Public-Key Encryption Example in C#

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How to public-key encrypt and decrypt a string using a digital certificate in C#

This is a simple example demonstrating how to public-key encrypt and decrypt a string in C#.

// Encrypt text using a digital certificate (i.e. public key encryption)
// The public-key associated with the certificate is needed to encrypt,
// but to decrypt, the private key must be available.
private void PKEncrypt_Click(object sender, System.EventArgs e)
{
	String s = "This string is to be encrypted.";
	listBox1.Items.Add(s);
	
	Chilkat.Crypt crypt = new Chilkat.Crypt();
	crypt.UnlockComponent("UnlockCode");

	// Use RSA public-key encryption.
	crypt.SetAlgorithmRSA();

	// Tell Chilkat Crypt to find and use the first certificate found
	// where one of the certificate's subject fields matches the
	// string passed here.
	crypt.EncryptCertSubject = "harry@chilkatsoft.com";

 // Encrypt and convert the result bytes to Base-64.
	byte [] encryptedBytes = crypt.EncryptStr(s);
	String encrypted = crypt.EncodeBase64(encryptedBytes);

	textBox1.Text = encrypted;

	// Display the last certificate subject and algorithm used.
	listBox1.Items.Add(crypt.LastCertSubject);
	listBox1.Items.Add(crypt.LastAlgorithm);

	// Now decrypt...
	String originalText = crypt.DecryptStr(crypt.DecodeBase64(encrypted));
	listBox1.Items.Add(originalText);
}