decode base64url as uint8array - encoding

I'm trying to turn a string of a JWT token signature into a uint8array.
lX_aBSgGVYWd2FL6elRHoPJ2nab0IkmmX600cwZPCyK_SazZ-pzBUGDDQ0clthPVAtoS7roHg14xpEJlcSJUZBA7VTlPiDCOrkie_Hmulj765qS44t3kxAYduLhNQ-VN
The expected outcome should be the following with the size of 96 (base64url encoding)
[149, 127, 218, 5, 40, 6, 85, 133, 157, 216, 82, 250, 122, 84, 71, 160, 242, 118, 157, 166, 244, 34, 73, 166, 95, 173, 52, 115, 6, 79, 11, 34, 191, 73, 172, 217, 250, 156, 193, 80, 96, 195, 67, 71, 37, 182, 19, 213, 2, 218, 18, 238, 186, 7, 131, 94, 49, 164, 66, 101, 113, 34, 84, 100, 16, 59, 85, 57, 79, 136, 48, 142, 174, 72, 158, 252, 121, 174, 150, 62, 250, 230, 164, 184, 226, 221, 228, 196, 6, 29, 184, 184, 77, 67, 229, 77]
But I coudn't reverse engineer this I kept getting a size of 64 instead
[103, 10, 34, 6, 104, 125, 101, 234, 5, 23, 143, 198, 138, 228, 164, 134, 170, 116, 240, 159, 82, 223, 58, 73, 9, 49, 70, 51, 52, 229, 241, 5, 45, 146, 219, 135, 53, 177, 148, 181, 210, 164, 145, 59, 99, 95, 35, 46, 212, 62, 247, 142, 115, 234, 186, 88, 173, 148, 16, 157, 235, 29, 62, 93
Here's my function that was originally used for base16 and I'm now try to modify this to work for base64url
const convert = (str) => {
const segmented = str.match(/.{1,2}/g);
const arr = segmented.map((segment, i) => {
const powers = [16,1];
const alphabets = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_";
const two_bits = segment.split('');
const result_arr = two_bits.map((hex, i) => {
const decimal = alphabets.indexOf(hex);
const sum_of_power = powers[i] * decimal;
return sum_of_power;
});
const result = result.reduce((a, b) => a + b);
return result;
});
return new Uint8Array(arr);
};
Any help would be appreciated!

Here's the base64url decode code, taken from my jose universal javascript module which I suggest you use for any and all JOSE functionality instead of writing your own.
const decodeBase64 = (encoded) => {
return new Uint8Array(atob(encoded)
.split('')
.map((c) => c.charCodeAt(0)));
};
const decode = (input) => {
try {
return decodeBase64(input.replace(/-/g, '+').replace(/_/g, '/').replace(/\s/g, ''));
}
catch (_a) {
throw new TypeError('The input to be decoded is not correctly encoded.');
}
};
decode('lX_aBSgGVYWd2FL6elRHoPJ2nab0IkmmX600cwZPCyK_SazZ-pzBUGDDQ0clthPVAtoS7roHg14xpEJlcSJUZBA7VTlPiDCOrkie_Hmulj765qS44t3kxAYduLhNQ-VN')

