Question

我在AES算法中尝试确定加密和解密的经过时间我的代码是否属于真正的方法，如果没有请告诉我在哪里找到它？

import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.security.Security;

import javax.crypto.Cipher;
import javax.crypto.CipherInputStream;
import javax.crypto.CipherOutputStream;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;

import de.flexiprovider.core.FlexiCoreProvider;

public class ExampleCrypt123 {

    public static void main(String[] args) throws Exception {
        Security.addProvider(new FlexiCoreProvider());
        Cipher cipher = Cipher.getInstance("AES128_CBC", "FlexiCore");

        KeyGenerator keyGen = KeyGenerator.getInstance("AES", "FlexiCore");
        SecretKey secKey = keyGen.generateKey();

        String cleartextFile = "F:/java_projects/cleartext.txt";
        String ciphertextFile = "F:/java_projects/ciphertextSymm.txt";
        String cleartextAgainFile = "F:/java_projects/cleartextAgainSymm.txt";

        byte[] block = new byte[16];

        FileInputStream fis = new FileInputStream(cleartextFile);
        FileOutputStream fos = new FileOutputStream(ciphertextFile);

        cipher.init(Cipher.ENCRYPT_MODE, secKey);
        // Encrypt
        long startTime = System.nanoTime();

        for(int j=0; j< 1000000; j++){
            CipherOutputStream cos = new CipherOutputStream(fos, cipher);

            int i;
            while ((i = fis.read(block)) != -1) {
                cos.write(block, 0, i);
            }
            cos.close();
        }
        long elapsedTime = System.nanoTime() - startTime;

        System.out.println("Total execution time to create 1000 objects in Java in millis: "
                + elapsedTime/1000000);

        // Decrypt



        fis = new FileInputStream(ciphertextFile);

        fos = new FileOutputStream(cleartextAgainFile);

        cipher.init(Cipher.DECRYPT_MODE, secKey);

        long startTime2 = System.nanoTime();
        for(int j=0; j< 1000000; j++){
            CipherInputStream cis = new CipherInputStream(fis, cipher);
            int i;

            while (( i = cis.read(block)) != -1) {
                fos.write(block, 0, i);
            }
            fos.close();
        }
        long elapsedTime2 = System.nanoTime() - startTime2;

        System.out.println("Total execution time to create 1000  objects in Java in millis: "
                + elapsedTime2/1000000);
    }

在我的笔记本电脑上运行此程序时，会给我以下结果以毫秒为单位在Java中创建1000个对象的总执行时间：1416 以毫秒为单位在Java中创建1000个对象的总执行时间：1600

Answer 1

不，那不对。例如，您只打开fis一次流，因此您实际上只在加密循环中处理一次。

你在解密循环中犯了同样的错误。

如何确定在java中使用CipherOutputStream进行加密和解密所用的时间？

1 个答案: