u-boot/lib/mbedtls/sha256.c

// SPDX-License-Identifier: GPL-2.0+
/*
 * Hash shim layer on MbedTLS Crypto library
 *
 * Copyright (c) 2024 Linaro Limited
 * Author: Raymond Mao <raymond.mao@linaro.org>
 */
#ifndef USE_HOSTCC
#include <cyclic.h>
#endif /* USE_HOSTCC */
#include <u-boot/sha256.h>

const u8 sha256_der_prefix[SHA256_DER_LEN] = {
	0x30, 0x31, 0x30, 0x0d, 0x06, 0x09, 0x60, 0x86,
	0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x01, 0x05,
	0x00, 0x04, 0x20
};

void sha256_starts(sha256_context *ctx)
{
	mbedtls_sha256_init(ctx);
	mbedtls_sha256_starts(ctx, 0);
}

void
sha256_update(sha256_context *ctx, const uint8_t *input, uint32_t length)
{
	mbedtls_sha256_update(ctx, input, length);
}

void sha256_finish(sha256_context *ctx, uint8_t digest[SHA256_SUM_LEN])
{
	mbedtls_sha256_finish(ctx, digest);
	mbedtls_sha256_free(ctx);
}

void sha256_csum_wd(const unsigned char *input, unsigned int ilen,
		    unsigned char *output, unsigned int chunk_sz)
{
	sha256_context ctx;

	sha256_starts(&ctx);

	if (IS_ENABLED(CONFIG_HW_WATCHDOG) || IS_ENABLED(CONFIG_WATCHDOG)) {
		const unsigned char *curr = input;
		const unsigned char *end = input + ilen;
		int chunk;

		while (curr < end) {
			chunk = end - curr;
			if (chunk > chunk_sz)
				chunk = chunk_sz;
			sha256_update(&ctx, curr, chunk);
			curr += chunk;
			schedule();
		}
	} else {
		sha256_update(&ctx, input, ilen);
	}

	sha256_finish(&ctx, output);
}