Each time a signature is applied to a document, a new message digest is created. This digest stores an encrypted 'hash' version of the document (taken at the time of signing) and then embeds it along with the signature inside the document. When a recipient receives the file and validates the signature, another digest is generated and then compared with the original digest to confirm they have remained the same.
Tip: The embedded certificate verifies the signer's identity, while the message digest verifies the content has not changed. To digitally sign a document:
1. On the Secure and Sign ribbon, in the Signatures group, click Sign Nitro PDF icon. 2. One a page, click and drag to place where you would like the signature to appear. 3. In the Apply Digital Signature dialog, select the digital ID to use, and then click Next. 4. Select the reason for signing from the list, or type your own reason for signing. 5. Click the option to save the signed PDF as a new file or save it to the current document. 6. Click Finish.
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