/* sha512.h -- freestanding SHA-512 (FIPS 180-4 / RFC 6234), C99, no libc
 * beyond memcpy/memset (both available in the kernel via
 * src/starkernel/vm/host/shim.c). No __int128 used -- 64-bit words only,
 * portable to amd64/aarch64/riscv64 without libgcc helpers.
 */
#ifndef SHA512_H
#define SHA512_H

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

typedef struct {
    uint64_t state[8];
    uint64_t bitlen;      /* total message length in bits, low 64 bits
                            * (SHA-512 defines a 128-bit length field; a
                            * single uint64_t of bit-length is enough for
                            * any message this kernel will ever hash --
                            * capsules and certs, not exabyte streams) */
    uint8_t  buf[128];
    size_t   buf_len;
} sha512_ctx_t;

void sha512_init(sha512_ctx_t *ctx);
void sha512_update(sha512_ctx_t *ctx, const uint8_t *data, size_t len);
void sha512_final(sha512_ctx_t *ctx, uint8_t out[64]);

/* Convenience one-shot. */
void sha512(const uint8_t *data, size_t len, uint8_t out[64]);

#endif /* SHA512_H */