World Library  
Flag as Inappropriate
Email this Article

Gbde

Article Id: WHEBN0008708466
Reproduction Date:

Title: Gbde  
Author: World Heritage Encyclopedia
Language: English
Subject: Comparison of disk encryption software, Geli (software), FreeBSD, History of FreeBSD, Disk encryption
Collection: Disk Encryption, Freebsd
Publisher: World Heritage Encyclopedia
Publication
Date:
 

Gbde

GBDE, standing for GEOM Based Disk Encryption, is a block device-layer disk encryption system written for FreeBSD, initially introduced in version 5.0. It is based on the GEOM disk framework. GBDE was designed and implemented by Poul-Henning Kamp and Network Associates Inc. (now known as McAfee).[1]

Contents

  • Design decisions 1
  • Limitations 2
  • See also 3
  • References 4

Design decisions

Unlike most disk encryption software, GBDE does not attempt to defeat watermarking attacks through the use of disk encryption-specific modes of operation (see disk encryption theory), but instead generates a random key each time a sector is written.[2] Unlike some alternatives, such as CBC with sector-specific initialization vectors, this approach does not reveal any information to the attacker even if they have access to snapshots of the disk image from different points in time, since encryption keys are never re-used.

The one time sector key is encrypted using a pseudorandom key. This pseudorandom key is derived from the sector number and a static 2048-bit master key with 128 bits of salt. The pseudorandom number generator used for this purpose is called the Cherry Picker. This is not a well established PRNG, but rather one invented for GBDE. This generator may not meet the security levels of standard algorithms, and could be distinguishable from random numbers.[3]

Limitations

Due to this unique approach, GBDE only supports 128-bit AES. Using a different key for each write also introduces a significant CPU overhead, as most block ciphers use key-specific precomputations, and makes disk updates non-atomic since the keys are written separately from the data. As a result, data loss can occur on unexpected power drops, even when used with journaling file systems. GBDE also has a disk space overhead of about 3% to store the per-sector keys.

To address these shortcomings, a more typical disk encryption solution for FreeBSD, GELI, was written later by Pawel Jakub Dawidek.

See also

References

  1. ^ "gbde(4) man page in FreeBSD 5.0". GBDE manual page. Retrieved 2007-01-01. 
  2. ^  
  3. ^ Roland C. Dowdeswell (2005-03-26). "Initial Analysis of GBDE". Retrieved 2007-01-26. 
This article was sourced from Creative Commons Attribution-ShareAlike License; additional terms may apply. World Heritage Encyclopedia content is assembled from numerous content providers, Open Access Publishing, and in compliance with The Fair Access to Science and Technology Research Act (FASTR), Wikimedia Foundation, Inc., Public Library of Science, The Encyclopedia of Life, Open Book Publishers (OBP), PubMed, U.S. National Library of Medicine, National Center for Biotechnology Information, U.S. National Library of Medicine, National Institutes of Health (NIH), U.S. Department of Health & Human Services, and USA.gov, which sources content from all federal, state, local, tribal, and territorial government publication portals (.gov, .mil, .edu). Funding for USA.gov and content contributors is made possible from the U.S. Congress, E-Government Act of 2002.
 
Crowd sourced content that is contributed to World Heritage Encyclopedia is peer reviewed and edited by our editorial staff to ensure quality scholarly research articles.
 
By using this site, you agree to the Terms of Use and Privacy Policy. World Heritage Encyclopedia™ is a registered trademark of the World Public Library Association, a non-profit organization.
 


Copyright © World Library Foundation. All rights reserved. eBooks from Project Gutenberg are sponsored by the World Library Foundation,
a 501c(4) Member's Support Non-Profit Organization, and is NOT affiliated with any governmental agency or department.