2 files changed, 93 insertions, 6 deletions

diff --git a/site/content/JWT.md b/site/content/JWT.md
index 91a7a73..f55ab17 100644
--- a/site/content/JWT.md
+++ b/site/content/JWT.md
@@ -4,8 +4,38 @@ description = "JSON Web Token Documentation"
 weight = 5
 +++
 
-Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod
-tempor invidunt ut labore et dolore magna aliquyam erat, sed diam voluptua. At
-vero eos et accusam et justo duo dolores et ea rebum. Stet clita kasd
-ubergren, no sea takimata sanctus est Lorem ipsum dolor sit amet.
+> JSON Web Tokens are representations of claims, or authorization proofs that fit into the `Header` of HTTP requests.
+
+# How?
+
+JWTs are used as the [MAC](https://en.wikipedia.org/wiki/Message_authentication_code) of operations that require authorization:
+- block proposal
+- transaction proposal.
+
+They are send alongside the JSON request body in the `Header`;
+
+```html
+Authorization: Bearer aaaaaa.bbbbbb.ccccc
+```
+
+Gradecoin uses 3 fields for the JWTs;
+
+```json
+{
+"tha": "Hash of the payload, check invididual references",
+"iat": "Issued At, Unix Time",
+"exp": "Expiration Time, epoch"
+}
+```
+
+- `tha` is explained in [blocks](@/block_docs.md) and [transactions](@/transaction_docs.md) documentations.
+- `iat` when the JWT was created in [Unix Time](https://en.wikipedia.org/wiki/Unix_time) format
+- `exp` when the JWT will expire & be rejected in [Unix Time](https://en.wikipedia.org/wiki/Unix_time)
+
+# Algorithm
+We are using [RS256](https://www.rfc-editor.org/rfc/rfc7518.html#section-3.1), `RSASSA-PKCS1-v1_5 using SHA-256`. The JWTs you encode with your private RSA key will be decoded using the public key you have authenticated with. You can see how the process works [here](https://jwt.io/).
+
+# References
+- [RFC, the ultimate reference](https://tools.ietf.org/html/rfc7519)
+- [JWT Debugger](https://jwt.io/)
 
diff --git a/site/content/_index.md b/site/content/_index.md
index 7dd7a7c..bf33eef 100644
--- a/site/content/_index.md
+++ b/site/content/_index.md
@@ -3,8 +3,35 @@ title = "Gradecoin"
 sort_by = "weight"
 +++
 
-- Don't know where to start? Gradecoin uses RESTful API, simple `curl` commands or even your browser will work! [This website can help as well](https://curl.trillworks.com/).
-- [JWT Debugger](https://jwt.io) and the corresponding [RFC](https://tools.ietf.org/html/rfc7519)
+# Welcome to Gradecoin!
+
+Blockchains are incredibly simple yet can appear very complicated, we will see how they work and practice programming _production_ cryptography code.
+
+This server is the sandbox for the PA1, it's currently running the Gradecoin application. Gradecoin is the faux currency we will use to simulate a blockchain network. At the end of the simulation, the amount of Gradecoin you hold will be your PA1 grade.
+
+**A quick summary**: authenticate yourself to the system using public key encryption.
+Craft [Transaction](@/transaction_docs.md) proposals and tag them using [JWTs](@/JWT.md).
+When there are enough transactions then you can propose [Blocks](@/block_docs.md) in the same way.
+Blocks need to be _mined_ beforehand using Proof-of-work, or brute force.
+
+Gradecoin offers 3 endpoints at [/register](/register), [/block](/block) and [/transaction](/transaction). You can only send GET requests to /block and /transaction without authorization.
+The server is programmed in [RESTful](https://www.service-architecture.com/articles/web-services/representational_state_transfer_rest.html) architecture, there are no `DELETE`, `PUT` or `UPDATE` operations, though.
+
+Gradecoin uses a Proof-of-work block accepting mechanism. It uses single round [Blake2s](https://www.blake2.net/) hashing which produces 256-bit (64 hexadecimal characters) output. The [target](https://wiki.bitcoinsv.io/index.php/Target) hash is _24 bits_ or _6 hexadecimal characters_ of 0. During testing, I could mine a block on average around 2-7 minutes.
+
+> We're expecting you to use existing tools and implementations. Standards are hard. [Don't roll your own crypto](https://www.reddit.com/r/crypto/comments/2coqsy/dont_roll_your_own/). Feel free to ask questions. Collaborate.
+
+You might ask,
+
+> But if nobody has any Gradecoin then how do we have transactions?
+
+There is a bank! Their public key is `31415926535897932384626433832795028841971693993751058209749445923` and they have some amount of Gradecoin preloaded. It's also the only account that you can send transactions requests _to_ yourself.
+
+# Coinbase
+The first transactions of a block is called the `coinbase`. They are the **author** of the block proposal and if the block is accepted then they get compensated for their efforts with some Gradecoin.
+
+# Public Key Signatures
+Gradecoin uses 2048 bit RSA keyspairs.
 
 # Services
 ## /register
@@ -26,3 +53,33 @@ sort_by = "weight"
 - fetch the last accepted [`schema::Block`] - GET request
 
 `Authorization`: The request header should have Bearer JWT.Token signed with Student Public Key
+
+# Questions
+## This all sound complicated!
+- I've drawn inspiration from [actual Bitcoin transactions](https://explorer.bitcoin.com/btc) and [warp](https://github.com/seanmonstar/warp/blob/master/examples/todos.rs). The simplicity of the system is how little interfaces it has.
+- Don't know where to start? Gradecoin uses RESTful API; simple `curl` commands or even your browser will work! [This website can help as well](https://curl.trillworks.com/).
+- [JWT Debugger](https://jwt.io) and the corresponding [RFC](https://tools.ietf.org/html/rfc7519)
+- Remember that you are absolutely encouraged to grab off-the-shelf implementations for every cryptography primitive you will use. You can start by finding a code snippet to generate a RSA keypair?
+
+## I found a bug!
+Thank you! Please [let me know](mailto:yigit@ceng.metu.edu.tr) so we can solve it.
+
+## I hacked the server!
+That wasn't supposed to happen :( I did not place any intentional vulnerabilities to the system so if you cracked something, it was not intended. Please don't abuse it and let me know so I can patch it.
+
+## Submission?
+At the end of the _simulation_, your Gradecoin balance will be your grade. I will also expect a unique client programmed in either;
+- c
+- c++
+- perl
+- rust
+- python
+- random assortment of bash scripts
+
+If your favourite programming language is missing please let me know 🤷?
+
+## Can my friends play?
+Sadly, no. Student's who are enrolled to the class will receive one-time-passwords for authentication.
+
+## How and or Why?
+- [Built](https://xkcd.com/2314/), with [Rust](https://xkcd.com/2418/)