Pad byte array to correct length for ECB and CBC encryption.
public static byte[] Pad( byte[] input, CipherAlgorithm cipherAlg, Padding pad = Padding.Pkcs5 )
Public Shared Function Pad ( input As Byte(), cipherAlg As CipherAlgorithm, Optional pad As Padding = Padding.Pkcs5 ) As Byte()
VB6/C equivalent: PAD_BytesBlock