Develop Reference

Encoding, decoding and re-encoding not producing original results

I suspect that my decoding is not working properly. That is why I am testing it by encoding, decoding and the re-encoding to see if I am getting the same result. That is however not the case.
I encoded a byte[] named model.PDF to a base64 string.
Now, for decoding, I converted model.PDF to a decoded base64 string. However the output looks faulty or corrupted upon debugging and I suspect this is where something is going wrong.
To encode again, the decoded data is turned into byte[] again and then into an encoded base64 string. However base64EncodedData does not match plainTextEncodedData. Please help me create a flawless encode to decode to re-encode flow.
// ENCODING - Byte array -> base64 encoded string
string base64EncodedData = Convert.ToBase64String(model.PDF);
// DECODING - Byte array -> base64 decoded string
var base64DecodedData = Encoding.UTF8.GetString(model.PDF);
// ENCODING AGAIN
byte[] plainTextBytes = Encoding.UTF8.GetBytes(base64DecodedData);
var plainTextEncodedData = Convert.ToBase64String(plainTextBytes);
To elaborate, the re-encoding matches the initial encoding perfectly if executed like this.
var PDF = System.Text.Encoding.UTF8.GetBytes("redgreenblue");
string base64EncodedData = Convert.ToBase64String(PDF);
// DECODING - Byte array -> base64 decoded string
var base64DecodedData = Encoding.UTF8.GetString(PDF);
// ...
But, my model.PDF is fetched from the database as shown below, in which case the re-encoding does not match.
while (reader.Read()) {
model.PDF = reader["PDF"] == DBNull.Value ? null : (byte[])reader["PDF"];
}
On an online base64 decoder (https://www.base64decode.org/), decoding an example value of base64EncodedData shows the ideal and correct value.
%PDF-1.5
%
1 0 obj
<</Type/Catalog/Pages 2 0 R/Lang(en-IN) /StructTreeRoot 8 0 R/MarkInfo<</Marked true>>>>
endobj
2 0 obj
<</Type/Pages/Count 1/Kids[ 4 0 R] >>
endobj
3 0 obj
<</Author(admin) /CreationDate(D:20190724114817+05'30')
/ModDate(D:20190724114817+05'30') /Producer(Microsoft Excel 2013) /Creator(Microsoft Excel 2013) >>
endobj
4 0 obj
<</Type/Page/Parent 2 0 R/Resources<</Font<</F1 6 0 R>>/ProcSet[/PDF/Text/ImageB/ImageC/ImageI] >>/MediaBox[ 0 0 612 792] /Contents 5 0 R/Group<</Type/Group/S/Transparency/CS/DeviceRGB>>/Tabs/S/StructParents 0>>
endobj
5 0 obj
<</Filter/FlateDecode/Length 171>>
stream
...
However, in my program, the value of base64DecodedData shows up in its entirety as:
%PDF-1.5
%����
1 0 obj
<</Type/Catalog/Pages 2 0 R/Lang(en-IN) /StructTreeRoot 8 0 R/MarkInfo<</Marked true>>>>
endobj
2 0 obj
<</Type/Pages/Count 1/Kids[ 4 0 R] >>
endobj
3 0 obj
<</Author(admin) /CreationDate(D:20190724114817+05'30')
/ModDate(D:20190724114817+05'30') /Producer(��
The 2 look similar in ways but my program seems to be producing a corrupt version of what the actual base64 decoded string should be.

A PDF is an ASCII file that can contain binary data (including strings in other encodings).
So you cannot read it as plain text.
If a PDF file contains binary data, as most do [...] the header line
shall be immediately followed by a comment line containing at least
four binary characters—that is, characters whose codes are 128 or
greater.
Taken from this answer, which has some more infos
You see exactly these four characters in your own output.

