diff --git a/src/Makefile.test.include b/src/Makefile.test.include
index e1c590a1fb9..7823bf4c058 100644
--- a/src/Makefile.test.include
+++ b/src/Makefile.test.include
@@ -35,6 +35,7 @@ FUZZ_TARGETS = \
   test/fuzz/hex \
   test/fuzz/integer \
   test/fuzz/inv_deserialize \
+  test/fuzz/key \
   test/fuzz/key_origin_info_deserialize \
   test/fuzz/merkle_block_deserialize \
   test/fuzz/messageheader_deserialize \
@@ -430,6 +431,12 @@ test_fuzz_inv_deserialize_LDADD = $(FUZZ_SUITE_LD_COMMON)
 test_fuzz_inv_deserialize_LDFLAGS = $(RELDFLAGS) $(AM_LDFLAGS) $(LIBTOOL_APP_LDFLAGS)
 test_fuzz_inv_deserialize_SOURCES = $(FUZZ_SUITE) test/fuzz/deserialize.cpp
 
+test_fuzz_key_CPPFLAGS = $(AM_CPPFLAGS) $(BITCOIN_INCLUDES)
+test_fuzz_key_CXXFLAGS = $(AM_CXXFLAGS) $(PIE_FLAGS)
+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_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)
diff --git a/src/test/fuzz/key.cpp b/src/test/fuzz/key.cpp
new file mode 100644
index 00000000000..1919a5f881f
--- /dev/null
+++ b/src/test/fuzz/key.cpp
@@ -0,0 +1,309 @@
+// 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 <chainparamsbase.h>
+#include <key.h>
+#include <key_io.h>
+#include <outputtype.h>
+#include <policy/policy.h>
+#include <pubkey.h>
+#include <rpc/util.h>
+#include <script/keyorigin.h>
+#include <script/script.h>
+#include <script/sign.h>
+#include <script/signingprovider.h>
+#include <script/standard.h>
+#include <streams.h>
+#include <test/fuzz/fuzz.h>
+#include <util/memory.h>
+#include <util/strencodings.h>
+
+#include <cassert>
+#include <cstdint>
+#include <numeric>
+#include <string>
+#include <vector>
+
+void initialize()
+{
+    static const ECCVerifyHandle ecc_verify_handle;
+    ECC_Start();
+    SelectParams(CBaseChainParams::REGTEST);
+}
+
+void test_one_input(const std::vector<uint8_t>& buffer)
+{
+    const CKey key = [&] {
+        CKey k;
+        k.Set(buffer.begin(), buffer.end(), true);
+        return k;
+    }();
+    if (!key.IsValid()) {
+        return;
+    }
+
+    {
+        assert(key.begin() + key.size() == key.end());
+        assert(key.IsCompressed());
+        assert(key.size() == 32);
+        assert(DecodeSecret(EncodeSecret(key)) == key);
+    }
+
+    {
+        CKey invalid_key;
+        assert(!(invalid_key == key));
+        assert(!invalid_key.IsCompressed());
+        assert(!invalid_key.IsValid());
+        assert(invalid_key.size() == 0);
+    }
+
+    {
+        CKey uncompressed_key;
+        uncompressed_key.Set(buffer.begin(), buffer.end(), false);
+        assert(!(uncompressed_key == key));
+        assert(!uncompressed_key.IsCompressed());
+        assert(key.size() == 32);
+        assert(uncompressed_key.begin() + uncompressed_key.size() == uncompressed_key.end());
+        assert(uncompressed_key.IsValid());
+    }
+
+    {
+        CKey copied_key;
+        copied_key.Set(key.begin(), key.end(), key.IsCompressed());
+        assert(copied_key == key);
+    }
+
+    {
+        CKey negated_key = key;
+        negated_key.Negate();
+        assert(negated_key.IsValid());
+        assert(!(negated_key == key));
+
+        negated_key.Negate();
+        assert(negated_key == key);
+    }
+
+    const uint256 random_uint256 = Hash(buffer.begin(), buffer.end());
+
+    {
+        CKey child_key;
+        ChainCode child_chaincode;
+        const bool ok = key.Derive(child_key, child_chaincode, 0, random_uint256);
+        assert(ok);
+        assert(child_key.IsValid());
+        assert(!(child_key == key));
+        assert(child_chaincode != random_uint256);
+    }
+
+    const CPubKey pubkey = key.GetPubKey();
+
+    {
+        assert(pubkey.size() == 33);
+        assert(key.VerifyPubKey(pubkey));
+        assert(pubkey.GetHash() != random_uint256);
+        assert(pubkey.begin() + pubkey.size() == pubkey.end());
+        assert(pubkey.data() == pubkey.begin());
+        assert(pubkey.IsCompressed());
+        assert(pubkey.IsValid());
+        assert(pubkey.IsFullyValid());
+        assert(HexToPubKey(HexStr(pubkey.begin(), pubkey.end())) == pubkey);
+        assert(GetAllDestinationsForKey(pubkey).size() == 3);
+    }
+
+    {
+        CDataStream data_stream{SER_NETWORK, INIT_PROTO_VERSION};
