feat: expose a public API which allows to build a SpentProof from a g…

…iven set of proof shares
maidsafe · Jul 28, 2022 · d25a01b · d25a01b
1 parent bdd649f
commit d25a01b
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Showing 2 changed files with 36 additions and 29 deletions.
diff --git a/src/builder.rs b/src/builder.rs
@@ -19,9 +19,8 @@ use std::{
 
 use crate::{
     rand::{CryptoRng, RngCore},
-    AmountSecrets, Commitment, Dbc, DbcContent, Error, Hash, IndexedSignatureShare, KeyImage,
-    OwnerOnce, Result, SpentProof, SpentProofContent, SpentProofKeyVerifier, SpentProofShare,
-    TransactionVerifier,
+    AmountSecrets, Commitment, Dbc, DbcContent, Error, Hash, KeyImage, OwnerOnce, Result,
+    SpentProof, SpentProofKeyVerifier, SpentProofShare, TransactionVerifier,
 };
 
 #[cfg(feature = "serde")]
@@ -484,36 +483,12 @@ impl DbcBuilder {
 
     /// build spent proofs from shares.
     pub fn spent_proofs(&self) -> Result<BTreeSet<SpentProof>> {
+        let transaction_hash = Hash::from(self.transaction.hash());
         let spent_proofs: BTreeSet<SpentProof> = self
             .spent_proof_shares
             .iter()
             .map(|(key_image, shares)| {
-                let any_share = shares
-                    .iter()
-                    .next()
-                    .ok_or(Error::MissingSpentProofShare(*key_image))?;
-
-                let spentbook_pub_key = any_share.spentbook_pks().public_key();
-                let spentbook_sig = any_share.spentbook_pks.combine_signatures(
-                    shares
-                        .iter()
-                        .map(SpentProofShare::spentbook_sig_share)
-                        .map(IndexedSignatureShare::threshold_crypto),
-                )?;
-
-                let public_commitments: Vec<Commitment> = any_share.public_commitments().clone();
-
-                let spent_proof = SpentProof {
-                    content: SpentProofContent {
-                        key_image: *key_image,
-                        transaction_hash: Hash::from(self.transaction.hash()),
-                        public_commitments,
-                    },
-                    spentbook_pub_key,
-                    spentbook_sig,
-                };
-
-                Ok(spent_proof)
+                SpentProof::try_from_proof_shares(*key_image, transaction_hash, shares.iter())
             })
             .collect::<Result<_>>()?;
 

diff --git a/src/spent_proof.rs b/src/spent_proof.rs
@@ -182,6 +182,38 @@ pub struct SpentProof {
 }
 
 impl SpentProof {
+    /// Attempts to build a SpentProof by combining a given set of proof shares
+    pub fn try_from_proof_shares<'a>(
+        key_image: KeyImage,
+        transaction_hash: Hash,
+        shares: impl Iterator<Item = &'a SpentProofShare>,
+    ) -> Result<Self> {
+        let mut peekable_shares = shares.peekable();
+        let any_share = peekable_shares
+            .peek()
+            .cloned()
+            .ok_or(Error::MissingSpentProofShare(key_image))?;
+
+        let spentbook_pub_key = any_share.spentbook_pks().public_key();
+        let spentbook_sig = any_share.spentbook_pks.combine_signatures(
+            peekable_shares
+                .map(SpentProofShare::spentbook_sig_share)
+                .map(IndexedSignatureShare::threshold_crypto),
+        )?;
+
+        let public_commitments: Vec<Commitment> = any_share.public_commitments().clone();
+
+        Ok(SpentProof {
+            content: SpentProofContent {
+                key_image,
+                transaction_hash,
+                public_commitments,
+            },
+            spentbook_pub_key,
+            spentbook_sig,
+        })
+    }
+
     /// get KeyImage of input Dbc
     pub fn key_image(&self) -> &KeyImage {
         &self.content.key_image