使用 CipherInputStream 和 CipherOutputStream 加密和解密文件

问题描述

我一直在尝试用 AES 编写一个加密文件，然后使用 JCA 中提供的密码流对其进行解密.但是，我在读取文件时遇到了问题，因为解密过程失控.

I've been trying to write an encrypted file in AES and decrypt it subsequently by using Cipher Streams provided in JCA. However, I'm having problems while reading the file, as the decryption is going haywire.

public class CipherStreams {
public static void main(String[] args) {
    try {
        KeyGenerator keygen = KeyGenerator.getInstance("AES");
        Key k = keygen.generateKey();

        Cipher aes = Cipher.getInstance("AES/ECB/PKCS5Padding");
        aes.init(Cipher.ENCRYPT_MODE, k);
        FileOutputStream fs = new FileOutputStream("Encrypyed.txt");
        CipherOutputStream out = new CipherOutputStream(fs, aes);
        out.write("[Hello:Okay]
Okay".getBytes());
        out.close();

        Cipher aes2 = Cipher.getInstance("AES/ECB/PKCS5Padding");
        aes2.init(Cipher.DECRYPT_MODE, k);

        FileInputStream fis = new FileInputStream("Encrypyed.txt");
        CipherInputStream in = new CipherInputStream(fis,aes2);
        byte[] b = new byte[8];
        int i = in.read(b);
        while(i!=-1) {
            System.out.print((char)i);
            i = in.read(b);
        }
    } catch (NoSuchAlgorithmException | NoSuchPaddingException | InvalidKeyException | IOException ex) {
        Logger.getLogger(CipherStreams.class.getName()).log(Level.SEVERE, null, ex);
    }
}
}

我收到一个单字节输出为 5.有人可以帮忙指出问题吗?

I'm receiving a single byte output as 5. Can anyone please help point out the problem?

推荐答案

您不是在写入读取的字节数，而是写入正在读取的字节数.

You're not writing the bytes read, you're writing the number of bytes being read.

您还假设默认平台编码只是将每个字符转换为一个字节.

You're also assuming that the default platform encoding just transforms each character to a byte.

只需执行与写入时相反的操作:读取所有内容，并将读取的字节数组转换为字符串，然后打印该字符串:

Just do the reverse of what you did when writing: read everything, and transform the read byte array to a String, then print that string:

public class CipherStreams {
    public static void main(String[] args) {
        try {
            KeyGenerator keygen = KeyGenerator.getInstance("AES");
            Key k = keygen.generateKey();

            Cipher aes = Cipher.getInstance("AES/ECB/PKCS5Padding");
            aes.init(Cipher.ENCRYPT_MODE, k);
            String fileName = "Encrypted.txt";
            FileOutputStream fs = new FileOutputStream(fileName);
            CipherOutputStream out = new CipherOutputStream(fs, aes);
            out.write("[Hello:Okay]
Okay".getBytes());
            out.flush();
            out.close();

            Cipher aes2 = Cipher.getInstance("AES/ECB/PKCS5Padding");
            aes2.init(Cipher.DECRYPT_MODE, k);

            FileInputStream fis = new FileInputStream(fileName);
            CipherInputStream in = new CipherInputStream(fis, aes2);
            ByteArrayOutputStream baos = new ByteArrayOutputStream();

            byte[] b = new byte[1024];
            int numberOfBytedRead;
            while ((numberOfBytedRead = in.read(b)) >= 0) {
                baos.write(b, 0, numberOfBytedRead);
            }
            System.out.println(new String(baos.toByteArray()));
        }
        catch (NoSuchAlgorithmException | NoSuchPaddingException | InvalidKeyException | IOException ex) {
            ex.printStackTrace();
            ;
        }
    }
}

这篇关于使用 CipherInputStream 和 CipherOutputStream 加密和解密文件的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！