NetworkStream.read() reads all bytes but won't convert to string

I am trying to read the response of the server when attempting to log on using networkStream.read() using the following code:
if (connectionStream.DataAvailable && connectionStream.CanRead)
{
byte[] myReadBuffer = new byte[64];
string responseMessage = string.Empty;
int numberOfBytesRead = 0;
do
{
numberOfBytesRead = connectionStream.Read(myReadBuffer, 0, myReadBuffer.Length);
responseMessage = Encoding.ASCII.GetString(myReadBuffer, 0, numberOfBytesRead);
} while (connectionStream.DataAvailable);
Debug.Log("Message:" + responseMessage);
#breakpoint
if (responseMessage.Contains("OK"))
{
Debug.Log("logon sucessful");
}
else
{
Debug.LogError("Logon denied!");
}
}
By inspecting my local variables at breakpoint i know the Read() is excecuted without problem as numberOfBytesRead is set to 32, and myReadBuffer is filled with 32 bytes (all bytes in myReadBuffer match the bytes sent by the server). However after trying to extract the string from myReadbuffer using Encoding.ASCII.GetString() the string is still empty (Visual studio also says it is empty at the breakpoint), even though myReadBuffer isn't.
The bytes in myReadBuffer read:
32 0 0 0
1 0 0 0
0 0 0 0
76 79 71 79
78 58 32 48
59 79 75 59
32 83 83 61
54 66 67 0
which translates to: _ _ _ _ _ _ _ _ _ _ L O G O N : 0 ; O K ; S S = 5 A 8 _
Any suggestions as to what can cause this?

The response from the server contains some null ('\0') characters. Despite what the docs on Strings (C#) say about null termination in C#:
There is no null-terminating character at the end of a C# string; therefore a C# string can contain any number of embedded null characters ('\0').
Unity does not seem to comply to this, and actually does terminate a string after a null character has been encountered. Though I couldn't find any references to this in the unity docs.
The fix i ended up going with was replacing the null characters by spaces (Could also remove the null characters completely, but i want to know the characters were there at some point) like so: responseMessage = responseMessage.Replace('\x0', '\x0020');
While creating this post i figured it out, but coulnd't find any other posts on SO describing my problem. So answering it myself for future references. If anyone has any other/better solutions or additional information i'd still be glad to hear/accept that.

How do I convert this filestream from an API to a PDF or XML file?

I am trying to use an API to download documents which will be in either PDF or Word document formats. The service gives directions only up to how to construct the request URL, which I have done.
The API offers an xml or json method in the url, I am using xml.
I have tried to get the string and parsing it to an XDocument:
XDocument response;
using (var webClient = new System.Net.WebClient())
{
response = XDocument.Parse(webClient.DownloadString(url));
}
Console.WriteLine(response);
I also tried downloading as a file:
using (var webClient = new System.Net.WebClient())
{
webClient.DownloadFile(url, filepath));
}
Both produce the same result:
%PDF-1.5
%µµµµ
1 0 obj
<</Type/Catalog/Pages 2 0 R/Lang(en-US) >>
endobj
2 0 obj
<</Type/Pages/Count 2/Kids[ 3 0 R 27 0 R] >>
endobj
3 0 obj
<</Type/Page/Parent 2 0 R/Resources<</Font<</F1 5 0 R/F2 7 0 R/F3 9 0 R/F4 11 0 R/F5 13 0 R/F6 21 0 R>>/ProcSet[/PDF/Text/ImageB/ImageC/ImageI] >>/Annots[ 18 0 R 19 0 R 20 0 R 26 0 R] /MediaBox[ 0 0 612 792] /Contents 4 0 R/Group<</Type/Group/S/Transparency/CS/DeviceRGB>>/Tabs/S>>
endobj
4 0 obj
<</Filter/FlateDecode/Length 6592>>
stream
xœÝ=k“Û6’ß]åÿÀOYÍžÍo2ÙrÝ8‰sÙ‡Çn²Æ2=¦­¡|ó°ãÔþøën€/‘ÐH r]¥"%ˆÝht7ú…KÎïÞ:Q™H•0#R©®xš©ä²¼{çå_ïÞùßíC~ùkRÓ“åi.›B¥Fï÷Œ‡ÏîÞùôK¸I<{y÷K2ø%ŒóTfR™'Ï.îÞÉRø,ÉRžkx•Ery>ñá_ß½óÛ"9ùwòìïwï|ÏÿÑ…J‹¼A„ñ4×r®<a,Í䮺ÈS×\¤ïáZÌ"ë6Ts•*UCd
NUÃS„ªÊ¤<.UU‘š T•9)&U¥NMª
–ʸTðû Te9rRLªò•L
and a lot more like this goes on. It's very odd characters, I am not sure how to parse an XML or PDF document from this.

