Permanent Watermark

Hi @Ronen288583, 

Thanks for reaching out. 

It sounds like you might be referring to how a digital signature in Acrobat makes a document “permanent” or unalterable after signing. Here’s how it works:

• When you apply a digital signature in Acrobat, the document is cryptographically sealed using your digital ID (certificate).

• Acrobat creates a hash (a unique digital fingerprint) of the document’s exact state at the time of signing.

• This hash is encrypted with your private key and embedded into the PDF along with your certificate details.

• If any change is made to the file afterward — even a small edit — the hash no longer matches, and Acrobat will clearly show that the document has been modified after signing.

• This ensures integrity (no one can alter the content unnoticed) and authenticity (verifies the signer’s identity).

In short, it’s not how digital signature locks the “watermark” that you can see; it’s a security seal built into the PDF that’s verifiable by anyone opening it. That’s what makes the signed document “permanent” from a security standpoint.

For more information on Digital Signature: https://adobe.ly/4mhx1Ww