(Excel) RSA Encrypt Randomly Generated AES Key

Demonstrates how to RSA encrypt a randomly generated AES key.

Download Excel Class Modules Chilkat Excel Class Modules

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

' First generate a 256-bit AES key (32 bytes).
Dim prng As Chilkat.Prng
Set prng = Chilkat.NewPrng
Dim bdAesKey As Chilkat.BinData
Set bdAesKey = Chilkat.NewBinData

success = prng.GenRandomBd(32,bdAesKey)

' Use a public key from a certificate for RSA encryption.
Dim cert As Chilkat.Cert
Set cert = Chilkat.NewCert

success = cert.LoadFromFile("qa_data/pem/mf_public_rsa.pem")
If (success = False) Then
    Debug.Print cert.LastErrorText
    Exit Sub
End If


Set pubKey = cert.ExportPublicKey()
If (cert.LastMethodSuccess <> True) Then
    Debug.Print cert.LastErrorText
    Exit Sub
End If

Dim rsa As Chilkat.Rsa
Set rsa = Chilkat.NewRsa
success = rsa.ImportPublicKeyObj(pubKey)
If (success = False) Then
    Debug.Print rsa.LastErrorText
    Exit Sub
End If

' RSA encrypt our 32-byte AES key.
' The contents of bdAesKey are replaced with result of the RSA encryption.
success = rsa.EncryptBd(bdAesKey,False)
If (success = False) Then
    Debug.Print rsa.LastErrorText
    Exit Sub
End If

' Return the result as a base64 string

encryptedAesKey = bdAesKey.GetEncoded("base64")

Debug.Print "encrypted AES key = "; encryptedAesKey