How to Encrypt and Decrypt Text and Files

List of sections on this page:


4.0 How to Encrypt Text Messages with gpg4usb

The process for encrypting text messages is easy and fast; in the example that follows, Terence will encrypt an email for his friend Salima, using the following steps:

Step 1. Double click to open the gpg4usb console.

Step 2. Compose your message as shown in the example below:

Figure 1: The gpg4usb console displaying an example of a message

Step 3. Check the check box associated with the intended recipient of your email as follows:

Figure 2: The gpg4usb console displaying the intended recipient, outlined in black

Note: You can encrypt a message to more than one recipient by simply checking their corresponding check boxes in the Encrypt for: pane. Also, it may prove useful for your personal records to encrypt that message to yourself, so you can read what you sent later.

Step 4. Either click or select Encrypt from the Crypt menu to encrypt your message as follows:

Figure 3: The gpg4usb console displaying an example of an encrypted message

Step 5. Click to select the entire encrypted message, and then click to copy the message to the clipboard.

Note: Alternatively, you may use the short-cut keys associated with each item in the menu, in this case Ctrl + E.

Step 6. Open your email account and then open a blank message page, and then paste this message so that it resembles the following:

Figure 4: An example of a message encrypted in gpg4usb pasted into a Gmail account email

Note: Rich Text Formats (RTF) can corrupt the encrypted message format; hence, it is better to compose your messages in plain text. To convert RTF into plain text in Gmail simply click displayed in the formatting toolbar above the message pane.

4.1 How to Decrypt Text Messages with gpg4usb

To decrypt an encrypted email, perform the following steps:

Step 1. Double click to open the gpg4usb program.

Step 2. Open your email account, and then open the message.

Step 3. Select, copy and then paste the encrypted message into the gpg4usb console untitled1.txt tab as follows:

Figure 5: The gpg4usb console displaying a message for decryption

Note: If the encrypted text appears with double line breaks as shown in Figure 6 below, gpg4usb might not be able to automatically decrypt it. To remove these double line breaks, select the Remove double Linebreaks from the Edit menu to remove them and then continue the decryption process at Step 4.

Figure 6: The gpg4usb console displaying a message for decryption with double linebreaks

Step 4. Click and enter the password you created when generating a key pair, as shown in the following screen:

Figure 7: The Enter Password prompt window

Step 5. Click to activate a gpg4usb console resembling Figure 2 above.

4.2 How to Encrypt Files with gpg4usb

The process for encrypting a file is similar to encrypting text messages; in the example that follows, Salima will encrypt a file for Terence, using the following steps:

Step 1. Double click to open the gpg4usb program.

Step 2. Click to activate the following screen:

Figure 8: The Encrypt / Decrypt File window, with the default Decrypt option enabled

The Encrypt / Decrypt File window scroll list (outlined in black) lets you select the email account and corresponding key you will use to encrypt a message.

Step 3. Check the Encrypt radio button and then click to activate the following screen:

Figure 9: The Open File browser window

Step 4. Click to attach the file to be encrypted and return to the Encrypt / Decrypt window as follows:

Figure 10: The Encrypt / Decrypt File window displaying the file designated for encryption

Step 5. Click to activate the following screen:

Figure 11: The Done confirmation dialog box

The Done confirmation dialog box shows you where the newly encrypted file resides. An encrypted file can also be identified by either a .asc file extension, for example, Technical White Paper.doc.asc.

Step 6. Click to complete the file encryption process.

Note: You can encrypt a text message you might send along with the encrypted file separately.

Step 7. Using your email account, navigate to the location specified in the Done confirmation dialog box (Figure 11), and then attach the encrypted file to you email as you would any other file.

IMPORTANT: Observe that the name of the file is not encrypted. Make sure that this name does not reveal any important information! Do not forget that an unencrypted version of the file continues to reside on the disk.

4.3 How to Decrypt Files with gpg4usb

In the example that follows, Terence will decrypt the file Salima has sent to him, using the following steps:

Step 1. Double click to open the gpg4usb program.

Step 2. Open your email account, open the message and download the attached file.

Note: If your correspondent has sent a message accompanying the encrypted file, you may decrypt that message by using the method outlined in section 4.1 How to Decrypt Text Messages with gpg4usb

Step 3. In the gpg4usb console (as shown in Figure 1 above), click to activate Encrypt / Decrypt File window (as in Figure 12 below).

Step 4. Click to browse to the location of the downloaded encrypted file as follows:

Figure 12: The Encrypt / Decrypt window, displaying the path to the encrypted file

Step 5. Click to activate the following screen:

Figure 13: The Done confirmation dialog box displaying the location of the decrypted file

Important: If you are working from an internet café or at workstations other people will have access to, it is better to copy the .asc file to your USB or portable drive, and take it with you so you may decrypt it in the privacy of your own home.