?
Solved

CRC or Checksum or XOR or DES

Posted on 2001-07-11
3
Medium Priority
?
1,318 Views
Last Modified: 2007-02-12
Hi,

There is any part or someone that can tell me what is the difference between them and what is the advantages of each one ??

I need to know how they work and if they are efficience.

Thank you
0
Comment
Question by:arocio
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
3 Comments
 
LVL 5

Expert Comment

by:Droby10
ID: 6275969
crc (cyclical redundancy check) is most comonly used as data verification in the form of a parity bit...it is mostly used for handling data transfers from modulated or spindle devices; crc represents a form of checksum...but you could also say that an md5 hash is a checksum, which in no way resembles a crc value.

xor is a binary function performed on two values.
1 xor 255 = 254, 128 xor 128 = 0, 128 xor 127 = 255...

des is a shared key cryptography system...some of the algorithms used in des make use of xor.
0
 
LVL 1

Accepted Solution

by:
tonimargiotta earned 400 total points
ID: 6343764
A check sum is a hash, a piece of data derived by an alogorithm from a larger piece of data.  Which algorithm you choose will depend on the use you want to make of it rather than any difference in performance.

Order of decreasing efficiency probably (though depending on library)

XOR
CRC
MD5
DES
3DES

If you want protect data from deliberate modification then you should use MD5 and encrypt the hash, there are many commercial and freeware libraries to assist you.  

If you just want to detect accidental corruption then XOR and CRC are accepted algorithms, but remember there is a chance (theoretically over 1:billion for CRC 32) that they can miss errors.

MD5 should be more reliable but is computationally more intensive.
0
 
LVL 1

Expert Comment

by:Moondancer
ID: 6400710
Did this help you, arocio, so you may award expert(s) who helped you or is more needed here?  You have a number of old questions dating back to last year that remain open, awaiting your response as well.

Thank you for remaining active in your questions here and keeping experts who help you updated with progress.

Moondancer
Community Support Moderator @ Experts Exchange
0

Featured Post

Want to be a Web Developer? Get Certified Today!

Enroll in the Certified Web Development Professional course package to learn HTML, Javascript, and PHP. Build a solid foundation to work toward your dream job!

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

A look at what happened in the Verizon cloud breach.
Let's recap what we learned from yesterday's Skyport Systems webinar.
Nobody understands Phishing better than an anti-spam company. That’s why we are providing Phishing Awareness Training to our customers. According to a report by Verizon, only 3% of targeted users report malicious emails to management. With compan…
This video Micro Tutorial shows how to password-protect PDF files with free software. Many software products can do this, such as Adobe Acrobat (but not Adobe Reader), Nuance PaperPort, and Nuance Power PDF, but they are not free products. This vide…
Suggested Courses

743 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question