From 4026ea203bdd4a65e56e06043084472ae47d7f19 Mon Sep 17 00:00:00 2001
From: Alexander Block <ablock84@gmail.com>
Date: Tue, 22 Jan 2019 14:12:47 +0100
Subject: [PATCH] Implement VerifyRecoveredSig to allow verifcation of sigs
 found in P2P messages

---
 src/llmq/quorums_signing.cpp | 13 +++++++++++++
 src/llmq/quorums_signing.h   |  3 +++
 2 files changed, 16 insertions(+)

diff --git a/src/llmq/quorums_signing.cpp b/src/llmq/quorums_signing.cpp
index 1d29890da..08b18f59c 100644
--- a/src/llmq/quorums_signing.cpp
+++ b/src/llmq/quorums_signing.cpp
@@ -548,4 +548,17 @@ bool CSigningManager::IsConflicting(Consensus::LLMQType llmqType, const uint256&
     return false;
 }
 
+bool CSigningManager::VerifyRecoveredSig(Consensus::LLMQType llmqType, const uint256& signedAtTip, const uint256& id, const uint256& msgHash, const CBLSSignature& sig)
+{
+    auto& llmqParams = Params().GetConsensus().llmqs.at(Params().GetConsensus().llmqTypeForChainLocks);
+
+    auto quorum = quorumManager->SelectQuorum(llmqParams.type, signedAtTip, id);
+    if (!quorum) {
+        return false;
+    }
+
+    uint256 signHash = CLLMQUtils::BuildSignHash(llmqParams.type, quorum->quorumHash, id, msgHash);
+    return sig.VerifyInsecure(quorum->quorumPublicKey, signHash);
+}
+
 }
diff --git a/src/llmq/quorums_signing.h b/src/llmq/quorums_signing.h
index 33dc16561..e1c4178e1 100644
--- a/src/llmq/quorums_signing.h
+++ b/src/llmq/quorums_signing.h
@@ -146,6 +146,9 @@ public:
     bool HasRecoveredSigForId(Consensus::LLMQType llmqType, const uint256& id);
     bool HasRecoveredSigForSession(const uint256& signHash);
     bool IsConflicting(Consensus::LLMQType llmqType, const uint256& id, const uint256& msgHash);
+
+    // Verifies a recovered sig that was signed while the chain tip was at signedAtTip
+    bool VerifyRecoveredSig(Consensus::LLMQType llmqType, const uint256& signedAtTip, const uint256& id, const uint256& msgHash, const CBLSSignature& sig);
 };
 
 extern CSigningManager* quorumSigningManager;