Restrictions

An optional block with an ID of PB (padding block), also called a PB optional block, cannot be added by the user. The TR31 Translate verb adds a padding block of the appropriate size as needed when building the TR-31 key block. Unlike the padding within the encrypted key portion of the key block, the padding block for optional blocks serves no security purpose.

KP optional blocks with algorithm '01' cannot be created with CSNBT31O, they should be built when the key is built or can be added later using CSNBT31X. KP optional blocks with algorithm ’00’ can be built with CSNBT31O, but caution is advised.