RSA加密演算法java簡單實現
阿新 • • 發佈:2018-12-26
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簡單完整的程式碼,通過這個程式碼你將對RSA加密演算法在Java中的實現方法有一個初步的瞭解,這個類,你可以直接使用,水平高的,就自己修改完善下程式碼。
package security; import java.security.*; import java.security.spec.*; import java.security.interfaces.*; import javax.crypto.spec.*; import javax.crypto.interfaces.*; import java.io.*; import java.math.*; public class RSADemo { public RSADemo() { } public static void generateKey() { try { KeyPairGenerator kpg = KeyPairGenerator.getInstance("RSA"); kpg.initialize(1024); KeyPair kp = kpg.genKeyPair(); PublicKey pbkey = kp.getPublic(); PrivateKey prkey = kp.getPrivate(); // 儲存公鑰 FileOutputStream f1 = new FileOutputStream("pubkey.dat"); ObjectOutputStream b1 = new ObjectOutputStream(f1); b1.writeObject(pbkey); // 儲存私鑰 FileOutputStream f2 = new FileOutputStream("privatekey.dat"); ObjectOutputStream b2 = new ObjectOutputStream(f2); b2.writeObject(prkey); } catch (Exception e) { } } public static void encrypt() throws Exception { String s = "Hello World!"; // 獲取公鑰及引數e,n FileInputStream f = new FileInputStream("pubkey.dat"); ObjectInputStream b = new ObjectInputStream(f); RSAPublicKey pbk = (RSAPublicKey) b.readObject(); BigInteger e = pbk.getPublicExponent(); BigInteger n = pbk.getModulus(); System.out.println("e= " + e); System.out.println("n= " + n); // 獲取明文m byte ptext[] = s.getBytes("UTF-8"); BigInteger m = new BigInteger(ptext); // 計算密文c BigInteger c = m.modPow(e, n); System.out.println("c= " + c); // 儲存密文 String cs = c.toString(); BufferedWriter out = new BufferedWriter( new OutputStreamWriter(new FileOutputStream("encrypt.dat"))); out.write(cs, 0, cs.length()); out.close(); } public static void decrypt() throws Exception { // 讀取密文 BufferedReader in = new BufferedReader( new InputStreamReader(new FileInputStream("encrypt.dat"))); String ctext = in.readLine(); BigInteger c = new BigInteger(ctext); // 讀取私鑰 FileInputStream f = new FileInputStream("privatekey.dat"); ObjectInputStream b = new ObjectInputStream(f); RSAPrivateKey prk = (RSAPrivateKey) b.readObject(); BigInteger d = prk.getPrivateExponent(); // 獲取私鑰引數及解密 BigInteger n = prk.getModulus(); System.out.println("d= " + d); System.out.println("n= " + n); BigInteger m = c.modPow(d, n); // 顯示解密結果 System.out.println("m= " + m); byte[] mt = m.toByteArray(); System.out.println("PlainText is "); for (int i = 0; i < mt.length; i++) { System.out.print((char) mt[i]); } } public static void main(String args[]) { try { generateKey(); encrypt(); decrypt(); } catch (Exception e) { System.out.println(e.toString()); } } }