?
Solved

Encrypt a string or a byte?

Posted on 2007-04-11
5
Medium Priority
?
256 Views
Last Modified: 2010-04-24
How can I encrypt a stream or a byte?

Thanks
0
Comment
Question by:Ruttensoft
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
5 Comments
 
LVL 96

Accepted Solution

by:
Bob Learned earned 672 total points
ID: 18891768
Here is an example from an MSDN help topic:

   Sub EncryptTextToFile(ByVal Data As String, ByVal FileName As String, ByVal Key() As Byte, ByVal IV() As Byte)
        Try
            ' Create or open the specified file.
            Dim fStream As FileStream = File.Open(FileName, FileMode.OpenOrCreate)

            ' Create a new Rijndael object.
            Dim RijndaelAlg As Rijndael = Rijndael.Create

            ' Create a CryptoStream using the FileStream
            ' and the passed key and initialization vector (IV).
            Dim cStream As New CryptoStream(fStream, _
                                           RijndaelAlg.CreateEncryptor(Key, IV), _
                                           CryptoStreamMode.Write)

            ' Create a StreamWriter using the CryptoStream.
            Dim sWriter As New StreamWriter(cStream)

            Try

                ' Write the data to the stream
                ' to encrypt it.
                sWriter.WriteLine(Data)
            Catch e As Exception

                Console.WriteLine("An error occurred: {0}", e.Message)

            Finally

                ' Close the streams and
                ' close the file.
                sWriter.Close()
                cStream.Close()
                fStream.Close()

            End Try
        Catch e As CryptographicException
            Console.WriteLine("A Cryptographic error occurred: {0}", e.Message)
        Catch e As UnauthorizedAccessException
            Console.WriteLine("A file error occurred: {0}", e.Message)
        End Try
    End Sub

CryptoStream class:
http://msdn2.microsoft.com/en-us/library/system.security.cryptography.cryptostream.aspx

Bob
0
 
LVL 3

Assisted Solution

by:dmagliola
dmagliola earned 664 total points
ID: 18891770
Check out this article:
http://www.codeproject.com/dotnet/SimpleEncryption.asp

The part under the "Encryption.Symmetric" title is probably what you're most interested in.
0
 
LVL 86

Assisted Solution

by:Mike Tomlinson
Mike Tomlinson earned 664 total points
ID: 18895273
Here is a very simple Encryption/Decryption class that works with Strings.  

Imports System.IO
Imports System.Text
Imports System.Security.Cryptography

Public Class Crypto

    Private Shared DES As New TripleDESCryptoServiceProvider
    Private Shared MD5 As New MD5CryptoServiceProvider

    Public Shared Function MD5Hash(ByVal value As String) As Byte()
        Return MD5.ComputeHash(ASCIIEncoding.ASCII.GetBytes(value))
    End Function

    Public Shared Function Encrypt(ByVal stringToEncrypt As String, ByVal key As String) As String
        DES.Key = Crypto.MD5Hash(key)
        DES.Mode = CipherMode.ECB
        Dim Buffer As Byte() = ASCIIEncoding.ASCII.GetBytes(stringToEncrypt)
        Return Convert.ToBase64String(DES.CreateEncryptor().TransformFinalBlock(Buffer, 0, Buffer.Length))
    End Function

    Public Shared Function Decrypt(ByVal encryptedString As String, ByVal key As String) As String
        Try
            DES.Key = Crypto.MD5Hash(key)
            DES.Mode = CipherMode.ECB
            Dim Buffer As Byte() = Convert.FromBase64String(encryptedString)
            Return ASCIIEncoding.ASCII.GetString(DES.CreateDecryptor().TransformFinalBlock(Buffer, 0, Buffer.Length))
        Catch ex As Exception
            MessageBox.Show("Invalid Key", "Decryption Failed", MessageBoxButtons.OK, MessageBoxIcon.Exclamation)
        End Try
    End Function

End Class
0

Featured Post

NFR key for Veeam Agent for Linux

Veeam is happy to provide a free NFR license for one year.  It allows for the non‑production use and valid for five workstations and two servers. Veeam Agent for Linux is a simple backup tool for your Linux installations, both on‑premises and in the public cloud.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Whether you’re a college noob or a soon-to-be pro, these tips are sure to help you in your journey to becoming a programming ninja and stand out from the crowd.
Q&A with Course Creator, Mark Lassoff, on the importance of HTML5 in the career of a modern-day developer.
Viewers will learn how to properly install Eclipse with the necessary JDK, and will take a look at an introductory Java program. Download Eclipse installation zip file: Extract files from zip file: Download and install JDK 8: Open Eclipse and …
In this fifth video of the Xpdf series, we discuss and demonstrate the PDFdetach utility, which is able to list and, more importantly, extract attachments that are embedded in PDF files. It does this via a command line interface, making it suitable …
Suggested Courses

777 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question