Rsa Key Pair Generator C#

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Rsa
C# Rsa Key Generation
Rsa Key Pair Generator C Code

Aug 04, 2009 RSA encryption can't handle more data the the key size (a few KB at most), without performing voodoo maneuvers of slicing the data. The obvious solution is to encrypt the data using symmetric key algorithm like AES. If asymmetric (two keys) algorithm is required, you can use the RSA asymmetric algorithm to encrypt the AES key. To generate a set of RSA keys with PuTTYgen: Start the PuTTYgen utility, by double-clicking on its.exe file; For Type of key to generate, select RSA; In the Number of bits in a generated key field, specify either 2048 or 4096 (increasing the bits makes it harder to crack the key by brute-force methods. Makes initial auth a bit slower but the.

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This walkthrough demonstrates how to encrypt and decrypt content. The code examples are designed for a Windows Forms application. This application does not demonstrate real world scenarios, such as using smart cards. Instead, it demonstrates the fundamentals of encryption and decryption.

This walkthrough uses the following guidelines for encryption:

Use the RijndaelManaged class, a symmetric algorithm, to encrypt and decrypt data by using its automatically generated Key and IV.
Use the RSACryptoServiceProvider, an asymmetric algorithm, to encrypt and decrypt the key to the data encrypted by RijndaelManaged. Asymmetric algorithms are best used for smaller amounts of data, such as a key.
Note
If you want to protect data on your computer instead of exchanging encrypted content with other people, consider using the ProtectedData or ProtectedMemory classes.

The following table summarizes the cryptographic tasks in this topic.

Task	Description
Creating a Windows Forms application	Lists the controls that are required to run the application.
Declaring global objects	Declares string path variables, the CspParameters, and the RSACryptoServiceProvider to have global context of the Form class.
Creating an asymmetric key	Creates an asymmetric public and private key value pair and assigns it a key container name.
Encrypting a file	Displays a dialog box to select a file for encryption and encrypts the file.
Decrypting a file	Displays a dialog box to select an encrypted file for decryption and decrypts the file.
Getting a private key	Gets the full key pair using the key container name.
Exporting a public key	Saves the key to an XML file with only public parameters.
Importing a public key	Loads the key from an XML file into the key container.
Testing the application	Lists procedures for testing this application.

Prerequisites

You need the following components to complete this walkthrough:

References to the System.IO and System.Security.Cryptography namespaces.

Creating a Windows Forms Application

Most of the code examples in this walkthrough are designed to be event handlers for button controls. The following table lists the controls required for the sample application and their required names to match the code examples.

Control	Name	Text property (as needed)
Button	`buttonEncryptFile`	Encrypt File
Button	`buttonDecryptFile`	Decrypt File
Button	`buttonCreateAsmKeys`	Create Keys
Button	`buttonExportPublicKey`	Export Public Key
Button	`buttonImportPublicKey`	Import Public Key
Button	`buttonGetPrivateKey`	Get Private Key
Label	`label1`	Key not set
OpenFileDialog	`openFileDialog1`
OpenFileDialog	`openFileDialog2`

Ulead video studio 11 free download. Double-click the buttons in the Visual Studio designer to create their event handlers.

Declaring Global Objects

Add the following code to the Form's constructor. Edit the string variables for your environment and preferences.

Creating an Asymmetric Key

This task creates an asymmetric key that encrypts and decrypts the RijndaelManaged key. This key was used to encrypt the content and it displays the key container name on the label control.

Add the following code as the Click event handler for the Create Keys button (buttonCreateAsmKeys_Click).

Encrypting a File

This task involves two methods: the event handler method for the Encrypt File button (buttonEncryptFile_Click) and the EncryptFile method. The first method displays a dialog box for selecting a file and passes the file name to the second method, which performs the encryption.

The encrypted content, key, and IV are all saved to one FileStream, which is referred to as the encryption package.

The EncryptFile method does the following:

Creates a RijndaelManaged symmetric algorithm to encrypt the content.
Creates an RSACryptoServiceProvider object to encrypt the RijndaelManaged key.
Uses a CryptoStream object to read and encrypt the FileStream of the source file, in blocks of bytes, into a destination FileStream object for the encrypted file.
Determines the lengths of the encrypted key and IV, and creates byte arrays of their length values.
Writes the Key, IV, and their length values to the encrypted package.

