diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -346,6 +346,7 @@
 	util/bip32.cpp
 	util/bytevectorhash.cpp
 	util/error.cpp
+	util/message.cpp
 	util/moneystr.cpp
 	util/settings.cpp
 	util/spanparsing.cpp
diff --git a/src/qt/signverifymessagedialog.cpp b/src/qt/signverifymessagedialog.cpp
--- a/src/qt/signverifymessagedialog.cpp
+++ b/src/qt/signverifymessagedialog.cpp
@@ -10,7 +10,7 @@
 #include <qt/guiutil.h>
 #include <qt/platformstyle.h>
 #include <qt/walletmodel.h>
-#include <util/validation.h> // For strMessageMagic
+#include <util/message.h> // For MessageSign(), MessageVerify()
 #include <wallet/wallet.h>
 
 #include <QClipboard>
@@ -148,12 +148,11 @@
         return;
     }
 
-    CHashWriter ss(SER_GETHASH, 0);
-    ss << strMessageMagic;
-    ss << ui->messageIn_SM->document()->toPlainText().toStdString();
+    const std::string &message =
+        ui->messageIn_SM->document()->toPlainText().toStdString();
+    std::string signature;
 
-    std::vector<uint8_t> vchSig;
-    if (!key.SignCompact(ss.GetHash(), vchSig)) {
+    if (!MessageSign(key, message, signature)) {
         ui->statusLabel_SM->setStyleSheet("QLabel { color: red; }");
         ui->statusLabel_SM->setText(QString("<nobr>") +
                                     tr("Message signing failed.") +
@@ -165,8 +164,7 @@
     ui->statusLabel_SM->setText(QString("<nobr>") + tr("Message signed.") +
                                 QString("</nobr>"));
 
-    ui->signatureOut_SM->setText(
-        QString::fromStdString(EncodeBase64(vchSig.data(), vchSig.size())));
+    ui->signatureOut_SM->setText(QString::fromStdString(signature));
 }
 
 void SignVerifyMessageDialog::on_copySignatureButton_SM_clicked() {
@@ -194,62 +192,55 @@
 }
 
 void SignVerifyMessageDialog::on_verifyMessageButton_VM_clicked() {
-    CTxDestination destination = DecodeDestination(
-        ui->addressIn_VM->text().toStdString(), model->getChainParams());
-    if (!IsValidDestination(destination)) {
-        ui->statusLabel_VM->setStyleSheet("QLabel { color: red; }");
-        ui->statusLabel_VM->setText(
-            tr("The entered address is invalid.") + QString(" ") +
-            tr("Please check the address and try again."));
-        return;
-    }
-    if (!boost::get<PKHash>(&destination)) {
-        ui->addressIn_VM->setValid(false);
-        ui->statusLabel_VM->setStyleSheet("QLabel { color: red; }");
-        ui->statusLabel_VM->setText(
-            tr("The entered address does not refer to a key.") + QString(" ") +
-            tr("Please check the address and try again."));
-        return;
-    }
+    const std::string &address = ui->addressIn_VM->text().toStdString();
+    const std::string &signature = ui->signatureIn_VM->text().toStdString();
+    const std::string &message =
+        ui->messageIn_VM->document()->toPlainText().toStdString();
 
-    bool fInvalid = false;
-    std::vector<uint8_t> vchSig = DecodeBase64(
-        ui->signatureIn_VM->text().toStdString().c_str(), &fInvalid);
+    const auto result =
+        MessageVerify(model->getChainParams(), address, signature, message);
 
-    if (fInvalid) {
-        ui->signatureIn_VM->setValid(false);
+    if (result == MessageVerificationResult::OK) {
+        ui->statusLabel_VM->setStyleSheet("QLabel { color: green; }");
+    } else {
         ui->statusLabel_VM->setStyleSheet("QLabel { color: red; }");
-        ui->statusLabel_VM->setText(
-            tr("The signature could not be decoded.") + QString(" ") +
-            tr("Please check the signature and try again."));
-        return;
     }
 
