B4J Question Problem Encrypting a string using a Public Certificate

Private Sub EncryptRSAWithPublicKey1(Text As String,PublicKey As String) As String
    Dim kpg     As KeyPairGenerator
    Dim Cipher  As Cipher
    Dim su      As StringUtils
    Dim pubkey() As Byte = su.DecodeBase64(PublicKey)
 
    Cipher.Initialize("RSA/ECB/PKCS1Padding")
    kpg.Initialize("RSA", 1024)
    kpg.PublicKeyFromBytes(pubkey)
    Dim bytes() As Byte = Text.GetBytes("UTF8")
  
   Return su.EncodeBase64(Cipher.Encrypt(bytes,kpg.PublicKey,False))
End Sub