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- Encryption has been part
of signals intelligence

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for quite some time.

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Caesar cipher, vigenere
cipher, ROT13 et cetera.

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If there is a secret you
want protected, encrypt it.

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One way hashing is not encryption

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but it is used to protect passwords.

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While not reversible,

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hashing algorithms were
designed to be computed quickly.

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So you can compute many
hashes from a dynamic source

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like a Word list or
permutations, brute force

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and compare the result to find a match.

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Lets take a look at how hashing works.

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We first start with clear
text like "pearson".

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We send it through a hash function.

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In this case we are using MD5.

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As the hash function applies
a one way hashing algorithm,

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the output of the function
is a string of characters

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that is unique to that specific
clear text that we input.

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Now this string can be
used in different ways

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to verify the integrity of
clear text that was provided.

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For instance, if a clear text email

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is sent through a hash
function by the sender

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and the hash was provided
to the recipient,

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they can use it to verify that the email

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was not changed in transit.

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So in this demo,

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I want to just show you a
really quick and easy way

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to generate a hash of clear text.

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Just like we did in the previous slides.

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Of course we are not gonna use MD5

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because today we have better algorithms

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for hashing like SHA256.

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So what I am gonna show here is

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how to do this from a Kali commandline.

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What you will do is type "echo"

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then type in your clear text

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and simply pipe it over

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to the SHA256SUM command.

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And we can see here

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it spits out a long set of characters

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that are hash of the
clear text word "pearson".

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If we run it again, we
see its the same hash.

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This is the way that
hashing algorithm works.

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It should always be the
same unless it was modified.

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So if we were to,

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say, add a "1" to "pearson",

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and run it through again,
the hash should change.

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As you can imagine, this
is how hashing can be used

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for things like email
integrity validation.