There are two ways in which you can verify a digital signature. The first one is through SignFlow itself, and the second is in Adobe Acrobat Reader. In this FAQ, we are going to cover both means of verification.

Method 1: 

After signing the document, click on the signature appearance on the document, as in the screenshot below:

This pop-up window helps a user to verify a digital signature. The information on the pop-up window gives you the following information: the date and time the document was signed, full names of the signer, the certificate information, expiry date of the certificate and the issuer of the certificate. 

Method 2: 

Now we will use an Adobe Acrobat Reader to verify the legitimacy of a digital signature. Please follow the instructions on the below screenshot.

Now open the document in Adobe Acrobat Reader and scroll down to where you placed your signature, then double click on your digital signature.

A pop-up window will appear, as in the screenshot below. 

The signature properties further confirm the legitimacy of the signer, the signing time, the Source of Trust and the integrity of the document since it was signed. For information on Source of Trust, click here.

Click on the "Signature Properties" button for detailed information about the digital signature and its embedded certificate.

The highlighted information is included in the certificate that is embedded in the digital signature. This information includes the signer's full names and place of employment, the type of certificate (SAPO Class 4 CA Advanced Electronic Signatures) and the time period the certificate is valid from. That is how you verify if a digital signature is valid. 

The below screenshot illustrates what you will see in the event of a digital signature being invalid:

The excerpts circled in red on the above screenshot indicate the digital signature is invalid

In most such cases, the pop-up box will offer the reason as above, i.e. "The signer's identity is unknown because it has not be included in your list of trusted certificates and none of its present certificates are trusted certificates". 

Below is how you rectify this situation:

In Adobe Acrobat Reader, click the "Edit" tab, then click "Preferences" and follow the guideline below: 

The Preferences box gives you a number of options. You are looking for the "Trust Manager" (illustrate below) option, which will enable you to update the digital signature and add it to the list of trusted certificates in Adobe Acrobat Reader.

In the Trust Manager window, you will see "Update now" buttons (highlighted in yellow above). You will need to click on these to update your digital signature to the Adobe Approved Trust List. After clicking Update Now, a small window, such as the one in the screenshot below, will pop up:

Click "OK" (highlighted in yellow) and another small window confirming the digital signature update in the Adobe Approved Trust List (AATL) will pop up:


You can also easily see whether the AATL update was successful or whether there are invalid signatures that require updating at the top of your PDF document preview in Adobe Acrobat Reader. See below: