/** * file sha2.h */#ifndef _SHA2_H#define _SHA2_H/** * brief          SHA-256 context structure */typedef struct{    unsigned long total[2];     /*!< number of bytes processed  */    unsigned long state[8];     /*!< intermediate digest state  */    unsigned char buffer[64];   /*!< data block being processed */    unsigned char ipad[64];     /*!< HMAC: inner padding        */    unsigned char opad[64];     /*!< HMAC: outer padding        */    int is224;                  /*!< 0 => SHA-256, else SHA-224 */}sha2_context;#ifdef __cplusplusextern "C" {#endif	/**	 * brief          SHA-256 context setup	 * param ctx      context to be initialized	 * param is224    0 = use SHA256, 1 = use SHA224	 */	void sha2_starts( sha2_context *ctx, int is224 );	/**	 * brief          SHA-256 process buffer	 * param ctx      SHA-256 context	 * param input    buffer holding the  data	 * param ilen     length of the input data	 */	void sha2_update( sha2_context *ctx, unsigned char *input, int ilen );	/**	 * brief          SHA-256 final digest	 * param ctx      SHA-256 context	 * param output   SHA-224/256 checksum result	 */	void sha2_finish( sha2_context *ctx, unsigned char output[32] );#ifdef __cplusplus}#endif#endif /* sha2.h */