#ifndef _CRYPTO_GCM_H
#define _CRYPTO_GCM_H

#include <linux/errno.h>

#include <crypto/aes.h>
#include <crypto/gf128mul.h>

#define GCM_AES_IV_SIZE 12
#define GCM_RFC4106_IV_SIZE 8
#define GCM_RFC4543_IV_SIZE 8

/*
 * validate authentication tag for GCM
 */
static inline int crypto_gcm_check_authsize(unsigned int authsize)
{
    switch (authsize) {
    case 4:
    case 8:
    case 12:
    case 13:
    case 14:
    case 15:
    case 16:
        break;
    default:
        return -EINVAL;
    }

    return 0;
}

/*
 * validate authentication tag for RFC4106
 */
static inline int crypto_rfc4106_check_authsize(unsigned int authsize)
{
    switch (authsize) {
    case 8:
    case 12:
    case 16:
        break;
    default:
        return -EINVAL;
    }

    return 0;
}

/*
 * validate assoclen for RFC4106/RFC4543
 */
static inline int crypto_ipsec_check_assoclen(unsigned int assoclen)
{
    switch (assoclen) {
    case 16:
    case 20:
        break;
    default:
        return -EINVAL;
    }

    return 0;
}

struct aesgcm_ctx {
    be128            ghash_key;
    struct crypto_aes_ctx    aes_ctx;
    unsigned int        authsize;
};

int aesgcm_expandkey(struct aesgcm_ctx *ctx, const u8 *key,
             unsigned int keysize, unsigned int authsize);

void aesgcm_encrypt(const struct aesgcm_ctx *ctx, u8 *dst, const u8 *src,
            int crypt_len, const u8 *assoc, int assoc_len,
            const u8 iv[GCM_AES_IV_SIZE], u8 *authtag);

bool __must_check aesgcm_decrypt(const struct aesgcm_ctx *ctx, u8 *dst,
                 const u8 *src, int crypt_len, const u8 *assoc,
                 int assoc_len, const u8 iv[GCM_AES_IV_SIZE],
                 const u8 *authtag);

#endif