+        pubkey.Serialize(data_stream);
+
+        CPubKey pubkey_deserialized;
+        pubkey_deserialized.Unserialize(data_stream);
+        assert(pubkey_deserialized == pubkey);
+    }
+
+    {
+        const CScript tx_pubkey_script = GetScriptForRawPubKey(pubkey);
+        assert(!tx_pubkey_script.IsPayToScriptHash());
+        assert(!tx_pubkey_script.IsPayToWitnessScriptHash());
+        assert(!tx_pubkey_script.IsPushOnly());
+        assert(!tx_pubkey_script.IsUnspendable());
+        assert(tx_pubkey_script.HasValidOps());
+        assert(tx_pubkey_script.size() == 35);
+
+        const CScript tx_multisig_script = GetScriptForMultisig(1, {pubkey});
+        assert(!tx_multisig_script.IsPayToScriptHash());
+        assert(!tx_multisig_script.IsPayToWitnessScriptHash());
+        assert(!tx_multisig_script.IsPushOnly());
+        assert(!tx_multisig_script.IsUnspendable());
+        assert(tx_multisig_script.HasValidOps());
+        assert(tx_multisig_script.size() == 37);
+
+        FillableSigningProvider fillable_signing_provider;
+        assert(IsSolvable(fillable_signing_provider, tx_pubkey_script));
+        assert(IsSolvable(fillable_signing_provider, tx_multisig_script));
+        assert(!IsSegWitOutput(fillable_signing_provider, tx_pubkey_script));
+        assert(!IsSegWitOutput(fillable_signing_provider, tx_multisig_script));
+        assert(fillable_signing_provider.GetKeys().size() == 0);
+        assert(!fillable_signing_provider.HaveKey(pubkey.GetID()));
+
+        const bool ok_add_key = fillable_signing_provider.AddKey(key);
+        assert(ok_add_key);
+        assert(fillable_signing_provider.HaveKey(pubkey.GetID()));
+
+        FillableSigningProvider fillable_signing_provider_pub;
+        assert(!fillable_signing_provider_pub.HaveKey(pubkey.GetID()));
+
+        const bool ok_add_key_pubkey = fillable_signing_provider_pub.AddKeyPubKey(key, pubkey);
+        assert(ok_add_key_pubkey);
+        assert(fillable_signing_provider_pub.HaveKey(pubkey.GetID()));
+
+        txnouttype which_type_tx_pubkey;
+        const bool is_standard_tx_pubkey = IsStandard(tx_pubkey_script, which_type_tx_pubkey);
+        assert(is_standard_tx_pubkey);
+        assert(which_type_tx_pubkey == txnouttype::TX_PUBKEY);
+
+        txnouttype which_type_tx_multisig;
+        const bool is_standard_tx_multisig = IsStandard(tx_multisig_script, which_type_tx_multisig);
+        assert(is_standard_tx_multisig);
+        assert(which_type_tx_multisig == txnouttype::TX_MULTISIG);
+
+        std::vector<std::vector<unsigned char>> v_solutions_ret_tx_pubkey;
+        const txnouttype outtype_tx_pubkey = Solver(tx_pubkey_script, v_solutions_ret_tx_pubkey);
+        assert(outtype_tx_pubkey == txnouttype::TX_PUBKEY);
+        assert(v_solutions_ret_tx_pubkey.size() == 1);
+        assert(v_solutions_ret_tx_pubkey[0].size() == 33);
+
+        std::vector<std::vector<unsigned char>> v_solutions_ret_tx_multisig;
+        const txnouttype outtype_tx_multisig = Solver(tx_multisig_script, v_solutions_ret_tx_multisig);
+        assert(outtype_tx_multisig == txnouttype::TX_MULTISIG);
+        assert(v_solutions_ret_tx_multisig.size() == 3);
+        assert(v_solutions_ret_tx_multisig[0].size() == 1);
+        assert(v_solutions_ret_tx_multisig[1].size() == 33);
+        assert(v_solutions_ret_tx_multisig[2].size() == 1);
+
+        OutputType output_type{};
+        const CTxDestination tx_destination = GetDestinationForKey(pubkey, output_type);
+        assert(output_type == OutputType::LEGACY);
+        assert(IsValidDestination(tx_destination));
+        assert(CTxDestination{PKHash{pubkey}} == tx_destination);
+
+        const CScript script_for_destination = GetScriptForDestination(tx_destination);
+        assert(script_for_destination.size() == 25);
+
+        const std::string destination_address = EncodeDestination(tx_destination);
+        assert(DecodeDestination(destination_address) == tx_destination);
+
+        const CPubKey pubkey_from_address_string = AddrToPubKey(fillable_signing_provider, destination_address);
+        assert(pubkey_from_address_string == pubkey);
+
+        CKeyID key_id = pubkey.GetID();
+        assert(!key_id.IsNull());
