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[cryptography / python] Caesar Shift encryption

encryption

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15 replies to this topic

#13 MindiAbair

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Posted 12 September 2013 - 02:47 AM

Your key will be as long as the message to be encrypted, right ?

 

Correct. I know this method has limited practical application, but it was fun to think about. Can you think of a way to shorten the key? I'm thinking about it myself.


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#14 gonerogue

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Posted 12 September 2013 - 02:59 AM

The point with this kind of scheme is that it has little practical value because of the length of the key.

If we could afford this we would have use OTP which is unconditionally secure.

If all you need is to encrypt something, use established ciphers like AES, Serpent or Twofish.

If you want to understand how AES is working, read this book: http://www.amazon.co...y/dp/3540425802

Don't implement the AES algorithm in Python, use PyCrypto ... is already there.


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#15 MindiAbair

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Posted 12 September 2013 - 03:09 AM

Hi, xyv,

 

I can understand the legal requirement to advise new programmers not to use homebrew encryption solutions in practical application. But relax. I have no practical application in mind for encryption code right now, and I know that encryption is such a well-developed field that a newcomer like me would be unlikely to come up with anything better than already exists. What's really happening is that I am self-studying Python purely for entertainment, and I came to this forum looking for people who enjoy either writing code or learning how to do it, and who don't mind pooling ideas and helping a newbie out. :)

 

With that in mind, I can google OTP, AES, Serpent and Twofish, or you can tell me where I can read up on those things for free. I am too poor to buy books from Amazon, and the local library is terrible.

 

I am also going to put some thought into how I can shorten the encryption key in the above code, as well as make the code leaner and more professional-looking.


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#16 gonerogue

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Posted 12 September 2013 - 04:13 AM

A good source of free information is the Cryptography I course on coursera:

https://www.coursera.org/course/crypto

A free book:

http://www.cs.bris.a...el/Crypto_Book/


Edited by xyv123, 12 September 2013 - 04:20 AM.

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