Cannot Decrypt PDF Files Properly
Dec 26, 2011
I'm joining several files and would like to encrypt them with AES. As a test I'm joining the exact same file twice, but I'm never able to properly decrypt the second file.
Steps to reproduce:
Make sure you have a file "C:Original.pdf" or change the filepath.
1) Click Button1 to encrypt the file. This will create an encrypted file named "Encrypted.bin"
2) Click Button2 to decrypt the file. This will create a decrypted file named "Decrypted.pdf"
Both "Original.pdf" and "Decrypted.pdf" are 100% the same.
3) Uncomment the code between the hash character lines.
4) Repeat the first two steps.
"Original.pdf" and "Decrypted.pdf" are now not the same.
vb.net
Private enc As New Encrypt
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
'Encrypt
enc.EncryptDecrypt("C:Original.pdf", "C:Encrypted.bin", True)
[Code] .....
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Jan 29, 2009
I would like to decrypt a files that sis coming to me as pgp, is there anyway of doing this. without the pgp command or any other third party dll. or I rememeber A long time ago there was a .dll called NSDpgp3.dll but it only works with vb6 ( sdpgp3 was free)
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Jan 1, 2010
VS 2010 How to decrypt .NET files for against decompile?
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Dec 26, 2011
I'm designing a program to encrypt and decrypt files using TripleDes Encryption algorithms but am having issues decrypting an image file. The file encrypts in the correct manner, but when I go to decrypt the file and open as an image I get an error message. One example is when trying to open the file in paint a message appears stating 'c:New FolderDecrypted.jpg Paint cannot read this file. This is not a valid bitmap file, or its format is not currently supported. My coding for the form is shown below:
"Imports System.Windows.Forms
Imports System.Security.Cryptography
Imports System.Security
[Code]....
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Jan 12, 2009
Lets get down to it, Basically, I'm making a kind of "Anti-Hack" for a project I'm working on.The basis of the "Anti-Hack" is the check processes for names of known Memory Editors, For example, one memory editor I am scanning for is Cheat Engine.exe, I am using this code to scan for it, then I use the result to activate a different piece of code.
If Process.GetProcessesByName("Cheat Engine").Length = 0 The
'It's OK
Else
<Removed for obvious reasons>
End If
Basically, I don't want my code to look like a library of If statements when the only thing I am changing is the process name, what I want to do, is have an encrypted .dat file with an array or list of known tools. I want to then go through the array/list and keep checking for instances of them running.I know nothing of how to encrypt/decrypt .dat files through VB. (I'm not an expert at it atm )I am open to other ways (Easier ways) of doing this, like a Class with a list of names etc.
**NOTE** I would rather it be a separate file as the program features an Auto-Update feature, so it will be easier to update the list.
**IMPORTANT**Also, I would like to know how to hide my process, so it cant simply be ended, It may sound suspicious but people will be able to just close it and start hacking T_T, Unless there is another way, I would appreciate it (Like making it so it cant be ended etc.)**IMPORTANT.
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Sep 20, 2011
I'm attempting to create a little library to encrypt and decrypt Files with AES. There are loads of examples of how to do this on the internet so coding is not a problem. There are however a few questions regarding cryptography and AES in general.
#1 Does the IV need to be kept a secret like the key ?
#2 Can I just hash a string with SHA512 to make a key for AES ? or do I need to use PasswordDeriveBytes ?
#3 In the case of me using PasswordDeriveBytes Do I need to keep the salt a secret ?(or do I need to keep it at all)
#4 Can I generate the IV from the same password that the Key is derived from ?(if so How ?)
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Jun 24, 2011
I'm a beginner so i'm just trying my hand. There might be easier ways to do this but i want to learn how to manipulate text files properly.
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Mar 1, 2011
I borrowed part of this routine to download files, and it works great; except when I download text files the returns aren't written into the outputted file. I've tried different web request and techniques with no luck in solving the problem.
