Solved

Maximum length of encoded 20-character string

Posted on 2008-06-15
1
480 Views
Last Modified: 2008-06-26
I am using DESCryptoServiceProvider to encrypt strings of various length. The key I'm using is a byte[8] and the iv is a byte[8].
I am wondering what the maximum length of a 20-character string encrypted this way would be?
Or in other words, is there some function that would say what the maximum length of the encryptred string would be for a given string length?

Also, would it be the same if I used DESX instead?

Thanks!
0
Comment
Question by:PapaparaTudu
[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
1 Comment
 
LVL 33

Accepted Solution

by:
Dave Howe earned 500 total points
ID: 21790289
ok. you need to include the iv (at one block, or eight bytes), and one eight byte data block per eight bytes of data. 20 is not a multiple of 8, so the next biggest multiple would be 24, giving you 24+8 or 32 bytes. overhead is the 8 byte iv, plus rounding your date up to the next multiple of 8. This will be binary data (regardless of how it started) so you may need to further expand that (using bin64 or similar) if you need it 7 bit clean for email purposes.

desx is xor (key1, des (key 2, xor (key 3, data ) ) )  and has the same block size as straight des - so no further data will be needed. the same is true of 3DES.
0

Featured Post

SharePoint Admin?

Enable Your Employees To Focus On The Core With Intuitive Onscreen Guidance That is With You At The Moment of Need.

Question has a verified solution.

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

Provide an easy one stop to quickly get the relevant information on common asked question on Ransomware in Expert Exchange.
Performance in games development is paramount: every microsecond counts to be able to do everything in less than 33ms (aiming at 16ms). C# foreach statement is one of the worst performance killers, and here I explain why.
With Secure Portal Encryption, the recipient is sent a link to their email address directing them to the email laundry delivery page. From there, the recipient will be required to enter a user name and password to enter the page. Once the recipient …
The Email Laundry PDF encryption service allows companies to send confidential encrypted  emails to anybody. The PDF document can also contain attachments that are embedded in the encrypted PDF. The password is randomly generated by The Email Laundr…

690 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