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FromBase64Transform Class
Visual Studio 2010
Converts a CryptoStream from base 64.
Assembly: mscorlib (in mscorlib.dll)
The FromBase64Transform type exposes the following members.
| Name | Description | |
|---|---|---|
![]() | FromBase64Transform | Initializes a new instance of the FromBase64Transform class. |
![]() | FromBase64Transform(FromBase64TransformMode) | Initializes a new instance of the FromBase64Transform class with the specified transformation mode. |
| Name | Description | |
|---|---|---|
![]() | CanReuseTransform | Gets a value indicating whether the current transform can be reused. |
![]() | CanTransformMultipleBlocks | Gets a value that indicates whether multiple blocks can be transformed. |
![]() | InputBlockSize | Gets the input block size. |
![]() | OutputBlockSize | Gets the output block size. |
| Name | Description | |
|---|---|---|
![]() | Clear | Releases all resources used by the FromBase64Transform. |
![]() | Dispose | Releases all resources used by the current instance of the FromBase64Transform class. |
![]() | Dispose(Boolean) | Releases the unmanaged resources used by the FromBase64Transform and optionally releases the managed resources. |
![]() | Equals(Object) | Determines whether the specified Object is equal to the current Object. (Inherited from Object.) |
![]() | Finalize | Releases the unmanaged resources used by the FromBase64Transform. (Overrides Object.Finalize.) |
![]() | GetHashCode | Serves as a hash function for a particular type. (Inherited from Object.) |
![]() | GetType | Gets the Type of the current instance. (Inherited from Object.) |
![]() | MemberwiseClone | Creates a shallow copy of the current Object. (Inherited from Object.) |
![]() | ToString | Returns a string that represents the current object. (Inherited from Object.) |
![]() | TransformBlock | Converts the specified region of the input byte array from base 64 and copies the result to the specified region of the output byte array. |
![]() | TransformFinalBlock | Converts the specified region of the specified byte array from base 64. |
The following example decrypts a base 64-encoded file to an output text file.
Imports System.IO Imports System.Security.Cryptography Friend Class Members <STAThread()> _ Shared Sub Main(ByVal args() As String) Dim appPath As String = (System.IO.Directory.GetCurrentDirectory()) appPath = appPath & "..\\..\\..\" ' Insert your file names into this method call. EncodeFromFile(appPath & "program.vb", appPath & "code.enc") DecodeFromFile(appPath & "code.enc", appPath & "roundtrip.txt") End Sub ' Read in the specified source file and write out an encoded target file. Private Shared Sub EncodeFromFile(ByVal sourceFile As String, ByVal targetFile As String) ' Verify members.cs exists at the specified directory. If Not File.Exists(sourceFile) Then Console.Write("Unable to locate source file located at ") Console.WriteLine(sourceFile & ".") Console.Write("Please correct the path and run the ") Console.WriteLine("sample again.") Return End If ' Retrieve the input and output file streams. Using inputFileStream As New FileStream(sourceFile, FileMode.Open, FileAccess.Read) Using outputFileStream As New FileStream(targetFile, FileMode.Create, FileAccess.Write) ' Create a new ToBase64Transform object to convert to base 64. Dim base64Transform As New ToBase64Transform() ' Create a new byte array with the size of the output block size. Dim outputBytes(base64Transform.OutputBlockSize - 1) As Byte ' Retrieve the file contents into a byte array. Dim inputBytes(inputFileStream.Length - 1) As Byte inputFileStream.Read(inputBytes, 0, inputBytes.Length) ' Verify that multiple blocks can not be transformed. If Not base64Transform.CanTransformMultipleBlocks Then ' Initializie the offset size. Dim inputOffset As Integer = 0 ' Iterate through inputBytes transforming by blockSize. Dim inputBlockSize As Integer = base64Transform.InputBlockSize Do While inputBytes.Length - inputOffset > inputBlockSize base64Transform.TransformBlock(inputBytes, inputOffset, inputBytes.Length - inputOffset, outputBytes, 0) inputOffset += base64Transform.InputBlockSize outputFileStream.Write(outputBytes, 0, base64Transform.OutputBlockSize) Loop ' Transform the final block of data. outputBytes = base64Transform.TransformFinalBlock(inputBytes, inputOffset, inputBytes.Length - inputOffset) outputFileStream.Write(outputBytes, 0, outputBytes.Length) Console.WriteLine("Created encoded file at " & targetFile) End If ' Determine if the current transform can be reused. If Not base64Transform.CanReuseTransform Then ' Free up any used resources. base64Transform.Clear() End If End Using End Using End Sub Public Shared Sub DecodeFromFile(ByVal inFileName As String, ByVal outFileName As String) Using myTransform As New FromBase64Transform(FromBase64TransformMode.IgnoreWhiteSpaces) Dim myOutputBytes(myTransform.OutputBlockSize - 1) As Byte 'Open the input and output files. Using myInputFile As New FileStream(inFileName, FileMode.Open, FileAccess.Read) Using myOutputFile As New FileStream(outFileName, FileMode.Create, FileAccess.Write) 'Retrieve the file contents into a byte array. Dim myInputBytes(myInputFile.Length - 1) As Byte myInputFile.Read(myInputBytes, 0, myInputBytes.Length) 'Transform the data in chunks the size of InputBlockSize. Dim i As Integer = 0 Do While myInputBytes.Length - i > 4 'myTransform.InputBlockSize Dim bytesWritten As Int32 = myTransform.TransformBlock(myInputBytes, i, 4, myOutputBytes, 0) 'myTransform.InputBlockSize i += 4 'myTransform.InputBlockSize myOutputFile.Write(myOutputBytes, 0, bytesWritten) Loop 'Transform the final block of data. myOutputBytes = myTransform.TransformFinalBlock(myInputBytes, i, myInputBytes.Length - i) myOutputFile.Write(myOutputBytes, 0, myOutputBytes.Length) 'Free up any used resources. myTransform.Clear() End Using End Using End Using End Sub End Class End Class
Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2
The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.
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