(VB.NET) RSA Encrypt and Decrypt Strings

VB.NET sample code to RSA public-key encrypt and decrypt strings using public and private keys.

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' This example assumes the Chilkat API to have been previously unlocked.
' See Global Unlock Sample for sample code.

Dim rsa As New Chilkat.Rsa

' This example also generates the public and private
' keys to be used in the RSA encryption.
' Normally, you would generate a key pair once,
' and distribute the public key to your partner.
' Anything encrypted with the public key can be
' decrypted with the private key.  The reverse is 
' also true: anything encrypted using the private
' key can be decrypted using the public key.

' Generate a 1024-bit key.  Chilkat RSA supports
' key sizes ranging from 512 bits to 4096 bits.
Dim success As Boolean = rsa.GenerateKey(1024)
If (success <> True) Then
    Debug.WriteLine(rsa.LastErrorText)
    Exit Sub
End If


' Keys are exported in XML format:
Dim publicKey As String = rsa.ExportPublicKey()
Dim privateKey As String = rsa.ExportPrivateKey()

Dim plainText As String = "Encrypting and decrypting should be easy!"

' Start with a new RSA object to demonstrate that all we
' need are the keys previously exported:
Dim rsaEncryptor As New Chilkat.Rsa

' Encrypted output is always binary.  In this case, we want
' to encode the encrypted bytes in a printable string.
' Our choices are "hex", "base64", "url", "quoted-printable".
rsaEncryptor.EncodingMode = "hex"

' We'll encrypt with the public key and decrypt with the private
' key.  It's also possible to do the reverse.
success = rsaEncryptor.ImportPublicKey(publicKey)

Dim usePrivateKey As Boolean = False
Dim encryptedStr As String = rsaEncryptor.EncryptStringENC(plainText,usePrivateKey)
Debug.WriteLine(encryptedStr)

' Now decrypt:
Dim rsaDecryptor As New Chilkat.Rsa

rsaDecryptor.EncodingMode = "hex"
success = rsaDecryptor.ImportPrivateKey(privateKey)

usePrivateKey = True
Dim decryptedStr As String = rsaDecryptor.DecryptStringENC(encryptedStr,usePrivateKey)

Debug.WriteLine(decryptedStr)