-    CHashWriter ss(SER_GETHASH, 0);
-    ss << strMessageMagic;
-    ss << ui->messageIn_VM->document()->toPlainText().toStdString();
-
-    CPubKey pubkey;
-    if (!pubkey.RecoverCompact(ss.GetHash(), vchSig)) {
-        ui->signatureIn_VM->setValid(false);
-        ui->statusLabel_VM->setStyleSheet("QLabel { color: red; }");
-        ui->statusLabel_VM->setText(
-            tr("The signature did not match the message digest.") +
-            QString(" ") + tr("Please check the signature and try again."));
-        return;
+    switch (result) {
+        case MessageVerificationResult::OK:
+            ui->statusLabel_VM->setText(QString("<nobr>") +
+                                        tr("Message verified.") +
+                                        QString("</nobr>"));
+            return;
+        case MessageVerificationResult::ERR_INVALID_ADDRESS:
+            ui->statusLabel_VM->setText(
+                tr("The entered address is invalid.") + QString(" ") +
+                tr("Please check the address and try again."));
+            return;
+        case MessageVerificationResult::ERR_ADDRESS_NO_KEY:
+            ui->addressIn_VM->setValid(false);
+            ui->statusLabel_VM->setText(
+                tr("The entered address does not refer to a key.") +
+                QString(" ") + tr("Please check the address and try again."));
+            return;
+        case MessageVerificationResult::ERR_MALFORMED_SIGNATURE:
+            ui->signatureIn_VM->setValid(false);
+            ui->statusLabel_VM->setText(
+                tr("The signature could not be decoded.") + QString(" ") +
+                tr("Please check the signature and try again."));
+            return;
+        case MessageVerificationResult::ERR_PUBKEY_NOT_RECOVERED:
+            ui->signatureIn_VM->setValid(false);
+            ui->statusLabel_VM->setText(
+                tr("The signature did not match the message digest.") +
+                QString(" ") + tr("Please check the signature and try again."));
+            return;
+        case MessageVerificationResult::ERR_NOT_SIGNED:
+            ui->statusLabel_VM->setText(QString("<nobr>") +
+                                        tr("Message verification failed.") +
+                                        QString("</nobr>"));
+            return;
     }
-
-    if (!(CTxDestination(PKHash(pubkey)) == destination)) {
-        ui->statusLabel_VM->setStyleSheet("QLabel { color: red; }");
-        ui->statusLabel_VM->setText(QString("<nobr>") +
-                                    tr("Message verification failed.") +
-                                    QString("</nobr>"));
-        return;
-    }
-
-    ui->statusLabel_VM->setStyleSheet("QLabel { color: green; }");
-    ui->statusLabel_VM->setText(QString("<nobr>") + tr("Message verified.") +
-                                QString("</nobr>"));
 }
 
 void SignVerifyMessageDialog::on_clearButton_VM_clicked() {
diff --git a/src/rpc/misc.cpp b/src/rpc/misc.cpp
--- a/src/rpc/misc.cpp
+++ b/src/rpc/misc.cpp
@@ -17,10 +17,10 @@
 #include <scheduler.h>
 #include <script/descriptor.h>
 #include <util/check.h>
+#include <util/message.h> // For MessageSign(), MessageVerify()
 #include <util/ref.h>
 #include <util/strencodings.h>
 #include <util/system.h>
-#include <util/validation.h>
 
 #include <univalue.h>
 
@@ -342,35 +342,23 @@
     std::string strSign = request.params[1].get_str();
     std::string strMessage = request.params[2].get_str();
 
