EncryptPDF is a software specially used to encrypt PDF files. The download address is /encryptpdf /encryptpdf.exe, and the specific steps to crack the pdf file are as follows:

(1) After downloading the software, double-click the encryptpdf.exe file to display the dialog box as shown in Figure 9- 1-7. Click the Yes button, and then follow the installation wizard to install.

(2) After the installation is completed, you can run the program, and its operation interface is shown in Figure 9- 1-8.

Figure 9- 1-7 Continue to install the EncryptPDF operation interface of Figure 9-1-8.

(3) Click the Settings button to open the Encrypted PDF Options dialog box, where the user can set the password when opening the PDF file and the password when modifying the file, as shown in Figure 9- 1-9. In addition, the user can also choose the encryption method of the password and some options to restrict other operations: select the Don't print check box, and the encrypted file cannot be printed and output; If you select the "Do not change the document" check box, you cannot modify the encrypted file; If you select the Do not copy or extract content check box, you cannot copy content from the encrypted file. If you select the Do not add or change form fields check box, you cannot add or modify table frames in encrypted files.

Figure 9- 1-9 Setting the EncryptPDF option

(4) After setting the options, click the Open PDF(S) button to open the encrypted PDF dialog box, as shown in Figure 9- 1- 10.

⑤ Select the file to be encrypted, click the Open button, then enter a new file name in the Save As dialog box, and click the Save button to generate an encrypted file. If you don't want to save the original file, you can delete the original file and keep only the encrypted file.

Figure 9- 1- 10 Select the file to be encrypted Figure 9-1-1Password dialog box

When you open an encrypted file with Adobe Reader, a password dialog box as shown in Figure 9-1-1will appear. Only after entering the correct password can you open the file.

point out

After encrypting with Encrypt PDF, the encrypted file can no longer be encrypted with Encrypt PDF, and of course it can't be used to cancel the password that has already taken effect.

9. 1.3 Use advanced PDF password to recover and decrypt PDF encrypted files.

Advanced PDF Password Recovery (AEPR) is a tool software specially used to crack the protection measures of PDF files, which can easily remove the inherent protection of PDF files. The installation method of the software is very simple, so I won't go into details. APPR is the same series of tools as the advanced ZIP password recovery tool used to decrypt WinZip, and it is similar in operation and decryption characteristics.

The specific cracking operation steps are as follows:

① After the installation is completed, double-click the advanced PDF password on the desktop to restore the Chinese version of Pro 1.70 icon to start the program, as shown in Figure 9- 1- 12.

Figure 9- 1- 12 Advanced PDF password recovery interface

(2) Click the button, select the PDF file to be decrypted in the opened dialog box, and click the button to directly save the PDF file to the folder specified by the user with a new file name.

③ In the drop-down list box of attack type, users can choose brute force attack, mask, dictionary file, password search and other cracking methods.

④ In the Scope tab, users can set the scope of violent attacks; You can set the range of password length in the Length tab; In the dictionary file tab, the user can select the dictionary file to use when cracking; In the Password Search tab, users can set the scope of password search; In the Auto Save tab, users can set the time interval of auto save, saved file name and folder; In the Options tab, users can set various options when using the software.

Because the author uses the Chinese version, he can select the Simplified Chinese option in the language drop-down list box to make the software's operation interface become a Chinese interface. In the Advanced tab, users can select any password, user password, owner password and other options.

⑤ After setting all the options, click Start! Button, you can start cracking according to the options set by the user, and give the final prompt.

⑥ To cancel the restrictions such as "No Printing" and "No Content Copying", just click the Decryption button. If the file is not encrypted, APPR will display "This file is not encrypted", which means the file is not encrypted; If the document is an encrypted PDF file without password protection, the Save As window will appear, just enter the decrypted file.

⑦ If the file is password protected, you can only get the password by searching the password, otherwise you can't decrypt the PDF file; The operation method of searching password is similar to advanced ZIP password recovery. Please refer to the previous chapter.

9. 1.4 Use the PDF Password Eraser to delete the password of the PDF file.

PDF Password Eraser is a software used with EncryptPDF, which is specially used to delete PDF passwords. Its operation interface and method are similar to those of EncryptPDF, as shown in Figure 9- 1- 13.

The specific operation steps are as follows:

(1) Click the Open PDF file button and select the PDF file to unlock.

(2) Click the Open button, and then enter a new file name in the file name text box. Click the Save button to display the dialog box as shown in Figure 9- 1- 14. After entering the user password and the owner password, click the OK button.

③ If the password entered is correct, you can cancel the password; If the password entered is incorrect, the password is incorrect and cannot be cancelled.

Figure 9- 1- 13 pdf password deletion operation interface Figure 9- 1- 14 Enter the password.

Is there any way to better protect your own PDF files?

Set the options to be protected as required, such as "Do not print" and "Do not extract content", and then set the password. A good password should be long enough, contain uppercase and lowercase letters and numbers, and difficult to guess. A good suggestion is to construct a short sentence that is easy to understand but difficult to guess, which is easy to remember and has a good encryption effect. For example, "Rmb$95 18" is a good password.