Wp2LaTeX could read encrypted documents for wordperfect 4.x and 5.x. Unfortunatally I have insufficient information about Wordperfect 6.x Please could you tell me any information about used encryption method. Do you know some document, link or any other source of information?

No knowledge of OLE is needed. I could provide to anybody several series of data unencrypted and encrypted with different passwords. So there is also no need for knowledge of wordperfect internal objects.

(I am not interested in password cracking only in decrypting).

I know this:
1, The date is somehow stored and influences data.
2,Data are XORead with some serie of data.
3,The seed of serie is stored from 20h to 96h.
4,Most probably the LFSR algorithm is employed but I am unable to guess polynom order.
5,Some block is placed after data.

Documents: alleged WP6 cipher.pdf obtained from Dr Fauzan Mirza