiceProvider MyRsa;
public RSAEncode()
{
MyRsa = new RSACryptoServiceProvider();
}
public void RSAKey(out string XmlKey,out string XmlPublicKey)
{
try
{
XmlKey = MyRsa.ToXmlString(true);
XmlPublicKey = MyRsa.ToXmlString(false);
string xx = MyRsa.ToXmlString(true);
//Console.Write(XmlKey + "/n");
//Console.Write(xx);
//WriteInKeys("E://key.xml", XmlKey);
}
catch (Exception ex)
{
throw ex;
}
finally
{
}
}
/////加密
public string RSAEncodeData(string XmlPublicKey, string InputString)
{
byte[] BlankStr;
byte[] EncodeStr;
int len, len1,blockLen;
string temp;
string result="";
try
{
len = InputString.Length;
if (len % 128 == 0) len1 = len / 128;
else len1 = len / 128 + 1;
MyRsa.FromXmlString(XmlPublicKey);
for (int i = 0; i < len1; i++)
{
if (len >= 128)
blockLen = 128;
else blockLen = len;
len -= blockLen;
BlankStr = (new UnicodeEncoding()).GetBytes(InputString.Substring(i * 128, blockLen));
EncodeStr = MyRsa.Encrypt(BlankStr, false);
temp = Convert.ToBase64String(EncodeStr);
result += temp;
}
return result;
}
catch (Exception ex)
{
throw ex;
}
}
////解密
public string RSADecodeData(string PrivateKey, string InputString)
{
string result="";
byte[] EncodeStr;
byte[] BlankStr;
int len, len1, blockLen;
string temp;
try
{
len = InputString.Length;
if (len % 256 == 0) len1 = len / 256;
else len1 = len / 256 + 1;
MyRsa.FromXmlString(PrivateKey);
for (int i = 0; i < len1; i++)
{
if (len >= 256)
blockLen = 256;
else blockLen = len;
len -= blockLen;
EncodeStr = Convert.FromBase64String(InputString.Substring(i*256,blockLen));
BlankStr=MyRsa.Decrypt(EncodeStr, false);
temp =(new UnicodeEncoding()).GetString(BlankStr);
result += temp;
}
return result;
//Console.Write(result);
}
catch (Exception ex)
{
throw ex;
}
}
////獲取hash簽名
public bool GetHash(string SendData, out string CreateHashSign)
{
try
{
byte[] Buffer;
byte[] HashData;
System.Security.Cryptography.HashAlgorithm MD5 = System.Security.Cryptography.HashAlgorithm.Create("MD5");
Buffer = System.Text.Encoding.GetEncoding("GB2312").GetBytes(SendData);
HashData = MD5.ComputeHash(Buffer);
CreateHashSign = Convert.ToBase64String(HashData);
//Console.Write(CreateHashSign);
return true;
}
catch (Exception ex)
{
throw ex;
}
finally
{
//return true;
}
}
/// <summary>
/// 簽名
/// </summary>
/// <param name="PrivateKey"></param>
/// <param name="HashSign"></param>
/// <param name="EncodedSignData"></param>
/// <returns></returns>
public bool SignatureFormatter(string PrivateKey, string HashSign, out string EncodedSignData)
{
try
{
byte[] ByteHashSign;
byte[] ByteData;
ByteHashSign = Convert.FromBase64String(HashSign);
//ByteData = Convert.FromBase64String(EncodedData);
MyRsa.FromXmlString(PrivateKey);
RSAPKCS1SignatureFormatter RSAFormat = new RSAPKCS1SignatureFormatter(MyRsa);
RSAFormat.SetHashAlgorithm("MD5");
ByteData = RSAFormat.CreateSignature(ByteHashSign);
EncodedSignData = Convert.ToBase64String(ByteData);
return true;
}
catch (Exception ex)
{
throw ex;
}
}
//驗證簽名
//p_strHashbyteDeformatter
//p_strDeformatterData
public bool SignatureDeformatter(string PublicKey, string p_strHashbyteDeformatter, string p_strDeformatterData)
{
try
{
byte[] DeformatterData;
byte[] HashbyteDeformatter;
HashbyteDeformatter = Convert.FromBase64String(p_strHashbyteDeformatter);
System.Security.Cryptography.RSACryptoServiceProvider RSA = new System.Security.Cryptography.RSACryptoServiceProvider();
RSA.FromXmlString(PublicKey);
System.Security.Cryptography.RSAPKCS1SignatureDeformatter RSADeformatter = new System.Security.Cryptography.RSAPKCS1SignatureDeformatter(RSA);
//指定解密的時候HASH算法爲MD5
RSADeformatter.SetHashAlgorithm("MD5");
DeformatterData =Convert.FromBase64String(p_strDeformatterData);
if(RSADeformatter.VerifySignature(HashbyteDeformatter,DeformatterData))
{
return true;
}
else
{
return false;
}
}
catch(Exception ex)
{
throw ex;
}
}
///寫入密鑰
///
private void WriteInKeys(string path,string key)
{
FileStream File = new FileStream(path, FileMode.Create);
StreamWriter sw = new StreamWriter(File);
sw.WriteLine(key);
sw.Close();
File.Close();
}
///讀取密鑰
///
public bool ReadKeys(string path, out string Keys)
{
try
{
StreamReader sr = new StreamReader(path);
XmlPublicKey = sr.ReadToEnd();
sr.Close();
return true;
}
catch (Exception ex)
{
return false;
}
}
上面是加密解密簽名驗證的類
結合自己的理解 RSA加密解密的就一句話：公鑰加密 私鑰解密 私鑰簽名 公鑰驗證
不足之處還忘指出