Wallet: added methods to sign and verify arbitrary message with multisig public signer's key (libwallet & wallet api)

src/wallet/api/wallet.cpp

@@ -1694,6 +1694,50 @@ bool WalletImpl::verifySignedMessage(const std::string &message, const std::stri
   return m_wallet->verify(message, info.address, signature);
 }
 
+std::string WalletImpl::signMultisigParticipant(const std::string &message) const
+{
+    clearStatus();
+
+    bool ready = false;
+    if (!m_wallet->multisig(&ready) || !ready) {
+        m_status = Status_Error;
+        m_errorString = tr("The wallet must be in multisig ready state");
+        return {};
+    }
+
+    try {
+        return m_wallet->sign_multisig_participant(message);
+    } catch (const std::exception& e) {
+        m_status = Status_Error;
+        m_errorString = e.what();
+    }
+
+    return {};
+}
+
+bool WalletImpl::verifyMessageWithPublicKey(const std::string &message, const std::string &publicKey, const std::string &signature) const
+{
+    clearStatus();
+
+    cryptonote::blobdata pkeyData;
+    if(!epee::string_tools::parse_hexstr_to_binbuff(publicKey, pkeyData) || pkeyData.size() != sizeof(crypto::public_key))
+    {
+        m_status = Status_Error;
+        m_errorString = tr("Given string is not a key");
+        return false;
+    }
+
+    try {
+        crypto::public_key pkey = *reinterpret_cast<const crypto::public_key*>(pkeyData.data());
+        return m_wallet->verify_with_public_key(message, pkey, signature);
+    } catch (const std::exception& e) {
+        m_status = Status_Error;
+        m_errorString = e.what();
+    }
+
+    return false;
+}
+
 bool WalletImpl::connectToDaemon()
 {
     bool result = m_wallet->check_connection(NULL, DEFAULT_CONNECTION_TIMEOUT_MILLIS);

src/wallet/api/wallet.h

@@ -157,6 +157,8 @@ public:
     virtual bool checkReserveProof(const std::string &address, const std::string &message, const std::string &signature, bool &good, uint64_t &total, uint64_t &spent) const;
     virtual std::string signMessage(const std::string &message);
     virtual bool verifySignedMessage(const std::string &message, const std::string &address, const std::string &signature) const;
+    virtual std::string signMultisigParticipant(const std::string &message) const;
+    virtual bool verifyMessageWithPublicKey(const std::string &message, const std::string &publicKey, const std::string &signature) const;
     virtual void startRefresh();
     virtual void pauseRefresh();
     virtual bool parse_uri(const std::string &uri, std::string &address, std::string &payment_id, uint64_t &amount, std::string &tx_description, std::string &recipient_name, std::vector<std::string> &unknown_parameters, std::string &error);

src/wallet/api/wallet2_api.h

@@ -747,6 +747,21 @@ struct Wallet
      */
     virtual bool verifySignedMessage(const std::string &message, const std::string &addres, const std::string &signature) const = 0;
 
+    /*!
+     * \brief signMultisigParticipant   signs given message with the multisig public signer key
+     * \param message                   message to sign
+     * \return                          signature in case of success. Sets status to Error and return empty string in case of error
+     */
+    virtual std::string signMultisigParticipant(const std::string &message) const = 0;
+    /*!
+     * \brief verifyMessageWithPublicKey verifies that message was signed with the given public key
+     * \param message                    message
+     * \param publicKey                  hex encoded public key
+     * \param signature                  signature of the message
+     * \return                           true if the signature is correct. false and sets error state in case of error
+     */
+    virtual bool verifyMessageWithPublicKey(const std::string &message, const std::string &publicKey, const std::string &signature) const = 0;
+
     virtual bool parse_uri(const std::string &uri, std::string &address, std::string &payment_id, uint64_t &amount, std::string &tx_description, std::string &recipient_name, std::vector<std::string> &unknown_parameters, std::string &error) = 0;
 
     virtual std::string getDefaultDataDir() const = 0;

src/wallet/wallet2.cpp

@@ -115,6 +115,8 @@ using namespace cryptonote;
 #define STAGENET_SEGREGATION_FORK_HEIGHT 1000000
 #define SEGREGATION_FORK_VICINITY 1500 /* blocks */
 
+static const std::string MULTISIG_SIGNATURE_MAGIC = "SigMultisigPkV1";
+
 
 namespace
 {
@@ -9149,6 +9151,40 @@ bool wallet2::verify(const std::string &data, const cryptonote::account_public_a
   memcpy(&s, decoded.data(), sizeof(s));
   return crypto::check_signature(hash, address.m_spend_public_key, s);
 }
+
+std::string wallet2::sign_multisig_participant(const std::string& data) const
+{
+  CHECK_AND_ASSERT_THROW_MES(m_multisig, "Wallet is not multisig");
+
+  crypto::hash hash;
+  crypto::cn_fast_hash(data.data(), data.size(), hash);
+  const cryptonote::account_keys &keys = m_account.get_keys();
+  crypto::signature signature;
+  crypto::generate_signature(hash, get_multisig_signer_public_key(), keys.m_spend_secret_key, signature);
+  return MULTISIG_SIGNATURE_MAGIC + tools::base58::encode(std::string((const char *)&signature, sizeof(signature)));
+}
+
+bool wallet2::verify_with_public_key(const std::string &data, const crypto::public_key &public_key, const std::string &signature) const
+{
+  if (signature.size() < MULTISIG_SIGNATURE_MAGIC.size() || signature.substr(0, MULTISIG_SIGNATURE_MAGIC.size()) != MULTISIG_SIGNATURE_MAGIC) {
+    MERROR("Signature header check error");
+    return false;
+  }
+  crypto::hash hash;
+  crypto::cn_fast_hash(data.data(), data.size(), hash);
+  std::string decoded;
+  if (!tools::base58::decode(signature.substr(MULTISIG_SIGNATURE_MAGIC.size()), decoded)) {
+    MERROR("Signature decoding error");
+    return false;
+  }
+  crypto::signature s;
+  if (sizeof(s) != decoded.size()) {
+    MERROR("Signature decoding error");
+    return false;
+  }
+  memcpy(&s, decoded.data(), sizeof(s));
+  return crypto::check_signature(hash, public_key, s);
+}
 //----------------------------------------------------------------------------------------------------
 crypto::public_key wallet2::get_tx_pub_key_from_received_outs(const tools::wallet2::transfer_details &td) const
 {

src/wallet/wallet2.h

@@ -964,6 +964,22 @@ namespace tools
     std::string sign(const std::string &data) const;
     bool verify(const std::string &data, const cryptonote::account_public_address &address, const std::string &signature) const;
 
+    /*!
+     * \brief sign_multisig_participant signs given message with the multisig public signer key
+     * \param data                      message to sign
+     * \throws                          if wallet is not multisig
+     * \return                          signature
+     */
+    std::string sign_multisig_participant(const std::string& data) const;
+    /*!
+     * \brief verify_with_public_key verifies message was signed with given public key
+     * \param data                   message
+     * \param public_key             public key to check signature
+     * \param signature              signature of the message
+     * \return                       true if the signature is correct
+     */
+    bool verify_with_public_key(const std::string &data, const crypto::public_key &public_key, const std::string &signature) const;
+
     // Import/Export wallet data
     std::vector<tools::wallet2::transfer_details> export_outputs() const;
     size_t import_outputs(const std::vector<tools::wallet2::transfer_details> &outputs);