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What does an encrypted document look like

Encryption is a way of coding the information in a file or e-mail message so that if it is intercepted by a third party as it travels over a network it cannot be read. Only the persons sending and receiving the information have the key and this makes it unreadable to anyone except the intended persons.

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

By default Word and Excel documents are plaintext (not encrypted). If you open such a document in a simple viewer, you are able to read most of the written text. On the other hand, if it's encrypted you will only see a mix of strange characters. This is illustrated by the next pictures.


Encrypted Illustration
On the left the original Word document in a simple viewer. On the right, the encrypted version of the same document.

Encrypted Illustration Word
The original Word document.

Encryption details

Word and Excel documents are encrypted with RC4. RC4 is a stream cipher designed by Rivest for RSA Security. It is a variable key-size stream cipher with byte-oriented operations. The algorithm is based on the use of a random permutation. Analysis shows that the period of the cipher is overwhelmingly likely to be greater than 10100. Eight to sixteen machine operations are required per output byte, and the cipher can be expected to run very quickly in software. Independent analysts have scrutinized the algorithm and it is considered secure.

RC4 is used for file encryption in products such as RSA SecurPC and PDF. It is also used for secure communications, as in the encryption of traffic to and from secure web sites using the SSL protocol and for the protection of wireless networks (WiFi).

EncOffice: Easy and Safe Encryption of Word documents
  • Adds a "Safe Encrypted" button to the Word toolbar
  • Helps to choose a strong password
  • Makes encrypted copy of the original document with extension ".enc.doc"
  • You can open the encrypted document with a standard Word version
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