Are Digital Signatures Encrypted in PDF Documents?
Are Digital Signatures Encrypted in PDF Documents?
Digital signatures have become widely used in business transactions. The technology works by creating a verified timestamp that contains the signer’s unique digital identity.
However, the process is not foolproof. Despite its popularity, it is still possible to spoof digital signatures with targeted attacks. This article will discuss some of the most common methods of attack to learn how to better protect your documents.
Verification
The verification process ensures that your signature in a PDF document has not been tampered with. It works by using a hashing function, which turns an arbitrary block of data into a fixed-size string that cannot be changed. When you digitally sign a document, it sends the original data and a signature to the verifier, who can use both keys to decrypt the data and then check that the output is identical to the original. If the output is not the same, then the document has been tampered with.
This is done to ensure that the person sending a document with a digital signature pdf is actually the author of that document, and not someone else. This is called nonrepudiation, and it is one of the main reasons why digital signatures are necessary in documents with a legal value, such as contracts.
In addition to the hashing, a digital signature uses encryption to bind the signer with the document in a mathematically secure way. This prevents unauthorized access to the file’s content. This form of protection is known as public key cryptography, and it requires two mutually authenticating, public and private keys to function. Both keys are encrypted with the same algorithm, which makes it very difficult for anyone to obtain or modify the contents of a signed file.
Encryption
When a digital signature is added to a PDF document, it’s actually encrypted using the same encryption process used by the document itself. It’s a kind of tamper-evident seal that verifies that the person who signed the document has the private key that goes with it, protecting against man-in-the-middle attacks and other malicious activities.
However, that doesn’t mean that password-protected PDFs are secure against bad actors. A malicious attacker could still use brute force to guess the password and modify the contents of a PDF file, but that would be more difficult to do than just cracking an encrypted PDF.
In addition to encrypting the document itself, PDF files can also be encrypted with different permissions. This allows for a variety of restrictions, such as preventing users from editing the document or denying them the ability to print it. This is the kind of protection that makes sense for documents like contracts, which need to be highly secured.
The other problem with protecting PDF files in this way is that it’s impossible to prevent unauthorized users from simply handing the file to someone else to open on their device. The PDF format was not built with security in mind, and Adobe has tacked on some half-hearted controls, but it’s a far cry from the robust security that purpose-made software can provide.
Hashing
A digital signature is a way to verify that a document has not been altered since it was signed, and to identify the signer. This is accomplished by using a cryptographic process called hashing to create an encrypted version of the original document that includes information about the signing certificate. This is then attached to the document with a digital signature. This verification makes it impossible for anyone to spoof the document or pretend that they signed it.
Digital signatures require public and private keys, which are generated by a trusted Certificate Authority (CA), and they need to be valid in order to work. This is why many people opt for a dedicated solution like PandaDoc, which can simplify the process of creating and managing digital signatures on PDF documents.
The hashing process in PSPDFKit encrypts almost all of the contents of a document before it is signed, including any text, images, or layout changes. This means that if you send a signed document to someone else, they can check its integrity by computing the same hash for the same parts of the document. Alternatively, they can verify the signature by looking at the signer’s public key in the document’s metadata and comparing it to the digital encryption fingerprint stored in the signing certificate. Neither of these methods provides complete security, however. It is still possible for a malicious person to guess the hash function used, change the document’s contents, and then recalculate the hashing for the document.
Signatures
The digital signature process is a good way to ensure that a document has not been modified by an unknown person. It also helps to verify that the author of a document is who they claim to be. This is important to protect information of a sensitive nature, and to prevent forgery and fraud.
The process of creating a digital signature uses hashing and encryption to make sure that the data in a document remains unchanged. It also includes a public and private key pair, which makes it extremely difficult for anyone to forge a signature. In addition, most modern digital signatures use time stamping, which can show that the document was signed at a specific date and time.
This is a great feature for businesses that need to ensure the integrity of their documents, and can help reduce or eliminate the need for paper signing. It can also save companies valuable time and resources, by reducing or eliminating the need to send and receive documents through the mail.
Adding a digital signature to a PDF document is easy with an eSigning solution like PandaDoc. To get started, simply click the button below to sign your PDF files with a secure, trusted digital signature. You can even try a free 14-day trial!