From 18dfea0dd082af18dfb02981b7ee1cd44d514388 Mon Sep 17 00:00:00 2001 From: Andrew Chow Date: Sat, 14 Jul 2018 16:03:28 -0700 Subject: Always create 70 byte signatures with low R values When extra entropy is not specified by the caller, CKey::Sign will now always create a signature that has a low R value and is at most 70 bytes. The resulting signature on the stack will be 71 bytes when the sighash byte is included. Using low R signatures means that the resulting DER encoded signature will never need to have additional padding to account for high R values. --- src/test/key_tests.cpp | 36 ++++++++++++++++++++++++++++++++++++ 1 file changed, 36 insertions(+) (limited to 'src/test/key_tests.cpp') diff --git a/src/test/key_tests.cpp b/src/test/key_tests.cpp index 64c57f0705..acd213dac2 100644 --- a/src/test/key_tests.cpp +++ b/src/test/key_tests.cpp @@ -152,4 +152,40 @@ BOOST_AUTO_TEST_CASE(key_test1) BOOST_CHECK(detsigc == ParseHex("2052d8a32079c11e79db95af63bb9600c5b04f21a9ca33dc129c2bfa8ac9dc1cd561d8ae5e0f6c1a16bde3719c64c2fd70e404b6428ab9a69566962e8771b5944d")); } +BOOST_AUTO_TEST_CASE(key_signature_tests) +{ + // When entropy is specified, we should see at least one high R signature within 20 signatures + CKey key = DecodeSecret(strSecret1); + std::string msg = "A message to be signed"; + uint256 msg_hash = Hash(msg.begin(), msg.end()); + std::vector sig; + bool found = false; + + for (int i = 1; i <=20; ++i) { + sig.clear(); + key.Sign(msg_hash, sig, false, i); + found = sig[3] == 0x21 && sig[4] == 0x00; + if (found) { + break; + } + } + BOOST_CHECK(found); + + // When entropy is not specified, we should always see low R signatures that are less than 70 bytes in 256 tries + // We should see at least one signature that is less than 70 bytes. + found = true; + bool found_small = false; + for (int i = 0; i < 256; ++i) { + sig.clear(); + std::string msg = "A message to be signed" + std::to_string(i); + msg_hash = Hash(msg.begin(), msg.end()); + key.Sign(msg_hash, sig); + found = sig[3] == 0x20; + BOOST_CHECK(sig.size() <= 70); + found_small |= sig.size() < 70; + } + BOOST_CHECK(found); + BOOST_CHECK(found_small); +} + BOOST_AUTO_TEST_SUITE_END() -- cgit v1.2.3