Related

Display contents of text file uploaded from device flutter

Using the _localFile and readFile functions below I can choose the correct file and read it as bytes however I am unable to convert back to the correct text in the file. When using utf8 decode I get the following error
Unhandled Exception: FormatException: Unexpected extension byte (at offset 10).
The List of int I get from reading the file starts with
[80, 75, 3, 4, 20, 0, 8, 8, 8, 0, 135, 117, 116, 81, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 11, 0, 0, 0, 95, 114, 101, 108, 115, 47, 46, 114, 101, 108, 115, 173, 210, 193, 74, 3, 49, 16, 6, 224, 123, 159, 98, 153, 123, 119, 182, 85, 68, 100, 179, 189, 136, 208, 155, 72, 125, 128, 144, 204, 238, 6, 155, 76, 72, 166, 90, 223, 222, 80, 10, 186, 80, 86, 193, 30, 51, 249, 231, 231, 35, 164, 221, 28, 253, 190, 122, 167, 148, 29, 7, 5, 171, 186, 129, 138, 130, 97, 235, 194, 160, 224, 117, 247, 180, 188, 135, 77, 183, 104, 95, 104, 175, 165, 68, 242, 232, 98, 174, 202, 78, 200, 10, 70, 145, 248, 128, 152, 205, 72, 94, 231, 154, 35, 133, 114, 211, 115, 242, 90, 202, 49, 13, 24, 181, 121, 211, 3, 225, 186, 105, 238, 48, 253, 236, 128, 110, 210, 89, 109, 173, 130, 180, 181, 43, 168, 118, 159, 145, 254, 215, 141, 158, 68, 91, 45, 26, 13, 39, 90, 198, 84, 182, 147, 56, 202, 165, 92, 167, 129, 68, 129, 101, 243, 92, 198, 249, 148, 168, 75, 51, 224, 101, 208, 250, 239, 32, 238, 123, 103, 232, 145, 205, 193, 83, 144, 75, 46, 5...
and has a length of 24596 where as the text file only has 5601 characters. How do I get the contents of the file I have read in?
Thanks
Future<List<int>> readFile() async {
try {
final file = await _localFile;
// Read the file.
List<int> contents = await file.readAsBytes();
return contents;
} catch (e) {
print(e);
// If encountering an error, return 0.
return [0];
}
}
Future<File> get _localFile async {
final path = await FlutterDocumentPicker.openDocument();
return File('$path');
}
To convert the List<int> data correctly, you need to know how it was encoded. If you do not know, it may be useful to try to open the file with the Windows notepad and see which encoding offers you in the "Save as" window, and/or do some conversion tests with online tools (this is a practical approach, because it is not always possible to understand in retrospect which encoding was used). Then you can proceed with the decoding:
for UTF-8, you can use the built-in dart:convert package;
for UTF-16 and UTF-32, you can use the utf package (it's discontinued, but I didn't find alternatives);
for ANSI: ANSI characters after 128 change according to the country, so the exact charset ("code page") used must be identified. For example in Western Europe (for latin scripts), this can be Windows-1250 or Windows-1252. The only package I found that supports these encodings is charset_converter (it supports various charset, but it's available only for Android and iOS, because it relies on the native API of these systems, for example in Android on the API offered by Java).
Example for ANSI (which seems to be your case), for the "windows1250" code page:
(after including charset_converter in dependencies and importing it)
List<int> contents = await file.readAsBytes();
var decoded = await CharsetConverter.decode("windows1250", Uint8List.fromList(contents));
To read ANSI encoded files, the enough_convert package can read them and it works on all platforms! 😀

converting binary data to audio in flutter

I have my server in C# (windows forms) from which I record the sound of the system and send the sound as byte array segment through websocket. I created the client is in flutter to play the data received from the websocket sever,
when I print the data received from the server, it gives me something like this
[44, 208, 240, 11, 78, 112, 62, 234, 159, 35, 145, 128, 240, 99, 91,
123, 252, 181, 56, 44, 222, 214, 137, 206, 45, 55, 59, 114, 199, 206,
47, 230, 77, 154, 200, 12, 218, 187, 187, 100, 219, 225, 6, 82, 123,
75, 133, 251, 105, 44, 243, 232, 69, 24, 31, 95, 39, 136, 43, 152,
121, 233, 56, 22, 197, 141, 44, 213, 47, 182, 77, 59, 171, 201, 37,
101, 125, 203, 126, 113, 131, 175, 194, 244, 7, 158, 154, 138, 25,
223, 217, 123, 112, 225, 133, 139, 59, 230, 31, 227, 110, 92, 4, 187,
187, 99, 222, 217, 173, 153, 185, 54, 145, 63, 128, 102, 34, 148, 64,
242, 188, 131, 4, 127, 49, 217, 38, 41, 58, 39, 53, 209, 46, 216, 160,
164, 142, 102, 226, 151, 223, 133, 150, 201, 66, 131, 133, 89, 216,
69, 174, 181, 117, 114, 23, 188, 73, 1, 180, 156, 179, 254, 119, 219,
231, 142, 139, 40, 214, 75, 187, 97, 126, 85, 2, 86, 178, 7, 33, 112,
4, 121, 242, 39, 185, 155, 27, 173, 24, 185, 226, 167, 141, 105, 58,
104, 202, 47]
and when I print the runtime type of the data the result is
_uint8arrayView
I have surf the net found nothing in similar to my case in flutter so I don't know what to do again. I want to use soundpool package or AssetAudioPlayer package to play it. Any ideas will be well appreciated. Thanks in advance!.
Here is the main logic of what I have done so far in flutter
Future client() async {
Random r = new Random();
String key = base64.encode(List<int>.generate(8, (_) => r.nextInt(255)));
HttpClient client = HttpClient(/* optional security context here */);
Uri uri = new Uri(
scheme: "http",
host: _controller.text.trim(),
port: int.parse("5970", radix: 10),
path: "");
HttpClientRequest request = await client.getUrl(uri);
// HttpClientRequest request = await client.get(
// 'ws://${_controller.text.trim()}',
// int.parse("5970", radix: 10),
// 'chat'); // form the correct url here
request.headers.add('Connection', 'upgrade');
request.headers.add('Upgrade', 'websocket');
request.headers
.add('sec-websocket-version', '13'); // insert the correct version here
request.headers.add('sec-websocket-key', key);
HttpClientResponse response = await request.close();
// todo check the status code, key etc
Socket socket = await response.detachSocket();
WebSocket ws = WebSocket.fromUpgradedSocket(
socket,
serverSide: false,
);
ws.listen(
(event) {
connected = true;
var bytes = File.fromRawPath(event);
var s = openBytesStream(event);
//streamController.addStream(event);
//stream(s);
print(event.runtimeType);
//soudpool();
},
onError: (error) {
connected = false;
},
onDone: () {
connected = false;
},
cancelOnError: false,
);
}
final assetsAudioPlayer = AssetsAudioPlayer();
Future stream(String url) async {
try {
await assetsAudioPlayer.open(
Audio.liveStream(url),
showNotification: true,
autoStart: true,
);
} catch (t) {
//stream unreachable
print(t);
}
}
Future<void> soudpool(Uint8List soundData) async {
Soundpool pool = Soundpool(streamType: StreamType.notification);
int soundId = await pool.loadAndPlayUint8List(soundData);
int streamId = await pool.play(soundId);
}

