tests: Add key_io fuzzing harness

src/Makefile.test.include

@@ -36,6 +36,7 @@ FUZZ_TARGETS = \
   test/fuzz/integer \
   test/fuzz/inv_deserialize \
   test/fuzz/key \
+  test/fuzz/key_io \
   test/fuzz/key_origin_info_deserialize \
   test/fuzz/locale \
   test/fuzz/merkle_block_deserialize \
@@ -438,6 +439,12 @@ test_fuzz_key_LDADD = $(FUZZ_SUITE_LD_COMMON)
 test_fuzz_key_LDFLAGS = $(RELDFLAGS) $(AM_LDFLAGS) $(LIBTOOL_APP_LDFLAGS)
 test_fuzz_key_SOURCES = $(FUZZ_SUITE) test/fuzz/key.cpp
 
+test_fuzz_key_io_CPPFLAGS = $(AM_CPPFLAGS) $(BITCOIN_INCLUDES)
+test_fuzz_key_io_CXXFLAGS = $(AM_CXXFLAGS) $(PIE_FLAGS)
+test_fuzz_key_io_LDADD = $(FUZZ_SUITE_LD_COMMON)
+test_fuzz_key_io_LDFLAGS = $(RELDFLAGS) $(AM_LDFLAGS) $(LIBTOOL_APP_LDFLAGS)
+test_fuzz_key_io_SOURCES = $(FUZZ_SUITE) test/fuzz/key_io.cpp
+
 test_fuzz_key_origin_info_deserialize_CPPFLAGS = $(AM_CPPFLAGS) $(BITCOIN_INCLUDES) -DKEY_ORIGIN_INFO_DESERIALIZE=1
 test_fuzz_key_origin_info_deserialize_CXXFLAGS = $(AM_CXXFLAGS) $(PIE_FLAGS)
 test_fuzz_key_origin_info_deserialize_LDADD = $(FUZZ_SUITE_LD_COMMON)

src/test/fuzz/key_io.cpp

@@ -0,0 +1,48 @@
+// Copyright (c) 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 <chainparams.h>
+#include <key_io.h>
+#include <rpc/util.h>
+#include <script/signingprovider.h>
+#include <script/standard.h>
+#include <test/fuzz/fuzz.h>
+
+#include <cassert>
+#include <cstdint>
+#include <string>
+#include <vector>
+
+void initialize()
+{
+    SelectParams(CBaseChainParams::REGTEST);
+}
+
+void test_one_input(const std::vector<uint8_t>& buffer)
+{
+    const std::string random_string(buffer.begin(), buffer.end());
+
+    const CKey key = DecodeSecret(random_string);
+    if (key.IsValid()) {
+        assert(key == DecodeSecret(EncodeSecret(key)));
+    }
+
+    const CExtKey ext_key = DecodeExtKey(random_string);
+    if (ext_key.key.size() == 32) {
+        assert(ext_key == DecodeExtKey(EncodeExtKey(ext_key)));
+    }
+
+    const CExtPubKey ext_pub_key = DecodeExtPubKey(random_string);
+    if (ext_pub_key.pubkey.size() == CPubKey::COMPRESSED_SIZE) {
+        assert(ext_pub_key == DecodeExtPubKey(EncodeExtPubKey(ext_pub_key)));
+    }
+
+    const CTxDestination tx_destination = DecodeDestination(random_string);
+    (void)DescribeAddress(tx_destination);
+    (void)GetKeyForDestination(/* store */ {}, tx_destination);
+    (void)GetScriptForDestination(tx_destination);
+    (void)IsValidDestination(tx_destination);
+
+    (void)IsValidDestinationString(random_string);
+}

test/fuzz/test_runner.py

@@ -27,6 +27,7 @@ FUZZERS_MISSING_CORPORA = [
     "flat_file_pos_deserialize",
     "float",
     "hex",
+    "key_io",
     "integer",
     "key",
     "key_origin_info_deserialize",