/*  Bluetooth Mesh */

/*
 * Copyright (c) 2017 Intel Corporation
 * Additional Copyright (c) 2018 Espressif Systems (Shanghai) PTE LTD
 *
 * SPDX-License-Identifier: Apache-2.0
 */

#include <string.h>
#include <stdbool.h>
#include <errno.h>

#define BT_DBG_ENABLED IS_ENABLED(CONFIG_BLE_MESH_DEBUG_CRYPTO)

#include "crypto.h"
#include "mesh_aes_encrypt.h"
#include "mesh_bearer_adapt.h"

#define NET_MIC_LEN(pdu) (((pdu)[1] & 0x80) ? 8 : 4)
#define APP_MIC_LEN(aszmic) ((aszmic) ? 8 : 4)

int bt_mesh_aes_cmac(const u8_t key[16], struct bt_mesh_sg *sg,
                     size_t sg_len, u8_t mac[16])
{
    struct tc_aes_key_sched_struct sched = {0};
    struct tc_cmac_struct state = {0};

    if (tc_cmac_setup(&state, key, &sched) == TC_CRYPTO_FAIL) {
        return -EIO;
    }

    for (; sg_len; sg_len--, sg++) {
        if (tc_cmac_update(&state, sg->data,
                           sg->len) == TC_CRYPTO_FAIL) {
            return -EIO;
        }
    }

    if (tc_cmac_final(mac, &state) == TC_CRYPTO_FAIL) {
        return -EIO;
    }

    return 0;
}

int bt_mesh_k1(const u8_t *ikm, size_t ikm_len, const u8_t salt[16],
               const char *info, u8_t okm[16])
{
    int err = 0;

    err = bt_mesh_aes_cmac_one(salt, ikm, ikm_len, okm);
    if (err < 0) {
        return err;
    }

    return bt_mesh_aes_cmac_one(okm, info, strlen(info), okm);
}

int bt_mesh_k2(const u8_t n[16], const u8_t *p, size_t p_len,
               u8_t net_id[1], u8_t enc_key[16], u8_t priv_key[16])
{
    struct bt_mesh_sg sg[3] = {0};
    u8_t salt[16] = {0};
    u8_t out[16] = {0};
    u8_t t[16] = {0};
    u8_t pad = 0U;
    int err = 0;

    BT_DBG("n %s", bt_hex(n, 16));
    BT_DBG("p %s", bt_hex(p, p_len));

    err = bt_mesh_s1("smk2", salt);
    if (err) {
        return err;
    }

    err = bt_mesh_aes_cmac_one(salt, n, 16, t);
    if (err) {
        return err;
    }

    pad = 0x01;

    sg[0].data = NULL;
    sg[0].len  = 0;
    sg[1].data = p;
    sg[1].len  = p_len;
    sg[2].data = &pad;
    sg[2].len  = sizeof(pad);

    err = bt_mesh_aes_cmac(t, sg, ARRAY_SIZE(sg), out);
    if (err) {
        return err;
    }

    net_id[0] = out[15] & 0x7f;

    sg[0].data = out;
    sg[0].len  = sizeof(out);
    pad = 0x02;

    err = bt_mesh_aes_cmac(t, sg, ARRAY_SIZE(sg), out);
    if (err) {
        return err;
    }

    memcpy(enc_key, out, 16);

    pad = 0x03;

    err = bt_mesh_aes_cmac(t, sg, ARRAY_SIZE(sg), out);
    if (err) {
        return err;
    }

    memcpy(priv_key, out, 16);

    BT_DBG("NID 0x%02x enc_key %s", net_id[0], bt_hex(enc_key, 16));
    BT_DBG("priv_key %s", bt_hex(priv_key, 16));

    return 0;
}

int bt_mesh_k3(const u8_t n[16], u8_t out[8])
{
    u8_t id64[] = { 'i', 'd', '6', '4', 0x01 };
    u8_t tmp[16] = {0};
    u8_t t[16] = {0};
    int err = 0;

    err = bt_mesh_s1("smk3", tmp);
    if (err) {
        return err;
    }

    err = bt_mesh_aes_cmac_one(tmp, n, 16, t);
    if (err) {
        return err;
    }

    err = bt_mesh_aes_cmac_one(t, id64, sizeof(id64), tmp);
    if (err) {
        return err;
    }

    memcpy(out, tmp + 8, 8);

    return 0;
}

int bt_mesh_k4(const u8_t n[16], u8_t out[1])
{
    u8_t id6[] = { 'i', 'd', '6', 0x01 };
    u8_t tmp[16] = {0};
    u8_t t[16] = {0};
    int err = 0;

    err = bt_mesh_s1("smk4", tmp);
    if (err) {
        return err;
    }

    err = bt_mesh_aes_cmac_one(tmp, n, 16, t);
    if (err) {
        return err;
    }

    err = bt_mesh_aes_cmac_one(t, id6, sizeof(id6), tmp);
    if (err) {
        return err;
    }

    out[0] = tmp[15] & BIT_MASK(6);

    return 0;
}

int bt_mesh_id128(const u8_t n[16], const char *s, u8_t out[16])
{
    const char *id128 = "id128\x01";
    u8_t salt[16] = {0};
    int err = 0;

    err = bt_mesh_s1(s, salt);
    if (err) {
        return err;
    }

    return bt_mesh_k1(n, 16, salt, id128, out);
}

static int bt_mesh_ccm_decrypt(const u8_t key[16], u8_t nonce[13],
                               const u8_t *enc_msg, size_t msg_len,
                               const u8_t *aad, size_t aad_len,
                               u8_t *out_msg, size_t mic_size)
{
    u8_t msg[16] = {0}, pmsg[16] = {0}, cmic[16] = {0},
         cmsg[16] = {0}, Xn[16] = {0}, mic[16] = {0};
    u16_t last_blk = 0U, blk_cnt = 0U;
    size_t i = 0U, j = 0U;
    int err = 0;

    if (msg_len < 1 || aad_len >= 0xff00) {
        return -EINVAL;
    }

    /* C_mic = e(AppKey, 0x01 || nonce || 0x0000) */
    pmsg[0] = 0x01;
    memcpy(pmsg + 1, nonce, 13);
    sys_put_be16(0x0000, pmsg + 14);

    err = bt_mesh_encrypt_be(key, pmsg, cmic);
    if (err) {
        return err;
    }

    /* X_0 = e(AppKey, 0x09 || nonce || length) */
    if (mic_size == sizeof(u64_t)) {
        pmsg[0] = 0x19 | (aad_len ? 0x40 : 0x00);
    } else {
        pmsg[0] = 0x09 | (aad_len ? 0x40 : 0x00);
    }

    memcpy(pmsg + 1, nonce, 13);
    sys_put_be16(msg_len, pmsg + 14);

    err = bt_mesh_encrypt_be(key, pmsg, Xn);
    if (err) {
        return err;
    }

    /* If AAD is being used to authenticate, include it here */
    if (aad_len) {
        sys_put_be16(aad_len, pmsg);

        for (i = 0; i < sizeof(u16_t); i++) {
            pmsg[i] = Xn[i] ^ pmsg[i];
        }

        j = 0;
        aad_len += sizeof(u16_t);
        while (aad_len > 16) {
            do {
                pmsg[i] = Xn[i] ^ aad[j];
                i++, j++;
            } while (i < 16);

            aad_len -= 16;
            i = 0;

            err = bt_mesh_encrypt_be(key, pmsg, Xn);
            if (err) {
                return err;
            }
        }

        for (; i < aad_len; i++, j++) {
            pmsg[i] = Xn[i] ^ aad[j];
        }

        for (i = aad_len; i < 16; i++) {
            pmsg[i] = Xn[i];
        }

        err = bt_mesh_encrypt_be(key, pmsg, Xn);
        if (err) {
            return err;
        }
    }

    last_blk = msg_len % 16;
    blk_cnt = (msg_len + 15) / 16;
    if (!last_blk) {
        last_blk = 16U;
    }

    for (j = 0; j < blk_cnt; j++) {
        if (j + 1 == blk_cnt) {
            /* C_1 = e(AppKey, 0x01 || nonce || 0x0001) */
            pmsg[0] = 0x01;
            memcpy(pmsg + 1, nonce, 13);
            sys_put_be16(j + 1, pmsg + 14);

            err = bt_mesh_encrypt_be(key, pmsg, cmsg);
            if (err) {
                return err;
            }

            /* Encrypted = Payload[0-15] ^ C_1 */
            for (i = 0; i < last_blk; i++) {
                msg[i] = enc_msg[(j * 16) + i] ^ cmsg[i];
            }

            memcpy(out_msg + (j * 16), msg, last_blk);

            /* X_1 = e(AppKey, X_0 ^ Payload[0-15]) */
            for (i = 0; i < last_blk; i++) {
                pmsg[i] = Xn[i] ^ msg[i];
            }

            for (i = last_blk; i < 16; i++) {
                pmsg[i] = Xn[i] ^ 0x00;
            }

            err = bt_mesh_encrypt_be(key, pmsg, Xn);
            if (err) {
                return err;
            }

            /* MIC = C_mic ^ X_1 */
            for (i = 0; i < sizeof(mic); i++) {
                mic[i] = cmic[i] ^ Xn[i];
            }
        } else {
            /* C_1 = e(AppKey, 0x01 || nonce || 0x0001) */
            pmsg[0] = 0x01;
            memcpy(pmsg + 1, nonce, 13);
            sys_put_be16(j + 1, pmsg + 14);

            err = bt_mesh_encrypt_be(key, pmsg, cmsg);
            if (err) {
                return err;
            }

            /* Encrypted = Payload[0-15] ^ C_1 */
            for (i = 0; i < 16; i++) {
                msg[i] = enc_msg[(j * 16) + i] ^ cmsg[i];
            }

            memcpy(out_msg + (j * 16), msg, 16);

