Visual Basic 6.0

RSA Encrypt Bytes to Base64 and Reverse

See more RSA Examples

Demonstrates how to RSA encrypt bytes to base64 and the reverse. Visual Basic 6.0

Dim success As Long
success = 0

' 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 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 = 0) Then
    Debug.Print pubKey.LastErrorText
    Exit Sub
End If

Dim rsa As New ChilkatRsa

' Tell RSA to use the public key.
success = 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 ChilkatPrng
Dim keyBytes() As Byte
keyBytes = prng.GenRandomBytes(32)

rsa.EncodingMode = "base64"
Dim encryptedB64 As String
encryptedB64 = rsa.EncryptBytesENC(keyBytes,0)

Debug.Print "Result:"
Debug.Print 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 PrivateKey
Dim password As String
password = "secret"
success = privKey.LoadAnyFormatFile("qa_data/rsaKeys/myTestRsaPrivate.pem",password)
If (success = 0) Then
    Debug.Print privKey.LastErrorText
    Exit Sub
End If

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

Dim decBytes() As Byte
decBytes = rsa.DecryptBytesENC(encryptedB64,1)
If (success = 0) Then
    Debug.Print rsa.LastErrorText
    Exit Sub
End If

Debug.Print "Success."