Comments on: Three Ways to Protect Your Email Privacy Using Low-Tech Encryption (Caesar Cipher, Vigenere Cipher, Three-Pass Protocol) http://mindyourdecisions.com/blog/2008/05/13/three-ways-to-protect-your-email-privacy-using-low-tech-encryption-caesar-cipher-vigenere-cipher-three-pass-protocol/ Articles on game theory and personal finance Thu, 09 Feb 2012 18:20:00 +0000 hourly 1 http://wordpress.org/?v=3.3.1 By: Monday puzzle: hide and seek with a twist - Mind Your Decisions http://mindyourdecisions.com/blog/2008/05/13/three-ways-to-protect-your-email-privacy-using-low-tech-encryption-caesar-cipher-vigenere-cipher-three-pass-protocol/comment-page-1/#comment-12065 Monday puzzle: hide and seek with a twist - Mind Your Decisions Mon, 17 Oct 2011 05:07:48 +0000 http://mindyourdecisions.com/blog/2008/05/13/three-ways-to-protect-your-email-privacy-using-low-tech-encryption-caesar-cipher-vigenere-cipher-three-pass-protocol/#comment-12065 [...] have encoded the answer using rot13 (an example of a Caesar cipher) so the casual reader does not accidentally have the answer [...] [...] have encoded the answer using rot13 (an example of a Caesar cipher) so the casual reader does not accidentally have the answer [...]

]]> By: A Day in the Life of a Game Theorist: A Tribute to One Year of Game Theory Tuesdays - Mind Your Decisions http://mindyourdecisions.com/blog/2008/05/13/three-ways-to-protect-your-email-privacy-using-low-tech-encryption-caesar-cipher-vigenere-cipher-three-pass-protocol/comment-page-1/#comment-9509 A Day in the Life of a Game Theorist: A Tribute to One Year of Game Theory Tuesdays - Mind Your Decisions Sat, 20 Aug 2011 06:04:25 +0000 http://mindyourdecisions.com/blog/2008/05/13/three-ways-to-protect-your-email-privacy-using-low-tech-encryption-caesar-cipher-vigenere-cipher-three-pass-protocol/#comment-9509 [...] Thanks for the discussion, Presh. This is basically my area of expertise so it is fun to see a post on the topic. Especially when it is clear and lucid. Paul in Three Low-tech Ways to Protect Your Email Privacy (link) [...] [...] Thanks for the discussion, Presh. This is basically my area of expertise so it is fun to see a post on the topic. Especially when it is clear and lucid. Paul in Three Low-tech Ways to Protect Your Email Privacy (link) [...]

]]> By: Game theory and salary transparency - Mind Your Decisions http://mindyourdecisions.com/blog/2008/05/13/three-ways-to-protect-your-email-privacy-using-low-tech-encryption-caesar-cipher-vigenere-cipher-three-pass-protocol/comment-page-1/#comment-8584 Game theory and salary transparency - Mind Your Decisions Mon, 20 Jun 2011 20:20:59 +0000 http://mindyourdecisions.com/blog/2008/05/13/three-ways-to-protect-your-email-privacy-using-low-tech-encryption-caesar-cipher-vigenere-cipher-three-pass-protocol/#comment-8584 [...] A hint to get started: read the article on email encryption [...] [...] A hint to get started: read the article on email encryption [...]

]]> By: mimi http://mindyourdecisions.com/blog/2008/05/13/three-ways-to-protect-your-email-privacy-using-low-tech-encryption-caesar-cipher-vigenere-cipher-three-pass-protocol/comment-page-1/#comment-5752 mimi Tue, 03 Nov 2009 19:09:00 +0000 http://mindyourdecisions.com/blog/2008/05/13/three-ways-to-protect-your-email-privacy-using-low-tech-encryption-caesar-cipher-vigenere-cipher-three-pass-protocol/#comment-5752 how do you use this ???? The plain text is then encoded using the Vigenère square, which indicates how letters translate. (image from user:Matt Crypto) Vigenere square The top row of letters is for the plain text, the left hand column of letters is for the key word, and the middle characters are the encoded letters. For instance, the letter “C” on the top row and the letter “H” on the left column translate to the letter “J” in cipher text. Vigenere square example Repeating the process for all letters, here is the coded, or cipher, text that would result: Plain text: COLLEGE DEBT Key word: HELPHEL PHEL Cipher text: jswalkp slfe The Vigenère Cipher does have a practical flaw: the receiving person has to know the key word. If you put the key word in the email, the message is no more secure than the Caesar Cipher. If you can’t communicate it, the message becomes incomprehensible. Also, you might not even want to reveal your key word to the other party if it happens to be a special password that you use for other accounts. So is there a way you can send an encoded message without revealing your key word? Amazingly, there is a way. The extra restrictions are the other person needs a key word and the message has to travel three times. how do you use this ????

The plain text is then encoded using the Vigenère square, which indicates how letters translate. (image from user:Matt Crypto)

Vigenere square

The top row of letters is for the plain text, the left hand column of letters is for the key word, and the middle characters are the encoded letters. For instance, the letter “C” on the top row and the letter “H” on the left column translate to the letter “J” in cipher text.

Vigenere square example

Repeating the process for all letters, here is the coded, or cipher, text that would result:

Plain text: COLLEGE DEBT
Key word: HELPHEL PHEL
Cipher text: jswalkp slfe

The Vigenère Cipher does have a practical flaw: the receiving person has to know the key word. If you put the key word in the email, the message is no more secure than the Caesar Cipher. If you can’t communicate it, the message becomes incomprehensible.

Also, you might not even want to reveal your key word to the other party if it happens to be a special password that you use for other accounts.

So is there a way you can send an encoded message without revealing your key word?

Amazingly, there is a way. The extra restrictions are the other person needs a key word and the message has to travel three times.

]]> By: Presh Talwalkar http://mindyourdecisions.com/blog/2008/05/13/three-ways-to-protect-your-email-privacy-using-low-tech-encryption-caesar-cipher-vigenere-cipher-three-pass-protocol/comment-page-1/#comment-2448 Presh Talwalkar Wed, 27 Aug 2008 20:34:10 +0000 http://mindyourdecisions.com/blog/2008/05/13/three-ways-to-protect-your-email-privacy-using-low-tech-encryption-caesar-cipher-vigenere-cipher-three-pass-protocol/#comment-2448 <b><em>Eyal</b></em>: Thank you for the comprehensive and understandable response. I especially overlooked that you can use the same cipher to decode the password since it is an addition/subtraction cipher method, which you point out is quickly reversible. I'll make a correction in the article and point people towards your comment. Thanks again! Eyal:
Thank you for the comprehensive and understandable response. I especially overlooked that you can use the same cipher to decode the password since it is an addition/subtraction cipher method, which you point out is quickly reversible.

I’ll make a correction in the article and point people towards your comment. Thanks again!

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