SOS Computation DigestValue (appendix i)

Hello,

I've a big problem to compute ths DigestValue.

What is exactly the first object that i have to digest? I think it is the Catalog but it's false because ths DigestValue is the same after one signature.

I need a help precise please...

I've a hashFunction for each pdfObject and i think they are correct but i don't understand precisely which object to digest.

Thanks a lot! (sorry for ma bad english ^^)