我目前正在研究Raspberry Pi与Android设备之间的连接。
此连接使用河豚加密，并且在较小的大小（通常小于1 kB）下似乎可以正常工作。在下一步中，我尝试将照片从我的Pi发送到我的设备，该照片也应加密。我的设备抛出异常javax.crypto.BadPaddingException: pad block corrupted，经过一些调试后，我发现传输的数据中约有90％设置为零（使用大小为2444368的数组进行测试，位置212536之后，一切均为零）。
我的第一个猜测是Android不能为我的数组分配足够的内存，但是也没有异常告诉我，在我告诉Android我的应用通过largeHeap=true使用了很多ram之后，这不再是问题了。可能是因为我对Android的工作方式了解得不够多，所以我想请您帮助我。有问题的部分（未显示EncryptionUtil，这不是问题的一部分）：
客户端：
public final byte[] readWithAppend() throws IOException, InvalidKeyException, IllegalBlockSizeException, BadPaddingException, NoSuchAlgorithmException, NoSuchPaddingException{
byte[] b = new byte[read()]; //works fine, tells me the size of the array
System.out.println("Trying to read an array with the size " + b.length);
in.read(b,0,b.length);//No Exception here, so allocation works
if(b.length >= 10000){ //Just some debug for me to compare both sides, server and client.
File f;
FileOutputStream out = new FileOutputStream(f = new File(debugFile,EncryptionUtil.randomString(80)));
System.out.println("PATH: " + f);
out.write(b);out.close();
}
System.out.println("After position " + searchPos(b) + " everything is 0 ?!?!?");
b = EncryptionUtil.decrypt(enc, b, sessionKey); //The Exception gets thrown here.
return b;
}
private int searchPos(byte[] b){
int pos = b.length;
for(int i = b.length-1;i >= 0;i--){
if(b[i] != 0)return pos;
else pos--;
}
return pos;
}
服务器端：
private final void write(byte[] b,int off,int len,boolean appendLength) throws IOException{
try {
byte[] b2;
if(len != b.length || off != 0){ //Just ignore this case
byte[] buffer = new byte[len-off];System.arraycopy(b, off, buffer, 0, len);
b2 = EncryptionUtil.encrypt(enc, buffer, sessionKey);
}else{ //This is the case we have to look at
b2 = EncryptionUtil.encrypt(enc, b, sessionKey);
System.out.println("Sending an array with the size " + b2.length);
System.out.println("Decrypting to check for mistakes");
EncryptionUtil.decrypt(SymmetricEncryption.Blowfish, b2, sessionKey); //Debug.
if(b2.length >= 10000){ //Again, debug to compare the both files
FileOutputStream out2 = new FileOutputStream(new File("serverFile"));
out2.write(b2);out2.close();
}
}
if(appendLength)write(b2.length); //Works as well
System.out.println("Length: " + b2.length + "; only writing: " + ((int)len/b.length)*b2.length);// it writes everything.
out.write(b2,0,((int)len/b.length)*b2.length); //The flush part happens somewhere else.
} catch (InvalidKeyException | NoSuchAlgorithmException| NoSuchPaddingException | IllegalBlockSizeException| BadPaddingException e) {
e.printStackTrace();
//throw new IOException(e.getMessage());
}
}
我知道编写代码需要花费一些时间，但是如果您能帮助我，我将不胜感激。
编辑：
有关EncryptionUtil的代码
public static final byte[] encrypt(final SymmetricEncryption enc,final byte[] content,final SecretKey key) throws NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeyException, IllegalBlockSizeException, BadPaddingException, UnsupportedEncodingException {
final Cipher cipher = Cipher.getInstance(enc.toString());
cipher.init(Cipher.ENCRYPT_MODE, key);
return cipher.doFinal(content);
}
public static final byte[] decrypt(final SymmetricEncryption enc,final byte[] text,final SecretKey key) throws IllegalBlockSizeException, BadPaddingException, InvalidKeyException, NoSuchAlgorithmException, NoSuchPaddingException {
final Cipher cipher = Cipher.getInstance(enc.toString());
cipher.init(Cipher.DECRYPT_MODE, key);
return cipher.doFinal(text);
}
经过更多测试后，我发现树莓派无法正确发送数据，因此我现在尝试按块发送数据。
最佳答案
我怀疑您的问题是对in.read的调用没有读取整个输入流。 InputStream.read不能保证读取您要求的整个长度。在while循环中读取输入流，读入缓冲区直到到达流的末尾，这是很正常的做法-更像是：
byte[] buffer = new byte[1024];
int read;
while ((read = in.read(buffer)) != -1) {
out.write(buffer, 0, read);
}
out.flush();
out.close();
请注意，您现有的代码不会检查
in.read的返回值以查看实际读取了多少字节。