fw_sha256.h File Reference

SHA-256 (Secure Hash Algorithm, 256 bit), FIPS 180-4, in portable C. More...

#include <stddef.h>
#include <stdint.h>

Go to the source code of this file.

Data Structures
struct	fw_sha256_t

Macros
#define	FW_SHA256_BYTES   32u

Functions
void	fw_sha256_init (fw_sha256_t *s)
void	fw_sha256_add (fw_sha256_t *s, const void *data, size_t n)
void	fw_sha256_done (fw_sha256_t *s, uint8_t out[FW_SHA256_BYTES])
void	fw_sha256 (const void *data, size_t n, uint8_t out[FW_SHA256_BYTES])

Detailed Description

SHA-256 (Secure Hash Algorithm, 256 bit), FIPS 180-4, in portable C.

The panel's application image carries the SHA-256 of everything before it in its last 32 bytes; the update checks it before the first erase. Written here rather than taken from mbedTLS so the check is the same code on the host and on the panel, and the host suite can feed it the cases a card produces. Speed is not the point: a 1.2MB image is hashed once per update.

Pure C, no ESP-IDF (Espressif Internet-of-Things Development Framework).

SPDX-License-Identifier: MIT

Function Documentation

fw_sha256()

void fw_sha256	(	const void *	data,
		size_t	n,
		uint8_t	out[FW_SHA256_BYTES] )

The digest of n bytes at data in one call.