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@@ -299,6 +299,60 @@ comparison the tx in Bitcoin with the most outputs has 2501.
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| `canonical` | `Blockchain` | Canonical (confirmed) blockchain |
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| `forks` | `Vec<Blockchain>` | Fork chains containing block proposals |
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+## Contracts states Monotree(SMT)
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+
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+DarkFi is using an optimized Sparse Merkle Tree implementation,
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+called Monotree.
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+This tree is constructed using all contracts states trees checksums,
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+along with the wasm bincodes tree checksum, excluding native contracts
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+zkas tree and wasm bincodes.
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+The checksum of each tree is computed by hashing all its key and values,
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+using `blake3` hasher.
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+For each block, we compute the current tree root and keep it in its header,
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+enabling us to both verify the contacts state after the block insertion,
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+and create proofs commiting to that specific state.
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+
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+## Usage example
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+
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+In this pseudocode we can see how we can use the Monotree to produce
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+a proof for a specific state. First, we will create a random set of
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+key-value `blake3` hash pairs, representing our contract states
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+checksums:
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+
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+```
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+keys = random_hashes(100);
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+values = random_hashes(100);
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+```
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+
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+We compute our monotree, by inserting all the pairs:
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+```
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+root = None;
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+tree = Monotree::new();
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+for (key, value) in keys.zip(values) {
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+ root = tree.insert(root, key, value);
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+ tree.set_headroot(root);
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+}
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+```
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+
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+Each node in the network holds a similar tree agains the current
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+database state, as described earlier. On each new block, we commit
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+to the state by appending the monotree root to the block header.
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+Lets assume we now created a block commiting to that state,
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+and want to get a Merkle proof for a specific key-value pair
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+we want to commit to:
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+```
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+root = tree.get_headroot()?
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+block.header.state_root = root;
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+proof = tree.get_merkle_proof(root, our_key);
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+```
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+
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+No matter how many blocks have passed, or how the state/tree has
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+mutated, we can always verify that proof against the specific block
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+it corresponds, by using its header root:
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+```
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+assert!(verify_proof(block.header.state_root, our_key_value, proof));
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+```
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+
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# Appendix: Ranking Blocks
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## Sequences
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skoupidi