contract/money/client: UnstakeV1 API added

src/contract/consensus/src/client/stake_v1.rs

@@ -88,9 +88,9 @@ pub struct ConsensusStakeCallBuilder {
     pub nullifier: Nullifier,
     /// Revealed Merkle root
     pub merkle_root: MerkleNode,
-    /// `Mint_V1` zkas circuit ZkBinary
+    /// `Consensus_Mint_V1` zkas circuit ZkBinary
     pub mint_zkbin: ZkBinary,
-    /// Proving key for the `Mint_V1` zk circuit
+    /// Proving key for the `Consensus_Mint_V1` zk circuit
     pub mint_pk: ProvingKey,
 }
 
@@ -113,7 +113,7 @@ impl ConsensusStakeCallBuilder {
         let user_data = pallas::Base::random(&mut OsRng);
         let coin_blind = pallas::Base::random(&mut OsRng);
 
-        info!("Creating transfer mint proof for output");
+        info!("Creating stake mint proof for output");
         let (proof, public_inputs) = create_stake_mint_proof(
             &self.mint_zkbin,
             &self.mint_pk,

src/contract/money/src/client/mod.rs

@@ -47,6 +47,9 @@ pub mod freeze_v1;
 /// `Money::StakeV1` API
 pub mod stake_v1;
 
+/// `Money::UnstakeV1` API
+pub mod unstake_v1;
+
 // Wallet SQL table constant names. These have to represent the `wallet.sql`
 // SQL schema.
 // TODO: They should also be prefixed with the contract ID to avoid collisions.

