IOS/KD: Implement NWC24_CHECK_MAIL_NOW

Source/Core/Common/Crypto/HMAC.cpp

@@ -0,0 +1,27 @@
+// Copyright 2023 Dolphin Emulator Project
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#include <mbedtls/hmac_drbg.h>
+
+#include "Common/Crypto/HMAC.h"
+#include "Common/ScopeGuard.h"
+
+namespace Common::HMAC
+{
+bool HMACWithSHA1(std::span<const u8> key, std::span<const u8> msg, u8* out)
+{
+  mbedtls_md_context_t ctx;
+  Common::ScopeGuard guard{[&ctx] { mbedtls_md_free(&ctx); }};
+  mbedtls_md_init(&ctx);
+  if (mbedtls_md_setup(&ctx, mbedtls_md_info_from_type(MBEDTLS_MD_SHA1), 1))
+    return false;
+
+  if (mbedtls_md_hmac_starts(&ctx, key.data(), key.size()) ||
+      mbedtls_md_hmac_update(&ctx, msg.data(), msg.size()) || mbedtls_md_hmac_finish(&ctx, out))
+  {
+    return false;
+  }
+
+  return true;
+}
+}  // namespace Common::HMAC