Add fuzzing

fuzzing/fuzz_sha512.cpp

@@ -0,0 +1,41 @@
+// Copyright 2024 Matt Borland
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt
+
+#include <boost/crypt2/hash/sha512.hpp>
+#include <iostream>
+#include <exception>
+#include <string>
+
+extern "C" int LLVMFuzzerTestOneInput(const std::uint8_t* data, std::size_t size)
+{
+    try
+    {
+        auto c_data = reinterpret_cast<const char*>(data);
+        std::string c_data_str {c_data, size}; // Guarantee null termination since we can't pass the size argument
+
+        boost::crypt::sha512(c_data_str);
+
+        std::string_view view {c_data_str};
+        boost::crypt::sha512(view);
+
+        std::span data_span {c_data, size};
+        boost::crypt::sha512(data_span);
+
+        // Fuzz the hasher object
+        boost::crypt::sha512_hasher hasher;
+        hasher.process_bytes(data_span);
+        hasher.process_bytes(data_span);
+        hasher.process_bytes(data_span);
+        hasher.finalize();
+        hasher.get_digest();
+        hasher.process_bytes(data_span); // State is invalid but should not crash
+    }
+    catch(...)
+    {
+        std::cerr << "Error with: " << data << std::endl;
+        std::terminate();
+    }
+
+    return 0;
+}