[RESOLVED] Output decrypted text with CryptoStream

[herpez]

Hi. Im using a sample code from msnd website - CryptoStream Class (http://msdn.microsoft.com/en-us/libr...ptostream.aspx)

Using this code, i was expecting that

Final would show me the decrypted text from the file

Dim Final As String = DecryptTextFromFile(FileName, RijndaelAlg.Key, RijndaelAlg.IV)

However, when i try to do something to display Final, like MsgBox(Final) or Label1.text = Final , it outputs nothing.

Where am i wrong?

[petevick]

Hi,
are you sure Compact Framework supports this?

Take a look at http://msdn.microsoft.com/en-us/library/aa446559.aspx - there are notes on cryptographt part way down the page - I think you just have to use the crypto API

[herpez]

Hi,
are you sure Compact Framework supports this?

Take a look at http://msdn.microsoft.com/en-us/library/aa446559.aspx - there are notes on cryptographt part way down the page - I think you just have to use the crypto API

Yes, it does. I found out that If i do the sample code from msdn like

' Create a string to encrypt.
            Dim sData As String = "Here is some data to encrypt."
            Dim FileName As String = "CText.txt"

            ' Encrypt text to a file using the file name, key, and IV.
            EncryptTextToFile(sData, FileName, RijndaelAlg.Key, RijndaelAlg.IV)

            ' Decrypt the text from a file using the file name, key, and IV.
            Dim Final As String = DecryptTextFromFile(FileName, RijndaelAlg.Key, RijndaelAlg.IV)

It works on my mobile.
However, if i already have the CText.txt and just try to decrypt it like

' Create a string to encrypt.
            Dim sData As String = "Here is some data to encrypt."
            Dim FileName As String = "CText.txt"

            ' Encrypt text to a file using the file name, key, and IV.
           ' EncryptTextToFile(sData, FileName, RijndaelAlg.Key, RijndaelAlg.IV)

            ' Decrypt the text from a file using the file name, key, and IV.
            Dim Final As String = DecryptTextFromFile(FileName, RijndaelAlg.Key, RijndaelAlg.IV)

It does not work.

I dont understand why drecrypt only does not work (even if it was previously encrypted with the same program, and only works if its first encrypted.

Maybe because it generates a Key and IV each time the program runs? Maybe i need to store the Key and IV in the registry or in somewhere else so i can get it later?