在 Android 上使用 AES 加密文件

Question

所以我正在为自己做一个个人项目，我正在尝试加密 phone 上的文件。这些文件可以是任何文件，即文档、照片等。现在我正在努力让它正常工作。每当我运行加密时，它似乎都能正常工作并加密文件。当我运行解密时，有时它可以工作，有时则不能。当它失败时，我通常会收到 "Error while finalizing cipher, pad block corrupted" 错误。我也没有使用不同的测试文件，所以它不像某些文件有效而其他文件无效。这是我每次尝试的两个相同的文件。

public static void encryptfile(String path,String Pass) throws IOException, NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeyException {
    FileInputStream fis = new FileInputStream(path);
    FileOutputStream fos = new FileOutputStream(path.concat(".crypt"));
    byte[] key = (salt + Pass).getBytes("UTF-8");
    MessageDigest sha = MessageDigest.getInstance("SHA-1");
    key = sha.digest(key);
    key = Arrays.copyOf(key,16);
    SecretKeySpec sks = new SecretKeySpec(key, "AES");
    Cipher cipher = Cipher.getInstance("AES");
    cipher.init(Cipher.ENCRYPT_MODE, sks);
    CipherOutputStream cos = new CipherOutputStream(fos, cipher);
    int b;
    byte[] d = new byte[8];
    while((b = fis.read(d)) != -1) {
        cos.write(d, 0, b);
    }
    cos.flush();
    cos.close();
    fis.close();
}

public static void decrypt(String path,String Pass) throws IOException, NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeyException {
    FileInputStream fis = new FileInputStream(path);
    FileOutputStream fos = new FileOutputStream(path.replace(".crypt",""));
    byte[] key = (salt + Pass).getBytes("UTF-8");
    MessageDigest sha = MessageDigest.getInstance("SHA-1");
    key = sha.digest(key);
    key = Arrays.copyOf(key,16);
    SecretKeySpec sks = new SecretKeySpec(key, "AES");
    Cipher cipher = Cipher.getInstance("AES");
    cipher.init(Cipher.DECRYPT_MODE, sks);
    CipherInputStream cis = new CipherInputStream(fis, cipher);
    int b;
    byte[] d = new byte[8];
    while((b = cis.read(d)) != -1) {
        fos.write(d, 0, b);
    }
    fos.flush();
    fos.close();
    cis.close();
}

目前盐和密码是静态的，不会为了测试目的而改变。大约一半的时间仍然会出错。

有人知道为什么会这样吗？我一直在四处搜索，发现了一些可以尝试的方法，none 其中有效。我已经查看了以下一些问题以寻求解决方案：

Android decryption: Error while finalizing cipher

last block incomplete with CipherInputStream/CipherOutputStream, even with padding AES/CBC/PKCS5Padding

Encryption error on Android 4.2

Decrypting error : "no iv set when one expected"

How to handle "last block incomplete in decryption"

Encryption and decryption of image file

Tips on encryption/decryption of images in java using AES

非常感谢任何帮助！我想我只是缺少一些简单的东西...

更新！

人们是对的，当它是盐时。当我移除盐时，问题就解决了......再挖掘一点，结果是 salt+Pass 是问题所在，但因为盐是一个字节 [] 而 Pass 是一个字符串。我把salt改成了String，然后用salt.concat(Pass)，问题就解决了！

Answer 1

也许我遗漏了一些东西，但在我这边它没有问题。您可以尝试以下 class 只需更改 fileToBeCrypted、fileToBeDecrypted 和 fileDecryptedOutput 变量吗？

package test;

import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.security.InvalidKeyException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.Arrays;

import javax.crypto.Cipher;
import javax.crypto.CipherInputStream;
import javax.crypto.CipherOutputStream;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.spec.SecretKeySpec;

public class TestCrypt{

    private static final String salt = "t784";
    private static final String cryptPassword = "873147cbn9x5'2 79'79314";
    private static final String fileToBeCrypted = "c:\Temp\sampleFile.conf";
    private static final String fileToBeDecrypted = "c:\Temp\sampleFile.conf.crypt";
    private static final String fileDecryptedOutput = "c:\Temp\sampleFile.conf.decrypted";

    public static void main(String[] args) throws Exception
    {
        for (int i=0; i<100; i++)
        {
            encryptfile(fileToBeCrypted, cryptPassword);
            decrypt(fileToBeDecrypted, cryptPassword, fileDecryptedOutput);
            System.out.println(i);
        }
    }

    public static void encryptfile(String path,String password) throws IOException, NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeyException {
        FileInputStream fis = new FileInputStream(path);
        FileOutputStream fos = new FileOutputStream(path.concat(".crypt"));
        byte[] key = (salt + password).getBytes("UTF-8");
        MessageDigest sha = MessageDigest.getInstance("SHA-1");
        key = sha.digest(key);
        key = Arrays.copyOf(key,16);
        SecretKeySpec sks = new SecretKeySpec(key, "AES");
        Cipher cipher = Cipher.getInstance("AES");
        cipher.init(Cipher.ENCRYPT_MODE, sks);
        CipherOutputStream cos = new CipherOutputStream(fos, cipher);
        int b;
        byte[] d = new byte[8];
        while((b = fis.read(d)) != -1) {
            cos.write(d, 0, b);
        }
        cos.flush();
        cos.close();
        fis.close();
    }

    public static void decrypt(String path,String password, String outPath) throws IOException, NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeyException {
        FileInputStream fis = new FileInputStream(path);
        FileOutputStream fos = new FileOutputStream(outPath);
        byte[] key = (salt + password).getBytes("UTF-8");
        MessageDigest sha = MessageDigest.getInstance("SHA-1");
        key = sha.digest(key);
        key = Arrays.copyOf(key,16);
        SecretKeySpec sks = new SecretKeySpec(key, "AES");
        Cipher cipher = Cipher.getInstance("AES");
        cipher.init(Cipher.DECRYPT_MODE, sks);
        CipherInputStream cis = new CipherInputStream(fis, cipher);
        int b;
        byte[] d = new byte[8];
        while((b = cis.read(d)) != -1) {
            fos.write(d, 0, b);
        }
        fos.flush();
        fos.close();
        cis.close();
    }

}

我可以多次迭代不出错！我正在使用 Oracle JDK 1.8，但运行处于 1.7 兼容模式。

希望对您有所帮助。

再见皮耶罗

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