-    CTxDestination destination =
-        DecodeDestination(strAddress, config.GetChainParams());
-    if (!IsValidDestination(destination)) {
-        throw JSONRPCError(RPC_TYPE_ERROR, "Invalid address");
-    }
-
-    const PKHash *pkhash = boost::get<PKHash>(&destination);
-    if (!pkhash) {
-        throw JSONRPCError(RPC_TYPE_ERROR, "Address does not refer to key");
-    }
-
-    bool fInvalid = false;
-    std::vector<uint8_t> vchSig = DecodeBase64(strSign.c_str(), &fInvalid);
-
-    if (fInvalid) {
-        throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY,
-                           "Malformed base64 encoding");
-    }
-
-    CHashWriter ss(SER_GETHASH, 0);
-    ss << strMessageMagic;
-    ss << strMessage;
-
-    CPubKey pubkey;
-    if (!pubkey.RecoverCompact(ss.GetHash(), vchSig)) {
-        return false;
-    }
-
-    return (pubkey.GetID() == *pkhash);
+    switch (MessageVerify(config.GetChainParams(), strAddress, strSign,
+                          strMessage)) {
+        case MessageVerificationResult::ERR_INVALID_ADDRESS:
+            throw JSONRPCError(RPC_TYPE_ERROR, "Invalid address");
+        case MessageVerificationResult::ERR_ADDRESS_NO_KEY:
+            throw JSONRPCError(RPC_TYPE_ERROR, "Address does not refer to key");
+        case MessageVerificationResult::ERR_MALFORMED_SIGNATURE:
+            throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY,
+                               "Malformed base64 encoding");
+        case MessageVerificationResult::ERR_PUBKEY_NOT_RECOVERED:
+        case MessageVerificationResult::ERR_NOT_SIGNED:
+            return false;
+        case MessageVerificationResult::OK:
+            return true;
+    }
+
+    return false;
 }
 
 static UniValue signmessagewithprivkey(const Config &config,
@@ -407,16 +395,13 @@
         throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Invalid private key");
     }
 
-    CHashWriter ss(SER_GETHASH, 0);
-    ss << strMessageMagic;
-    ss << strMessage;
+    std::string signature;
 
-    std::vector<uint8_t> vchSig;
-    if (!key.SignCompact(ss.GetHash(), vchSig)) {
+    if (!MessageSign(key, strMessage, signature)) {
         throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Sign failed");
     }
 
-    return EncodeBase64(vchSig.data(), vchSig.size());
+    return signature;
 }
 
 static UniValue setmocktime(const Config &config,
diff --git a/src/test/util_tests.cpp b/src/test/util_tests.cpp
--- a/src/test/util_tests.cpp
+++ b/src/test/util_tests.cpp
@@ -4,11 +4,16 @@
 
 #include <util/system.h>
 
+#include <chainparams.h>
 #include <clientversion.h>
+#include <hash.h> // For Hash()
+#include <key.h>  // For CKey
 #include <optional.h>
 #include <sync.h>
 #include <test/util/logging.h>
 #include <test/util/str.h>
+#include <uint256.h>
+#include <util/message.h> // For MessageSign(), MessageVerify(), MESSAGE_MAGIC
 #include <util/moneystr.h>
 #include <util/spanparsing.h>
 #include <util/strencodings.h>
@@ -22,6 +27,7 @@
 
 #include <boost/test/unit_test.hpp>
 
+#include <array>
 #include <cstdint>
 #include <utility>
 #ifndef WIN32
@@ -2314,4 +2320,102 @@
     BOOST_CHECK_EQUAL(v8[2].copies, 0);
 }
 
