JAVA實現RSA加密解密

標籤：加密   rsa   

RSA 工具類。提供加密，解密，產生金鑰組等方法。 

RSA加密原理概述   ：
RSA的安全性依賴於大數的分解，公開金鑰和私密金鑰都是兩個大素數（大於100的十進位位）的函數。
據猜測，從一個密鑰和密文推斷出明文的難度等同於分解兩個大素數的積   
密鑰的產生：   
 1.選擇兩個大素數 p,q ,計算 n=p*q;   
 2.隨機播放加密金鑰 e ,要求 e 和 (p-1)*(q-1)互質   
 3.利用 Euclid 演算法計算解密密鑰 d , 使其滿足 e*d = 1(mod(p-1)*(q-1)) (其中 n,d 也要互質)   
 4:至此得出公開金鑰為 (n,e) 私密金鑰為 (n,d)   
 RSA速度   
 由於進行的都是大數計算，使得RSA最快的情況也比DES慢上100倍，無論 是軟體還是硬體實現。   
 速度一直是RSA的缺陷。一般來說只用於少量資料 加密。

package com.security.rsa;import java.security.KeyFactory;import java.security.KeyPair;import java.security.KeyPairGenerator;import java.security.PrivateKey;import java.security.PublicKey;import java.security.interfaces.RSAPrivateKey;import java.security.interfaces.RSAPublicKey;import java.security.spec.PKCS8EncodedKeySpec;import java.security.spec.X509EncodedKeySpec;import javax.crypto.Cipher;public class RSAsecurity {public static String src="RSA 加密字串";        public void priENpubDE() {    try {      //1.初始化秘鑰     KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance("RSA");     //秘鑰長度     keyPairGenerator.initialize(512);     //初始化秘鑰對     KeyPair keyPair = keyPairGenerator.generateKeyPair();     //公開金鑰     RSAPublicKey rsaPublicKey = (RSAPublicKey) keyPair.getPublic();     //私密金鑰     RSAPrivateKey rsaPrivateKey = (RSAPrivateKey) keyPair.getPrivate();    //2.私密金鑰加密，公開金鑰解密----加密     //產生私密金鑰     PKCS8EncodedKeySpec pkcs8EncodedKeySpec = new PKCS8EncodedKeySpec(rsaPrivateKey.getEncoded());     KeyFactory keyFactory =KeyFactory.getInstance("RSA");     PrivateKey privateKey = keyFactory.generatePrivate(pkcs8EncodedKeySpec);     //Cipher類為加密和解密提供密碼功能，通過getinstance執行個體化對象     Cipher cipher =Cipher.getInstance("RSA");     //初始化加密     cipher.init(Cipher.ENCRYPT_MODE,privateKey);     byte[] result = cipher.doFinal(src.getBytes());     System.out.println("私密金鑰加密，公開金鑰解密----加密:"+Base64.encode(result));               //3.私密金鑰加密，公開金鑰解密----解密     //產生公開金鑰     X509EncodedKeySpec x509EncodedKeySpec = new X509EncodedKeySpec(rsaPublicKey.getEncoded());     keyFactory=KeyFactory.getInstance("RSA");     PublicKey publicKey= keyFactory.generatePublic(x509EncodedKeySpec);     cipher = Cipher.getInstance("RSA");     //初始化解密     cipher.init(Cipher.DECRYPT_MODE,publicKey);     result = cipher.doFinal(result);     System.out.println("私密金鑰加密，公開金鑰解密----解密:"+new String(result));    } catch (Exception e) {     // TODO Auto-generated catch block     e.printStackTrace(); }             }           public void pubENpriDE() {       try {         //1.初始化秘鑰        KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance("RSA");        //秘鑰長度        keyPairGenerator.initialize(512);        //初始化秘鑰對        KeyPair keyPair = keyPairGenerator.generateKeyPair();        //公開金鑰        RSAPublicKey rsaPublicKey = (RSAPublicKey) keyPair.getPublic();        //私密金鑰        RSAPrivateKey rsaPrivateKey = (RSAPrivateKey) keyPair.getPrivate();                               //2.公開金鑰加密，私密金鑰解密----加密       X509EncodedKeySpec x509EncodedKeySpec=new X509EncodedKeySpec(rsaPublicKey.getEncoded());    KeyFactory keyFactory = KeyFactory.getInstance("RSA");    PublicKey publicKey = keyFactory.generatePublic(x509EncodedKeySpec);     //初始化加密    //Cipher類為加密和解密提供密碼功能，通過getinstance執行個體化對象    Cipher cipher =Cipher.getInstance("RSA");    cipher.init(Cipher.ENCRYPT_MODE,publicKey);     //加密字串    byte[] result = cipher.doFinal(src.getBytes());     System.out.println("公開金鑰加密，私密金鑰解密----加密:"+Base64.encode(result));          //3.公開金鑰加密，私密金鑰解密-----解密   PKCS8EncodedKeySpec pkcs8EncodedKeySpec = new PKCS8EncodedKeySpec(rsaPrivateKey.getEncoded());          keyFactory=KeyFactory.getInstance("RSA");   PrivateKey  privateKey = keyFactory.generatePrivate(pkcs8EncodedKeySpec);     //初始化解密     cipher.init(Cipher.DECRYPT_MODE, privateKey);     //解密字串     result = cipher.doFinal(result);     System.out.println("公開金鑰加密，私密金鑰解密-----解密:"+new String(result));            } catch (Exception e) {        // TODO Auto-generated catch block        e.printStackTrace();    }                   }}

測試：

package com.secutiry.rsa;import com.security.rsa.RSAsecurity;public class RSAtest {public static void main(String[] args) {    RSAsecurity rsAsecurity = new RSAsecurity();    System.out.println("私密金鑰加密公開金鑰解密例：");    rsAsecurity.priENpubDE();    System.out.println("公開金鑰加密私密金鑰解密例：");    rsAsecurity.pubENpriDE();         }}

測試結果：

原始碼

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JAVA實現RSA加密解密