core-lightning/common/hmac.c

#include <bitcoin/privkey.h>
#include <ccan/array_size/array_size.h>
#include <ccan/mem/mem.h>
#include <common/hmac.h>
#include <wire/wire.h>

void hmac(const void *src, size_t slen,
	  const void *key, size_t klen,
	  struct hmac *hmac)
{
	crypto_auth_hmacsha256_state state;

	crypto_auth_hmacsha256_init(&state, memcheck(key, klen), klen);
	crypto_auth_hmacsha256_update(&state, memcheck(src, slen), slen);
	crypto_auth_hmacsha256_final(&state, hmac->bytes);
}

void subkey_from_hmac(const char *prefix,
		      const struct secret *base,
		      struct secret *key)
{
	struct hmac h;
	hmac(base->data, sizeof(base->data), prefix, strlen(prefix), &h);
	BUILD_ASSERT(sizeof(h.bytes) == sizeof(key->data));
	memcpy(key->data, h.bytes, sizeof(key->data));
}

void towire_hmac(u8 **pptr, const struct hmac *hmac)
{
	towire_u8_array(pptr, hmac->bytes, ARRAY_SIZE(hmac->bytes));
}

void fromwire_hmac(const u8 **ptr, size_t *max, struct hmac *hmac)
{
	fromwire_u8_array(ptr, max, hmac->bytes, ARRAY_SIZE(hmac->bytes));
}