The Digital Signature widget is one of the very few form types that does not support multiple appearances (e.g. a copy of the signature on each page). ... View more

The comment that there is a link to a transaction number leads me to believe you are using Adobe Sign. You can't easily clear a digital signature because you can't remove the link to the transaction, and because what you have is only a copy of the "master" that is kept by Adobe Sign. ... View more

You can use the Action Wizard to create a single action that will encrypt (protect) all files in a folder. You run it from Acrobat, so Acrobat has to be open, but the several files are automatically opened, protected, closed without having to individually open them. ... View more

Start here: Certificate-based signatures, Adobe Acrobat ... View more

A little kludgy, but: You can save the PDF as Image, which will give you one image per page, then create a PDF from the images. That gives you a flattened PDF with no text to select. Of course, the user could just run OCR on the images... ... View more

You can store certificates on LDAP servers for each individual. And you can tell Acrobat not to allow self-signed certificates (This is probably a registry setting, but can be set during deployment). ... View more

It's a combination of the software on the card and the Driver (OS level). Often, updating the driver software will enable SHA256. In other cases, the card or driver insist on doing the hash themselves, but may not have SHA256 capability. When signing with Microsoft OS calls, it's the OS (or card driver) that does the hash. That's because the padding is dependent on the size of the data being encrypted, and the driver does the padding, since the caller doesn't necessarily know the size of the RSA key. Back in Windows XP days, SHA256 wasn't available until SP3. But many 3rd party drivers didn't upgrade their software to handle SHA256 until much later. Wait until we all move to SHA384... or SHA512... or the SHA3 series of hash algorithms. ... View more

Hash is used multiple places. Your CAC certificate may be signed with SHA1/RSA, but the PDF is being hashed with SHA256. The SHA1 warning comes when the smart-card driver can't sign a SHA256 hash, which is 32 bytes (256 bits) long, Earlier drivers could only sign a SHA1 hash (160 bits) so Acrobat dropped back to SHA1 for the PDF. The RSA encryption of the PDF hash is independent of the hash used in the certificate itself. ... View more

Well, no, it is possible to fill in fields and add attachments to a signed file. Also possible for signing after a signature is already applied. What you can't do is change page content, or add or delete pages. ... View more

You could send the invoices as individual files in a portfolio. After signing, the files can be separated and saved independently. ... View more

This isn't really about adding a signature handler, but about adding new ECC curves to the current handler. Different incarnations of Acrobat/Reader for Windows/Mac can validate curves other than the FIPS standard P256, P384, P521, but those three are the only ones guaranteed to be supported in all versions. This is a limitation of the crypto libraries used in the product. Adding a new signature handler would mean adding the handler plugin to all copies of Acrobat/Reader that might need to validate Brainpool, which is kind of a non-starter for widespread use (e.g. Brazil and Germany want to use Brainpool for government certificates). You need to find an Acrobat Product Manager and convince him/her that Brainpool support would be a good idea. Good luck. ... View more

Look for an Encrypt dictionary in the File Trailer Dictionary. If you need to distinguish Password ("Standard") encryption from other types, you will need to look inside the Encrypt dictionary. The Encrypt dictionary is not, itself, encrypted. See section 3.5 is the PDF specification. Section 7.6 in the latest (ISO) specification. ... View more

Use a Certification signature. (Tools->Certificates->Certify). Set permitted actions to "No Changes Allowed" ... View more

If you are the creator of the file, and you haven't closed Acrobat between setting the security and checking, then Acrobat remembers that you are the owner and grants all permissions when the file is reopened (part of the recent-files cache). ... View more

Yes. Even with a null Open password the document is encrypted. But in order to display the PDF, it is necessary to be able to decrypt the document. Many non-Adobe viewers will willingly re-save the document without encryption, and ignore all the restrictions, too. The closest to what you want is LiveCycle, an adobe product that uses a different, certificate based, encryption. The details of the encryption are not public, so no 3rd party viewers can open such a document. Acrobat and Reader promise to respect the permissions. ... View more

If you have multiple certificates on your PC, and one of them (not the one you used to set security) is listed as a recipient certificate, it is possible that Acrobat opened the document using the recipient certificate. There is no way to control this, other than making all the recipient certificates unavailable when you open the file. If the file is opened with the owner certificate, you should be able to change the security settings. ... View more

Use Password security, with "Require a password to open the document". But do not restrict any editing (leave that box unchecked). Then the "open" password will also be the "owner" password, and all editing operations will be available to anyone who opens the document. ... View more

There is a signature option: "Lock Document after Signing". If this is set, all further  modifications (including another signature) are prohibited. Make sure this option is not checked in the signing dialog, and not (accidentally?) set in the Seed Values. ... View more

Deleting a signature is not the same thing as changing the security settings. If you are talking about a signature, you can just delete it if you have the certificate used to sign. You can't delete a Certifying signature until all following signing signatures have been deleted. ... View more

Without going into a detailed analysis, I would conjecture that the second signature incremental file section is not properly formed. The PDF spec says that the last line of a file must be %%EOF, and Each line shall be terminated by an end-of-line (EOL) marker, which may be a CARRIAGE RETURN (0Dh), a LINE FEED (0Ah), or both. In this file, the %%EOF at the end of the first section is followed immediately by an object in the incremental save section (1 0 obj) which deleted the EOL at the end of the first section. I notice that if I "Enable Editing" of the file, the second signature appearance disappears. You might also have words with the ShenZhen Certificate Authority, since they are still using SHA1, when that has been deprecated for several years in favor of SHA256. And, I expect, their certificates are also still malformed (using BER encoding rather than DER encoding). ... View more

Still happening. I started a Chat, waited 2 hours for my place in line to come down from 30 to 20, then got "Thanks for contacting Adobe." The chat was ended by Adobe. I did it again, again waited 2 hours, but got the same response. Really not satisfactory. I was an Adobe employee for 22 years, and I am ashamed at the customer service. ... View more