In PHP, what is the method to obtain the name(s) of the individual(s) who signed a PDF through digital means?

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To obtain the name(s) of the individual(s) who signed a PDF through digital means in PHP, you can use the pdftk library. First, you need to install the pdftk library on your server. Then, you can use the following PHP code to get the signature information:

// Path to the PDF file
$pdf_file = 'path/to/pdf/file.pdf';

// Command to get signature information using pdftk
$cmd = 'pdftk '.$pdf_file.' dump_data_fields | grep -A 2 SignatureFieldName | grep -v SignatureFieldName | grep -v FieldMDP';

// Execute the command and get the output
$output = shell_exec($cmd);

// Extract the signature names from the output
$names = array();
preg_match_all("/FieldName: (.*)\n/", $output, $matches);
if(!empty($matches[1])) {
    $names = $matches[1];
}

// Print the signature names
print_r($names);

This code will execute the pdftk command to get the signature information from the PDF file. It will then extract the signature names from the output using regular expressions and print them.