tests: Add fuzzing harness for AES256CBCEncrypt/AES256CBCDecrypt

Author: practicalswift

src/Makefile.test.include

@@ -34,6 +34,7 @@ FUZZ_TARGETS = \
   test/fuzz/coins_view \
   test/fuzz/crypto \
   test/fuzz/crypto_aes256 \
+  test/fuzz/crypto_aes256cbc \
   test/fuzz/crypto_common \
   test/fuzz/cuckoocache \
   test/fuzz/decode_tx \
@@ -493,6 +494,12 @@ test_fuzz_crypto_aes256_LDADD = $(FUZZ_SUITE_LD_COMMON)
 test_fuzz_crypto_aes256_LDFLAGS = $(RELDFLAGS) $(AM_LDFLAGS) $(LIBTOOL_APP_LDFLAGS)
 test_fuzz_crypto_aes256_SOURCES = test/fuzz/crypto_aes256.cpp
 
+test_fuzz_crypto_aes256cbc_CPPFLAGS = $(AM_CPPFLAGS) $(BITCOIN_INCLUDES)
+test_fuzz_crypto_aes256cbc_CXXFLAGS = $(AM_CXXFLAGS) $(PIE_FLAGS)
+test_fuzz_crypto_aes256cbc_LDADD = $(FUZZ_SUITE_LD_COMMON)
+test_fuzz_crypto_aes256cbc_LDFLAGS = $(RELDFLAGS) $(AM_LDFLAGS) $(LIBTOOL_APP_LDFLAGS)
+test_fuzz_crypto_aes256cbc_SOURCES = test/fuzz/crypto_aes256cbc.cpp
+
 test_fuzz_crypto_common_CPPFLAGS = $(AM_CPPFLAGS) $(BITCOIN_INCLUDES)
 test_fuzz_crypto_common_CXXFLAGS = $(AM_CXXFLAGS) $(PIE_FLAGS)
 test_fuzz_crypto_common_LDADD = $(FUZZ_SUITE_LD_COMMON)

src/test/fuzz/crypto_aes256cbc.cpp

@@ -0,0 +1,34 @@
+// 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 <crypto/aes.h>
+#include <test/fuzz/FuzzedDataProvider.h>
+#include <test/fuzz/fuzz.h>
+#include <test/fuzz/util.h>
+
+#include <cassert>
+#include <cstdint>
+#include <vector>
+
+void test_one_input(const std::vector<uint8_t>& buffer)
+{
+    FuzzedDataProvider fuzzed_data_provider{buffer.data(), buffer.size()};
+    const std::vector<uint8_t> key = ConsumeFixedLengthByteVector(fuzzed_data_provider, AES256_KEYSIZE);
+    const std::vector<uint8_t> iv = ConsumeFixedLengthByteVector(fuzzed_data_provider, AES_BLOCKSIZE);
+    const bool pad = fuzzed_data_provider.ConsumeBool();
+
+    AES256CBCEncrypt encrypt{key.data(), iv.data(), pad};
+    AES256CBCDecrypt decrypt{key.data(), iv.data(), pad};
+
+    while (fuzzed_data_provider.ConsumeBool()) {
+        const std::vector<uint8_t> plaintext = ConsumeRandomLengthByteVector(fuzzed_data_provider);
+        std::vector<uint8_t> ciphertext(plaintext.size() + AES_BLOCKSIZE);
+        const int encrypt_ret = encrypt.Encrypt(plaintext.data(), plaintext.size(), ciphertext.data());
+        ciphertext.resize(encrypt_ret);
+        std::vector<uint8_t> decrypted_plaintext(ciphertext.size());
+        const int decrypt_ret = decrypt.Decrypt(ciphertext.data(), ciphertext.size(), decrypted_plaintext.data());
+        decrypted_plaintext.resize(decrypt_ret);
+        assert(decrypted_plaintext == plaintext || (!pad && plaintext.size() % AES_BLOCKSIZE != 0 && encrypt_ret == 0 && decrypt_ret == 0));
+    }
+}