Java 解密创建附加符号

Question

我写的加解密代码如下

import java.io.*;
import java.security.InvalidAlgorithmParameterException;
import java.security.InvalidKeyException;
import java.security.Key;
import java.security.NoSuchAlgorithmException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;
import javax.crypto.BadPaddingException;
import java.nio.file.Files;
import java.util.Scanner;

public class EncryptFile
{
    public static void main(String args[]) throws IOException, NoSuchPaddingException, NoSuchAlgorithmException, InvalidKeyException, BadPaddingException, IllegalBlockSizeException, InvalidAlgorithmParameterException {
//Encrypt Mode
        FileOutputStream outputStream = new FileOutputStream(new File("D:\encryptedNewStringFile.txt"));
        Key secretKey = new SecretKeySpec("encKey".getBytes(), "Blowfish");
        Cipher cipher = Cipher.getInstance("Blowfish");
        cipher.init(Cipher.ENCRYPT_MODE, secretKey);
        byte[] getFileBytes = "writing a file using encryption ".getBytes();
        byte[] outputBytes = cipher.doFinal(getFileBytes);
        outputStream.write(outputBytes);
        getFileBytes = "\n".getBytes();
        outputBytes = cipher.doFinal(getFileBytes);
        outputStream.write(outputBytes);
        getFileBytes = "This is New Line 2 \nThis is NewLine 3".getBytes();
        outputBytes = cipher.doFinal(getFileBytes);
        outputStream.write(outputBytes);
        outputStream.close();
//Decrypt Mode
        File curFile = new File("D:\encryptedNewStringFile.txt");
        secretKey = new SecretKeySpec("encKey".getBytes(), "Blowfish");
        cipher = Cipher.getInstance("Blowfish/ECB/NoPadding");
        cipher.init(Cipher.DECRYPT_MODE, secretKey);
        getFileBytes = Files.readAllBytes(curFile.toPath());
        outputBytes = cipher.doFinal(getFileBytes);
        InputStream bai = new ByteArrayInputStream(outputBytes);
        BufferedReader bfReader = new BufferedReader(new InputStreamReader(bai));
        Scanner scan = new Scanner(bfReader);
        while(scan.hasNextLine())
        {
            System.out.println(scan.nextLine());
        }
}
}

这里我在输出中遇到问题，打印输出中有一些额外的符号（即问号和方框符号）。
我收到的输出是

提前致谢，任何建议都会很有帮助

Answer 1

Cipher cipher = Cipher.getInstance("Blowfish");

相当于

Cipher cipher = Cipher.getInstance("Blowfish/ECB/PKCS5Padding");

这意味着每次调用 cipher.doFinal 都会产生额外的填充。

为了写入没有间歇填充的文件，您应该使用

outputBytes = cipher.update(getFileBytes);

并仅在最后一次写入文件时使用cipher.doFinal。然后，您将能够在解密过程中使用 PKCS5Padding 而不是 NoPadding，以便自动删除末尾的有效填充。

安全注意事项：

ECB 模式不好，不应使用。只有极少数的用例才有意义。至少使用带有随机生成的 IV 的 CBC 模式。 IV 不需要保密，只是不可预测。我们通常将它添加到密文之前，并在解密之前将其切掉。由于它始终具有预定义的长度，因此很容易做到。
使用像 GCM 这样的经过身份验证的操作模式，或者使用像 HMAC-SHA256 这样的消息身份验证代码来检测密文的（恶意）操纵并做出反应。
今天不应该使用河豚。虽然它没有直接的漏洞，但它的小块大小可能会让你面临不同的基于协议的漏洞。建议使用块大小为 128 位的块密码。想到 AES。

Answer 2

每次将字符串转换为字节数组时，都会使用 VM 属性中的默认文件编码，而不是 UTF-8。

因此，要解决此问题，您有两个选择：在 java 系统属性中定义默认编码：

System.setProperty("file.encoding", StandardCharsets.UTF_8.name());

或通过每次将字符串转换为字节来添加字符集编码：

"writing a file using encryption ".getBytes(StandardCharsets.UTF_8);

Answer 3

结合@Artjom B. 和@The 5th column mouse 的答案，您将得到一个文件加密程序，它将在 CBC 模式 中使用 Blowfish 加密文件。加密和解密以块的形式完成，因此大文件（最多几 GB）可以在没有“内存不足错误”的情况下进行加密和解密。

密钥是随机生成的，您应该牢记——不知道密钥就无法解密文件。

输出：

file encryption with Blowfish CBC mode
used key (Base64): jsErS04so1NCC7Jmds6Grr+0tPkNoaj0hx/izLaW5H8=
result encryption: true
result decryption: true

安全警告：代码没有异常处理，没有正确的文件处理（例如覆盖，恕不另行通知），仅用于教育目的：

import javax.crypto.Cipher;
import javax.crypto.CipherInputStream;
import javax.crypto.CipherOutputStream;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.security.InvalidAlgorithmParameterException;
import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;
import java.util.Base64;

public class BlowfishCbcFileEncryption {
    public static void main(String[] args) throws NoSuchPaddingException, NoSuchAlgorithmException, IOException,
            InvalidKeyException, InvalidAlgorithmParameterException {
        System.out.println("file encryption with Blowfish CBC mode");

        String uncryptedFilename = "uncrypted.txt";
        String encryptedFilename = "encrypted.enc";
        String decryptedFilename = "decrypted.txt";

        // random blowfish 256 key
        byte[] key = new byte[32];
        SecureRandom secureRandom = new SecureRandom();
        secureRandom.nextBytes(key);
        System.out.println("used key (Base64): " + base64Encoding(key));

        // random iv
        byte[] iv = new byte[8]; // blowfish iv is 8 bytes long
        secureRandom.nextBytes(iv);

        boolean result;
        result = encryptCbcFileBufferedCipherOutputStream(uncryptedFilename, encryptedFilename, key, iv);
        System.out.println("result encryption: " + result);
        result = decryptCbcFileBufferedCipherInputStream(encryptedFilename, decryptedFilename, key);
        System.out.println("result decryption: " + result);

    }

    public static boolean encryptCbcFileBufferedCipherOutputStream(String inputFilename, String outputFilename, byte[] key, byte[] iv)
            throws IOException, NoSuchPaddingException, NoSuchAlgorithmException, InvalidKeyException, InvalidAlgorithmParameterException {
        Cipher cipher = Cipher.getInstance("Blowfish/CBC/PKCS5Padding");
        try (FileInputStream in = new FileInputStream(inputFilename);
             FileOutputStream out = new FileOutputStream(outputFilename);
             CipherOutputStream encryptedOutputStream = new CipherOutputStream(out, cipher);) {
            out.write(iv);
            SecretKeySpec secretKeySpec = new SecretKeySpec(key, "Blowfish");
            IvParameterSpec ivParameterSpec = new IvParameterSpec(iv);
            cipher.init(Cipher.ENCRYPT_MODE, secretKeySpec, ivParameterSpec);
            byte[] buffer = new byte[8096];
            int nread;
            while ((nread = in.read(buffer)) > 0) {
                encryptedOutputStream.write(buffer, 0, nread);
            }
            encryptedOutputStream.flush();
        }
        if (new File(outputFilename).exists()) {
            return true;
        } else {
            return false;
        }
    }

    public static boolean decryptCbcFileBufferedCipherInputStream(String inputFilename, String outputFilename, byte[] key) throws
            IOException, NoSuchPaddingException, NoSuchAlgorithmException, InvalidKeyException, InvalidAlgorithmParameterException {
        byte[] iv = new byte[8]; // blowfish iv is 8 bytes long
        Cipher cipher = Cipher.getInstance("Blowfish/CBC/PKCS5Padding");
        try (FileInputStream in = new FileInputStream(inputFilename); // i don't care about the path as all is local
             CipherInputStream cipherInputStream = new CipherInputStream(in, cipher);
             FileOutputStream out = new FileOutputStream(outputFilename)) // i don't care about the path as all is local
        {
            byte[] buffer = new byte[8192];
            in.read(iv);
            SecretKeySpec secretKeySpec = new SecretKeySpec(key, "Blowfish");
            IvParameterSpec ivParameterSpec = new IvParameterSpec(iv);
            cipher.init(Cipher.DECRYPT_MODE, secretKeySpec, ivParameterSpec);
            int nread;
            while ((nread = cipherInputStream.read(buffer)) > 0) {
                out.write(buffer, 0, nread);
            }
            out.flush();
        }
        if (new File(outputFilename).exists()) {
            return true;
        } else {
            return false;
        }
    }

    private static String base64Encoding(byte[] input) {
        return Base64.getEncoder().encodeToString(input);
    }
}

Java 解密创建附加符号

Java Decryption creating additional symbols

java

encryption

blowfish