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技術社區[雲棲]
RSA加密算法
RSA算法基於一個十分簡單的數論事實：將兩個大素數相乘十分容易，但那時想要對其乘積進行因式分解卻極其困難，因此可以將乘積公開作為加密密鑰。RSA算法是第一個能同時用於加密和數字簽名的算法，也易於理解和操作。
原理圖：
C# 代碼實現：
using System;
using System.Collections.Generic;
using System.Text;
using System.Security.Cryptography;
using Microsoft.Win32;
using System.IO;
namespace SRA
{
class Program
{
static void Main(string[] args)
{
string publicKeyFile = "publicKey.txt";
string privateKeyFile = "privateKey.txt";
string publicKey = string.Empty;
string privateKey = string.Empty;
Console.WriteLine("①創建公私鑰對：");
RSA.GenneralRSAKey(privateKeyFile, publicKeyFile);
publicKey = RSA.ReadPublicKey(publicKeyFile);
privateKey = RSA.ReadPrivateKey(privateKeyFile);
Console.WriteLine("公鑰：" + publicKey);
Console.WriteLine("私鑰：" + privateKey);
string orgStr = "HelloWord";
Console.WriteLine("②使用公鑰加密字符串：");
string secStr = RSA.RSAEncrypt(publicKey, orgStr);
Console.WriteLine(secStr);
Console.WriteLine("③使用私鑰解密字符串：");
Console.WriteLine(SRA.RSA.RSADecrypt(privateKey, secStr));
Console.Read();
}
}
public class RSA
{
#region ①生成公私鑰對
/// <summary>
/// ①生成公私鑰對
/// </summary>
/// <param name="PrivateKeyPath">私鑰文件路徑</param>
/// <param name="PublicKeyPath">公鑰文件路徑</param>
public static void GenneralRSAKey(string PrivateKeyPath, string PublicKeyPath)
{
try
{
RSACryptoServiceProvider provider = new RSACryptoServiceProvider();
CreatePrivateKeyXML(PrivateKeyPath, provider.ToXmlString(true));
CreatePublicKeyXML(PublicKeyPath, provider.ToXmlString(false));
}
catch (Exception exception)
{
throw exception;
}
}
#region 創建密鑰文件
/// <summary>
/// 創建公鑰文件
/// </summary>
/// <param name="path"></param>
/// <param name="publickey"></param>
public static void CreatePublicKeyXML(string path, string publickey)
{
try
{
if (File.Exists(path))
{
File.Delete(path);
}
FileStream publickeyxml = new FileStream(path, FileMode.Create);
StreamWriter sw = new StreamWriter(publickeyxml);
sw.WriteLine(publickey);
sw.Close();
publickeyxml.Close();
}
catch
{
throw;
}
}
/// <summary>
/// 創建私鑰文件
/// </summary>
/// <param name="path"></param>
/// <param name="privatekey"></param>
public static void CreatePrivateKeyXML(string path, string privatekey)
{
try
{
if (File.Exists(path))
{
File.Delete(path);
}
FileStream privatekeyxml = new FileStream(path, FileMode.Create);
StreamWriter sw = new StreamWriter(privatekeyxml);
sw.WriteLine(privatekey);
sw.Close();
privatekeyxml.Close();
}
catch
{
throw;
}
}
#endregion
#endregion
#region ②讀取密鑰
/// <summary>
/// 讀取公鑰
/// </summary>
/// <param name="path"></param>
/// <returns></returns>
public static string ReadPublicKey(string path)
{
StreamReader reader = new StreamReader(path);
string publickey = reader.ReadToEnd();
reader.Close();
return publickey;
}
/// <summary>
/// 讀取私鑰
/// </summary>
/// <param name="path"></param>
/// <returns></returns>
public static string ReadPrivateKey(string path)
{
StreamReader reader = new StreamReader(path);
string privatekey = reader.ReadToEnd();
reader.Close();
return privatekey;
}
#endregion
#region ③加密解密
/// <summary>
/// RSA加密
/// </summary>
/// <param name="xmlPublicKey">公鑰</param>
/// <param name="m_strEncryptString">MD5加密後的數據</param>
/// <returns>RSA公鑰加密後的數據</returns>
public static string RSAEncrypt(string xmlPublicKey, string m_strEncryptString)
{
string str2;
try
{
RSACryptoServiceProvider provider = new RSACryptoServiceProvider();
provider.FromXmlString(xmlPublicKey);
byte[] bytes = new UnicodeEncoding().GetBytes(m_strEncryptString);
str2 = Convert.ToBase64String(provider.Encrypt(bytes, false));
}
catch (Exception exception)
{
throw exception;
}
return str2;
}
/// <summary>
/// RSA解密
/// </summary>
/// <param name="xmlPrivateKey">私鑰</param>
/// <param name="m_strDecryptString">待解密的數據</param>
/// <returns>解密後的結果</returns>
public static string RSADecrypt(string xmlPrivateKey, string m_strDecryptString)
{
string str2;
try
{
RSACryptoServiceProvider provider = new RSACryptoServiceProvider();
provider.FromXmlString(xmlPrivateKey);
byte[] rgb = Convert.FromBase64String(m_strDecryptString);
byte[] buffer2 = provider.Decrypt(rgb, false);
str2 = new UnicodeEncoding().GetString(buffer2);
}
catch (Exception exception)
{
throw exception;
}
return str2;
}
#endregion
}
}
算法介紹：
算法的名字以發明者的名字命名：Ron Rivest, AdiShamir 和Leonard Adleman。早在1973年，英國國家通信總局的數學家Clifford Cocks就發現了類似的算法。但是他的發現被列為絕密，直到1998年才公諸於世。
RSA算法是一種非對稱密碼算法，所謂非對稱，就是指該算法需要一對密鑰，使用其中一個加密，則需要用另一個才能解密。
RSA的算法涉及三個參數，n、e1、e2。
其中，n是兩個大質數p、q的積，n的二進製表示時所占用的位數，就是所謂的密鑰長度。
e1和e2是一對相關的值，e1可以任意取，但要求e1與(p-1)*(q-1)互質；再選擇e2，要求(e2*e1)mod((p-1)*(q-1))=1。
(n及e1),(n及e2)就是密鑰對。
RSA加解密的算法完全相同,設A為明文，B為密文，則：A=B^e1 mod n；B=A^e2 mod n；
e1和e2可以互換使用，即：A=B^e2 mod n；B=A^e1 mod n;
最後更新：2017-04-02 06:51:55