/* SPDX-License-Identifier: GPL-2.0 */
/*
 * Common values for the Poly1305 algorithm
 */

#ifndef _CRYPTO_POLY1305_H
#define _CRYPTO_POLY1305_H

#include <linux/types.h>

#define POLY1305_BLOCK_SIZE     16
#define POLY1305_KEY_SIZE       32
#define POLY1305_DIGEST_SIZE    16

/* The poly1305_key and poly1305_state types are mostly opaque and
 * implementation-defined. Limbs might be in base 2^64 or base 2^26, or
 * different yet. The union type provided keeps these 64-bit aligned for the
 * case in which this is implemented using 64x64 multiplies.
 */

struct poly1305_key {
        union {
                u32 r[5];
                u64 r64[3];
        };
};

struct poly1305_core_key {
        struct poly1305_key key;
        struct poly1305_key precomputed_s;
};

struct poly1305_state {
        union {
                u32 h[5];
                u64 h64[3];
        };
};

/* Combined state for block function. */
struct poly1305_block_state {
        /* accumulator */
        struct poly1305_state h;
        /* key */
        union {
                struct poly1305_key opaque_r[CONFIG_CRYPTO_LIB_POLY1305_RSIZE];
                struct poly1305_core_key core_r;
        };
};

struct poly1305_desc_ctx {
        /* partial buffer */
        u8 buf[POLY1305_BLOCK_SIZE];
        /* bytes used in partial buffer */
        unsigned int buflen;
        /* finalize key */
        u32 s[4];
        struct poly1305_block_state state;
};

void poly1305_init(struct poly1305_desc_ctx *desc,
                   const u8 key[at_least POLY1305_KEY_SIZE]);
void poly1305_update(struct poly1305_desc_ctx *desc,
                     const u8 *src, unsigned int nbytes);
void poly1305_final(struct poly1305_desc_ctx *desc, u8 *digest);

#endif