iText 2.1.6 Released on June 16, 2009, and announced the support timestamps and ocsp (timestamp support inspired by contributions by Aiken Sam and Martin Brunecky). also introduced many other changes,

PdfPKCS7: Added the RIPEMD algorithm.
AcroFields: Some tools produce invisible signatures without an entry in the page annotation array.
SpecialSymbol: If PHI is ‘F’ the phi should be [...]

Today I recommend a free open source program, bookbinder, with it, you can easily create a bindable book from a PDF document.

Bookbinder is a program that will convert a PDF document into signatures suitable for traditional bookbinding.
While there are a lot of programs on the net that will create a single booklet from a small [...]

Here is a Windows command line version PdfSigner with TimeStamp(TSA) support,

Usage pdfsigner InPdf OutPdf Pkcs12KeyStore Pkcs12KeyStorePassword

because It is a demo application, so the TSA server only supports http://tss.pki.gva.es:8318/tsa
If you have interest, please download it here,pdfsigner(4.9M)