Test file:[URL]
Private Sub DownloadFile(ByRef FileSource As String, ByRef FileDestination As string)
Dim request As WebRequest
Dim response As WebResponse
[Code].....
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Jun 13, 2011
Need to design a program that can encrypt and decrypt messages stored in simple text files using a private key stored in a separate file. Software should also be able to allow the users to enter simple messages that either displays the encrypted or decrypted message. The encryption method should use a simple substitution method. It should be set out in the following format:
Example (the "@" is the separator):
@
The character The Code End of line
A @ 4gh EOL
B @ 84!9 EOL
Has to use the 256 ASCII character codes. The separator will be used to separate the character and its corresponding code.Here are the pseudocodes I have come up with:
� Read any private key file
separator = readline(file);
while not EOF(file) do
tempStr = readline(file);
[code].....
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Jun 22, 2010
I am looking for a code snippet which opens a image, creates a clone of this bitmap in memory disposes this opened image so that all handles are closed.
Usually we can open a bitmap using this[code...]
the following code however keeps the Image File locked until the application is running, any suggestions how to dispose it properly. (So that no handle is left open )
Things i already tried: use dispose method of bitmap <= doesnt work (need to write implementation)
Using Block also doesnt work.
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Apr 1, 2009
I have a classic ASP page which constructed a querystring for a link to an ASP.NET page. Certain elements in the querystring are somewhat sensitive so I want to encrypt them. I've come across some techniques for doing this in ASP.NET and also in classic ASP but I'm not sure how to do it from classic ASP to ASP.NET. I'm using .NET 3.5.
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Jul 6, 2011
i got encrypt way so how can i decrypt it and the encrypt way is :
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Jan 2, 2010
i need a standard way of encrypting a string and decrypting it using AES. I am aware of the Cryptography class, however almost every example creates a class to do the encryption,If .Net already has this implemented and ready to use why would we create classes for encryption and decryption, isn't it as simple as calling the encrypt method of the class or decrpyt and passing in the text. Unless everyone is wanting to centralize the code. But even then i see so many different examples from File,Data Protection etc..
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Jun 13, 2010
There is a problem with the source code. I cannot convert the string to decrypt from encrypt string.[code]I went on breakpoint on that line and I have looked on quickwatch. The error I have caught is that convert is a type and cannot be used as an expression.
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Nov 10, 2011
i am trying to decrypt a file that was encrypted with Des. However not all of the file is encrypted just a few lines are. Here is an example of the file im trying to decrypt:
Random text
Encrypted Text
MD5 Hash
Encryption Key(Only there for tests)
Number of encrypted lines
The idea is to read the last three lines into variables and use them to decrypt the text. At the moment i use the number of lines - (the number of encrypted lines + 3) to find where the encrypted text starts. Then i was trying to copy the encrypted text to a temp file so i could run the code bellow on it, however i am getting an encoding error apparently i need to be using base64 or something. So my question is can anybody explain to me or show me how i can pull the encrypted text out of the file so that i can use the code bellow on it.
Dim DES As New DESCryptoServiceProvider()
'A 64-bit key and an IV are required for this provider.
'Set the secret key for the DES algorithm.
[Code].....
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May 10, 2012
THIS IS THE SAMPLE OF ENCRYPTED DATA PLEASE HELP ME HOW TO DECRYPT THIS KIND OF ENCRYPTION
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Jun 22, 2011
I need some help on saving/reading xml from/to dataset. I would like to make that complete file is encrypted and not only some elements inside or part of file.Currently this is not working in any way at all.[code]
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Dec 23, 2011
I ended up getting this properly working, as far as encrypting a file goes:How to encrypt and decrypt a file by using Visual Basic .NET or Visual Basic 2005 However, the catch is I have to change the name of the output file. What I was hoping to do is overwrite the original with the encrypted file, but when I tried that on a large file, it ended up only getting about 8 bytes of it.
Does anybody have any suggestions or recommendations? The overall idea is that I want to keep a file encrypted until it needs to be unencrypted for use by a program, but I'm not sure if there are better tools out there or if there's a better way of accomplishing this.
