Is it possible (and practical) to search a string for arbitrary-length repeating patterns?

Posted by blz on Programmers See other posts from Programmers or by blz
Published on 2012-11-05T09:21:02Z Indexed on 2012/11/05 11:24 UTC
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I've recently developed a huge interest in cryptography, and I'm exploring some of the weaknesses of ECB-mode block ciphers. A common attack scenario involves encrypted cookies, whose fields can be represented as (relatively) short hex strings.

Up until now, I've relied on my eyes to pick out repeating blocks, but this is rather tedious. I'm wondering what kind of algorithms (if any) could help me automate my search for repeating patterns within a string.

Can anybody point me in the right direction?

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