Is there a way to reverse the bit order in UInt64?

I am building a chess engine in Swift based off a tutorial written in Java. In the tutorial, Java's signed 64 bit integer long has a static method called reverse(long i) that "Returns the value obtained by reversing the order of the bits in the two's complement binary representation of the specified long value." It basically reverses the order of the binary bits so that, using 8-bit for simplicity's sake, 01000000 would become 00000010.
I am curious if there is a way to accomplish the same thing with Swift's UInt64. I understand that Java's long (signed, 2s complement) and Swift's UInt64 (unsigned) are different, but I imagine it wouldn't be hard to do this with UInt64.
I tried UInt64.byteSwapped, but this doesn't seem to be getting me the behavior I expect.
No, the Swift standard libraries do not provide a method to reverse the order of bits in an integer, see for example the discussion Bit reversal in the Swift forum.
One can use the C methods from Bit Twiddling Hacks, either by importing C code to Swift, or by translating it to Swift.
As an example, I have taken the loop-based variant
unsigned int s = sizeof(v) * CHAR_BIT; // bit size; must be power of 2
unsigned int mask = ~0;
while ((s >>= 1) > 0)
{
mask ^= (mask << s);
v = ((v >> s) & mask) | ((v << s) & ~mask);
}
because that is not restricted to a certain integer size. It can be translated to Swift as an extension to FixedWidthInteger so that it works with integers of all sizes:
extension FixedWidthInteger {
var bitSwapped: Self {
var v = self
var s = Self(v.bitWidth)
precondition(s.nonzeroBitCount == 1, "Bit width must be a power of two")
var mask = ~Self(0)
repeat {
s = s >> 1
mask ^= mask << s
v = ((v >> s) & mask) | ((v << s) & ~mask)
} while s > 1
return v
}
}
Examples:
print(String(UInt64(1).bitSwapped, radix: 16))
// 8000000000000000
print(String(UInt64(0x8070605004030201).bitSwapped, radix: 16))
// 8040c0200a060e01
print(String(UInt16(0x1234).bitSwapped, radix: 16))
// 2c48
Another option would be to use byteSwapped to reverse the order of bytes first, and then reverse the order of the bits in each byte with a (precomputed) lookup table:
fileprivate let bitReverseTable256: [UInt8] = [
0, 128, 64, 192, 32, 160, 96, 224, 16, 144, 80, 208, 48, 176, 112, 240,
8, 136, 72, 200, 40, 168, 104, 232, 24, 152, 88, 216, 56, 184, 120, 248,
4, 132, 68, 196, 36, 164, 100, 228, 20, 148, 84, 212, 52, 180, 116, 244,
12, 140, 76, 204, 44, 172, 108, 236, 28, 156, 92, 220, 60, 188, 124, 252,
2, 130, 66, 194, 34, 162, 98, 226, 18, 146, 82, 210, 50, 178, 114, 242,
10, 138, 74, 202, 42, 170, 106, 234, 26, 154, 90, 218, 58, 186, 122, 250,
6, 134, 70, 198, 38, 166, 102, 230, 22, 150, 86, 214, 54, 182, 118, 246,
14, 142, 78, 206, 46, 174, 110, 238, 30, 158, 94, 222, 62, 190, 126, 254,
1, 129, 65, 193, 33, 161, 97, 225, 17, 145, 81, 209, 49, 177, 113, 241,
9, 137, 73, 201, 41, 169, 105, 233, 25, 153, 89, 217, 57, 185, 121, 249,
5, 133, 69, 197, 37, 165, 101, 229, 21, 149, 85, 213, 53, 181, 117, 245,
13, 141, 77, 205, 45, 173, 109, 237, 29, 157, 93, 221, 61, 189, 125, 253,
3, 131, 67, 195, 35, 163, 99, 227, 19, 147, 83, 211, 51, 179, 115, 243,
11, 139, 75, 203, 43, 171, 107, 235, 27, 155, 91, 219, 59, 187, 123, 251,
7, 135, 71, 199, 39, 167, 103, 231, 23, 151, 87, 215, 55, 183, 119, 247,
15, 143, 79, 207, 47, 175, 111, 239, 31, 159, 95, 223, 63, 191, 127, 255]
extension FixedWidthInteger {
var bitSwapped: Self {
var value = self.byteSwapped
withUnsafeMutableBytes(of: &value) {
let bytes = $0.bindMemory(to: UInt8.self)
for i in 0..<bytes.count {
bytes[i] = bitReverseTable256[Int(bytes[i])]
}
}
return value
}
}

