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<h1>RSA: what is it?</h1>
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<h4 class="post-date line-under"></h4>
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<p>In this article I will explain what RSA is, and where it is used at a high level. The next parts to this will focus more on what RSA is at a technical level: how it uses numbers to store secrets in the open. Here, I plan to explain simple the idea.</p>
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<p>Let’s imagine we have two people. Bob, and Alice. Bob wants to send Alice a love letter. But Eve, the sneaky wreetch, wants to listen in on Alice and Bob’s conversation. How can we avoid sending messeges between Alice and Bob like postcards would be sent in the mail: the postman, sorters, and the delivery man can all read it?</p>
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<p>We could, in theory, use a Ceaser Cipher to do this. So Alice can send a messege with a key like A=B, meaning that all A’s get converted to B’s, B’s to C’s, C’s to D’s, et cetera. However, this solution fails when we realize that Bob and Alice would have to agree on some key to make this work. Either A=B, or 1, meaning shift the letters by one character. How can we get them to share this key without meeting in person, where Alice could just tell Bob in person, removing he need for a key.</p>
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<p>Well, what if we used something called asymetric encryption? This would mean we have two keys. A and B, A can decrypt any messeges encrypted with B, and B can decreypy any messeges encrypted with A. But A cannot decrypt its own messeges, and neither can B. You choose one of these keys, it doesn’t matter which one, to be your “public key” (although it acts more like a lock), and one to be your private key. The key that you do not share anywhere. You give anyone your lock. You put it on your email signatue, you put it on your blog. You share this! Then anyone who wants to send a secret messege to you can send you a messege and use your public lock (key) to encrypt the messege.</p>
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<p>In this scenario, we could get Alice to have one set of these keys, and Bob to have one set of these keys. They can exchange public keys, allowing Bob to communicate with Alice and vice-versa. Now Alice can send “Bob, I ove you!” over the wire! It will look like “iU0oo–!@EFb` z” or some such other nonesense to anyone else, and Eve especially, listening in.</p>
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