diff --git a/include/rde/rde_handler.hpp b/include/rde/rde_handler.hpp
new file mode 100644
index 0000000..65e9361
--- /dev/null
+++ b/include/rde/rde_handler.hpp
@@ -0,0 +1,219 @@
+#pragma once
+
+#include "bej_decoder_json.hpp"
+#include "external_storer_interface.hpp"
+#include "rde_dictionary_manager.hpp"
+
+#include <cstdint>
+#include <span>
+#include <string_view>
+
+namespace bios_bmc_smm_error_logger
+{
+namespace rde
+{
+
+/**
+ * @brief Supported RDE commands.
+ *
+ * The values used are the same as what BIOS uses.
+ */
+enum class RdeCommandType : char
+{
+    // Used for RDE BEJ dictionary transfer.
+    RdeMultiPartReceiveResponse = 1,
+    // Used for RDE BEJ encoded data.
+    RdeOperationInitRequest = 2,
+};
+
+/**
+ * @brief Used to keep track of RdeMultiPartReceiveResponse START flag
+ * reception.
+ */
+enum class RdeDictTransferFlagState
+{
+    RdeStateIdle,
+    RdeStateStartRecvd,
+};
+
+/**
+ * @brief Status of RDE command processing.
+ */
+enum class RdeDecodeStatus
+{
+    RdeOk,
+    RdeInvalidCommand,
+    RdeUnsupportedOperation,
+    RdeNoDictionary,
+    RdePayloadOverflow,
+    RdeBejDecodingError,
+    RdeInvalidPktOrder,
+    RdeDictionaryError,
+    RdeFileCreationFailed,
+    RdeExternalStorerError,
+    // This implies that the stop flag has been received.
+    RdeInvalidChecksum,
+    // This implies that the checksum is correct.
+    RdeStopFlagReceived,
+};
+
+/**
+ * @brief Handles RDE messages from the BIOS - BMC circular buffer and updates
+ * ExternalStorer.
+ */
+class RdeCommandHandler
+{
+  public:
+    /**
+     * @brief Constructor for RdeExternalStorer.
+     *
+     * @param[in] exStorer - valid ExternalStorerInterface. This class will take
+     * the ownership of this object.
+     */
+    explicit RdeCommandHandler(
+        std::unique_ptr<ExternalStorerInterface> exStorer);
+
+    /**
+     * @brief Decode a RDE command.
+     *
+     * @param[in] rdeCommand - RDE command.
+     * @param[in] type - RDE command type.
+     * @return RdeDecodeStatus code.
+     */
+    RdeDecodeStatus decodeRdeCommand(std::span<const uint8_t> rdeCommand,
+                                     RdeCommandType type);
+
+    /**
+     * @brief Get the number of complete dictionaries received.
+     *
+     * @return number of complete dictionaries.
+     */
+    uint32_t getDictionaryCount();
+
+  private:
+    /**
+     * @brief This keeps track of whether we received the dictionary start flag
+     * or not.
+     */
+    RdeDictTransferFlagState flagState;
+
+    std::unique_ptr<ExternalStorerInterface> exStorer;
+
+    /**
+     * @brief We are using the prevDictResourceId to detect a new dictionary.
+     *
+     * BIOS-BMC buffer uses RdeMultiPartReceiveResponse START flag to indicate
+     * the first dictionary data chunk. BMC will not receive this flag at start
+     * of every new dictionary but only for the first data chunk. Therefore
+     * difference between resource ID is used to identify a new dictionary
+     * start. prevDictResourceId keeps track of the resource ID of the last
+     * dictionary data chunk.
+     */
+    uint32_t prevDictResourceId;
+
+    DictionaryManager dictionaryManager;
+    libbej::BejDecoderJson decoder;
+
+    uint32_t crc;
+    std::array<uint32_t, UINT8_MAX + 1> crcTable;
+
+    /**
+     * @brief Handles OperationInit request messages.
+     *
+     * @param[in] rdeCommand - RDE command.
+     * @return RdeDecodeStatus
+     */
+    RdeDecodeStatus operationInitRequest(std::span<const uint8_t> rdeCommand);
+
+    /**
+     * @brief Handles MultiPartReceive response messages.
+     *
+     * @param[in] rdeCommand - RDE command.
+     * @return RdeDecodeStatus
+     */
+    RdeDecodeStatus multiPartReceiveResp(std::span<const uint8_t> rdeCommand);
+
+    /**
+     * @brief Initializes the CRC table.
+     */
+    void calcCrcTable();
+
+    /**
+     * @brief Update the existing CRC using the provided byte stream.
+     *
+     * According to the RDE BEJ specification: "32-bit CRC for the entire block
+     * of data (all parts concatenated together, excluding this checksum)".
+     * Therefore when calculating the CRC whole RDEMultipartReceive Response
+     * data packet is considered, not just the dictionary data contained within
+     * it.
+     *
+     * @param[in] stream - a byte stream.
+     */
+    void updateCrc(std::span<const uint8_t> stream);
+
+    /**
+     * @brief Get the final checksum value.
+     *
+     * @return uint32_t - final checksum value.
+     */
+    uint32_t finalChecksum();
+
+    /**
+     * @brief Process received CRC field from a multi receive response command.
+     * END or START_AND_END flag should be set in the command.
+     *
+     * @param multiReceiveRespCmd - payload with a checksum field populated.
+     * @return RdeDecodeStatus
+     */
+    RdeDecodeStatus handleCrc(std::span<const uint8_t> multiReceiveRespCmd);
+
+    /**
+     * @brief Handle dictionary data with flag Start.
+     *
+     * @param[in] header -  RDE header portion of the RDE command.
+     * @param[in] data - data portion of the RDE command.
+     * @param[in] resourceId - PDR resource ID of the dictionary.
+     */
+    void handleFlagStart(const MultipartReceiveResHeader* header,
+                         const uint8_t* data, uint32_t resourceId);
+
+    /**
+     * @brief Handle dictionary data with flag Middle.
+     *
+     * @param[in] header -  RDE header portion of the RDE command.
+     * @param[in] data - data portion of the RDE command.
+     * @param[in] resourceId - PDR resource ID of the dictionary.
+     * @return RdeDecodeStatus
+     */
+    RdeDecodeStatus handleFlagMiddle(const MultipartReceiveResHeader* header,
+                                     const uint8_t* data, uint32_t resourceId);
+    /**
+     * @brief Handle dictionary data with flag End.
+     *
+     * @param[in] rdeCommand - RDE command.
+     * @param[in] header -  RDE header portion of the RDE command.
+     * @param[in] data - data portion of the RDE command.
+     * @param[in] resourceId - PDR resource ID of the dictionary.
+     * @return RdeDecodeStatus
+     */
+    RdeDecodeStatus handleFlagEnd(std::span<const uint8_t> rdeCommand,
+                                  const MultipartReceiveResHeader* header,
+                                  const uint8_t* data, uint32_t resourceId);
+
+    /**
+     * @brief Handle dictionary data with flag StartAndEnd.
+     *
+     * @param[in] rdeCommand - RDE command.
+     * @param[in] header -  RDE header portion of the RDE command.
+     * @param[in] data - data portion of the RDE command.
+     * @param[in] resourceId - PDR resource ID of the dictionary.
+     * @return RdeDecodeStatus
+     */
+    RdeDecodeStatus
+        handleFlagStartAndEnd(std::span<const uint8_t> rdeCommand,
+                              const MultipartReceiveResHeader* header,
+                              const uint8_t* data, uint32_t resourceId);
+};
+
+} // namespace rde
+} // namespace bios_bmc_smm_error_logger