+BOOST_AUTO_TEST_CASE(message_sign) {
+    const std::array<uint8_t, 32> privkey_bytes = {
+        {// just some random data
+         // derived address from this private key:
+         // 15CRxFdyRpGZLW9w8HnHvVduizdL5jKNbs
+         0xD9, 0x7F, 0x51, 0x08, 0xF1, 0x1C, 0xDA, 0x6E, 0xEE, 0xBA, 0xAA,
+         0x42, 0x0F, 0xEF, 0x07, 0x26, 0xB1, 0xF8, 0x98, 0x06, 0x0B, 0x98,
+         0x48, 0x9F, 0xA3, 0x09, 0x84, 0x63, 0xC0, 0x03, 0x28, 0x66}};
+
+    const std::string message = "Trust no one";
+
+    const std::string expected_signature =
+        "IED/"
+        "JtZs3huKX9JEQIBPZPSZwOiMyDQ+"
+        "yNWQvL7YcFzCOGTcfleWOWSvfggenKCinqvOX8t1Iw+HYZqQjxzXQm0=";
+
+    CKey privkey;
+    std::string generated_signature;
+
+    BOOST_REQUIRE_MESSAGE(!privkey.IsValid(),
+                          "Confirm the private key is invalid");
+
+    BOOST_CHECK_MESSAGE(!MessageSign(privkey, message, generated_signature),
+                        "Sign with an invalid private key");
+
+    privkey.Set(privkey_bytes.begin(), privkey_bytes.end(), true);
+
+    BOOST_REQUIRE_MESSAGE(privkey.IsValid(),
+                          "Confirm the private key is valid");
+
+    BOOST_CHECK_MESSAGE(MessageSign(privkey, message, generated_signature),
+                        "Sign with a valid private key");
+
+    BOOST_CHECK_EQUAL(expected_signature, generated_signature);
+}
+
+BOOST_AUTO_TEST_CASE(message_verify) {
+    const auto params = CreateChainParams(CBaseChainParams::MAIN);
+    BOOST_CHECK_EQUAL(MessageVerify(*params, "invalid address",
+                                    "signature should be irrelevant",
+                                    "message too"),
+                      MessageVerificationResult::ERR_INVALID_ADDRESS);
+
+    BOOST_CHECK_EQUAL(
+        MessageVerify(*params, "3B5fQsEXEaV8v6U3ejYc8XaKXAkyQj2MjV",
+                      "signature should be irrelevant", "message too"),
+        MessageVerificationResult::ERR_ADDRESS_NO_KEY);
+
+    BOOST_CHECK_EQUAL(MessageVerify(*params,
+                                    "1KqbBpLy5FARmTPD4VZnDDpYjkUvkr82Pm",
+                                    "invalid signature, not in base64 encoding",
+                                    "message should be irrelevant"),
+                      MessageVerificationResult::ERR_MALFORMED_SIGNATURE);
+
+    BOOST_CHECK_EQUAL(
+        MessageVerify(*params, "1KqbBpLy5FARmTPD4VZnDDpYjkUvkr82Pm",
+                      "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"
+                      "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA=",
+                      "message should be irrelevant"),
+        MessageVerificationResult::ERR_PUBKEY_NOT_RECOVERED);
+
+    BOOST_CHECK_EQUAL(
+        MessageVerify(*params, "15CRxFdyRpGZLW9w8HnHvVduizdL5jKNbs",
+                      "IPojfrX2dfPnH26UegfbGQQLrdK844DlHq5157/P6h57WyuS/Qsl+h/"
+                      "WSVGDF4MUi4rWSswW38oimDYfNNUBUOk=",
+                      "I never signed this"),
+        MessageVerificationResult::ERR_NOT_SIGNED);
+
+    BOOST_CHECK_EQUAL(
+        MessageVerify(*params, "15CRxFdyRpGZLW9w8HnHvVduizdL5jKNbs",
+                      "IPojfrX2dfPnH26UegfbGQQLrdK844DlHq5157/P6h57WyuS/Qsl+h/"
+                      "WSVGDF4MUi4rWSswW38oimDYfNNUBUOk=",
+                      "Trust no one"),
+        MessageVerificationResult::OK);
+
+    BOOST_CHECK_EQUAL(
+        MessageVerify(*params, "11canuhp9X2NocwCq7xNrQYTmUgZAnLK3",
+                      "IIcaIENoYW5jZWxsb3Igb24gYnJpbmsgb2Ygc2Vjb25kIGJhaWxvdXQg"
+                      "Zm9yIGJhbmtzIAaHRtbCeDZINyavx14=",
+                      "Trust me"),
+        MessageVerificationResult::OK);
+}
+
+BOOST_AUTO_TEST_CASE(message_hash) {
+    const std::string unsigned_tx = "...";
+    const std::string prefixed_message =
+        std::string(1, (char)MESSAGE_MAGIC.length()) + MESSAGE_MAGIC +
+        std::string(1, (char)unsigned_tx.length()) + unsigned_tx;
+
+    const uint256 signature_hash = Hash(unsigned_tx.begin(), unsigned_tx.end());
+    const uint256 message_hash1 =
+        Hash(prefixed_message.begin(), prefixed_message.end());
+    const uint256 message_hash2 = MessageHash(unsigned_tx);
+
+    BOOST_CHECK_EQUAL(message_hash1, message_hash2);
+    BOOST_CHECK_NE(message_hash1, signature_hash);
+}
+
 BOOST_AUTO_TEST_SUITE_END()
diff --git a/src/util/message.h b/src/util/message.h
new file mode 100644
--- /dev/null
+++ b/src/util/message.h
@@ -0,0 +1,77 @@
+// Copyright (c) 2009-2010 Satoshi Nakamoto
+// Copyright (c) 2009-2020 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#ifndef BITCOIN_UTIL_MESSAGE_H
+#define BITCOIN_UTIL_MESSAGE_H
+
+#include <uint256.h>
+
+#include <string>
+
+class CChainParams;
+class CKey;
+
+extern const std::string MESSAGE_MAGIC;
+
+/**
+ * The result of a signed message verification.