Flutter Archive Plugin returns data in Uint8List format of my XML file

Flutter Archive Plugin returns data in Uint8List format of my XML file. How can i convert the List data into String so that i can parse the XML in the app
Here is the piece of code i wrote
unarchiveAndSave(var zippedFile,String filepath) async {
// String _dir = (await
getApplicationSupportDirectory()).path+"/SampleFolder";
List<int> bytes = await zippedFile.readAsBytesSync();
if (bytes != null) {
print("FILE FOUND: $_path");
}
else {
print("ERROR NO FILE FOUND: $_path");
return null;
}
Archive archive = new ZipDecoder().decodeBytes(bytes);
for (ArchiveFile file in archive) {
String filename = file.name;
Uint8List fileContent = file.content;
print("File Content ::: $fileContent");
if (file.isFile) {
List<int> data = file.content;
print(data);
/*File contentFile = new File('$filepath/'+filename)
..createSync(recursive: true)
..writeAsBytesSync(bytes);*/
}
else {
new Directory('$filepath/'+filename)
..create(recursive: true);
print('Created and written $filepath/$filename');
}
}
}
here is the data i'm getting
[45, 246, 8, 26, 241, 251, 150, 86, 156, 194, 16, 162, 231, 138, 40, 95, 178, 209, 62, 79, 136, 196, 26, 234, 97, 105, 44, 50, 93, 141, 26, 111, 253, 199, 19, 255, 250, 57, 105, 27, 114, 86, 164, 144, 98, 101, 84, 114, 192, 236, 19, 187, 225, 186, 188, 91, 152, 187, 20, 228, 69, 23, 219, 34, 51, 85, 241, 124, 230, 224, 36, 7, 56, 5, 235, 172, 34, 199, 63, 108, 69, 239, 161, 52, 11, 56, 138, 246, 57, 218, 93, 147, 89, 85, 252, 26, 45, 117, 76, 50, 73, 76, 170, 38, 91, 122, 97, 151, 175, 57, 135, 30, 30, 115, 224, 106, 4, 86, 164, 118, 190, 48, 118, 211, 104, 194, 96, 229, 57, 173, 22, 230, 143, 217, 204, 82, 177, 201, 224, 121, 136, 47, 147, 217, 217, 111, 60, 143, 133, 79, 162, 255, 71, 127, 162, 155, 20, 43, 144, 5, 116, 215, 179, 97, 7, 193, 24, 234, 193, 235, 181, 115, 193, 150, 29, 83, 232, 48, 8, 4, 84, 214, 255, 177, 230, 99, 64, 19, 39, 78, 127, 59, 1, 138, 158, 152, 104, 235, 216, 69, 68, 133, 23, 15, 99, 162, 29, 127, 253, 56, 180, 231, 32, 77, 93, 188, 2, 152, 248, 157, 46, 47, 72, 161, 153, 168, 8
package:archive is a pure Dart package to handle zip and gzip compression. If you know that the zip file contains UTF-8 encoded text files you can decompress each file in memory and then convert the decompressed contents to characters using a character codec - presumably the UTF-8 one, especially as this is the most frequent character encoding of XML.
As the package is pure Dart you can use it from a pure Dart program, which may be easier to test than on your phone. (Incidentally, also included in the package is the dart:io based version, which may be more efficient than the pure Dart version as long as you aren't targetting the web.)
Here's a working snippet that reads a zip file containing text files, prints the file names and the first few characters of each file.
import 'dart:convert';
import 'dart:io';
import 'package:archive/archive.dart';
void main() async {
var zipBytes = await File('zip1.zip').readAsBytes();
Archive archive = ZipDecoder().decodeBytes(zipBytes);
for (var archiveFile in archive) {
print(archiveFile.name);
var content = archiveFile.content;
print(utf8.decode(content).substring(0, 10));
}
}

