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Format

Microsoft Office Encrypted Document

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Summary

Name
Microsoft Office Encrypted Document
Version
2007 Onwards
Identifiers
PUID: fmt/494
Format type
  • Presentation
  • Spreadsheet
  • Word Processor
Description
A Microsoft Office - Word, Excel, or PowerPoint document, that has been encrypted. The encrypted document conforms to the MS-OFFCRYPTO specification, as found here: http://msdn.microsoft.com/en-us/library/cc313071(v=office.12).aspx The document is an OLE2 compound that contains a number of files: EncryptionInfo - This file contains information used by the Office-compatible application to decrypt the encrypted package. There are multiple variants of this file, as described in 2.3.4.5, and 2.3.4.6 of the format specification. EncryptedPackage - This file contains the whole of the encrypted document. DataSpaces folder (and sub-files) - This structure associates protected content with data space definitions. The data space definition, in turn, describes the series of transforms that must be applied to that protected content to restore it to its original form. Since the method of identifying and distinguishing specific types of OOXML documents relies on seeking and analysing specific elements within the document, and in the case of encryption this information is obfuscated, it does not currently seem possible to determine with any specificity whether an encrypted file is either an Excel, Word, or PowerPoint document, apart from the file extension.
File extensions
xlsx, pptx, docx
Source
Digital Preservation Department / The National Archives
Developed by
Microsoft Corporation
Supported by
Microsoft Corporation

Container signatures

Type: OLE2

16000 - Microsoft Office 2007 and later encrypted document

File path
EncryptedPackage

Changelog

  • Updated in V75

    Release date
    17 July 2014

    Microsoft Office Encrypted Document 2007 onwards: Error corrected in file extension details.

  • Added in V67

    Release date
    26 February 2013

    Microsoft Office Encrypted Document 2007 Onwards: Container signature developed through PRONOM Research.

    Microsoft Office Encrypted Document 2007 Onwards: Outline Entry Added.