Question 2: I would really, really like to encrypt an entire folder, which I'm guessing would be faster than file by file, but when I try I keep getting access denied errors, even with DOS Cipher. Is there a way to do this with a key?
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Jul 18, 2010
there is anyone know how to encrypt and decrypt app config in vb.net??i want encrypt connection string and appsettings .
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Aug 15, 2011
How to encrypt and decrypt database..
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How to encrypt and decrypt database
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Jan 10, 2009
I am using vb.net 2008 i want to Know how can i encrypt text in a text box save it to a file then read the file decrypt the text and finaly display it in text box .
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Jul 28, 2011
I am trying to encrypt a zip in VB.NET to send to an android device using Air. Then once its on the device, decrypt it using the key and IV.
Here is part of my VB.NET Code:
Private Sub EncryptBytes(ByVal fileIn As String, ByVal fileOut As String, ByVal pass As String, ByVal ivString As String)
Dim crypt As New RijndaelManaged
crypt.KeySize = 256
[Code]...
This is not working ... Note that I tried to write a PKCS7 class based on a Java class I found. The hurlant package I downloaded only had PKCS5. VB.NET did not provide any of the same padding classes as hurlant comes with. I wish I could using "None" but I couldn't get passed the error in VB.I think there may also be an issue with the way I am converting a string into a byte array in VB vs Air.
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Mar 17, 2010
I give a file as parameter it crypts it with anything I don't really care if its safe or not I just want to person to not understand anything if he try's to read the file directly.so something like
[code]...
I want it to open the file, rechange it to the uncrypted value then close the file. I'm using serialization so it has to be able to crypt and decrypt anything serialization does.
Reason:
When I open the file the file serialized I can still see some text.I can still see some text. =]
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Dec 15, 2011
Im having a problem in my coding. I am doing a username and password application (sumtthing like a password keeper).
So I have created the interface and i integrated vb 2008 with sql server 2008. So the adding of account and password all went fine.
I have applied aes 128 bits for the password. that means when the user enters a new record for example an email and he click save, the password will automatically be encrypted before it is saved in the database.
now im having a problem where when i want to display the password in the gridview of vb.net (i decided to use grid view to show all the username and password), i am having trouble in decrypting the password column to show the real password to the user.
of course user cant decrypt the password using their brains. so I want to know how to choose dat particular column (password column) and decrypt it before it appears in the gridview.
bcoz now it is appearing gibberish i.e. aes 128 bits. Below i show u some snippet of my codes in encrypting and storing it in the database. [code....]
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Oct 23, 2011
I'm using this function to encrypt data but how do I decrypt it?
Public Function GenerateHash(ByVal SourceText As String) As String
[code...]
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Nov 2, 2011
how to encrypt / decrypt a string in VB.Net.I followed the example given here and wrote the following code (below). There's a text box, an "encrypt" button, and a "decrypt" button. The idea is to type something into the text box ("like 'hello world'"), click "encrypt", and see the encrypted version appear in the text box. Clicking "decrypt" should then take you back to the original string.
But when I try to encrypt I get an error when I try to "FlushFinalBlock". The error is: "Length of the data to encrypt is invalid".The "decrypt" part is a total shot in the dark, as the example quoted above only deals with encryption, not decryption. I'm sure it's wrong, but since I can't get "encrypt" to work I haven't tested it yet.
Imports System.Data.SqlClient
Imports System.IO
Imports System.Security.Cryptography
Public Class Form1
[code]....
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Feb 13, 2009
how to encrypt and decrypt strings.
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Aug 18, 2011
I just know it works. So as a personal project I'm trying to learn in VB/C# all about Cryptographic methods and how to use those techniques to encrypt and decrypt files. [code]
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Is it possible to decrypt a SHA1 string in VB.Net, knowing the key? I have seen "decryption" of credentials before, however - in Java: [URL]
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