Extracting Blocks of Text from PDF

Before you can copy sections of text in a PDF document to the Clipboard or another open document, you need to select the text in the PDF document. To select text in a PDF document, you use two of the three different tools found on the Selection toolbar, which is attached to the Basic toolbar:

• Select Text tool (V): Use this tool to select lines or columns of text by dragging through them.
• Select Table tool (Shift+V): Use this tool to select a table or block of text with its formatting by drawing a bounding box around the table or text block.

You can also use the TouchUp Text tool (press T to select this tool) to select a block of text defined by its underlying document structure tags, such as whole headings or whole paragraphs. True to its name, this tool should be used only when you need to extract small amounts of text from a PDF document. Like the text selection tools on the Basic toolbar, text selected with the TouchUp Text tool can be copied, deleted, edited, and placed in other program documents . When you use the Select Text tool to select lines or columns of text in a PDF document, you can then copy the selected text to the Clipboard by choosing Edit➪Copy or by pressing Ctrl+C (Ô+C on the Mac). After you’ve copied the text to the Clipboard, you can switch to a document open in another program and then paste the copied text into the file by using that program’s Edit➪Paste command or by pressing Ctrl+V (Ô+V on the Mac).

Encrypting PDF Files

The last and most secure type of security that you can add to your PDF documents employs the Certificate Security system that you use to digitally sign documents, along with the list of Trusted Certificates in your user Digital ID file. When you encrypt a PDF document with Certificate Security, no one has access to the document other than those you specifically designate as recipients, and you can designate as recipients only those persons who are already on your Trusted Certificates list.
The steps for encrypting a PDF document with Certificate Security are as follows:

1. Choose Document➪Security➪Encrypt for Certain Identities Using Certificates. The Restrict Opening and Editing to Certain Identities dialog box opens.
2. In the Identity Directories list box, click the name of the person you want to add to the Recipients list box below, and then click the Add to Recipient List button.
3. Click the name of the newly added recipient to highlight it in the Recipients list box.
4. Click the Set Recipient Permissions button. By default, Acrobat grants the recipient full access to the PDF document whose user permissions include general editing, commenting and form field authoring privileges, the ability to print the document at any print resolution, and full copying and extraction privileges.
5. To restrict the recipient’s user permissions in some way, click the Restrict Printing and Editing of the Document and Its Security Settings button.
6. Limit the permissions by deselecting the Enable Text Access for Screen Reader Devices for the Visually Impaired check box and/or the Enable Copying of Text, Images and Other Content check box and/or by selecting new options in the Changes Allowed and Printing Allowed drop-down lists before you click OK.
7. Repeat Steps 3 through 6 (as they apply) to add your other recipients from the Identity Directories list box and set their user permissions in the Recipients list box.
8. After you’ve added all the recipients and set their user permissions, click the OK button. If the Certificate Security - Alert box appears, telling you that settings will not be applied until you save your PDF document, click OK. You can also opt to not show this dialog box in the future by selecting the Do Not Show This Message Again check box before you click OK.
9. Choose File➪Save to save the Certificate Security encryption settings for the current document. Alternatively, choose File➪Save As and edit the filename and/or folder location of the encrypted document before clicking the Save button. After you save your PDF file encrypted with Certificate Security, you can distribute copies to all the people you added to the Recipients list. When someone on the list tries to open the encrypted file, Acrobat displays the Select My Digital ID File dialog box, where the user selects his or her user Digital ID and enters his or her user password. When the user clicks the OK button to close the Select My Digital ID file dialog box, Acrobat checks the user’s public key against the certificate information (specifically the MD5 and SHA-1 fingerprints) in the encrypted file.

When Acrobat finds they match, it then opens the PDF document. The user then has access to the opened document according to user permissions that you set. To check these permissions, the user can right-click (Control+click on the Mac) the Document Encrypted key that now appears on the Document pane Status bar (a locked padlock on the left of the Status bar), select Document Security on the context menu, and then click the Security Settings button in the Document Properties dialog box.
If someone not on the Recipients list attempts to open a PDF document that’s encrypted with Certificate Security, upon logging in, he or she will receive the Certificate Security - Alert dialog box with the message You do not have access rights to this encrypted document. When the user clicks OK to clear this dialog box, the document will fail to open.

