Please Try a Different Browser

You are using an outdated browser that is not compatible with our website content. For an optimal viewing experience, please upgrade to Microsoft Edge or view our site on a different browser.

If you choose to continue using this browser, content and functionality will be limited.

Business man taking note via digital notepad application, graphic designer using electronic pen on digital tablet, working on laptop computer on table in modern office, close up

Everything to Know About MACs and Digital Signatures

Small to medium businesses that have the privilege of working with PDFs in their environment also require the ability to apply digital signatures to a document. Message Authentication Codes (MACs) and digital signatures aren’t interchangeable, and there are specific differences between the two. Kofax Power PDF allows its users to apply signatures to PDF files by using the SignDoc feature. However, before we delve into what Power PDF can do for your business, explore the intricate details of MACs and digital signatures.

MACs and signatures have completely different cryptographic features. The latter relies on asymmetric cryptography involving public and private key pairs. As a result, you require a private key to create a signature, but the public key should suffice for validation.

For MACs, both the sender and receiver use a shared secret to create and validate the MAC. Consequently, you can’t distinguish between the identities of the sender and receiver. Encrypting a PDF file with a MAC means that both the MAC key and file encryption key are obtainable from the password. However, with digital signatures, the key material doesn’t matter. Users can apply a signature to an encrypted file without knowing the encryption key, placing doubt over its authenticated encryption.

Digital signatures are asymmetric by nature, making them complex to work with. In this case, the signer’s identity must be associated with the public key, which requires infrastructure that the validator trusts. Furthermore, validation results can vary depending on external factors such as expiration dates on certificates or the availability of secure time stamps.

Document signing workflows often involve several different parties on multiple revised editions of a file. Some signatures, in this case, can be non-authenticating, raising questions about validation.

Conversely, MACs are far simpler since there’s a shared secret between every signing party. It eliminates the need to bind the key to an identity before you can trust it since all parties know the secret. Furthermore, message authentication codes are far more suitable for PDFs with several revisions. Every time a user makes a change to the document, they must recreate the MAC and only validate the outermost codes. Since MACs don’t distinguish between users, it’s easier to use, making the process more efficient.

When you’ve opened an encrypted document, it’s easy to validate a MAC token, as you’ll notice an error pop-up if there’s a mismatch. Validation of digital signatures could fail for various reasons. Considering how long encryption and digital signatures have been around PDFs, PDF software isn’t going to perform verification of signatures before the user opens the document. Either way, it won’t change anything as your employees would still dismiss warnings to view the document anyway.

With MACs, there’s no need for trust assessments. Upon opening an encrypted file through a MAC, you can treat a verification failure as a decryption error.

While it may seem like an oversimplification of the two, digital signatures are ideal for authenticating personnel when you need to know exactly who did something on the document.

Conversely, MACs act as a mechanism to restrict editing functions to those team members who know the key. MACs and digital signatures have their place in the world of PDFs, and neither can replace the other.

Power PDF

If you want a quality PDF editor and software that will satisfy your authentication needs, you shouldn’t look further than Power PDF and SignDoc. Take advantage of a 15-day trial to see exactly how the software makes your operation more secure and efficient.

cta banner

Ready to get started?

Work Like Tomorrow—today. Let's chat.