Simple Encryption/Decryption

SymmetricCryptoStream is a PipeStream type (see PowerTCP Secure Implementation Explained for more info on PipeStreams) which encrypts/decrypts data passing to/from the SymmetricCryptoStream to another stream. This implementation is useful for encrypting/decrypting any type of stream-based data. For this example, data will be encrypted and written to a file, then decrypted and displayed.

To encrypt/decrypt data.

First create a key and some test data to encrypt.

[C#]
// Create a key and some data.
byte[] key = System.Text.Encoding.Default.GetBytes("test key");
byte[] data = System.Text.Encoding.Default.GetBytes("This is the plain text data");

[Visual Basic]
' Create a key and some data.
Dim key As Byte() = System.Text.Encoding.Default.GetBytes("test key")
Dim data As Byte() = System.Text.Encoding.Default.GetBytes("This is the plain text data")

Create a FileStream to write the encrypted data to and a SymmetricCryptoStream to use to encrypt the data. SymmetricCryptoStream.Write the data to the file. It will be encrypted.

[C#]
// Create a FileStream to hold the data
System.IO.FileStream f = new System.IO.FileStream("C:\\encrypted", System.IO.FileMode.Create);
Dart.PowerTCP.SslSockets.SymmetricCryptoStream sc = new Dart.PowerTCP.SslSockets.SymmetricCryptoStream(key, f);

// Write to the file. This encrypts the data.
sc.Write(data, 0, data.Length);
sc.Position=0;
f.Close();

[Visual Basic]
' Create a FileStream to hold the data
Dim f As System.IO.FileStream = New System.IO.FileStream("C:\encrypted", System.IO.FileMode.Create)
Dim sc As New Dart.PowerTCP.SslSockets.SymmetricCryptoStream(key, f)

' Write to the file. This encrypts the data.
sc.Write(data, 0, data.Length)
sc.Position = 0
f.Close()

Now to decrypt the data. Reinitialize the FileStream to read the file and reinitialize the SymmetricCryptoStream. Read data from the file. It will automatically be decrypted.

[C#]
// Now read the data from the encrypted file to decrypt
f = new System.IO.FileStream("C:\\encrypted", System.IO.FileMode.Open);
sc = new Dart.PowerTCP.SslSockets.SymmetricCryptoStream(key, f);

data = new byte[sc.Length];
sc.Read(data, 0, data.Length);

sc.Position = 0;
f.Close();

// Display results
Debug.WriteLine(System.Text.Encoding.Default.GetString(data));

[Visual Basic]
' Now read the data from the encrypted file to decrypt
f = new System.IO.FileStream("C:\encrypted", System.IO.FileMode.Open)
sc = new Dart.PowerTCP.SslSockets.SymmetricCryptoStream(key, f)

data = new byte(sc.Length)
sc.Read(data, 0, data.Length)

sc.Position = 0
f.Close()

' Display results
Debug.WriteLine(System.Text.Encoding.Default.GetString(data))

The decrypted ("plain text") data should be displayed. To see the encrypted text, open the file "C:\Encrypted". Also, it is often useful to change the FileStream to another type of stream. For example, use a MemoryStream to encrypt/decrypt data in memory only.

In This Section

Security Overview: Provides an overview of basic security concepts such as digital certificates and authentication.
PowerTCP Secure Implementation Explained: Discusses how security is implemented in PowerTCP SSL Sockets for .NET
Creating an SSL Client: Discusses how to create an SSL Client using the Tcp component.
Creating an SSL Server: Discusses how to create an SSL Server using the Server component.
Using the CertificateListForm Object: Demonstrates how to use the CertificateListForm to assist users in selecting a certificate.
Using MMC to Manage SSL Certificates: Discusses how to use the Microsoft Management Console to manage SSL certificates.
Simple Encryption/Decryption: Demonstrates how to use the SymmetricCryptoStream to encrypt/decrypt stream-based data.
Windows 95/98 Security Compatibility: Discusses compatibility issues with Windows 95 and 98.

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Documentation version 1.1.2.0.