+        assert(key_id == CKeyID{key_id});
+        assert(key_id == GetKeyForDestination(fillable_signing_provider, tx_destination));
+
+        CPubKey pubkey_out;
+        const bool ok_get_pubkey = fillable_signing_provider.GetPubKey(key_id, pubkey_out);
+        assert(ok_get_pubkey);
+
+        CKey key_out;
+        const bool ok_get_key = fillable_signing_provider.GetKey(key_id, key_out);
+        assert(ok_get_key);
+        assert(fillable_signing_provider.GetKeys().size() == 1);
+        assert(fillable_signing_provider.HaveKey(key_id));
+
+        KeyOriginInfo key_origin_info;
+        const bool ok_get_key_origin = fillable_signing_provider.GetKeyOrigin(key_id, key_origin_info);
+        assert(!ok_get_key_origin);
+    }
+
+    {
+        const std::vector<unsigned char> vch_pubkey{pubkey.begin(), pubkey.end()};
+        assert(CPubKey::ValidSize(vch_pubkey));
+        assert(!CPubKey::ValidSize({pubkey.begin(), pubkey.begin() + pubkey.size() - 1}));
+
+        const CPubKey pubkey_ctor_1{vch_pubkey};
+        assert(pubkey == pubkey_ctor_1);
+
+        const CPubKey pubkey_ctor_2{vch_pubkey.begin(), vch_pubkey.end()};
+        assert(pubkey == pubkey_ctor_2);
+
+        CPubKey pubkey_set;
+        pubkey_set.Set(vch_pubkey.begin(), vch_pubkey.end());
+        assert(pubkey == pubkey_set);
+    }
+
+    {
+        const CPubKey invalid_pubkey{};
+        assert(!invalid_pubkey.IsValid());
+        assert(!invalid_pubkey.IsFullyValid());
+        assert(!(pubkey == invalid_pubkey));
+        assert(pubkey != invalid_pubkey);
+        assert(pubkey < invalid_pubkey);
+    }
+
+    {
+        // Cover CPubKey's operator[](unsigned int pos)
+        unsigned int sum = 0;
+        for (size_t i = 0; i < pubkey.size(); ++i) {
+            sum += pubkey[i];
+        }
+        assert(std::accumulate(pubkey.begin(), pubkey.end(), 0U) == sum);
+    }
+
+    {
+        CPubKey decompressed_pubkey = pubkey;
+        assert(decompressed_pubkey.IsCompressed());
+
+        const bool ok = decompressed_pubkey.Decompress();
+        assert(ok);
+        assert(!decompressed_pubkey.IsCompressed());
+        assert(decompressed_pubkey.size() == 65);
+    }
+
+    {
+        std::vector<unsigned char> vch_sig;
+        const bool ok = key.Sign(random_uint256, vch_sig, false);
+        assert(ok);
+        assert(pubkey.Verify(random_uint256, vch_sig));
+        assert(CPubKey::CheckLowS(vch_sig));
+
+        const std::vector<unsigned char> vch_invalid_sig{vch_sig.begin(), vch_sig.begin() + vch_sig.size() - 1};
+        assert(!pubkey.Verify(random_uint256, vch_invalid_sig));
+        assert(!CPubKey::CheckLowS(vch_invalid_sig));
+    }
+
+    {
+        std::vector<unsigned char> vch_compact_sig;
+        const bool ok_sign_compact = key.SignCompact(random_uint256, vch_compact_sig);
+        assert(ok_sign_compact);
+
+        CPubKey recover_pubkey;
+        const bool ok_recover_compact = recover_pubkey.RecoverCompact(random_uint256, vch_compact_sig);
+        assert(ok_recover_compact);
+        assert(recover_pubkey == pubkey);
+    }
+
+    {
+        CPubKey child_pubkey;
+        ChainCode child_chaincode;
+        const bool ok = pubkey.Derive(child_pubkey, child_chaincode, 0, random_uint256);
+        assert(ok);
+        assert(child_pubkey != pubkey);
+        assert(child_pubkey.IsCompressed());
+        assert(child_pubkey.IsFullyValid());
+        assert(child_pubkey.IsValid());
+        assert(child_pubkey.size() == 33);
+        assert(child_chaincode != random_uint256);
+    }
+
+    const CPrivKey priv_key = key.GetPrivKey();
+
+    {
+        for (const bool skip_check : {true, false}) {
+            CKey loaded_key;
+            const bool ok = loaded_key.Load(priv_key, pubkey, skip_check);
+            assert(ok);
+            assert(key == loaded_key);
+        }
+    }
+}
diff --git a/test/fuzz/test_runner.py b/test/fuzz/test_runner.py
index 0541b0d0322..5df2789638a 100755
--- a/test/fuzz/test_runner.py
+++ b/test/fuzz/test_runner.py
@@ -28,6 +28,7 @@ FUZZERS_MISSING_CORPORA = [
     "float",
     "hex",
     "integer",
+    "key",
     "key_origin_info_deserialize",
     "merkle_block_deserialize",
     "out_point_deserialize",