Export (0) Print
Expand All

FromBase64Transform Class

Converts a CryptoStream from base 64.

System::Object
  System.Security.Cryptography::FromBase64Transform

Namespace:  System.Security.Cryptography
Assembly:  mscorlib (in mscorlib.dll)

[ComVisibleAttribute(true)]
public ref class FromBase64Transform : ICryptoTransform, 
	IDisposable

The FromBase64Transform type exposes the following members.

  NameDescription
Public methodFromBase64Transform()Initializes a new instance of the FromBase64Transform class.
Public methodFromBase64Transform(FromBase64TransformMode)Initializes a new instance of the FromBase64Transform class with the specified transformation mode.
Top

  NameDescription
Public propertyCanReuseTransformGets a value indicating whether the current transform can be reused.
Public propertyCanTransformMultipleBlocksGets a value that indicates whether multiple blocks can be transformed.
Public propertyInputBlockSizeGets the input block size.
Public propertyOutputBlockSizeGets the output block size.
Top

  NameDescription
Public methodClearReleases all resources used by the FromBase64Transform.
Public methodDispose()Releases all resources used by the current instance of the FromBase64Transform class.
Protected methodDispose(Boolean)Releases the unmanaged resources used by the FromBase64Transform and optionally releases the managed resources.
Public methodEquals(Object)Determines whether the specified object is equal to the current object. (Inherited from Object.)
Protected methodFinalizeReleases the unmanaged resources used by the FromBase64Transform. (Overrides Object::Finalize().)
Public methodGetHashCodeServes as the default hash function. (Inherited from Object.)
Public methodGetTypeGets the Type of the current instance. (Inherited from Object.)
Protected methodMemberwiseCloneCreates a shallow copy of the current Object. (Inherited from Object.)
Public methodToStringReturns a string that represents the current object. (Inherited from Object.)
Public methodTransformBlockConverts the specified region of the input byte array from base 64 and copies the result to the specified region of the output byte array.
Public methodTransformFinalBlockConverts the specified region of the specified byte array from base 64.
Top

Base 64 Content-Transfer-Encoding represents arbitrary bit sequences in a form that is not human readable.

The following example decodes a base 64-encoded file to an output text file.

using namespace System;
using namespace System::IO;
using namespace System::Security::Cryptography;
class MyMainClass
{
public:
   static void DecodeFromFile( String^ inFileName, String^ outFileName )
   {
      FromBase64Transform^ myTransform = gcnew FromBase64Transform( FromBase64TransformMode::IgnoreWhiteSpaces );
      array<Byte>^myOutputBytes = gcnew array<Byte>(myTransform->OutputBlockSize);

      //Open the input and output files.
      FileStream^ myInputFile = gcnew FileStream( inFileName,FileMode::Open,FileAccess::Read );
      FileStream^ myOutputFile = gcnew FileStream( outFileName,FileMode::Create,FileAccess::Write );

      //Retrieve the file contents into a Byte array. 
      array<Byte>^myInputBytes = gcnew array<Byte>(myInputFile->Length);
      myInputFile->Read( myInputBytes, 0, myInputBytes->Length );

      //Transform the data in chunks the size of InputBlockSize. 
      int i = 0;
      while ( myInputBytes->Length - i > 4 )
      {
         myTransform->TransformBlock( myInputBytes, i, 4, myOutputBytes, 0 );

         /*myTransform->InputBlockSize*/
         i += 4;

         /*myTransform->InputBlockSize*/
         myOutputFile->Write( myOutputBytes, 0, myTransform->OutputBlockSize );
      }


      //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();
      myInputFile->Close();
      myOutputFile->Close();
   }

};

int main()
{
   MyMainClass * m = new MyMainClass;

   //Insert your file names into this method call.
   m->DecodeFromFile(  "c:\\encoded.txt",  "c:\\roundtrip.txt" );
}

.NET Framework

Supported in: 4.5, 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.
Show:
© 2014 Microsoft