pset: blind: return map instead of vec

Author: LeoComandini

src/pset/mod.rs

@@ -20,7 +20,7 @@
 //! Extension for PSET is based on PSET defined in BIP370.
 //! <https://github.com/bitcoin/bips/blob/master/bip-0174.mediawiki>
 
-use std::collections::HashMap;
+use std::collections::{BTreeMap, HashMap};
 use std::{cmp, io};
 
 mod error;
@@ -46,7 +46,10 @@ use crate::{
     confidential::{AssetBlindingFactor, ValueBlindingFactor},
     TxOutSecrets,
 };
-use crate::{OutPoint, LockTime, Sequence, SurjectionInput, Transaction, TxIn, TxInWitness, TxOut, TxOutWitness, Txid};
+use crate::{
+    LockTime, OutPoint, Sequence, SurjectionInput, Transaction, TxIn, TxInType,
+    TxInWitness, TxOut, TxOutWitness, Txid,
+};
 use secp256k1_zkp::rand::{CryptoRng, RngCore};
 use secp256k1_zkp::{self, RangeProof, SecretKey, SurjectionProof};
 
@@ -478,17 +481,17 @@ impl PartiallySignedTransaction {
         rng: &mut R,
         secp: &secp256k1_zkp::Secp256k1<C>,
         inp_txout_sec: &HashMap<usize, TxOutSecrets>,
-    ) -> Result<Vec<(AssetBlindingFactor, ValueBlindingFactor, SecretKey)>, PsetBlindError> {
+    ) -> Result<BTreeMap<TxInType, (AssetBlindingFactor, ValueBlindingFactor, SecretKey)>, PsetBlindError> {
         let (inp_secrets, outs_to_blind) = self.blind_checks(inp_txout_sec)?;
 
+        let mut ret = BTreeMap::new(); // return all the random values used
         if outs_to_blind.is_empty() {
             // Return empty values if no outputs are marked for blinding
-            return Ok(Vec::new());
+            return Ok(ret);
         }
         // Blind each output as non-last and save the secrets
         let surject_inputs = self.surjection_inputs(inp_txout_sec)?;
         let mut out_secrets = vec![];
-        let mut ret = vec![]; // return all the random values used
         for i in outs_to_blind {
             let txout = self.outputs[i].to_txout();
             let (txout, abf, vbf, ephemeral_sk) = txout
@@ -538,7 +541,7 @@ impl PartiallySignedTransaction {
                 ));
             }
             // return blinding factors used
-            ret.push((abf, vbf, ephemeral_sk));
+            ret.insert(TxInType::Input(i), (abf, vbf, ephemeral_sk));
         }
 
         // safe to unwrap because we have checked that there is atleast one output to blind
@@ -579,10 +582,10 @@ impl PartiallySignedTransaction {
         rng: &mut R,
         secp: &secp256k1_zkp::Secp256k1<C>,
         inp_txout_sec: &HashMap<usize, TxOutSecrets>,
-    ) -> Result<Vec<(AssetBlindingFactor, ValueBlindingFactor, SecretKey)>, PsetBlindError> {
+    ) -> Result<BTreeMap<TxInType, (AssetBlindingFactor, ValueBlindingFactor, SecretKey)>, PsetBlindError> {
         let (mut inp_secrets, mut outs_to_blind) = self.blind_checks(inp_txout_sec)?;
 
-        let mut ret = vec![];
+        let mut ret = BTreeMap::new();
         if outs_to_blind.is_empty() {
             // Atleast one output must be marked for blinding for pset blind_last
             return Err(PsetBlindError::AtleastOneOutputBlind);
@@ -658,7 +661,7 @@ impl PartiallySignedTransaction {
         );
         let (value_commitment, nonce, rangeproof) =
             blind_res.map_err(|e| PsetBlindError::ConfidentialTxOutError(last_out_index, e))?;
-        ret.push((out_abf, final_vbf, ephemeral_sk));
+        ret.insert(TxInType::Input(last_out_index), (out_abf, final_vbf, ephemeral_sk));
 
         // mutate the pset
         {