Code  to encrypt and then decrypt data using Rijndael class

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

Class RijndaelExample

Public Shared Sub Main()
Try

Dim original As String = “Here is some data to encrypt!”

‘ Create a new instance of the Rijndael
‘ class. This generates a new key and initialization
‘ vector (IV).
Using myRijndael = Rijndael.Create()

‘ Encrypt the string to an array of bytes.
Dim encrypted As Byte() = EncryptStringToBytes(original, myRijndael.Key, myRijndael.IV)

‘ Decrypt the bytes to a string.
Dim roundtrip As String = DecryptStringFromBytes(encrypted, myRijndael.Key, myRijndael.IV)

‘Display the original data and the decrypted data.
Console.WriteLine(“Original: {0}”, original)
Console.WriteLine(“Round Trip: {0}”, roundtrip)
End Using
Catch e As Exception
Console.WriteLine(“Error: {0}”, e.Message)
End Try

End Sub ‘Main

Shared Function EncryptStringToBytes(ByVal plainText As String, ByVal Key() As Byte, ByVal IV() As Byte) As Byte()
‘ Check arguments.
If plainText Is Nothing OrElse plainText.Length <= 0 Then Throw New ArgumentNullException("plainText") End If If Key Is Nothing OrElse Key.Length <= 0 Then Throw New ArgumentNullException("Key") End If If IV Is Nothing OrElse IV.Length <= 0 Then Throw New ArgumentNullException("IV") End If Dim encrypted() As Byte ' Create an Rijndael object ' with the specified key and IV. Using rijAlg = Rijndael.Create()rijAlg.Key = Key rijAlg.IV = IV' Create an encryptor to perform the stream transform. Dim encryptor As ICryptoTransform = rijAlg.CreateEncryptor(rijAlg.Key, rijAlg.IV) ' Create the streams used for encryption. Using msEncrypt As New MemoryStream() Using csEncrypt As New CryptoStream(msEncrypt, encryptor, CryptoStreamMode.Write) Using swEncrypt As New StreamWriter(csEncrypt)'Write all data to the stream. swEncrypt.Write(plainText) End Using encrypted = msEncrypt.ToArray() End Using End Using End Using' Return the encrypted bytes from the memory stream. Return encryptedEnd Function 'EncryptStringToBytesShared Function DecryptStringFromBytes(ByVal cipherText() As Byte, ByVal Key() As Byte, ByVal IV() As Byte) As String ' Check arguments. If cipherText Is Nothing OrElse cipherText.Length <= 0 Then Throw New ArgumentNullException("cipherText") End If If Key Is Nothing OrElse Key.Length <= 0 Then Throw New ArgumentNullException("Key") End If If IV Is Nothing OrElse IV.Length <= 0 Then Throw New ArgumentNullException("IV") End If ' Declare the string used to hold ' the decrypted text. Dim plaintext As String = Nothing' Create an Rijndael object ' with the specified key and IV. Using rijAlg = Rijndael.Create() rijAlg.Key = Key rijAlg.IV = IV' Create a decryptor to perform the stream transform. Dim decryptor As ICryptoTransform = rijAlg.CreateDecryptor(rijAlg.Key, rijAlg.IV)' Create the streams used for decryption. Using msDecrypt As New MemoryStream(cipherText)Using csDecrypt As New CryptoStream(msDecrypt, decryptor, CryptoStreamMode.Read)Using srDecrypt As New StreamReader(csDecrypt)' Read the decrypted bytes from the decrypting stream ' and place them in a string. plaintext = srDecrypt.ReadToEnd() End Using End Using End Using End UsingReturn plaintextEnd Function 'DecryptStringFromBytes End Class

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