How to store the all the file in encrypted format and download decrypted format

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We are already upload the all type of document in folder,but now we want to encrypt the file while storing and decrypt while download.

What I have tried:

I already store the file in folder but i dont know to store encrypted format

Posted 26-Dec-19 23:06pm

Jayamanickam

Updated 27-Dec-19 0:24am

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OriginalGriff · Answer 1 · 2019-12-27T00:24:00

Solution 1

Start here: Encrypting files C# - Google Search[^]

Posted 27-Dec-19 0:24am

OriginalGriff

Comments

Jayamanickam 27-Dec-19 8:04am

RijndaelManaged is which method of encryption.. its AES or DES. What type of byte used??

MadMyche 27-Dec-19 8:20am

You could always read the documentation to better understand the class and how it relates

This algorithm supports key lengths of 128, 192, or 256 bits; defaulting to 256 bits. This algorithm supports block sizes of 128, 192, or 256 bits; defaulting to 128 bits (Aes-compatible).

The Rijndael class is the predecessor of the Aes algorithm. You should use the Aes algorithm instead of Rijndael. For more information, see the entry The Differences Between Rijndael and AES in the .NET Security blog.

https://docs.microsoft.com/en-us/dotnet/api/system.security.cryptography.rijndael?view=netframework-4.8#remarks

OriginalGriff 27-Dec-19 8:21am

a byte is a bytem, is a byte: it's a defined size of memory which consists of eight bits, and can thus hold values between 0 and 255 inclusive. There is no "what type of byte" involved!

Jayamanickam 31-Dec-19 4:44am

I tried in google as per your guide, i got the solution. but i have facing another issue is, its only support .txt file only, but i need all type of document such as .xls,.xlsx and more importent PDF file format.

OriginalGriff 31-Dec-19 4:57am

No, encryption doesn't care what is in the file - it's just a stream of bytes regardless of being TXT, XLS, XLSX, DOCX, DBF, or EXE.
All the encryption method gets is a stream of binary data and a key of some sort - it doesn't know or care what the bytes contain!

Jayamanickam 31-Dec-19 5:38am

Encrypt Code:

public static void EncryptFile(string inputFile, string outputFile)
{

try
{

string password = @"myKey123"; // Your Key Here
UnicodeEncoding UE = new UnicodeEncoding();
byte[] key = UE.GetBytes(password);

string cryptFile = outputFile;
FileStream fsCrypt = new FileStream(cryptFile, FileMode.Create);

RijndaelManaged RMCrypto = new RijndaelManaged();

CryptoStream cs = new CryptoStream(fsCrypt,
RMCrypto.CreateEncryptor(key, key),
CryptoStreamMode.Write);

FileStream fsIn = new FileStream(inputFile, FileMode.Open);

int data;
while ((data = fsIn.ReadByte()) != -1)
cs.WriteByte((byte)data);

fsIn.Close();
cs.Close();
fsCrypt.Close();
}
catch
{
//MessageBox.Show("Encryption failed!", "Error");
}
}

Decrypt Code:

private static void DecryptFile(string inputFile, string outputFile)
{

{
string password = @"myKey123"; // Your Key Here

UnicodeEncoding UE = new UnicodeEncoding();
byte[] key = UE.GetBytes(password);

FileStream fsCrypt = new FileStream(inputFile, FileMode.Open);

RijndaelManaged RMCrypto = new RijndaelManaged();

CryptoStream cs = new CryptoStream(fsCrypt,
RMCrypto.CreateDecryptor(key, key),
CryptoStreamMode.Read);

FileStream fsOut = new FileStream(outputFile, FileMode.Create);

int data;
while ((data = cs.ReadByte()) != -1)
fsOut.WriteByte((byte)data);

fsOut.Close();
cs.Close();
fsCrypt.Close();

}
}

I used the above code, but its not working. can you please guide me...

OriginalGriff 31-Dec-19 5:47am

"It's not working" is one of the most useless problem descriptions we get: it tells us absolutely nothing about the problem. We don't know if you get an error message, or the wrong data, or even that that code compiles successfully!
Remember that we can't see your screen, access your HDD, or read your mind - we only get exactly what you type to work with.
So tell us what happens when you run that code, what you expected to happen, how you checked what happened. Help us to help you!

Jayamanickam 2-Jan-20 0:46am

I used above the code for encrypt and Decrypt, It's supports only the .txt file encrypt and decrypt. At same time i try to encrypt the .PDF,.xls,.xlsx are not supporting. Run with one sample PDF file try to encrypt after encrypt i open the Encrypted PDF file its showing the error message " Adobe Acrobat Reader could not open test.pdf file because it is either not a supported file type or because the file is damaged" like that message shows. I hope you may understand the scenerio.

OriginalGriff 2-Jan-20 2:05am

So let me see if what you are saying is what you are doing:

1) Read a file from "FileA"
2) Encrypt it to "FileB"
3) Try to Open "FileB" with Adobe PDFReader.
4) Complain that it doesn't open.

It's an encrypted file: it no longer resembles a PDF file in any way, shape, or means.

Encryption by your app is not the same as "creating an encrypted PDF file" - the latter creates a PDF file which contains encrypted data, while you are encrypting the whole file.

To create an encrypted PDF file that can be read, start here:
https://www.google.com/search?safe=off&sxsrf=ACYBGNQa1KFIpFD0B7meqPx99s_tIpWiHQ%3A1577948572916&ei=nJUNXsXJN4Wy8gKm7Iv4BA&q=encrypt+pdf+c%23&oq=encrypt+pdf+c%23&gs_l=psy-ab.3..0j0i22i30l6.6593.9232..9823...0.2..0.80.368.5......0....1..gws-wiz.......0i71j0i7i30j0i20i263.2Szrl9qNz_E&ved=0ahUKEwjFh6bBrOTmAhUFmVwKHSb2Ak8Q4dUDCAs&uact=5

Jayamanickam 2-Jan-20 5:54am

Thanks you so much..
And more help need. Can you guide me i want to encrypt Inside the folder files, I dont have an much idea about that.
For Ex: Main FolderA->ReportFolder->Test.Pdf,Test.Xls,Test.Xlsx
Main FolderA->AccountFolder->Test1.Pdf,Test21.xls

Like that. So Once i encrypted the main folderA all the subfolder and files need to be encrypt

OriginalGriff 2-Jan-20 6:33am

And?
You know how to read a folder and its subfolders, don't you?