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   ► MB LobbyPascal and Delphi Coding BoardDelphi Object PASCAL Topic   Print This     

Forum : Encryption

Forum : Encryption in Delphi Object PASCAL topic (part of our Pascal and Delphi Coding group).

Quick Search: Encryption   Forum Encryption  
Scott Wehrly
Prestwood IT
 (Inactive)
Las Vegas, NV USA
In the spirit of waking up these too-quiet Delphi forums, I want to open up a discussion of technical solutions, and begin a dialog between the board members on their experience with the subject.



I want to begin with data encryption. Having just built the first commercial release of our Password PocketBook application, naturally I had to analyze encryption methods.



What I want to know is what other Delphi developers have experienced in dealing with encryption - particulary encryption algorithms and data conversions.


  • 1. What have you used for encrypting passwords and other sensitive string data?
  • 2. What worked best for you?
  • 3. What caused problems for you?
  • 4. For database fields (any SQL database), what was the most efficient way you handled field value encryption?
  • 5. What libraries or component products would you recommend?




For our application, I did review a few libraries and source samples from Torry's and the Delphi SuperPage. But I'd like to get the feedback from other Delphi developers on this.
 Posted 16 years ago (Thread Starter)
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Post ID #9609, 2 replies
Thread Started 5/16/2003 9:49:00 AM
View Counter=3830
Last Reply Posted 9/11/2003 3:51:00 AM)
Location=Las Vegas, NV USA 
Joined=17 years ago   MB Posts=442   KB Posts=19  
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NevilleRichards
 (Inactive)
UK
Unfortunately, I think that any self-respecting hacker would unravel Angel's encryption very quickly.

I once read an interesting article which proposed using a mathematical procedure of a recurrence relation type:

D[i+1] := f(D) - D[i-1]

In english, the next string is some mixture of the current on minus the previous (however you define minus in this context).

This has the advantage that the reversal is of exactly the same form.

D[i-1] := f(D) - D[i+1]

In my implementation, my f() generally moves the characters around, and does some arithmetic on them (avoiding making them invisible).

The process can be repeated a number of times (so long as the decryption is done the same number of times). I generally divide a string in half, and treat the first half as D[1] and the second as D[2]. I can then go ahead and calc D[3] and onwards. I would divulge D[7] and D[6] as a composite string. Decryption just involves the same process in reverse.

I have experienced no examples of it being cracked in over 10 years of use.

Neville
 Posted 16 years ago
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Post ID #9898 (Level 1.1)  Reply to 9609
Thread Started 9/11/2003 3:51:00 AM
View Counter=2
Location=UK  
Joined=18 years ago   MB Posts=41  
Angel
 (Inactive)
England
I have only needed to encrypt sensitive data once before. It was a list of credit card numbers and expiration dates etc...

I cant remember the specifics, but I incremented the characters ascii values by a set number and then saved the new data to the tables. Depending on which number was being incremented, depended on how many places it was incremented. When viewing, I simply reversed the procedure. Confused

I have to do something similar again in the very near future so I would also be interested to hear others solutions to this. :)
 Posted 16 years ago
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Post ID #9633 (Level 1.2)  Reply to 9609
Reply Posted 5/20/2003 1:16:00 AM
Location=England  
Joined=18 years ago   MB Posts=199  

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