java加密算法，数字签名。

package com.eetrust.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; import org.apache.commons.codec.binary.Base64; public class DemoRSA { private static String src = "eetrust"; public static void main(String[] args) { jdkRSA(); } public static void jdkRSA() { try { //1.初始化密钥 KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance("RSA"); keyPairGenerator.initialize(512); KeyPair keyPair = keyPairGenerator.generateKeyPair(); RSAPublicKey rsaPublicKey = (RSAPublicKey)keyPair.getPublic(); RSAPrivateKey rsaPrivateKey = (RSAPrivateKey)keyPair.getPrivate(); System.out.println("Public Key : " + Base64.encodeBase64String(rsaPublicKey.getEncoded())); System.out.println("Private Key : " + Base64.encodeBase64String(rsaPrivateKey.getEncoded())); //2.私钥加密、公钥解密——加密 PKCS8EncodedKeySpec pkcs8EncodedKeySpec = new PKCS8EncodedKeySpec(rsaPrivateKey.getEncoded()); KeyFactory keyFactory = KeyFactory.getInstance("RSA"); PrivateKey privateKey = keyFactory.generatePrivate(pkcs8EncodedKeySpec); Cipher cipher = Cipher.getInstance("RSA"); cipher.init(Cipher.ENCRYPT_MODE, privateKey); byte[] result = cipher.doFinal(src.getBytes()); System.out.println("私钥加密、公钥解密——加密 : " + Base64.encodeBase64String(result)); //3.私钥加密、公钥解密——解密 X509EncodedKeySpec x509EncodedKeySpec = new X509EncodedKeySpec(rsaPublicKey.getEncoded()); keyFactory = KeyFactory.getInstance("RSA"); PublicKey publicKey = keyFactory.generatePublic(x509EncodedKeySpec); cipher = Cipher.getInstance("RSA"); cipher.init(Cipher.DECRYPT_MODE, publicKey); result = cipher.doFinal(result); System.out.println("私钥加密、公钥解密——解密：" + new String(result)); //4.公钥加密、私钥解密——加密 x509EncodedKeySpec = new X509EncodedKeySpec(rsaPublicKey.getEncoded()); keyFactory = KeyFactory.getInstance("RSA"); publicKey = keyFactory.generatePublic(x509EncodedKeySpec); cipher = Cipher.getInstance("RSA"); cipher.init(Cipher.ENCRYPT_MODE, publicKey); result = cipher.doFinal(src.getBytes()); System.out.println("公钥加密、私钥解密——加密 : " + Base64.encodeBase64String(result)); //5.公钥加密、私钥解密——解密 pkcs8EncodedKeySpec = new PKCS8EncodedKeySpec(rsaPrivateKey.getEncoded()); keyFactory = KeyFactory.getInstance("RSA"); privateKey = keyFactory.generatePrivate(pkcs8EncodedKeySpec); cipher = Cipher.getInstance("RSA"); cipher.init(Cipher.DECRYPT_MODE, privateKey); result = cipher.doFinal(result); System.out.println("公钥加密、私钥解密——解密：" + new String(result)); } catch (Exception e) { e.printStackTrace(); } } }