Hi I need to work with BLE integration using React-native.
I am using this package: https://polidea.github.io/react-native-ble-plx/
I have successfully searched a BLE device now I need to read it's manufacturer data and check for some values
issue: I am getting manufacturer data in string (Base64) format and I converted into byte array with following code.
convertStringToByteArray(str) {
String.prototype.encodeHex = function () {
var bytes = [];
for (var i = 0; i < this.length; ++i) {
bytes.push(this.charCodeAt(i));
}
return bytes;
};
var byteArray = str.encodeHex();
return byteArray
}
which results as below.
[xx, xx, xx, xx, xx, xx, xx, xx]
I am not sure how to go with it.
in Native iOS i get output in DATA format which is given by Apple itself. not sure how to handle in this
Requirement
I need to convert that subrange 2..<3 to Uint8 and check if Uint8 result contains some integeor
can anyone help me how I can parse such data ?
Using buffer js library, it can be achieved using the following snippet:
var Buffer = require('buffer/').Buffer
const strval = "base-64-encoded-string";
const buffer = new Buffer(strval, 'base64');
const bufStr = buffer.toString('hex'); //make sure to encode it as 'hex' and not 'string'
Found solution string was base64 ENCODED I have to decode string first then convert to byte array
Related
This is my first experiment of Kotlin Multiplatform and it seems that I've not got some pieces completely.
My backend sends a notification message via socket in UDP Multicast (I probably need to implement this part per platform as I don't think Kotlin does it for me). Then I want to pass this message (which in form of Byte Array) to my common module. This module is responsible to parse the message and return result to platforms.
Just to simplify my work, I want each platform to return ByteArray of test message.
This is my common.kt file:
package org.kotlin.mpp.mobile
expect fun receivedEASNotification(): ByteArray
fun parseEASNotification(msg: ByteArray) {
// Use receivedEASNotification()
}
This is Android file:
package org.kotlin.mpp.mobile
actual fun receivedEASNotification(): ByteArray {
return "test".toByteArray(Charsets.UTF_8)
}
My problem is in iOS part. I can't realize how to convert string to ByteArray. There is toCharArray() function but not toByteArray(). Also, there is toByte() function.
actual fun receivedEASNotification(): ByteArray {
return "test".toByteArray() // There is no such a function for iOS.
}
import Foundation
// An input string.
let name = "perls"
// Get the String.UTF8View.
let bytes = name.utf8
print(bytes)
// Get an array from the UTF8View.
// ... This is a byte array of character data.
var buffer = [UInt8](bytes)
// Change the first byte in the byte array.
// The byte array is mutable.
buffer[0] = buffer[0] + UInt8(1)
print(buffer)
// Get a string from the byte array.
if let result = String(bytes: buffer, encoding: NSASCIIStringEncoding) {
print(result)
}
OUTPUT:
perls
[113, 101, 114, 108, 115]
qerls
I am trying to implement an OTP generator for Blackberry OS10. I already use the reference implementation on Android side, you can find it here:
So I would like to convert it to C++ / QNX code and I have some troubles with hexadecimal conversion...
In java:
private static byte[] hexStr2Bytes(String hex){
// Adding one byte to get the right conversion
// Values starting with "0" can be converted
byte[] bArray = new BigInteger("10" + hex,16).toByteArray();
// Copy all the REAL bytes, not the "first"
byte[] ret = new byte[bArray.length - 1];
for (int i = 0; i < ret.length; i++)
ret[i] = bArray[i+1];
return ret;
}
In QNX:
QByteArray msg = QByteArray::fromHex(m.toLocal8Bit());
Problem is "m" start with '00' and so my final msg array is 0 length...
For example I try to encode the hex qstring:0000000002ca4e32
In blackberry: m=""
In Android: m="?M?"
So you can someone explain me how to deal with such a conversion ?
Thanks!
What I would do is to translate your Java function to plain C++, i.e. not QT format. Then adapt data type to QT.
I want to encrypt data in BlackBerry using the AES 256 encryption method. The requirement is to encrypt with No Padding; "AES/ECB/NoPadding". I am passing a 16 byte array and the encrypted data returned is a hex value of length 32. I have tried the following but it is not producing the correct result. The returned value is different from the expected encrypted value; tested in Android. The results between Android and BlackBerry do not tally. I have used the following method:
public static String EncryptData(byte[] keyData, byte[] data) throws Exception {
String encryptedData = "";
AESKey key = new AESKey(keyData);
NoCopyByteArrayOutputStream out = new NoCopyByteArrayOutputStream();
AESEncryptorEngine engine = new AESEncryptorEngine(key);
BlockEncryptor encryptor = new BlockEncryptor(engine, out);
encryptor.write(data, 0, data.length);
int finalLength = out.size();
byte[] cbytes = new byte[finalLength];
System.arraycopy(out.getByteArray(), 0, cbytes, 0, finalLength);
encryptedData = getHexString(cbytes);
return encryptedData;
}
Can anyone please guide?
