VB.NET

RSA Encrypt Bytes to Base64 and Reverse

See more RSA Examples

Demonstrates how to RSA encrypt bytes to base64 and the reverse. VB.NET

Dim success As Boolean = False

' The RSA public key is used for encryption, and the private key for decryption.

' The public key's role is to make encryption accessible to anyone while ensuring that
' only the private key holder can decrypt the messages.
' The public key is designed to be widely distributed so anyone can use it to encrypt messages
' intended for the owner of the private key.

' Load our 2048-bit RSA public key.
Dim pubKey As New Chilkat.PublicKey
' In all Chilkat methods expecting a path, you pass either absolute or relative paths.
success = pubKey.LoadFromFile("qa_data/rsaKeys/myTestRsaPublic.pem")
If (success = False) Then
    Debug.WriteLine(pubKey.LastErrorText)
    Exit Sub
End If


Dim rsa As New Chilkat.Rsa

' Tell RSA to use the public key.
rsa.UsePublicKey(pubKey)

' RSA encryption is for small amounts of data, on the order of 200 bytes or less.
' The maximum number of bytes that can be RSA encrypted depends
' on the RSA key size and padding scheme (OAEP padding vs PKCS#1 v1.5 padding).
' For specific limits, see: RSA Encryption Maximum Number of Bytes

' A typical use for RSA is to encrypt symmetric encryption keys, such as an AES key.
Dim prng As New Chilkat.Prng
Dim keyBytes() As Byte
keyBytes = prng.GenRandomBytes(32)

rsa.EncodingMode = "base64"
Dim encryptedB64 As String = rsa.EncryptBytesENC(keyBytes,False)

Debug.WriteLine("Result:")
Debug.WriteLine(encryptedB64)

' Sample output:
' hTTV4Lbmm2V7NCw/HaoJL8Aq/MM/HXblQnjitrF9HY1zBlISwui2jGVVZDtZcZ/rICOpPw44w8Qb8AswFVE1sryydmNEvcIfYAp/xgdBPXBERAS0y4AoEzUfuC5TJmJFvnFkl2lX8GAclANfcTik38V+k3EXu5wPzHKNFb07c6jnwh3Jm4f3PRUhmmB2NO5kSWqHsx0dNglOTq5BUZx34nxlXL5G8d7mXqITsUtrOHXAO/Gb7IrvB81Xk2vc5p4yHhiY/rFTHTTmZyzte2qHGm7V6xPRNURjiivnMY2jQU0Um1JKQcAiSe8Suwvd2LXP5PIhl71VLgO+fokjnynfRg==

' ------------------------------------------------------------------------------------------------------------------------
' Let's decrypt, which requires the matching private key...

' Load the matching 2048-bit RSA private key.
Dim privKey As New Chilkat.PrivateKey
Dim password As String = "secret"
success = privKey.LoadAnyFormatFile("qa_data/rsaKeys/myTestRsaPrivate.pem",password)
If (success = False) Then
    Debug.WriteLine(privKey.LastErrorText)
    Exit Sub
End If


' Tell the RSA object to use the private key.
rsa.UsePrivateKey(privKey)

Dim decBytes() As Byte
decBytes = rsa.DecryptBytesENC(encryptedB64,True)
If (success = False) Then
    Debug.WriteLine(rsa.LastErrorText)
    Exit Sub
End If


Debug.WriteLine("Success.")