:sparkles: SMT Storage by LesterEvSe · Pull Request #49 · BlockstreamResearch/simplicity-contracts

LesterEvSe · 2026-01-14T15:15:18Z

No description provided.

KyrylR · 2026-01-20T09:18:24Z

crates/contracts/Cargo.toml

 bytes32-tr-storage = []
 array-tr-storage = []
+smt-storage = []
+swap-with-change = []


Rebase to main pls

KyrylR · 2026-01-29T10:42:55Z

crates/cli/src/commands/smt_storage.rs

+    /// Lock collateral on the storage contract (Mint/Fund operation)
+    GetStorageAddress {
+        /// Collateral and fee UTXO
+        #[arg(long = "collateral-utxo")]
+        collateral_utxo: OutPoint,
+        /// Collateral amount in satoshis (LBTC)
+        #[arg(long = "collateral-amount")]
+        collateral_amount: u64,
+        /// Miner fee in satoshis (LBTC)
+        #[arg(long = "fee-amount")]
+        fee_amount: u64,
+
+        /// The initial 32-byte data payload to store in the tree at the specified path
+        #[arg(long = "storage-bytes", value_parser = parse_hex_32)]
+        storage_bytes: [u8; 32],
+        /// The path in the Merkle Tree use for the contract logic (e.g., "rrll...")
+        #[arg(long = "path", value_parser = parse_bit_path)]
+        path: [bool; DEPTH],
+
+        /// Account that will pay for transaction fees and that owns a tokens to send
+        #[arg(long = "account-index", default_value_t = 0)]
+        account_index: u32,
+        /// When set, broadcast the built transaction via Esplora and print txid
+        #[arg(long = "broadcast")]
+        broadcast: bool,
+    },


This command should not broadcast anything, just print the address to which user can send money

KyrylR · 2026-01-29T10:46:47Z

crates/contracts/src/sdk/storage/get_storage_address.rs

+/// Returns an error if:
+/// - The UTXO asset or amount validation fails (expects explicit amounts).
+/// - Transaction extraction or amount proof verification fails.
+pub fn build_smt_mint(


Suggested change

pub fn build_smt_mint(

pub fn get_storage_address(

KyrylR · 2026-01-29T10:47:22Z

crates/contracts/src/sdk/storage/get_storage_address.rs

+) -> Result<PartiallySignedTransaction, TransactionBuildError> {
+    let (collateral_out_point, collateral_tx_out) = collateral_utxo;
+
+    // TODO Change this validation to another func


Move this todo where the validate_amount is defined

KyrylR · 2026-01-29T10:48:20Z

crates/contracts/src/sdk/storage/get_storage_address.rs

+    let change_recipient_script = collateral_tx_out.script_pubkey.clone();
+
+    let mut pst = PartiallySignedTransaction::new_v2();
+
+    let mut collateral_input = Input::from_prevout(collateral_out_point);
+    collateral_input.witness_utxo = Some(collateral_tx_out.clone());
+    pst.add_input(collateral_input);
+
+    pst.add_output(Output::new_explicit(
+        mint_script_pubkey,
+        collateral_amount,
+        collateral_asset_id,
+        None,
+    ));
+
+    if change_amount > 0 {
+        pst.add_output(Output::new_explicit(
+            change_recipient_script,
+            change_amount,
+            collateral_asset_id,
+            None,
+        ));
+    }
+
+    pst.add_output(Output::from_txout(TxOut::new_fee(
+        fee_amount,
+        collateral_asset_id,
+    )));
+
+    pst.extract_tx()?
+        .verify_tx_amt_proofs(secp256k1::SECP256K1, &[collateral_tx_out])?;
+
+    Ok(pst)


Suggested change

let change_recipient_script = collateral_tx_out.script_pubkey.clone();

let mut pst = PartiallySignedTransaction::new_v2();

let mut collateral_input = Input::from_prevout(collateral_out_point);

collateral_input.witness_utxo = Some(collateral_tx_out.clone());

pst.add_input(collateral_input);

pst.add_output(Output::new_explicit(

mint_script_pubkey,

collateral_amount,

collateral_asset_id,

None,

));

if change_amount > 0 {

pst.add_output(Output::new_explicit(

change_recipient_script,

change_amount,

collateral_asset_id,

None,

));

}

pst.add_output(Output::from_txout(TxOut::new_fee(

fee_amount,

collateral_asset_id,

)));

pst.extract_tx()?