Comparing signed PDF documents

Each time a person digitally signs a PDF document that already has one signature, Acrobat saves the changes and signature of each subsequent signatory in a special appended version of the file. You can then compare the various versions to note what changes, if any, each signatory made.
Acrobat notes when a PDF document that you’ve sent out for subsequent signatures comes back to you with changes by adding a Document Was Modified item to the Signatures palette. You can then display the details of the modifications by clicking the Expand button (with the plus sign on Windows and the triangle pointing to the right on the Mac). Note that the detailed change items shown in the expanded list are purely informational and do not perform as bookmarks.
To have Acrobat do a side-by-side comparison of the versions to let you visually compare the changes, select View Signed Version on the Signatures palette Options pop-up menu. Acrobat then displays the original version of the PDF file and the most current version in a Document pane. To compare the files side by side, choose Window➪Tile➪Vertically. You can then scroll through the pages, visually noting the differences. When you’re finished checking the changes, close the original version on the left by clicking its document window’s Close button and maximize the latest version on the right by clicking its document window’s Maximize button. If you would prefer, you can have Acrobat do a page-by-page comparison and locate all the changes between the latest signed version and the original. To do this, select Compare Signed Version to Current Document on the Signatures palette Options pop-up menu. Acrobat then performs a page-by-page comparison and creates a second PDF document containing only the pages that have changed. These changed pages are displayed side by side. When you have finished comparing these pages, you can close this newly created document by pressing Ctrl+W (Ô+W). You can then save it in its own PDF file by clicking the Yes button in the alert dialog box that asks you if you want to save the changes before closing. If you have no further need for this comparison PDF file, you can click the No button to abandon the comparison document and just return to the most up-to-date signed version of the PDF document.

Adding certificates to your Trusted Certificates list

The way that you add the certificates that you receive to your Trusted Certificates list depends upon how you receive them. If you receive an e-mail message with a certificate attached, you can launch Acrobat, validate the certificate, and add the certificate to your Trusted Certificates list all by simply opening the certificate file attached to the message in your e-mail program (in most programs, you open an attachment by double-clicking the file attachment icon).
When Acrobat launches, it displays the Data Exchange File - Import Contact dialog box. To add the certificate to your list, click the Set Contact Trust button to open the Import Contact Settings dialog box. The Trust Signatures Created with this Certificate check box is selected by default. Click the Import button to import the certificate data and create a Digital ID certificate that will appear in your Trusted Identities list. If you have access to someone’s Self-Sign Security certificate file on your computer system, you can add it to your Trusted Certificates list by clicking the Import from File button in the Trusted Certificates portion of your User Settings dialog box. To do this, follow these steps:

1. Choose Advanced➪Manage Digital IDs➪Trusted Identities to open the Manage Trusted Identities dialog box.
2. Click the Add Contacts button to open the Select Contacts to Add dialog box, and then click the Browse for Certificates button.
3. Locate the certificate exchange file you want to import in the LocateCertificate File dialog box, and then click the Open button. The selected certificate data file appears in the upper list box of the Select Contacts to Add dialog box.
4. Click the Add to Contacts List button to display the certificate exchange file in the Contacts to Add list box below; then click OK.
5. Click OK to close the alert dialog box and return to your Manage Trusted Identities dialog box, where you see the name of the person you just added to your Trusted Identities list.
6. Click the Close button to close the Manage Trusted Identities dialog box.

Exchanging certificates with associates

You can simplify the process of validating signatures in the PDF files you review by having all the review team members exchange copies of their Self-Sign Security certificates. Acrobat makes this easy by adding an export function to the Manage Trusted Identities dialog box. To open this dialog box, choose Advanced➪Manage Digital IDs➪Trusted Identities. Select your Digital ID from the list box in the Manage Trusted Identities dialog box and click the Export button to open the Data Exchange File - Export Options dialog box. Two radio buttons appear in the Export options section. The first is the E-mail the Data to Someone radio button that you can select to send a copy of your certificate to team members in a new e-mail message. The second is the Save the Data to File radio button that you can use to make a copy of the certificate file that others can import into their Trusted Certificates list. (For example, you can use this option if you and your coworkers are on the same network and share access to certain folders.)
When you select the Save the Data to a File radio button, Acrobat opens an Export Data As dialog box, where you can designate the drive and folder on which the copy of your certificate is saved (saved in a special Acrobat Self-Sign key file format that uses a .fdf file extension) when you click the Save button. When you select the E-mail the Data to Someone radio button, Acrobat opens the Compose E-mail dialog box, To send the e-mail, fill in the recipient’s e-mail address in the To text box, make any necessary changes in the default text provided in the message window, and click the E-mail button. Acrobat transfers the information into your e-mail client in order to send your certificate data to someone else.