Elixir stream audio to users

The following code streams a file to a process.
I want to stream audio/mp3
to many users who will hear it via html5 audio tag.
How can it be done via File.stream!?
defmodule Test do
def start do
p = spawn(Test, :say, [])
send p, {self, "a message"}
end
def say do
receive do
{from, msg} ->
IO.puts "Process #{inspect self} says: #{msg}"
stream_bytes = 128
File.stream!("./song.mp3", [], stream_bytes)
|> Enum.each(fn chunk ->
IO.inspect chunk
end)
say
end
end
end
$: iex test.ex
iex(1)> Test.start
output:
<<171, 46, 254, 26, 163, 32, 178, 27, 0, 75, 17, 35, 4, 236, 51, 57, 5, 144, 154, 198, 166, 47, 62, 4, 61, 85, 67, 135, 16, 34, 82, 49, 57, 176, 131, 96, 116, 152, 232, 24, 32, 140, 220, 67, 73, 128, 165, 178, 230, 202, ...>>
<<100, 220, 156, 191, 38, 0, 161, 117, 80, 16, 102, 91, 22, 5, 8, 66, 26, 7, 193, 155, 193, 66, 198, 28, 157, 244, 65, 131, 204, 240, 5, 172, 143, 44, 173, 85, 144, 2, 157, 144, 145, 97, 200, 236, 16, 49, 149, 150, 133, 67, ...>>
<<150, 54, 37, 254, 192, 218, 218, 26, 69, 231, 88, 124, 33, 129, 169, 66, 117, 52, 214, 134, 130, 103, 85, 130, 48, 6, 144, 221, 153, 132, 8, 181, 26, 27, 83, 140, 54, 117, 149, 7, 60, 144, 237, 248, 132, 12, 210, 51, 103, 116, ...>>
<<57, 2, 143, 220, 198, 182, 22, 177, 231, 126, 187, 147, 33, 9, 1, 5, 164, 2, 36, 105, 47, 255, 255, 255, 255, 255, 245, 54, 51, 225, 104, 98, 1, 184, 148, 206, 50, 135, 230, 28, 50, 47, 144, 134, 53, 16, 64, 130, 192, 198, ...>>
..............
how can I use JavaScript to read this binary data and hear it via audio tag ?
If you're using a plug based web framework it should be reasonably straight forward. This is possible if you're using plug directly or if you're using it from within phoenix (which is based on plug).
Maybe a plug like this would do the trick
defmodule Audio do
#chunk_size 128
def init(opts), do: opts
def song(conn, _opts) do
conn = conn
|> send_chunked(200)
|> put_resp_header("content-type", "audio/mpeg")
File.stream!("/some/song/somewhere.mp3", [], #chunk_size)
|> Enum.into(conn)
end
end
Maybe you want to hook up your plug to a phoenix router like this
defmodule MyApp.Router do
use MyApp.Web, :router
get "/the_song", Audio, :song
end
Then in your page
<audio src="/the_song">
Your browser does not support the <code>audio</code> element.
</audio>