The encryption package uses the following format:

Key length, bytes 0 - 3
IV length, bytes 4 - 7
Encrypted key
IV
Cipher text

You can use the lengths of the key and IV to determine the starting points and lengths of all parts of the encryption package, which can then be used to decrypt the file.

Add the following code as the Click event handler for the Encrypt File button (buttonEncryptFile_Click).

Add the following EncryptFile method to the form.

Decrypting a File

This task involves two methods, the event handler method for the Decrypt File button (buttonDecryptFile_Click), and the DecryptFile method. The first method displays a dialog box for selecting a file and passes its file name to the second method, which performs the decryption.

The Decrypt method does the following:

Creates a RijndaelManaged symmetric algorithm to decrypt the content.
Reads the first eight bytes of the FileStream of the encrypted package into byte arrays to obtain the lengths of the encrypted key and the IV.
Extracts the key and IV from the encryption package into byte arrays.
Creates an RSACryptoServiceProvider object to decrypt the RijndaelManaged key.
Uses a CryptoStream object to read and decrypt the cipher text section of the FileStream encryption package, in blocks of bytes, into the FileStream object for the decrypted file. When this is finished, the decryption is completed.

Add the following code as the Click event handler for the Decrypt File button.

Add the following DecryptFile method to the form.

Exporting a Public Key

This task saves the key created by the Create Keys button to a file. It exports only the public parameters.

This task simulates the scenario of Alice giving Bob her public key so that he can encrypt files for her. He and others who have that public key will not be able to decrypt them because they do not have the full key pair with private parameters.

Add the following code as the Click event handler for the Export Public Key button (buttonExportPublicKey_Click).

Importing a Public Key

This task loads the key with only public parameters, as created by the Export Public KeyCsgo product key generator online. button, and sets it as the key container name.

This task simulates the scenario of Bob loading Alice's key with only public parameters so he can encrypt files for her.

Add the following code as the Click event handler for the Import Public Key button (buttonImportPublicKey_Click).

Getting a Private Key

This task sets the key container name to the name of the key created by using the Create Keys button. The key container will contain the full key pair with private parameters.

Rsa

This task simulates the scenario of Alice using her private key to decrypt files encrypted by Bob.

Add the following code as the Click event handler for the Get Private Key button (buttonGetPrivateKey_Click).

Testing the Application

After you have built the application, perform the following testing scenarios.

To create keys, encrypt, and decrypt

Click the Create Keys button. The label displays the key name and shows that it is a full key pair.
Click the Export Public Key button. Note that exporting the public key parameters does not change the current key.
Click the Encrypt File button and select a file.
Click the Decrypt File button and select the file just encrypted.
Examine the file just decrypted.
Close the application and restart it to test retrieving persisted key containers in the next scenario.

To encrypt using the public key

Click the Import Public Key button. The label displays the key name and shows that it is public only.
Click the Encrypt File button and select a file.
Click the Decrypt File button and select the file just encrypted. This will fail because you must have the private key to decrypt.

This scenario demonstrates having only the public key to encrypt a file for another person. Typically that person would give you only the public key and withhold the private key for decryption.

To decrypt using the private key

Click the Get Private Key button. The label displays the key name and shows whether it is the full key pair.
Click the Decrypt File button and select the file just encrypted. This will be successful because you have the full key pair to decrypt.

Create a key pair

To create a key pair, at a command prompt, type the following command:

sn –k <file name>

In this command, file name is the name of the output file containing the key pair.

The following example creates a key pair called sgKey.snk.

If you intend to delay sign an assembly and you control the whole key pair (which is unlikely outside test scenarios), you can use the following commands to generate a key pair and then extract the public key from it into a separate file. First, create the key pair:

C# Rsa Key Generation

Next, extract the public key from the key pair and copy it to a separate file:

Once you create the key pair, you must put the file where the strong name signing tools can find it.

When signing an assembly with a strong name, the Assembly Linker (Al.exe) looks for the key file relative to the current directory and to the output directory. When using command-line compilers, you can simply copy the key to the current directory containing your code modules.

If you are using an earlier version of Visual Studio that does not have a Signing tab in the project properties, the recommended key file location is the project directory with the file attribute specified as follows:

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