CODEWITHSUNDEEP
c#.net
Levitikon
Levitikon

Reputation: 7847

C# quickest two-way string shortening

What is the quickest and best performance way to turn a string into a string of numbers and/or letters, then reverse engineer to the original string. Similar to turning a string into it's hash code, but that's a one-way conversion. I need a two-way method. I'm creating a simple url shorting service and I don't want to deal with a database.

I considered MD5 encrypting/decrypting via a private key, but I imagine there's another way that might be better on performance.

If encrypting/decrypting is the way to go, then which is the easiest on the processor?

Thanks!

Upvotes: 2

Views: 3984

Answers (2)

Steve Wortham
Steve Wortham

Reputation: 22230

What you'd need is a lossless compression algorithm. I mean, that's the only way you'd be able to compress the text, and also be able to decompress it.

With compression the string length is going to vary, of course. On average the length isn't going to be as small as the Base64 ID's that tinyurl uses. They're able to do that because they're storing the ID and URL in a database.

Nevertheless, here are a couple options...

If you go this route I'd create a little console application to test the performance of all of this. If you have the RAM, it might even be worth it to cache the results into a Dictionary so you're not having to constantly compress and decompress URLs for every request.

UPDATE

There's a library called smaz which is apparently designed for compressing small strings...

It can compress URLS pretty well:

'http://google.com' compressed by 59%

'http://programming.reddit.com' compressed by 52%

'http://github.com/antirez/smaz/tree/master' compressed by 46%

Upvotes: 6

Martin Liversage
Martin Liversage

Reputation: 106856

When you encrypt you don't shorten anything. The cipher text is roughly the same length as the clear text. However, if you use a cryptographic hash you shorten the string to the length of hash. The drawback is that you are no longer able to reverse the hash back to the original string. I don't think you will be able to create a URL shortener using neither an encryption algorithm nor a cryptographic hash function. If that was possible to you could achieve infinite or at least very high compression of information.

Upvotes: 11

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