A digital signature is an encrypted hash of the document's bytes. In order to create a digital signature the signing process needs first to get all bytes of the document in the final form. That's why you need to save PDF in the process of signing. You can save the signed document in place of the original one. If you have a PDF document with pre-formated unsigned signature fields, these signature fields may contain [invisible] filename for the signed document, in which case Acrobat uses this filename to silently save without a "Save" dialog. It all depends on the way signature fields were created. You need to contact the document's authors so that they modify the signature fields to include instructions (seed values) to Acrobat where to save signed PDF.
First I want to acknowledge the assistance you offer. I have the same problem that Tina but I don't understand the solution that isakten has provide in this topic. I'm new developer and I don't know how I can apply the solution provided by isakten.
@Isakten, Could you please provide a further explanation about your solution?
Thank you in advance for your help and support.
Hi Pedro and Tina,
Let me see if I can simplify Isak's answer.
Short answer, you have to save the file when you sign, there is no getting around this.
If you are interested why, then read on (if not, I understand)...
When you sign a file you are signing the whole file, everything top to bottom, left to right. Like anything in the computer world all files, be they a PDF file or a Word Doc or an e-mail, or a picture, or a music file, that is any file; is made up of a blob of electronic bits.
When you sign the file you are really signing this the big blob of electronic bits. These bits (Isak mentioned bytes, but a bytes is just 8 bits) control how the file looks (or sounds) and it's important that when you sign them that they are not changed during the signing process. If they were to be changed during the signing process you could end up signing something that you didn't really agree to. As an example, if you were signing a document that said I owe you $10 you certainly would want the amount to change (or at least become larger ).
To prevent the bits from changing it is best practice to write all of the bits to disk before the signature is created. You could do what is known as "sign in memory" where the signature is created without saving the file to disk, but (and this is the sad part) this is where the bad guys can take over and change things. It's much harder for someone to manipulate the bits that have been saved to disk then it is for them to manipulate the bits in memory. If there were no bad guys then we could enable signing in memory, but alas...
The signing operation is really an operation based of trust, that is, you trust what you are signing is correct and the document recipient trusts you are who you say you are. Should the signed data be compromised it would be a very bad thing for all involved and that includes Adobe. Thus the ability for things to go wrong must be minimized and that's why you have to save when you sign.
Thanks for the response, I had contacted IT and they said the same thing about there not being a way to get around this. We had to just make a text field that acts as a "signature." This worked for us because the documents aren't very secure and only a few different people are looking at it. I understand why you do have to save the document after entering your electronic signature, I think it's just hard to do this if you're distributing a fillable form to many different people who might not understand why this is so.
Thanks for the reply,