我在我的电脑上创建了一个ZIP文件(我在查找程序中用os x zipper压缩它)然后用我的java程序加密它:
public class ResourceEncrypter {
static byte[] salt = { (byte)0xc7, (byte)0x73, (byte)0x21, (byte)0x8c,
(byte)0x7e, (byte)0xc8, (byte)0xee, (byte)0x99 };
public static void main(String[] args) {
new ResourceEncrypter().encryptAllFiles();
System.out.println("Okay, done");
}
private byte[] getKey() {
try {
KeyGenerator kgen = KeyGenerator.getInstance("AES");
SecureRandom sr = SecureRandom.getInstance("SHA1PRNG");
sr.setSeed(salt);
kgen.init(128, sr);
SecretKey skey = kgen.generateKey();
byte[] key = skey.getEncoded();
return key;
} catch(Exception e) {
e.printStackTrace();
}
return null;
}
private void encryptAllFiles() {
try {
byte[] key = getKey();
//Take a list of files and encrypt each file...
String srcFilesPath = System.getProperty("user.dir") + "/srcFiles";
String encryptedSrcFilesPath = System.getProperty("user.dir") + "/encryptedSrcFiles";
File[] listOfFiles = new File(srcFilesPath).listFiles();
for(int i = 0; i < listOfFiles.length; ++i) {
if(listOfFiles[i].getAbsolutePath().contains(".zip")) {
//Encrypt this file!
byte[] data = Files.readAllBytes(Paths.get(listOfFiles[i].getAbsolutePath()));
byte[] encryptedData = ResourceEncrypter.encrypt(key, data);
String filename = listOfFiles[i].getName();
System.out.println("Write result to " + encryptedSrcFilesPath + "/" + filename);
FileOutputStream output = new FileOutputStream(encryptedSrcFilesPath + "/" + filename);
output.write(encryptedData);
output.close();
}
}
} catch(Exception e) {
e.printStackTrace();
}
}
private static byte[] encrypt(byte[] key, byte[] data) throws Exception {
SecretKeySpec skeySpec = new SecretKeySpec(key, "AES");
Cipher cipher = Cipher.getInstance("AES");
cipher.init(Cipher.ENCRYPT_MODE, skeySpec);
byte[] encryptedData = cipher.doFinal(data);
return encryptedData;
}
因此,这会将任何zip文件加密并将结果保存到另一个文件夹。
现在,我有一个Android应用程序,我将加密的zip文件放入资产文件夹main/assets/pic.zip.encrypted
。
在我的Android应用程序中,我执行以下操作:
public class MainActivity extends AppCompatActivity {
static byte[] salt = { (byte)0xc7, (byte)0x73, (byte)0x21, (byte)0x8c,
(byte)0x7e, (byte)0xc8, (byte)0xee, (byte)0x99 };
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
decryptZipFile();
}
private byte[] getKey() {
try {
//Create the key for the encryption/decryption
KeyGenerator kgen = KeyGenerator.getInstance("AES");
SecureRandom sr = SecureRandom.getInstance("SHA1PRNG");
sr.setSeed(salt);
kgen.init(128, sr); // 192 and 256 bits may not be available
SecretKey skey = kgen.generateKey();
byte[] key = skey.getEncoded();
return key;
} catch(Exception e) {
e.printStackTrace();
}
return null;
}
private static byte[] decrypt(byte[] key, byte[] encryptedData) throws Exception {
SecretKeySpec skeySpec = new SecretKeySpec(key,"AES");
Cipher cipher = Cipher.getInstance("AES");
cipher.init(Cipher.DECRYPT_MODE, skeySpec);
byte[] decrypted = cipher.doFinal(encryptedData);
return decrypted;
}
public void decryptZipFile() {
// First decrypt the zip file
try {
InputStream is = getResources().getAssets().open("pics.zip.encrypted");
ByteArrayOutputStream baos = new ByteArrayOutputStream();
byte[] buffer = new byte[1024];
int count;
while ((count = is.read(buffer)) != -1)
baos.write(buffer, 0, count);
byte[] encryptedData = baos.toByteArray();
byte[] decryptedData = decrypt(getKey(), encryptedData);
} catch(Exception e) {
e.printStackTrace();
}
}
当我现在尝试使用此代码解密我的zip文件时,我收到以下错误:
09-23 18:41:21.117 30799-30799/demo.zip.app.zipapp W/System.err﹕ javax.crypto.BadPaddingException: pad block corrupted
09-23 18:41:21.117 30799-30799/demo.zip.app.zipapp W/System.err﹕ at com.android.org.bouncycastle.jcajce.provider.symmetric.util.BaseBlockCipher.engineDoFinal(BaseBlockCipher.java:854)
09-23 18:41:21.117 30799-30799/demo.zip.app.zipapp W/System.err﹕ at javax.crypto.Cipher.doFinal(Cipher.java:1340)
09-23 18:41:21.117 30799-30799/demo.zip.app.zipapp W/System.err﹕ at demo.zip.app.zipapp.MainActivity.decrypt(MainActivity.java:63)
但是,当我在我的电脑上应用相同的解密方法时,它可以正常工作。
这里发生了什么?
答案 0 :(得分:0)
好的,我找到了解决方案。
问题是SecureRandom
,特别是setSeed
方法在Android上的工作方式与普通Java不同。
所以,相反,你不应该像上面那样用盐键构造一个键。相反,您应该转到PC并从key
获取private byte[] getKey()
作为Base64字符串对象。然后在我的情况下,键看起来像这样:n9dReP+BPwHWGCLpDQe+MQ==
然后将其粘贴到android方法中,这将成为:
private byte[] getKey() {
byte[] key = Base64.decode(new String("n9dReP+BPwHWGCLpDQe+MQ==").getBytes(), 0);
return key;
}
那就是它。