Merge #17577: refactor: deduplicate the message sign/verify code

e193a84fb28068e38d5f54fbfd6208428c5bb655 Refactor message hashing into a utility function (Jeffrey Czyz)
f8f0d9893d7969bdaa870fadb94ec5d0dfa8334d Deduplicate the message signing code (Vasil Dimov)
2ce3447eb1e25ec7aec4b300dabf6c1e394f1906 Deduplicate the message verifying code (Vasil Dimov)

Pull request description:

  The message signing and verifying logic was replicated in a few places
  in the code. Consolidate in a newly introduced `MessageSign()` and
  `MessageVerify()` and add unit tests for them.

ACKs for top commit:
  Sjors:
    re-ACK e193a84fb28068e38d5f54fbfd6208428c5bb655
  achow101:
    ACK e193a84fb28068e38d5f54fbfd6208428c5bb655
  instagibbs:
    utACK https://github.com/bitcoin/bitcoin/pull/17577/commits/e193a84fb28068e38d5f54fbfd6208428c5bb655
  meshcollider:
    utACK e193a84fb28068e38d5f54fbfd6208428c5bb655

Tree-SHA512: b0e02a7d4623a98c8f8c77627af1725e6df07700de4630c2f75da6beacdf55414c38ba147bc6d2a757491ab07c827dddf93e8632fe600478760e255714ddab88

1 files changed, 110 insertions, 0 deletions

diff --git a/src/test/util_tests.cpp b/src/test/util_tests.cpp
index 42c2c50fa5..f86e713676 100644
--- a/src/test/util_tests.cpp
+++ b/src/test/util_tests.cpp
@@ -5,10 +5,14 @@
 #include <util/system.h>
 
 #include <clientversion.h>
+#include <hash.h> // For Hash()
+#include <key.h> // For CKey
 #include <optional.h>
 #include <sync.h>
 #include <test/util/setup_common.h>
 #include <test/util/str.h>
+#include <uint256.h>
+#include <util/message.h> // For MessageSign(), MessageVerify(), MESSAGE_MAGIC
 #include <util/moneystr.h>
 #include <util/strencodings.h>
 #include <util/string.h>
@@ -16,6 +20,7 @@
 #include <util/spanparsing.h>
 #include <util/vector.h>
 
+#include <array>
 #include <stdint.h>
 #include <thread>
 #include <univalue.h>
@@ -2025,4 +2030,109 @@ BOOST_AUTO_TEST_CASE(test_tracked_vector)
     BOOST_CHECK_EQUAL(v8[2].copies, 0);
 }
 
+BOOST_AUTO_TEST_CASE(message_sign)
+{
+    const std::array<unsigned char, 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 =
+        "IPojfrX2dfPnH26UegfbGQQLrdK844DlHq5157/P6h57WyuS/Qsl+h/WSVGDF4MUi4rWSswW38oimDYfNNUBUOk=";
+
+    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)
+{
+    BOOST_CHECK_EQUAL(
+        MessageVerify(
+            "invalid address",
+            "signature should be irrelevant",
+            "message too"),
+        MessageVerificationResult::ERR_INVALID_ADDRESS);
+
+    BOOST_CHECK_EQUAL(
+        MessageVerify(
+            "3B5fQsEXEaV8v6U3ejYc8XaKXAkyQj2MjV",
+            "signature should be irrelevant",
+            "message too"),
+        MessageVerificationResult::ERR_ADDRESS_NO_KEY);
+
+    BOOST_CHECK_EQUAL(
+        MessageVerify(
+            "1KqbBpLy5FARmTPD4VZnDDpYjkUvkr82Pm",
+            "invalid signature, not in base64 encoding",
+            "message should be irrelevant"),
+        MessageVerificationResult::ERR_MALFORMED_SIGNATURE);
+
+    BOOST_CHECK_EQUAL(
+        MessageVerify(
+            "1KqbBpLy5FARmTPD4VZnDDpYjkUvkr82Pm",
+            "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA=",
+            "message should be irrelevant"),
+        MessageVerificationResult::ERR_PUBKEY_NOT_RECOVERED);
+
+    BOOST_CHECK_EQUAL(
+        MessageVerify(
+            "15CRxFdyRpGZLW9w8HnHvVduizdL5jKNbs",
+            "IPojfrX2dfPnH26UegfbGQQLrdK844DlHq5157/P6h57WyuS/Qsl+h/WSVGDF4MUi4rWSswW38oimDYfNNUBUOk=",
+            "I never signed this"),
+        MessageVerificationResult::ERR_NOT_SIGNED);
+
+    BOOST_CHECK_EQUAL(
+        MessageVerify(
+            "15CRxFdyRpGZLW9w8HnHvVduizdL5jKNbs",
+            "IPojfrX2dfPnH26UegfbGQQLrdK844DlHq5157/P6h57WyuS/Qsl+h/WSVGDF4MUi4rWSswW38oimDYfNNUBUOk=",
+            "Trust no one"),
+        MessageVerificationResult::OK);
+
+    BOOST_CHECK_EQUAL(
+        MessageVerify(
+            "11canuhp9X2NocwCq7xNrQYTmUgZAnLK3",
+            "IIcaIENoYW5jZWxsb3Igb24gYnJpbmsgb2Ygc2Vjb25kIGJhaWxvdXQgZm9yIGJhbmtzIAaHRtbCeDZINyavx14=",
+            "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()