src/contract/money/src/client/unstake_v1.rs

@@ -0,0 +1,213 @@
+/* This file is part of DarkFi (https://dark.fi)
+ *
+ * Copyright (C) 2020-2023 Dyne.org foundation
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+//! This API is crufty. Please rework it into something nice to read and nice to use.
+
+use darkfi::{
+    zk::{halo2::Value, Proof, ProvingKey, Witness, ZkCircuit},
+    zkas::ZkBinary,
+    Result,
+};
+use darkfi_sdk::{
+    crypto::{
+        note::AeadEncryptedNote, pasta_prelude::*, pedersen_commitment_base,
+        pedersen_commitment_u64, poseidon_hash, Coin, MerkleNode, Nullifier, PublicKey, TokenId,
+        DARK_TOKEN_ID,
+    },
+    pasta::pallas,
+};
+use log::{debug, info};
+use rand::rngs::OsRng;
+
+use crate::{
+    client::{MoneyNote, OwnCoin},
+    model::{MoneyUnstakeParamsV1, Output, StakeInput},
+};
+
+pub struct MoneyUnstakeCallDebris {
+    pub params: MoneyUnstakeParamsV1,
+    pub proofs: Vec<Proof>,
+}
+
+pub struct MoneyMintRevealed {
+    pub coin: Coin,
+    pub value_commit: pallas::Point,
+    pub token_commit: pallas::Point,
+}
+
+impl MoneyMintRevealed {
+    pub fn to_vec(&self) -> Vec<pallas::Base> {
+        let valcom_coords = self.value_commit.to_affine().coordinates().unwrap();
+        let tokcom_coords = self.token_commit.to_affine().coordinates().unwrap();
+
+        // NOTE: It's important to keep these in the same order
+        // as the `constrain_instance` calls in the zkas code.
+        vec![
+            self.coin.inner(),
+            *valcom_coords.x(),
+            *valcom_coords.y(),
+            *tokcom_coords.x(),
+            *tokcom_coords.y(),
+        ]
+    }
+}
+
+pub struct TransactionBuilderOutputInfo {
+    pub value: u64,
+    pub token_id: TokenId,
+    pub public_key: PublicKey,
+}
+
+/// Struct holding necessary information to build a `Money::UnstakeV1` contract call.
+pub struct MoneyUnstakeCallBuilder {
+    /// `OwnCoin` we're given to use in this builder
+    pub coin: OwnCoin,
+    /// Recipient's public key
+    pub recipient: PublicKey,
+    /// Blinding factor for value commitment
+    pub value_blind: pallas::Scalar,
+    /// Blinding factor for `token_id`
+    pub token_blind: pallas::Scalar,
+    /// Revealed nullifier
+    pub nullifier: Nullifier,
+    /// Revealed Merkle root
+    pub merkle_root: MerkleNode,
+    /// `Mint_V1` zkas circuit ZkBinary
+    pub mint_zkbin: ZkBinary,
+    /// Proving key for the `Mint_V1` zk circuit
+    pub mint_pk: ProvingKey,
+}
+
+impl MoneyUnstakeCallBuilder {
+    pub fn build(&self) -> Result<MoneyUnstakeCallDebris> {
+        debug!("Building Money::UnstakeV1 contract call");
+        assert!(self.coin.note.value != 0);
+        assert!(self.coin.note.token_id == *DARK_TOKEN_ID);
+
+        debug!("Building anonymous output");
+        let output = TransactionBuilderOutputInfo {
+            value: self.coin.note.value,
+            token_id: self.coin.note.token_id,
+            public_key: self.recipient,
+        };
+        debug!("Finished building output");
+
+        let serial = pallas::Base::random(&mut OsRng);
+        let spend_hook = DARK_TOKEN_ID.inner();
+        let user_data = pallas::Base::random(&mut OsRng);
+        let coin_blind = pallas::Base::random(&mut OsRng);
+
+        info!("Creating unstake mint proof for output");
+        let (proof, public_inputs) = create_unstake_mint_proof(
+            &self.mint_zkbin,
+            &self.mint_pk,
+            &output,
+            self.value_blind,
+            self.token_blind,
+            serial,
+            spend_hook,
+            user_data,
+            coin_blind,
+        )?;
+
+        // Encrypted note
+        let note = MoneyNote {
+            serial,
+            value: output.value,
+            token_id: output.token_id,
+            spend_hook,
+            user_data,
+            coin_blind,
+            value_blind: self.value_blind,
+            token_blind: self.token_blind,
+            memo: vec![],
+        };
+
+        let encrypted_note = AeadEncryptedNote::encrypt(&note, &output.public_key, &mut OsRng)?;
+
+        let output = Output {
+            value_commit: public_inputs.value_commit,
+            token_commit: public_inputs.token_commit,
+            coin: public_inputs.coin,
+            note: encrypted_note,
+        };
+
+        let input = StakeInput {
+            token_blind: self.token_blind,
+            value_commit: public_inputs.value_commit,
+            nullifier: self.nullifier,
+            merkle_root: self.merkle_root,
+        };
+
+        // We now fill this with necessary stuff
+        let params = MoneyUnstakeParamsV1 { input, output };
+        let proofs = vec![proof];
+
+        // Now we should have all the params and zk proof.
+        // We return it all and let the caller deal with it.
+        let debris = MoneyUnstakeCallDebris { params, proofs };
+        Ok(debris)
+    }
+}
+
+pub fn create_unstake_mint_proof(
+    zkbin: &ZkBinary,
+    pk: &ProvingKey,
+    output: &TransactionBuilderOutputInfo,
+    value_blind: pallas::Scalar,
+    token_blind: pallas::Scalar,
+    serial: pallas::Base,
+    spend_hook: pallas::Base,
+    user_data: pallas::Base,
+    coin_blind: pallas::Base,
+) -> Result<(Proof, MoneyMintRevealed)> {
+    let value_commit = pedersen_commitment_u64(output.value, value_blind);
+    let token_commit = pedersen_commitment_base(output.token_id.inner(), token_blind);
+    let (pub_x, pub_y) = output.public_key.xy();
+
+    let coin = Coin::from(poseidon_hash([
+        pub_x,
+        pub_y,
+        pallas::Base::from(output.value),
+        output.token_id.inner(),
+        serial,
+        spend_hook,
+        user_data,
+        coin_blind,
+    ]));
+
+    let public_inputs = MoneyMintRevealed { coin, value_commit, token_commit };
+
+    let prover_witnesses = vec![
+        Witness::Base(Value::known(pub_x)),
+        Witness::Base(Value::known(pub_y)),
+        Witness::Base(Value::known(pallas::Base::from(output.value))),
+        Witness::Base(Value::known(output.token_id.inner())),
+        Witness::Base(Value::known(serial)),
+        Witness::Base(Value::known(coin_blind)),
+        Witness::Base(Value::known(spend_hook)),
+        Witness::Base(Value::known(user_data)),
+        Witness::Scalar(Value::known(value_blind)),
+        Witness::Scalar(Value::known(token_blind)),
+    ];
+
+    let circuit = ZkCircuit::new(prover_witnesses, zkbin.clone());
+    let proof = Proof::create(pk, &[circuit], &public_inputs.to_vec(), &mut OsRng)?;
+
+    Ok((proof, public_inputs))
+}