Define the blockchain

docs/protocol.md

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+# Protocol of the carrotcoin cryptocurrency
+
+The carrotcoin cryptocurrency is a bitcoin-like currency with proof-of-work, created just for learning purposes.
+
+# Blockchain
+
+The network should stabilize at around 1 block every 5 minutes.
+
+Blocks are hashed with SHA256 and need to start with a certain number of zeros (or, more precise, be below a given value depending on the difficulty)
+
+ed25519 keys are used to validate transactions.
+
+
+## block datastructure
+
+| content | size (bytes) |
+|---|---|
+| previous hash | 32 |
+| message (arbitrary) | 32 |
+| nonce | 8 |
+| timestamp (unix time in seconds, BE) | 8 |
+| block id (BE) | 4 |
+| miner pubkey | 32 |
+| transaction (optional) | 148 |
+
+If no transaction is included, its 148 bytes are all null.
+
+The first block has block id 0 and a "previous hash" value of 32 null bytes.
+
+## transaction datastructure
+
+1 carrotcoin (cc) consists of 100 cents
+
+| content | size (bytes) |
+|---|---|
+| id (arbitrary) | 4 |
+| sender (pubkey) | 32 |
+| receiver (pubkey) | 32 |
+| amount (BE, in cents) | 8 |
+| transaction fee (BE, in cents, can be zero) | 8 |
+| signature (signed by sender, over transaction fields before signature) | 64 |
+
+## transactions
+
+For every block, the miner gets a reward of 1,00 cc. (100 cents)
+
+If a transaction is included, the following happens additionally:
+
+- The sender needs to pay "amount" + "transaction fee"
+- The receiver gets "amount"
+- The miner gets "transaction fee" on top of the reward.