Kruptos Help

Welcome to Kruptos, the simple app to encrypt and decrypt messages with ease. This document will help you understand how to use Kruptos, and should answer any other questions that you have about Kruptos.

Kruptos Help

Contents

What does encryption mean?

What code does Kruptos use?

How do the keys work?

Where do the keys come from?

What can I encrypt?

How can I send a message to someone?

How can I receive a message from someone?

How secure are messages encrypted with Kruptos?

About

Bibliography

Legal Information

What does encryption mean?

Encryption is the process of converting information, like a word or a sentence into a code, especially to prevent unauthorized access. There are many different types of codes that can be used to encrypt information.

What code does Kruptos use?

Kruptos uses RSA, a code developed in 1978, to encrypt and decrypt messages securely. RSA uses two keys (like passwords); one to encrypt the message into code, and a different one to decrypt the message into its original form.

How do the keys work?

With RSA, there are two keys: one which is used to encrypt the message and is publicly known (called the public key), and one which is used to decrypt the message, and is kept a secret. In the RSA system, it is the responsibility of the person receiving the message to generate the keys, to publish the public key, and to keep the private key safe.

Where do the keys come from?

Kruptos generates the keys for you. To get your keys, run Kruptos, and select the “Create My Keys” option, as shown in the images below. For security reasons, the keys have been hidden.

You will be asked to choose your security/speed ratio. If you want to be able to encrypt and decrypt your message quickly, you should choose “Low Security/High Speed”. If you want your message to be encrypted very securely, you should choose “High Security/Low Speed”. If you do not care, you should choose “Medium Security/Medium Speed”.

What can I encrypt?

Only the English alphabet, numbers, spaces, and certain symbols (,.?!-£$€%^&*();'\:"|/<>`~=@_+[]{}…) can be encrypted. Any other characters will be replaced by a ∎ (black square).

How can I send a message to someone?

Run Kruptos, and choose to “Encrypt a Message”.
Enter your message.
Enter the public key of the recipient of your message. This will probably be on the recipient’s website, or in some other public place. If you cannot find the public key, you will need to ask your recipient to provide it.
Your message will be encrypted, and presented to you, giving you the opportunity to copy it elsewhere. If the encrypted message is over 500 characters long, it will be truncated, with the remainder of the message viewable through the copy function.
You can then send the message to its recipient over email, or any other form of communication. The message will be encrypted, so it doesn’t matter if other people can see the message, as they will not be able to decrypt it.

How can I receive a message from someone?

Create your keys, and save them in a safe place.
Publish your public key (not your private key) on your website, or in another public place.
Tell the sender of the message where they can find your public key.
Request that the sender encrypts their message using Kruptos and your public key, and then sends the message to you. The message will be encrypted, so it doesn’t matter if other people can see the message, as they will not be able to decrypt it.
Once you have received the message, run Kruptos, and choose to “Decrypt A Message”.
Enter the message.
Enter your private key.
The decrypted message will be presented to you, giving you the opportunity to copy it elsewhere. If the message is over 300 characters long, it will be truncated, with the remainder of the message viewable through the copy function.

How secure are messages encrypted with Kruptos?

Messages encrypted with Kruptos are quite secure. While an experienced cryptanalyst (someone who breaks codes) would be able to decrypt messages encrypted by Kruptos, there is no chance that anyone without considerable cryptanalytic experience would be able to decrypt a message.

About

Kruptos has been created by Sebastian Hallum Clarke for his 2011-2012 MYP Personal Project.

Bibliography

This is a list of sources used in the creation of my application:

"RSA Algorithm." DI Management Home Page. 3 Nov. 2011. Web. 08 Jan. 2012. <http://www.di-mgt.com.au/rsa_alg.html>.
"Preventing Reuse of Passwords." Matthew Slyman. 15 Feb. 2011. Web. 08 Jan. 2012. <http://www.slyman.org/blog/2011/02/preventing-password-reuse/>.
Levy, Steven. Crypto: Secrecy and Privacy in the New Code War. London: Allen Lane, 2000. Print.
Smith, Laurence Dwight. Cryptography: The Science of Secret Writing. New York: W.W. Norton &, 1943. Print.
Simon, William L., and Kevin D. Mitnick. The Art of Deception: Controlling the Human Element of Security. Indianapolis, IN: Wiley, 2002. Print.
Singh, Simon. The Code Book: How to Make It, Break It, Hack It, Crack It. New York: Delacorte, 2002. Print.
Popyack, JL. "RSA Calculator." Computer Science. Drexel University, Oct. 1997. Web. 8 Jan. 2012. <https://www.cs.drexel.edu/~jpopyack/IntroCS/HW/RSAWorksheet.html>.
Tagg, Paul. "Programmatic RSA." E-mail interview. 15 Nov. 2011.
Hueber, Lillian. "Divining the RSA Decryption Key." Personal interview. 12 Oct. 2011.
AppleScript Language Guide. Tech. Apple, Inc., 3 Nov. 2008. Web. September 2011 to January 2012. <http://developer.apple.com/library/mac/#documentation/applescript/conceptual/applescriptlangguide/introduction/ASLR_intro.html>.
Wikipedia contributors. "Letter frequency." Wikipedia, The Free Encyclopedia. Wikipedia, The Free Encyclopedia, 22 Nov. 2012. Web. 26 Nov. 2011.
Wiese, Jim, and H. Keith Melton. The Spy's Guide to Secret Codes and Ciphers. New York: Scholastic, 2002. Print. When I had my spy club, I subscribed to a series of books from "Spy University". This book was the one that contained the information about codes.
Wikipedia contributors. "Caesar cipher." Wikipedia, The Free Encyclopedia. Wikipedia, The Free Encyclopedia, 13 Dec. 2011. Web. 8 Jan. 2012.
Clarke, Jeffrey. "Beating Frequency Analysis with RSA." Personal interview. 6 Dec. 2011. We worked together to develop the method for preventing my encryption system from been attacked by frequency analysis.

Legal Information

Kruptos is licenced under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported with attribution to Sebastian of Zibity.

This application is provided as-is, with no warranty expressed or implied. Use this application at your own risk. The author assumes no liability for any loss or damages associated with the use of this application. The author assumes no liability for any loss or damages arising from insecure encryption, or any other failures associated with the use of this application. This application is for entertainment purposes only. If you do not agree with the terms of this license, do not install or use this application.