.verify_tx_amt_proofs(secp256k1::SECP256K1, &[collateral_tx_out])?;

Ok(pst)

// This should be converted to address

Ok(mint_script_pubkey)

KyrylR · 2026-01-29T10:49:52Z

crates/contracts/src/smt_storage/build_witness.rs

+use std::collections::HashMap;
+
+use simplicityhl::num::U256;
+use simplicityhl::types::{ResolvedType, TypeConstructible, UIntType};
+use simplicityhl::value::{UIntValue, ValueConstructible};
+use simplicityhl::{WitnessValues, str::WitnessName};
+
+#[allow(non_camel_case_types)]
+pub type u256 = [u8; 32];
+pub const DEPTH: usize = 7;
+
+#[derive(Debug, Clone, bincode::Encode, bincode::Decode, PartialEq, Eq)]
+pub struct SMTWitness {
+    key: u256,
+    leaf: u256,
+    merkle_data: [(u256, bool); DEPTH],
+}
+
+impl SMTWitness {
+    #[must_use]
+    pub fn new(key: &u256, leaf: &u256, merkle_data: &[(u256, bool); DEPTH]) -> Self {
+        Self {
+            key: *key,
+            leaf: *leaf,
+            merkle_data: *merkle_data,
+        }
+    }
+}
+
+impl Default for SMTWitness {
+    fn default() -> Self {
+        Self {
+            key: [0u8; 32],
+            leaf: [0u8; 32],
+            merkle_data: [([0u8; 32], false); DEPTH],
+        }
+    }
+}


Add more context (documentation) about how practically this witness is going to be used (i.e. explain rrrrrr witness argument)

Also if there are nuances, mention them

KyrylR · 2026-01-29T10:51:23Z

crates/contracts/src/smt_storage/mod.rs

+            0,
+            cmr,
+            ControlBlock::from_slice(
+                &control_block(cmr, &old_spend_info).serialize(), /*&control_block.serialize()*/


Suggested change

&control_block(cmr, &old_spend_info).serialize(), /*&control_block.serialize()*/

&control_block(cmr, &old_spend_info).serialize(),

KyrylR · 2026-01-29T10:52:00Z

crates/contracts/src/smt_storage/smt.rs

+use simplicityhl::simplicity::elements::hashes::HashEngine as _;
+use simplicityhl::simplicity::hashes::{Hash, sha256};
+
+use super::build_witness::{DEPTH, u256};
+
+#[derive(Debug, Clone, bincode::Encode, bincode::Decode, PartialEq, Eq)]
+pub enum TreeNode {
+    Leaf {
+        leaf_hash: u256,
+    },
+    Branch {
+        hash: u256,
+        left: Box<TreeNode>,
+        right: Box<TreeNode>,
+    },
+}
+
+impl TreeNode {
+    pub fn get_hash(&self) -> u256 {
+        match self {
+            TreeNode::Leaf { leaf_hash } => *leaf_hash,
+            TreeNode::Branch { hash, .. } => *hash,
+        }
+    }
+}
+
+pub struct SparseMerkleTree {
+    root: Box<TreeNode>,
+    precalculate_hashes: [u256; DEPTH],
+}


Add more context and documentation (great if there are any links to external sources)

KyrylR · 2026-01-29T10:52:38Z

crates/contracts/src/smt_storage/smt.rs

+impl SparseMerkleTree {
+    #[must_use]
+    pub fn new() -> Self {
+        let mut precalculate_hashes = [[0u8; 32]; DEPTH];
+        let mut eng = sha256::Hash::engine();
+        let zero = [0u8; 32];
+        eng.input(&zero);
+        precalculate_hashes[0] = *sha256::Hash::from_engine(eng).as_byte_array();
+
+        for i in 1..DEPTH {
+            let mut eng = sha256::Hash::engine();
+            eng.input(&precalculate_hashes[i - 1]);
+            eng.input(&precalculate_hashes[i - 1]);
+            precalculate_hashes[i] = *sha256::Hash::from_engine(eng).as_byte_array();
+        }
+
+        Self {
+            root: Box::new(TreeNode::Leaf {
+                leaf_hash: precalculate_hashes[0],
+            }),
+            precalculate_hashes,
+        }
+    }
+
+    fn calculate_hash(left: &mut TreeNode, right: &mut TreeNode) -> u256 {
+        let mut eng = sha256::Hash::engine();
+        eng.input(&left.get_hash());
+        eng.input(&right.get_hash());
+        *sha256::Hash::from_engine(eng).as_byte_array()
+    }
+
+    // Return array of hashes
+    fn traverse(
+        defaults: &[u256],
+        leaf: &u256,
+        path: &[bool],
+        root: &mut Box<TreeNode>,
+        hashes: &mut [u256],
+    ) {
+        let Some((is_right, remaining_path)) = path.split_first() else {
+            let tag = sha256::Hash::hash(b"TapData");
+            let mut eng = sha256::Hash::engine();
+            eng.input(tag.as_byte_array());
+            eng.input(tag.as_byte_array());
+            eng.input(leaf);
+
+            **root = TreeNode::Leaf {
+                leaf_hash: *sha256::Hash::from_engine(eng).as_byte_array(),
+            };
+            return;
+        };
+
+        let (child_zero, remaining_defaults) = defaults
+            .split_last()
+            .expect("Defaults length must match path length");
+
+        if matches!(**root, TreeNode::Leaf { .. }) {
+            let new_branch = Box::new(TreeNode::Branch {
+                hash: [0u8; 32],
+                left: Box::new(TreeNode::Leaf {
+                    leaf_hash: *child_zero,
+                }),
+                right: Box::new(TreeNode::Leaf {
+                    leaf_hash: *child_zero,
+                }),
+            });
+
+            *root = new_branch;
+        }
+
+        let (current_hash_slot, remaining_hashes) = hashes
+            .split_first_mut()
+            .expect("Hashes length must match path length");
+
+        if let TreeNode::Branch {
+            ref mut left,
+            ref mut right,
+            ref mut hash,
+        } = **root
+        {
+            if *is_right {
+                *current_hash_slot = left.get_hash();
+                Self::traverse(
+                    remaining_defaults,
+                    leaf,
+                    remaining_path,
+                    right,
+                    remaining_hashes,
+                );
+            } else {
+                *current_hash_slot = right.get_hash();
+                Self::traverse(
+                    remaining_defaults,
+                    leaf,
+                    remaining_path,
+                    left,
+                    remaining_hashes,
+                );
+            }
+
+            *hash = Self::calculate_hash(left, right);
+        } else {
+            unreachable!("Should be a branch at this point");
+        }
+    }
+
+    // For insert change 0 to leaf.
+    // For delete vice versa.
+    // And for udpate change old value to new.
+    // Then, recalculate hashes
+    pub fn update(&mut self, leaf: &u256, path: [bool; DEPTH]) -> [u256; DEPTH] {
+        let mut hashes = self.precalculate_hashes;
+        Self::traverse(
+            &self.precalculate_hashes,
+            leaf,
+            &path,
+            &mut self.root,
+            &mut hashes,
+        );
+        hashes
+    }
+}


