FromBase64Transform.TransformBlock Method
Definition
Important
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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.
public:
virtual int TransformBlock(cli::array <System::Byte> ^ inputBuffer, int inputOffset, int inputCount, cli::array <System::Byte> ^ outputBuffer, int outputOffset);public int TransformBlock (byte[] inputBuffer, int inputOffset, int inputCount, byte[] outputBuffer, int outputOffset);abstract member TransformBlock : byte[] * int * int * byte[] * int -> int
override this.TransformBlock : byte[] * int * int * byte[] * int -> intPublic Function TransformBlock (inputBuffer As Byte(), inputOffset As Integer, inputCount As Integer, outputBuffer As Byte(), outputOffset As Integer) As IntegerParameters
- inputBuffer
- Byte[]
The input to compute from base 64.
- inputOffset
- Int32
The offset into the input byte array from which to begin using data.
- inputCount
- Int32
The number of bytes in the input byte array to use as data.
- outputBuffer
- Byte[]
The output to which to write the result.
- outputOffset
- Int32
The offset into the output byte array from which to begin writing data.
Returns
The number of bytes written.
Implements
Exceptions
The current FromBase64Transform object has already been disposed.
inputOffset is out of range. This parameter requires a non-negative number.
inputBuffer is null.
Examples
The following example decrypts 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" );
}
using System;
using System.IO;
using System.Security.Cryptography;
class Members
{
[STAThread]
static void Main(string[] args)
{
string appPath = (System.IO.Directory.GetCurrentDirectory() );
appPath = appPath + "..\\\\..\\\\..\\";
// Insert your file names into this method call.
EncodeFromFile(appPath + "program.cs", appPath + "code.enc");
DecodeFromFile(appPath + "code.enc", appPath + "roundtrip.txt");
}
// Read in the specified source file and write out an encoded target file.
private static void EncodeFromFile(string sourceFile, string targetFile)
{
// Verify members.cs exists at the specified directory.
if (!File.Exists(sourceFile))
{
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;
}
// Retrieve the input and output file streams.
using (FileStream inputFileStream =
new FileStream(sourceFile, FileMode.Open, FileAccess.Read))
{
using (FileStream outputFileStream =
new FileStream(targetFile, FileMode.Create, FileAccess.Write))
{
// Create a new ToBase64Transform object to convert to base 64.
ToBase64Transform base64Transform = new ToBase64Transform();
// Create a new byte array with the size of the output block size.
byte[] outputBytes = new byte[base64Transform.OutputBlockSize];
// Retrieve the file contents into a byte array.
byte[] inputBytes = new byte[inputFileStream.Length];
inputFileStream.Read(inputBytes, 0, inputBytes.Length);
// Verify that multiple blocks can not be transformed.
if (!base64Transform.CanTransformMultipleBlocks)
{
// Initialize the offset size.
int inputOffset = 0;
// Iterate through inputBytes transforming by blockSize.
int inputBlockSize = base64Transform.InputBlockSize;
while (inputBytes.Length - inputOffset > inputBlockSize)
{
base64Transform.TransformBlock(
inputBytes,
inputOffset,
inputBytes.Length - inputOffset,
outputBytes,
0);
inputOffset += base64Transform.InputBlockSize;
outputFileStream.Write(
outputBytes,
0,
base64Transform.OutputBlockSize);
}
// 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);
}
// Determine if the current transform can be reused.
if (!base64Transform.CanReuseTransform)
{
// Free any used resources.
base64Transform.Clear();
}
}
}
}
public static void DecodeFromFile(string inFileName, string outFileName)
{
using (FromBase64Transform myTransform = new FromBase64Transform(FromBase64TransformMode.IgnoreWhiteSpaces))
{
byte[] myOutputBytes = new byte[myTransform.OutputBlockSize];
// Open the input and output files.
using (FileStream myInputFile = new FileStream(inFileName, FileMode.Open, FileAccess.Read))
{
using (FileStream myOutputFile = new FileStream(outFileName, FileMode.Create, FileAccess.Write))
{
// Retrieve the file contents into a byte array.
byte[] myInputBytes = new 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.InputBlockSize*/)
{
int bytesWritten = myTransform.TransformBlock(myInputBytes, i, 4/*myTransform.InputBlockSize*/, myOutputBytes, 0);
i += 4/*myTransform.InputBlockSize*/;
myOutputFile.Write(myOutputBytes, 0, bytesWritten);
}
// 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();
}
}
}
}
}
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
Applies to
See also
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