/*
 * Copyright 2019-2021 The OpenSSL Project Authors. All Rights Reserved.
 *
 * Licensed under the Apache License 2.0 (the "License").  You may not use
 * this file except in compliance with the License.  You can obtain a copy
 * in the file LICENSE in the source distribution or at
 * https://www.openssl.org/source/license.html
 */

#include <openssl/aes.h>
#include "prov/ciphercommon.h"
#include "crypto/aes_platform.h"

#define BLOCK_SIZE 16
#define NONCE_SIZE 12
#define TAG_SIZE 16

/* AAD manipulation macros */
#define UP16(x) (((x) + 15) & ~0x0F)
#define DOWN16(x) ((x) & ~0x0F)
#define REMAINDER16(x) ((x) & 0x0F)
#define IS16(x) (((x) & 0x0F) == 0)

typedef struct prov_cipher_hw_aes_gcm_siv_st {
    int (*initkey)(void *vctx);
    int (*cipher)(void *vctx, unsigned char *out, const unsigned char *in,
        size_t len);
    int (*dup_ctx)(void *vdst, void *vsrc);
    void (*clean_ctx)(void *vctx);
} PROV_CIPHER_HW_AES_GCM_SIV;

/* Arranged for alignment purposes */
typedef struct prov_aes_gcm_siv_ctx_st {
    EVP_CIPHER_CTX *ecb_ctx;
    const PROV_CIPHER_HW_AES_GCM_SIV *hw; /* maybe not used, yet? */
    uint8_t *aad; /* Allocated, rounded up to 16 bytes, from user */
    OSSL_LIB_CTX *libctx;
    OSSL_PROVIDER *provctx;
    size_t aad_len; /* actual AAD length */
    size_t key_len;
    uint8_t key_gen_key[32]; /* from user */
    uint8_t msg_enc_key[32]; /* depends on key size */
    uint8_t msg_auth_key[BLOCK_SIZE];
    uint8_t tag[TAG_SIZE]; /* generated tag, given to user or compared to user */
    uint8_t user_tag[TAG_SIZE]; /* from user */
    uint8_t nonce[NONCE_SIZE]; /* from user */
    u128 Htable[16]; /* Polyval calculations via ghash */
    unsigned int enc : 1; /* Set to 1 if we are encrypting or 0 otherwise */
    unsigned int have_user_tag : 1;
    unsigned int generated_tag : 1;
    unsigned int used_enc : 1;
    unsigned int used_dec : 1;
    unsigned int speed : 1;
} PROV_AES_GCM_SIV_CTX;

const PROV_CIPHER_HW_AES_GCM_SIV *ossl_prov_cipher_hw_aes_gcm_siv(size_t keybits);

void ossl_polyval_ghash_init(u128 Htable[16], const uint64_t H[2]);
void ossl_polyval_ghash_hash(const u128 Htable[16], uint8_t *tag, const uint8_t *inp, size_t len);

/* Define GSWAP8/GSWAP4 - used for BOTH little and big endian architectures */
static ossl_inline uint32_t GSWAP4(uint32_t n)
{
    return (((n & 0x000000FF) << 24)
        | ((n & 0x0000FF00) << 8)
        | ((n & 0x00FF0000) >> 8)
        | ((n & 0xFF000000) >> 24));
}
static ossl_inline uint64_t GSWAP8(uint64_t n)
{
    uint64_t result;

    result = GSWAP4(n & 0x0FFFFFFFF);
    result <<= 32;
    return result | GSWAP4(n >> 32);
}