+ * Message verification takes as an input:
+ * - address (with whose private key the message is supposed to have been
+ * signed)
+ * - signature
+ * - message
+ */
+enum class MessageVerificationResult {
+    //! The provided address is invalid.
+    ERR_INVALID_ADDRESS,
+
+    //! The provided address is valid but does not refer to a public key.
+    ERR_ADDRESS_NO_KEY,
+
+    //! The provided signature couldn't be parsed (maybe invalid base64).
+    ERR_MALFORMED_SIGNATURE,
+
+    //! A public key could not be recovered from the provided signature and
+    //! message.
+    ERR_PUBKEY_NOT_RECOVERED,
+
+    //! The message was not signed with the private key of the provided address.
+    ERR_NOT_SIGNED,
+
+    //! The message verification was successful.
+    OK
+};
+
+/**
+ * Verify a signed message.
+ * @param[in] chain params to be used to interpret the address.
+ * @param[in] address Signer's bitcoin address, it must refer to a public key.
+ * @param[in] signature The signature in base64 format.
+ * @param[in] message The message that was signed.
+ * @return result code
+ */
+MessageVerificationResult MessageVerify(const CChainParams &params,
+                                        const std::string &address,
+                                        const std::string &signature,
+                                        const std::string &message);
+
+/**
+ * Sign a message.
+ * @param[in] privkey Private key to sign with.
+ * @param[in] message The message to sign.
+ * @param[out] signature Signature, base64 encoded, only set if true is
+ * returned.
+ * @return true if signing was successful.
+ */
+bool MessageSign(const CKey &privkey, const std::string &message,
+                 std::string &signature);
+
+/**
+ * Hashes a message for signing and verification in a manner that prevents
+ * inadvertently signing a transaction.
+ */
+uint256 MessageHash(const std::string &message);
+
+#endif // BITCOIN_UTIL_MESSAGE_H
diff --git a/src/util/message.cpp b/src/util/message.cpp
new file mode 100644
--- /dev/null
+++ b/src/util/message.cpp
@@ -0,0 +1,74 @@
+// Copyright (c) 2009-2010 Satoshi Nakamoto
+// Copyright (c) 2009-2020 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#include <hash.h>            // For CHashWriter
+#include <key.h>             // For CKey
+#include <key_io.h>          // For DecodeDestination()
+#include <pubkey.h>          // For CPubKey
+#include <script/standard.h> // For CTxDestination, IsValidDestination(), PKHash
+#include <serialize.h>       // For SER_GETHASH
+#include <util/message.h>
+#include <util/strencodings.h> // For DecodeBase64()
+
+#include <string>
+#include <vector>
+
+/**
+ * Text used to signify that a signed message follows and to prevent
+ * inadvertently signing a transaction.
+ */
+const std::string MESSAGE_MAGIC = "Bitcoin Signed Message:\n";
+
+MessageVerificationResult MessageVerify(const CChainParams &params,
+                                        const std::string &address,
+                                        const std::string &signature,
+                                        const std::string &message) {
+    CTxDestination destination = DecodeDestination(address, params);
+    if (!IsValidDestination(destination)) {
+        return MessageVerificationResult::ERR_INVALID_ADDRESS;
+    }
+
+    if (boost::get<PKHash>(&destination) == nullptr) {
+        return MessageVerificationResult::ERR_ADDRESS_NO_KEY;
+    }
+
+    bool invalid = false;
+    std::vector<uint8_t> signature_bytes =
+        DecodeBase64(signature.c_str(), &invalid);
+    if (invalid) {
+        return MessageVerificationResult::ERR_MALFORMED_SIGNATURE;
+    }
+
+    CPubKey pubkey;
+    if (!pubkey.RecoverCompact(MessageHash(message), signature_bytes)) {
+        return MessageVerificationResult::ERR_PUBKEY_NOT_RECOVERED;
+    }
+
+    if (!(CTxDestination(PKHash(pubkey)) == destination)) {
+        return MessageVerificationResult::ERR_NOT_SIGNED;
+    }
+
+    return MessageVerificationResult::OK;
+}
+
+bool MessageSign(const CKey &privkey, const std::string &message,
+                 std::string &signature) {
+    std::vector<uint8_t> signature_bytes;
+
+    if (!privkey.SignCompact(MessageHash(message), signature_bytes)) {
+        return false;
+    }
+
+    signature = EncodeBase64(signature_bytes.data(), signature_bytes.size());
+
+    return true;
+}
+
+uint256 MessageHash(const std::string &message) {
+    CHashWriter hasher(SER_GETHASH, 0);
+    hasher << MESSAGE_MAGIC << message;
+
+    return hasher.GetHash();
+}
diff --git a/src/util/validation.h b/src/util/validation.h
--- a/src/util/validation.h
+++ b/src/util/validation.h
@@ -13,6 +13,4 @@
 /** Convert ValidationState to a human-readable message for logging */
 std::string FormatStateMessage(const ValidationState &state);
 
