Electronic/Digital Signature

Question

I have a client who wants to upload pdf document in the system and have certain pages signed online without downloading anything. Here is little bit more description:

1. Upload a Pdf of 5 pages
2. On page 2 and 4, he needs to print/sign name online.
3. I told him that there are services like docusign but he wants us to develop something like this even though I told him that this will take us long time to build.
4. Is there an opensource digital document signature component that we can use.

Any help would be appreciated.

Thanks