Base-64 encoding

Base-64 encoding is a commonly used encoding format useful for displaying and transporting encrypted data, where often appear bytes without visible representation.

DidiSoft OpenSSL Library for .NET offers a set of classes that provide Base-64 encoding and decoding methods:

DidiSoft.Base64.Base64Util – provides static methods for base-64 encoding decoding files, strings and byte arrays
DidiSoft.Base64.Base64InputStream – input Stream that reads transparently base-64 encoded data as if it wasn’t encoded at all
DidiSoft.Base64.Base64OutputStream – output Stream that writes transparently base-64 encoded data

Table of samples

Read Base-64 encoded data with Stream with Base64InputStream

DidiSoft.Base64.Base64InputStream is a System.IO.Stream sub class that can wrap another Stream containing base-64 encoded data and its read operations will return the decoded data transparently for the invoking code. Here is an example:

C# example

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Stream base64DataStream = ... // stream containing base-64 encoded data
// wrap the base-64 encoded Stream
using (Stream decoderStream = new Base64InputStream(dataStream))
// destination where decoded data will be written
using (Stream outputStream = File.Create("decoded.dat"))			{
	byte[] buffer = new byte[1024];
	int i = 0;
	while ((i = decoderStream.Read(buffer, 0, buffer.Length)) > 0)
	{
		outputStream.Write(buffer, 0, i);
	}
}

VB.NET example

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Dim dataStream As Stream = ... ' base64 encoded data stream
 
' wrap the base-64 encoded Stream
Using decoderStream As New Base64InputStream(dataStream)
	' destination where decoded data will be written
	Using decodedStream As File.Create("decoded.dat")		Dim buffer As Byte() = New Byte(1023) {}
		Dim i As Integer = 0
		While (InlineAssignHelper(i, decoderStream.Read(buffer, 0, buffer.Length))) > 0
			decodedStream.Write(buffer, 0, i)
		End While
	End Using
End Using

Write Base-64 encoded data with Stream with Base64OuptutStream

DidiSoft.Base64.Base64OuptutStream is a System.IO.Stream subclass designed to wrap output streams and convert the data passed to the Write methods into base-64 format. The examples below illustrate how to utilize this class:

C# example

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Stream dataStream = ... // input data
// destination where encoded data will be written
using (Stream outputStream = File.Create("base64.txt"))
// wrap base-64 encoded Stream
using (Stream encoderStream = new Base64OutputStream(outputStream)){
	byte[] buffer = new byte[1024];
	int i = 0;
	while ((i = dataStream.Read(buffer, 0, buffer.Length)) > 0)
	{
		encoderStream.Write(buffer, 0, i);
	}
}

VB.NET example

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Dim dataStream As Stream = ... ' input date
' destination where encoded data will be written
Using outputStream As File.Create("base64.txt")
	' wrap as base-64 encoded Stream
	Using encoderStream As Stream = New Base64OutputStream(outputStream)		Dim buffer As Byte() = New Byte(1023) {}
		Dim i As Integer = 0
		While (InlineAssignHelper(i, dataStream.Read(buffer, 0, buffer.Length))) > 0
			encoderStream.Write(buffer, 0, i)
		End While
	End Using
End Using

Convert file to/from Base-64

The class DidiSoft.Base64.Base64Util provides Encode/Decode methods that work with files,  strings, Streams and byte arrays. The example code below illustrates how to convert to and back from base-64 encoded format:

C# example

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using DidiSoft.Base64;
 
public class Base64FileDemo
{
	public void Demo()
	{
		Base64Util.Encode(@"Data\Input.txt", @"Data\Output.txt");		// Decoded.txt contains the same data as Input.txt
		Base64Util.Decode(@"Data\Output.txt", @"Data\Decoded.txt");
	}
}

VB.NET example

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Imports DidiSoft.Base64
 
Public Class Base64FileDemo
	Public Sub Demo()
		Base64Util.Encode("Data\Input.txt", "Data\Output.txt")		' Decoded.txt contains the same data as Input.txt
		Base64Util.Decode("Data\Output.txt", "Data\Decoded.txt")
	End Sub
End Class

Convert string to/from Base-64

Converting a string to and from base-64 format is similar to the example above. The specific point when working with strings is that we need an extra step when deconstructing a string message back from base-64 format. This is due to the fact that the Base64Util.Decode method cannot know for sure of the result from the decoding is a valid string message and this this extra step at the end of the sample code:

C# example

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using DidiSoft.Base64;
 
public class Base64StringDemo
{
	public void Demo()
	{
		string message = "Hello World"; 
		string encoded = Base64Util.Encode(message);
 
		// bae-64 decoding returns byte array as we don't know in advance 
		// is the decoded data a valid String message
		byte[] decoded = Base64Util.Decode(encoded);
		// we can now recreate the decoded String message
		string decodedMessage = UTF8Encoding.UTF8.GetString(decoded);
	}
}

VB.NET example

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Imports DidiSoft.Base64
 
Public Class Base64StringDemo
 Public Sub Demo()
	Dim message As String = "Hello World" 
	Dim encoded As String = Base64Util.Encode(message)
 
	' bae-64 decoding returns byte array as we don't know in advance 
	' is the decoded data a valid String message
	Dim decoded As Byte() = Base64Util.Decode(encoded)
	' we can now recreate the decoded String message
	Dim decodedMessage As String = UTF8Encoding.UTF8.GetString(decoded)
 End Sub
End Class

Convert byte array to/from Base-64

Converting a byte array to and back from base 64 encoded format is trivial as you can see from the sample code below:

C# example

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using DidiSoft.Base64;
 
public class Base64ByteArrayDemo
{
 public void Demo()
 {
	byte[] input = ... // input data 
	string encoded = Base64Util.Encode(input);
 
	// decoded data is the same as the input
	byte[] decoded = Base64Util.Decode(encoded);
 }
}

VB.NET example

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Imports DidiSoft.Base64
 
Public Class Base64ByteArrayDemo
 Public Sub Demo()
	Dim input As Byte() = ... ' input data 
	Dim encoded As String = Base64Util.Encode(input)
 
	' decoded data is the same as the input
	Dim decoded As Byte() = Base64Util.Decode(encoded)
 End Sub
End Class

Summary

This page illustrated how to perform Base-64 encoding of data stored in files, streams, string variables or byte arrays with C# and VB.NET examples. The sample code above can easily be adopted for any programming language supported on the .NET Framework or .NET Core.