/**
 * @page sigv4_porting Porting Guide
 * @brief Guide for porting the AWS SigV4 Library to a new
 * platform.
 *
 * To use the AWS SigV4 library, a platform must implement the following
 * components:
 * 1. [Configuration Macros](@ref sigv4_config_macros)
 * 2. [Crypto Interface](@ref sigv4_porting_cryptointerface)
 *
 * @section sigv4_config_macros Configuration Macros
 * @brief Configuration macros that can be set in the config header
 * `sigv4_config.h`, or passed in as compiler options.
 *
 * The following optional logging macros are used throughout the library:
 * - @ref LogError
 * - @ref LogWarn
 * - @ref LogInfo
 * - @ref LogDebug
 *
 * @see [Configurations](@ref sigv4_config) for more information.
 *
 * @note Regardless of whether the above macros are defined in
 * `sigv4_config.h` or passed as compiler options, by default the
 * `sigv4_config.h` file is needed to build the AWS SigV4 Library. To disable this requirement and build the library with
 * default configuration values, provide
 * `SIGV4_DO_NOT_USE_CUSTOM_CONFIG` as a compile time preprocessor
 * macro.
 *
 * @section sigv4_porting_cryptointerface Crypto Interface
 * @brief The AWS SigV4 library relies on the implementation of crypto interface
 * to provide hash functions used in generating the Authorization header by the library.
 *
 * A port must implement functions corresponding to the
 * following functions pointers:
 * - [Hash Initialize]: A function to initialize the Hash Context.
 * @code
 * int32_t ( * hashInit )( void * pHashContext );
 * @endcode
 * - [Hash Update]: A function to update the hash to be calculated with more input data.
 * @code
 * int32_t ( * hashUpdate )( void * pHashContext,
 *                            const uint8_t * pInput,
 *                            size_t inputLen );
 * @endcode
 * - [Hash Final]: A function to calculate the final binary digest of the hash from the context.
 * @code
 * int32_t ( * hashFinal )( void * pHashContext,
 *                           uint8_t * pOutput,
 *                           size_t outputLen );
 * @endcode
 *
 * The above three functions take in a pointer to pHashContext which defines the context used
 * by the above function in calculating the hash. The HashContext must also be
 * defined by the user's implementation and ought to contain any information
 * necessary to calculate the hash.
 * @code
 * void * pHashContext;
 * @endcode
 *
 * A port must also define the following:
 * - [Hash Block Length]: The block length of the hash function implemented by the user.
 * @code
 * size_t hashBlockLen;
 * @endcode
 *
 * - [Hash Digest Length]: The digest length of the hash function implemented by the user.
 * @code
 * size_t hashDigestLen;
 * @endcode
 *
 */