You could use HttpClient for Async requests Httpclient is a better option instead of webclient
public static async Task get()
{
HttpClient _httpClient = new HttpClient())
string url = "https://someurl.com";
var result = await _httpClient.GetAsync($"{url}");
// contents to a log file
string resultContent = await result.Content.ReadAsStringAsync();
File.WriteAllText("D://dT.pdf", resultContent);
// ... write to log
}

Encrypt jsPDF generated pdf to SharpPDF

i'm generating a pdf in my client using jsPDF, and want to encrypt it in my server app with SharpPDF, but when im trying to pass the jsPDF to SharpPDF i get that it can't recognize some characters:
here is the pdf value using jsPDF output and then encoding it into base 64
var out = doc.output();
var url = 'data:application/pdf;base64,' + out.toString(CryptoJS.enc.Base64);
%PDF-1.3
3 0 obj
<</Type /Page
/Parent 1 0 R
/Resources 2 0 R
/Contents 4 0 R>>
endobj
4 0 obj
<</Length 9717>>
stream
0.57 w
0 G
BT
/F1 14 Tf
16.099999999999998 TL
0 g
227.46 510.24 Td
(SOME TEXT) Tj
ET
BT
/F3 8 Tf
9.2 TL
0 g
42.52 48.19 Td
then at my server when im trying to encrypt it using this example http://www.pdfsharp.net/wiki/ProtectDocument-sample.ashx
i get an error in this line:
System.IO.File.WriteAllText("D://" + data.Texto, data.Valor);
HERE--> PdfDocument document = PdfReader.Open("D://" + data.Texto, "some text");
PdfSecuritySettings securitySettings = document.SecuritySettings;
securitySettings.UserPassword = "user";
securitySettings.OwnerPassword = "owner";
The error is Token 'obj' was not expected.

Read .dat file in c#

i want to read a .dat file that have following conditions:-
First name offset 21
First name format ASCIIz 15 chars + \0
Middle initials offset 37
ID offset -8
ID format/length Unsigned int (4 bytes)
so help me for sorting this issue in c#.
Thanks in advance.
Gurpreet
.dat file
( ÿ / rE ÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿ XÙþÞ¦d e e Mr. Sam Ascott Sam 9209 Sandpiper Lane 21204 410 5558987 410 5556700 275 MM229399098 (¬ Þ e ܤ•Þ„ œÔ£ÝáØáØ ’Þ[Þ €–˜ ä–˜ [Þ ¶ Norman Eaton Friend of Dr. Shultz Removal of #1,16,17 & 32 öÜÝ)Ý Ä d 01 21 21 21 e 101 22099 XÙþÞ¦d e . Mrs. Patty Baxter Patty 3838 Tommytrue Court 21234 410 2929290 410 3929209 FM218798127 HAY FEVER Þ . „¤¢Þè   _ÐÍÝBÒBÒ ’ÞÝ €–˜ ä–˜ ÍÝ f Joanne Abbey

Here is a tutorial how to use BinaryReader for this purpose:
http://dotnetperls.com/binaryreader

You can use Jet OleDB to query .dat files:
var query = "select * from file.dat";
var connection = new OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=C:\\file.dat;Extended Properties=\"text;HDR=NO;FMT=FixedLength\"");
See this link:
Code Project. Read Text File (txt, csv, log, tab, fixed length)
And check these:
Reading a sequential-access file
DAT files in C#
Read a file in C#
BinaryReader Class
Jon Skeet. Reading binary data in C#

As said, have a look at the BinaryReader
//Example...
BinaryReader reader = new BinaryReader(stream);
string name = Encoding.ASCII.GetString(reader.ReadBytes(8));
int number = reader.ReadInt32();

my .dat file content - " €U§µ­PÕ „ÕG¬u "
click here to see the content of my .dat file in Notepad and hexa editor
string fileName = #"W:\yourfilename.dat";
//Read the binary file as byte array
byte[] bHex = File.ReadAllBytes(fileName);
//Create string builder for extracting the HEX values
StringBuilder st = new StringBuilder();
//initialize the int for 0
int i = 0;
// check it worked
//Reverse the HEX array for readability
foreach (char c in bHex.Reverse())
{
i++;
// 12 to 21 byte in the reverse order for interseted value in ticks"
if (i > 12 && i < 21)
st.Append(Convert.ToInt32(c).ToString("X2"));
}
// Convert HEX to Deciamal
long Output = Convert.ToInt64(st.ToString(), 16);
//Convert ticks to date time
DateTime dt = new DateTime(Output);
//Write the output date to console
Console.Write(dt);
Final de-crypt binary content to data-time.
final output of the program