Friday, December 8, 2017

Explainer video shows how secure 256 bit security is

Hash functions are important in data security. SHA-256 (Secure Hash Algorithm) converts text of any length to a 64-digit hexadecimal number. Play around with the hash generator here by copying and pasting text into it.

Here's a Shakespeare quote:

Life’s but a walking shadow, a poor player, that struts and frets his hour upon the stage, and then is heard no more; it is a tale told by an idiot, full of sound and fury, signifying nothing.

The SHA-256 hash is:


If you change a single character, the hash is completely different. If you take the end period off the quote, the hash becomes:


Hashes are "one-way" -- it's easy to generate a hash from any text, but there is no know way to convert a hash back into the source text. In other words, if you are given this hash:


The only way to get the source text is by guessing. How long would it take? The video above shows you that it would take a long time, indeed.

If this kind of thing interests you, I highly recommend Simon Singh's The Code Book, which clearly explains cryptographic principles.

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