Validate signatures
When you open a document, all the signatures in the document are validated by default. Validation includes verifying the signer’s identity and assessing whether any changes were made since the document was signed. One way the signer’s identity can be verified is by adding the signer’s certificate to your list of trusted identities.
1.		Open the PDF document containing the signature you want to validate.
2.		If the signature is not validated, click the signature in the document window, or select the signature in the Signatures panel, and then choose Validate Signature from the Options menu.
3.		If the status is unknown, or if the document has been revised since it was signed, click Signature Properties, and then do any of the following:
		• Click Legal Notice to learn more about the legal restrictions of this signature, and then click Close.
		• If the document has more than one signature, click View Signed Version to view a copy of the signed version in a separate document window.
Note:  For the latest information about Digital Signatures, choose Help > Online Support to open the Adobe Acrobat support page on the Adobe Web site, and then search for “digital signatures”.
Signature Topics
Validating signatures in complete Help