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Secure email with encrypted PDF, ZIP, Word or Excel

Attach encrypted files to an email

Email encryption is needed to make sure that only the receiver can read the message. For secure email extra security measures are needed. One can encrypt documents that contain sensitive information. These encrypted files can be attached to an email message. The result is that the email text itself is not encrypted, but the email attachment is a password protected file. This is a form of secure email.

EncOffice - Easy and Safe Encryption of Word and Excel Files      Learn More

Secure e-mail with encrypted PDF, ZIP, Word or Excel attachment

  1. What is an email with a secure attachment?
  2. Document encryption in an office workspace
  3. Secure pdf documents
  4. Secure MS-Office files (Word, Excel, PowerPoint)
  5. MS-Office with EncOffice plug-in
  6. Password protected zip file
  7. Secure email in 5 steps

What is an email with a secure attachment?

secure email with encrypted attachment

An email with a secure attachment is like the situation in the picture. The email text, To, From and Subject are all plaintext, like in a postcard. Attached is the encrypted file, like a locked envelope that can only be opened if you have the key. Without the key you can only see scrambled characters. Someone who intercepts the e-mail is able to read the e-mail message, but he cannot read the secure file in the attachment.

Document encryption in a standard workspace

In a standard workspace, a few file types that support file encryption are familiar to many users. These are discussed in the following section.

secure pdf documents Secure pdf documents

The pdf reader is free software and general available on workstations.
Opening a secure pdf is transparent because pdf encryption is supported by the free Acrobat pdf reader.
Most users do not have the ability to create a secure pdf, because this requires additional pdf encryption software.
128 bit strong encryption (RC4) is supported from version 7.
Encrypted pdf is blocked by most email servers.

secure Excel spreadsheet encrypt Word files Secure MS-Office files (Word, Excel, PowerPoint)

The software to open and read a Word, Excel or PowerPoint file is widely available. These file formats are mainstream.
Opening an encrypted Word, Excel or PowerPoint document is transparent.
Everyone knows how to create an Office document and has the software to do that.
To password secure a Word, Excel or PowerPoint file is not user friendly. Click here for how to encrypt an Excel file.
When a password is set with the default settings, weak encryption is the result. Click here for a description of the strength of Office encryption. 128 bit strong encryption is available in Office XP, 2003 and 2007, but it cannot be expected from an end user to be used properly.
Encrypted Word documents are allowed by 70% of the email gateways.

secure Excel spreadsheet encrypt Word files MS-Office with EncOffice plug-in

EncOffice is a plug-in for MS-Word and Excel that provides ease of use and proper security settings of the encrypted file. This results in the following:
The software to open and read a Word, Excel or PowerPoint file is widely available. These file formats are mainstream.
Opening an encrypted Word, Excel or PowerPoint document is transparent.
Everyone knows how to create an Office document and has the software to do that.
To password secure a Word, Excel or PowerPoint file is easy with the "Safe Encrypted" button provided by EncOffice. See here for the EncOffice user manual.
128 bit strong encryption (RC4) is the result when EncOffice is used to encrypt documents.
Encrypted Word documents are allowed by 70% of the email gateways.

EncOffice - Easy and Safe Encryption of Word and Excel Files      Learn More

encrypt Word files Password protected zip file

The unzip software is built-in in Windows XP.
Opening an encrypted zip is transparent, on double-clicking it automatically prompts for the password.
The zip file encryption software is not standard available. You have to install for example WinZip to do that.
Setting a password to a zip file is not user-friendly. Our experience is that it's no problem for IT personnel, but it's too difficult for most end users. See here for how to password protect a zip file.
WinZip 9 supports 128 bit and 256 bit strong encryption with the AES algorithm (Advanced Encryption Standard). Both are considered strong encryption.
Virus builders have recently distributed malware via password protected zip archives. This is why companies block emails containing encrypted zip files. As a result, it is unlikely that one can use encrypted zip files for secure email.

Secure email in 5 steps

As we have seen above, Word and Excel documents are excellent for secure email if EncOffice is used to secure the files. Once the document is password encrypted, it can be sent by email:
  1. Save an encrypted version of the Word or Excel file (click the "Save Encrypted" button)
  2. Open the email client.
  3. Create the email message the usual way.
  4. Click "Attach" button (). Now select the secured file. ('*.enc.xls' or '*.enc.doc'). Click OK.
  5. Send the item. The information will be sent secure by email
That's it. The receiver just double-clicks on the attachment to open it. EncOffice is NOT needed to open the encrypted file because MS-Office built-in encryption is used.