-extern const std::string strMessageMagic;
-
 #endif // BITCOIN_UTIL_VALIDATION_H
diff --git a/src/util/validation.cpp b/src/util/validation.cpp
--- a/src/util/validation.cpp
+++ b/src/util/validation.cpp
@@ -22,5 +22,3 @@
     return strprintf("%s (code %i)", state.GetRejectReason(),
                      state.GetRejectCode());
 }
-
-const std::string strMessageMagic = "Bitcoin Signed Message:\n";
diff --git a/src/wallet/rpcwallet.cpp b/src/wallet/rpcwallet.cpp
--- a/src/wallet/rpcwallet.cpp
+++ b/src/wallet/rpcwallet.cpp
@@ -20,12 +20,12 @@
 #include <script/descriptor.h>
 #include <util/bip32.h>
 #include <util/error.h>
+#include <util/message.h> // For MessageSign()
 #include <util/moneystr.h>
 #include <util/string.h>
 #include <util/system.h>
 #include <util/translation.h>
 #include <util/url.h>
-#include <util/validation.h>
 #include <wallet/coincontrol.h>
 #include <wallet/psbtwallet.h>
 #include <wallet/rpcwallet.h>
@@ -634,16 +634,13 @@
         throw JSONRPCError(RPC_WALLET_ERROR, "Private key not available");
     }
 
-    CHashWriter ss(SER_GETHASH, 0);
-    ss << strMessageMagic;
-    ss << strMessage;
+    std::string signature;
 
-    std::vector<uint8_t> vchSig;
-    if (!key.SignCompact(ss.GetHash(), vchSig)) {
+    if (!MessageSign(key, strMessage, signature)) {
         throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Sign failed");
     }
 
-    return EncodeBase64(vchSig.data(), vchSig.size());
+    return signature;
 }
 
 static Amount GetReceived(const CWallet &wallet, const UniValue &params,