Validating PDF digital signatures

Whenever you add your own signature to a PDF document, Acrobat automatically uses your user Digital ID information to verify your signature as valid (indicated by the green check mark and the text Signature Valid underneath it). When you receive a document that has been signed by other people, their signatures will not automatically be recognized as valid when you open the PDF file.
You can then validate their signatures. As part of this process, you need to get in contact with the signatory and verify that one or both of the two socalled fingerprint numbers stored in the public key attached to the signature in your PDF document match the fingerprint numbers in the signatory’s public key stored as part of his or her certificate attributes on his or her hard drive. (The two fingerprints are made up of a combination of letters and numbers that make your software serial number look short; the first is called the MD5 Fingerprint, and the second is called the SHA-1 Fingerprint.) To validate a signature in a PDF document that you have open, follow these steps:

1. Open the Signatures palette and select the name of the unknown signatory you want to validate (indicated by a blue question mark before the name), and then select Validate Signature on the Signature palette Options pop-up menu.
2. If the unknown signatory has not been added to your list of trusted certificates, Acrobat next displays the Signature Validation Status dialog box.
3. Click the Signature Properties button. The Signature Properties dialog box appears.
4. Use the contact information (if listed) to get a hold of the signatory (preferably by telephone) to verify the MD5 and/or the SHA-1 Fingerprint numbers listed at the bottom of the Certificate Attributes dialog box. Click the Show Certificate button to view these numbers. To find these numbers to read off to you, the signatory must choose Advanced➪Manage Digital IDs➪My Digital ID, select their Digital ID in the Manage My Digital IDs dialog box, and click the Settings button to open the Set Digital ID Usage dialog box. The signatory then clicks the Show Certificate Details button to open the Certificate Attributes dialog box and view their MD5 and SHA-1 Fingerprint numbers.
5. If the fingerprint numbers on your screen match the numbers given to you over the phone, click the Trust Identity button. The Certificate Security-Alert dialog box opens, telling you that Trusting Certificates directly from a document is unwise.
6. Click OK to close the Alert box and open the Import Contact Settings dialog box.
7. Click the Import button and then click OK in the Import Complete dialog box to add the person to your list of trusted certificates and to validate the selected signature in the PDF document.

You can quickly validate individual signatures for the people you’ve added to your Trusted Certificates list by simply double-clicking their signature fields. Acrobat will quickly search your list and, upon finding the person’s certificate, display a Signature Validation Status alert dialog box, informing you that the signature is valid. You can also use this technique on your own signatures in the event that they show up as unknown signatures when you reopen the PDF document, even when your Digital ID file is open. To update all the signatures in your PDF at one time, simply choose Document➪Digital Signatures➪ Validate All Signatures in Document, or select the Validate All Signatures in Document option on the Signatures palette Options pop-up menu.

Signing a PDF document using a predefined signature field

You can also digitally sign a PDF document by using a signature form field that’s already been added to it. To sign a document in a predefined signature form field, you follow these steps:

1. Open your Digital ID file by choosing Advanced➪Manage Digital IDs➪My Digital ID Files➪Select My Digital ID File. The Select My Digital ID File dialog box opens.
2. Select the filename of your user Digital ID in the Digital ID File dropdown list, enter your password in User Password text box, and click the OK button.
3. If the Signatures palette isn’t open and selected in the Navigation pane, choose View➪Navigation Tabs➪Signatures.
4. Click the name of the signature field you want to sign in the Signatures palette to highlight it, and then select Sign Signature Field on the Signatures palette Options pop-up menu to open the Apply Signature to Document dialog box.
5. Enter your user Digital ID password in the Confirm Password text box if necessary, and then modify the settings in the other options (Reason for Signing, Location, Your Contact Information, and Signature Appearance) as desired. Refer to Steps 5 through 10 in preceding post, “Adding a visible or invisible signature to a PDF document,” for details.
6. Click the Sign and Save button to save your changes and signature in the selected signature field in its current location with the same filename.

Alternatively, click the Sign and Save As button to open the Save As dialog box, where you can modify the file’s location and/or save it under a new filename.
As with the other methods of digitally signing a PDF document, after Acrobat finishes saving the signed document, the program displays an alert dialog box, informing that you have successfully signed it. As soon as you click the OK button to close the alert dialog box, you can see your signature in the signature form field. Figure shows you a PDF document after I signed a signature form field beneath the book title and byline.