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News:
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Gradecoin is in testnet mode, API is not stable, everything might reset at any time.
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Transactions are now unique according to their "by" field, sorry for the trouble
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Blocks now require 5 transactions in them, during testnet phase
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It was possible (and hilarious) to mine a new block with just 1 transaction, it is now fixed
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Welcome to Gradecoin!
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Blockchains are incredibly simple yet can appear very complicated, we will see how they work and practice programming production cryptography code.
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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.
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A quick summary: authenticate yourself to the system using public key encryption.
-Craft Transaction proposals and tag them using JWTs.
-When there are enough transactions then you can propose Blocks in the same way.
-Blocks need to be mined beforehand using Proof-of-work, or brute force.
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Gradecoin offers 3 endpoints at /register, /block and /transaction. You can only send GET requests to /block and /transaction without authorization.
-The server is programmed in RESTful architecture, there are no DELETE, PUT or UPDATE operations, though.
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Gradecoin uses a Proof-of-work block accepting mechanism. It uses single round Blake2s hashing which produces 256-bit (64 hexadecimal characters) output. The target hash is 24 bits or 6 hexadecimal characters of 0. During testing, I could mine a block on average around 4-6 minutes.
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-We're expecting you to use existing tools and implementations. Standards are hard. Don't roll your own crypto. Feel free to ask questions. Collaborate.
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You might ask,
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-But if nobody has any Gradecoin then how do we have transactions?
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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.
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Coinbase
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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.
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Public Key Signatures
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Gradecoin uses 2048 bit RSA keypairs.
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Services
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/register
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-- Create your own 2048 bit RSA
keypair
-- Download
Gradecoin's Public Key from Moodle
-- Encrypt your JSON wrapped
Public Key, Student ID and one time passwd using Gradecoin's Public Key
-- Your public key is now in our database and can be used to sign your JWT's during requests
-- For more information, check the register page
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/transaction
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-- You can offer a Transaction with a POST request
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-- The request should have
Authorization
-- The request header should be signed by the Public Key of the
by field in the transaction
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-- Fetch the list of
Transactions with a GET request
-- For more information, check our transaction page
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/block
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--
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Offer a Block with a POST request
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-- The request should have
Authorization
-- The
transaction_list of the block should be a subset of pending transactions, available on /transaction
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--
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Fetch the last accepted Block with a GET request
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For more information, check our block page
-Authorization: The request header should have Bearer JWT.Token signed with Student Public Key
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/user
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-- Meant to be used in the browser, you can see the current list of users and their balance here
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Questions
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This all sound complicated!
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-- I've drawn inspiration from actual Bitcoin transactions and warp. 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.
-- JWT Debugger and the corresponding RFC.
-- 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?
-- Check out misc for everything else you might be curious about.
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How do you actually earn Gradecoin?
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-- Register yourself to at /register
-- Create transactions at /transaction
-- Create blocks to commit transactions at /block
-- See how everyone is doing and find people to trade with at /user
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I found a bug!
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Thank you! Please let me know so we can solve it.
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I hacked the server!
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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.
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Submission?
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At the end of the simulation, your Gradecoin balance will be your grade. I will also expect a unique client programmed in either;
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-- c
-- c++
-- perl
-- rust
-- python
-- random assortment of bash scripts
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If your favourite programming language is missing please let me know 🤷?
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Can my friends play?
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Sadly, no. Student's who are enrolled to the class will receive one-time-passwords for authentication.
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How and or Why?
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- Gradecoin
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