Here the same, mention nuances, especially attacks, etc

KyrylR · 2026-01-29T10:53:17Z

crates/contracts/Cargo.toml

 [dev-dependencies]
-anyhow = "1"
+anyhow = "1"
+rand = "0.9.2"


Do not add rand as a independent dep, use rand from the simplicityhl::elements dep

KyrylR · 2026-01-29T10:53:36Z

crates/contracts/Cargo.toml

 bytes32-tr-storage = []
 array-tr-storage = []
+smt-storage = []
+swap-with-change = []


Suggested change

swap-with-change = []

…tion against second preimage attack

KyrylR

ACK 93da027

LesterEvSe self-assigned this Jan 14, 2026

LesterEvSe requested a review from KyrylR as a code owner January 14, 2026 15:15

LesterEvSe added the enhancement New feature or request label Jan 14, 2026

LesterEvSe force-pushed the feature/smt-storage branch from 0990433 to b693be2 Compare January 14, 2026 15:58

LesterEvSe changed the title ~~✨ Unlimited SMT Storage~~ ✨ SMT Storage Jan 14, 2026

LesterEvSe force-pushed the feature/smt-storage branch 6 times, most recently from 9ad9025 to cfc92e0 Compare January 19, 2026 14:02

KyrylR reviewed Jan 20, 2026

View reviewed changes

LesterEvSe force-pushed the feature/smt-storage branch 2 times, most recently from d15e987 to b574a43 Compare January 20, 2026 11:26

LesterEvSe force-pushed the feature/smt-storage branch from 73349f6 to 6ff66b5 Compare January 28, 2026 15:26

LesterEvSe requested a review from KyrylR January 28, 2026 15:27

LesterEvSe force-pushed the feature/smt-storage branch from 6ff66b5 to 250295e Compare January 28, 2026 15:29

KyrylR requested changes Jan 29, 2026

View reviewed changes

LesterEvSe force-pushed the feature/smt-storage branch from 250295e to 2ca279d Compare January 29, 2026 16:26

LesterEvSe added 2 commits January 29, 2026 18:27

feat: add smt storage

1ce10a7

feat: add smt to rust and fill with some elements

f1943a6

LesterEvSe force-pushed the feature/smt-storage branch 3 times, most recently from 8035e03 to d19f4d5 Compare January 29, 2026 17:26

feat: implement cli and fix bugs in contracts/smt_storage. ADD protec…

93da027

…tion against second preimage attack

LesterEvSe force-pushed the feature/smt-storage branch from d19f4d5 to 93da027 Compare January 29, 2026 17:33

LesterEvSe requested a review from KyrylR January 29, 2026 17:35

KyrylR approved these changes Feb 5, 2026

View reviewed changes

KyrylR merged commit 3cffae8 into BlockstreamResearch:main Feb 5, 2026
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✨ SMT Storage#49

✨ SMT Storage#49
KyrylR merged 3 commits intoBlockstreamResearch:mainfrom
LesterEvSe:feature/smt-storage

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	&control_block(cmr, &old_spend_info).serialize(), /&control_block.serialize()/
	&control_block(cmr, &old_spend_info).serialize(),

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