EDIT: Below is the equivalent Android code:
Dim Kg As KeyGenerator
Dim c As Cipher
c.Initialize("AES/ECB/NoPadding") ' just "DES" actually performs "DES/ECB/PKCS5Padding".
Kg.Initialize("DESede")
Kg.KeyFromBytes(key)
bytes = Kg.KeyToBytes
msg_data = c.Encrypt(msg_data, Kg.key, False)
Return Bconv.HexFromBytes(msg_data)
There's a mistake in your Basic4Android code. You initialize the cipher with AES:
c.Initialize("AES/ECB/NoPadding")
but then initialize the key generator with TripleDES:
Kg.Initialize("DESede")
According to this documentation, just change "DESede" to "AES":
Kg.Initialize("AES")
Also, I wouldn't recommend using AES with ECB and no padding. It's insecure, especially when it's just as easy to use CBC or CTR mode. See this wikipedia article for an example of how unsafe it really is.
All I need is convert byte[] to String. Then do something with that string and convert back to byte[] array. But in this testing I'm just convert byte[] to string and convert back to byte[] and the result is different.
to convert byte[] to string by using this:
byte[] byteEntity = EntityUtils.toByteArray(entity);
String s = new String(byteEntity,"UTF-8");
Then i tried:
byte[] byteTest = s.getBytes("UTF-8");
Then i complared it:
if (byteEntity.equals(byteTest) Log.i("test","equal");
else Log.i("test","diff");
So the result is different.
I searched in stackoverflow about this but it doesn't match my case. The point is my data is .png picture so the string converted is unreadable. Thanks in advance.
Solved
Using something like this.
byte[] mByteEntity = EntityUtils.toByteArray(entity);
byte[] mByteDecrypted = clip_xor(mByteEntity,"your_key".getBytes());
baos.write(mByteDecrypted);
InputStream in = new ByteArrayInputStream(baos.toByteArray());
and this is function clip_xor
protected byte[] clip_xor(byte[] data, byte[] key) {
int num_key = key.length;
int num_data = data.length;
try {
if (num_key > 0) {
for (int i = 0, j = 0; i < num_data; i++, j = (j + 1)
% num_key) {
data[i] ^= key[j];
}
}
} catch (Exception ex) {
Log.i("error", ex.toString());
}
return data;
}
Hope this will useful for someone face same problem. Thanks you your all for helping me solve this.
Special thanks for P'krit_s
primitive arrays are actually Objects (that's why they have .equals method) but they do not implement the contract of equality (hashCode and equals) needed for comparison. You cannot also use == since according to docs, .getBytes will return a new instance byte[]. You should use Arrays.equals(byteEntity, byteTest) to test equality.
Have a look to the answer here.
In that case my target was transform a png image in a bytestream to display it in embedded browser (it was a particular case where browser did not show directly the png).
You may use the logic of that solution to convert png to byte and then to String.
Then reverse the order of operations to get back to the original file.
I'm struggeling with code from this page: http://www.androidsnippets.com/encrypt-decrypt-between-android-and-php
I want to send data from a server to an Android application and vice versa, but it should be sent as an encrypted string. However, I manage to encrypt and decrypt the string in PHP. But on Android the application crashes with the following error message when decrypting:
java.lang.Exception: [decrypt] unable to parse ' as integer.
This error occours here in the for-loop:
public static byte[] hexToBytes(String str) {
if (str==null) {
return null;
} else if (str.length() < 2) {
return null;
} else {
int len = str.length() / 2;
byte[] buffer = new byte[len];
for (int i=0; i<len; i++) {
buffer[i] = (byte) Integer.parseInt(str.substring(i*2,i*2+2),16);
}
System.out.println("Buffer: " + buffer);
return buffer;
}
}
This is by the way the string that should be decrypted: f46d86e65fe31ed46920b20255dd8ea6
You're talking about encrypting and decrypting, but you're showing code which simply turns numeric bytes (such as 0x4F) into strings (such as "4F") -- which may be relevant to your transfer of data (if you cannot transfer binary format), but completely unrelated to encryption/decryption.
Since the Android code you have contains only a single Integer parse, have you examined the input you're giving it? str.substring(i*2,i*2+2) apparently contains data other than [0-9A-F] when the exception occurs. You should start by examining the string you've received and comparing it to what you sent, to make sure they agree and they only contain hexadecimal characters.
Edit -- passing the string "f46d86e65fe31ed46920b20255dd8ea6" through your hexToBytes() function works flawlessly. Your input is probably not what you think it is.