java加密解密初探-RSA

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//java提供的公钥私钥生成类         KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance("RSA");        SecureRandom secureRandom = new SecureRandom("参与随机秘钥的生成,此处固定则生成的秘钥固定".getBytes("utf-8"));        keyPairGenerator.initialize(1024, secureRandom);        KeyPair keypair = keyPairGenerator.generateKeyPair();        //此处即是产生的公钥和私钥        PrivateKey privateKey= keypair.getPrivate();        PublicKey publicKey = keypair.getPublic();        //我们往往把公钥私钥转换成字符串来保存或者传递        String privstr = new BASE64Encoder().encode(privateKey.getEncoded());        String pubstr = new BASE64Encoder().encode(publicKey.getEncoded());        System.out.println("私钥：" + privstr );        System.out.println("公钥：" + pubstr );        //接收方 把字符串格式的转换回来        //公钥转换 java中提供了字节数组转公钥的类  X509EncodedKeySpec        X509EncodedKeySpec x509 = new X509EncodedKeySpec(new BASE64Decoder().decodeBuffer(pubstr));        KeyFactory keyFactory = KeyFactory.getInstance("RSA");        PublicKey pubkey = keyFactory.generatePublic(x509);        //接收方 把字符串格式的转换回来        //私钥转换 java中提供了字节数组转公钥的类  PKCS8EncodedKeySpec        PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(new BASE64Decoder().decodeBuffer(privstr));          PrivateKey priKey = keyFactory.generatePrivate(keySpec);          //公钥加密        Cipher cipher = Cipher.getInstance("RSA");        cipher.init(Cipher.ENCRYPT_MODE, pubkey);        byte[] b = cipher.doFinal("要加密的字符串".getBytes("utf-8"));        //用base64把字节数组转换为字符串        String basestr = new BASE64Encoder().encode(b);        System.out.println("加密后在用base64转换成的字符串：" + basestr);        //私钥解密        cipher.init(Cipher.DECRYPT_MODE, priKey);        //先把字符串转换成原来的字节数组        byte[] bytetext = cipher.doFinal(new BASE64Decoder().decodeBuffer(basestr));        System.out.println("解密后的数据"+ new String(bytetext,"utf-8"));        //私钥加密        cipher.init(Cipher.ENCRYPT_MODE, priKey);        byte[] pb = cipher.doFinal("私钥加密的字符串".getBytes("utf-8"));        //用base64把字节数组转换为字符串        String pbasestr = new BASE64Encoder().encode(pb);        System.out.println("私钥加密后在用base64转换成的字符串：" + pbasestr);        //公钥解密        cipher.init(Cipher.DECRYPT_MODE, pubkey);        //先把字符串转换成原来的字节数组        byte[] pbytetext = cipher.doFinal(new BASE64Decoder().decodeBuffer(pbasestr));        System.out.println("公钥解密后的数据："+ new String(pbytetext,"utf-8"));
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