            /* X_1 = e(AppKey, X_0 ^ Payload[0-15]) */
            for (i = 0; i < 16; i++) {
                pmsg[i] = Xn[i] ^ msg[i];
            }

            err = bt_mesh_encrypt_be(key, pmsg, Xn);
            if (err) {
                return err;
            }
        }
    }

    if (memcmp(mic, enc_msg + msg_len, mic_size)) {
        return -EBADMSG;
    }

    return 0;
}

static int bt_mesh_ccm_encrypt(const u8_t key[16], u8_t nonce[13],
                               const u8_t *msg, size_t msg_len,
                               const u8_t *aad, size_t aad_len,
                               u8_t *out_msg, size_t mic_size)
{
    u8_t pmsg[16] = {0}, cmic[16] = {0}, cmsg[16] = {0},
         mic[16] = {0}, Xn[16] = {0};
    u16_t blk_cnt = 0U, last_blk = 0U;
    size_t i = 0U, j = 0U;
    int err = 0;

    BT_DBG("key %s", bt_hex(key, 16));
    BT_DBG("nonce %s", bt_hex(nonce, 13));
    BT_DBG("msg (len %u) %s", msg_len, bt_hex(msg, msg_len));
    BT_DBG("aad_len %u mic_size %u", aad_len, mic_size);

    /* Unsupported AAD size */
    if (aad_len >= 0xff00) {
        return -EINVAL;
    }

    /* C_mic = e(AppKey, 0x01 || nonce || 0x0000) */
    pmsg[0] = 0x01;
    memcpy(pmsg + 1, nonce, 13);
    sys_put_be16(0x0000, pmsg + 14);

    err = bt_mesh_encrypt_be(key, pmsg, cmic);
    if (err) {
        return err;
    }

    /* X_0 = e(AppKey, 0x09 || nonce || length) */
    if (mic_size == sizeof(u64_t)) {
        pmsg[0] = 0x19 | (aad_len ? 0x40 : 0x00);
    } else {
        pmsg[0] = 0x09 | (aad_len ? 0x40 : 0x00);
    }

    memcpy(pmsg + 1, nonce, 13);
    sys_put_be16(msg_len, pmsg + 14);

    err = bt_mesh_encrypt_be(key, pmsg, Xn);
    if (err) {
        return err;
    }

    /* If AAD is being used to authenticate, include it here */
    if (aad_len) {
        sys_put_be16(aad_len, pmsg);

        for (i = 0; i < sizeof(u16_t); i++) {
            pmsg[i] = Xn[i] ^ pmsg[i];
        }

        j = 0;
        aad_len += sizeof(u16_t);
        while (aad_len > 16) {
            do {
                pmsg[i] = Xn[i] ^ aad[j];
                i++, j++;
            } while (i < 16);

            aad_len -= 16;
            i = 0;

            err = bt_mesh_encrypt_be(key, pmsg, Xn);
            if (err) {
                return err;
            }
        }

        for (; i < aad_len; i++, j++) {
            pmsg[i] = Xn[i] ^ aad[j];
        }

        for (i = aad_len; i < 16; i++) {
            pmsg[i] = Xn[i];
        }

        err = bt_mesh_encrypt_be(key, pmsg, Xn);
        if (err) {
            return err;
        }
    }

    last_blk = msg_len % 16;
    blk_cnt = (msg_len + 15) / 16;
    if (!last_blk) {
        last_blk = 16U;
    }

    for (j = 0; j < blk_cnt; j++) {
        if (j + 1 == blk_cnt) {
            /* X_1 = e(AppKey, X_0 ^ Payload[0-15]) */
            for (i = 0; i < last_blk; i++) {
                pmsg[i] = Xn[i] ^ msg[(j * 16) + i];
            }
            for (i = last_blk; i < 16; i++) {
                pmsg[i] = Xn[i] ^ 0x00;
            }

            err = bt_mesh_encrypt_be(key, pmsg, Xn);
            if (err) {
                return err;
            }

            /* MIC = C_mic ^ X_1 */
            for (i = 0; i < sizeof(mic); i++) {
                mic[i] = cmic[i] ^ Xn[i];
            }

            /* C_1 = e(AppKey, 0x01 || nonce || 0x0001) */
            pmsg[0] = 0x01;
            memcpy(pmsg + 1, nonce, 13);
            sys_put_be16(j + 1, pmsg + 14);

            err = bt_mesh_encrypt_be(key, pmsg, cmsg);
            if (err) {
                return err;
            }

            /* Encrypted = Payload[0-15] ^ C_1 */
            for (i = 0; i < last_blk; i++) {
                out_msg[(j * 16) + i] =
                    msg[(j * 16) + i] ^ cmsg[i];
            }
        } else {
            /* X_1 = e(AppKey, X_0 ^ Payload[0-15]) */
            for (i = 0; i < 16; i++) {
                pmsg[i] = Xn[i] ^ msg[(j * 16) + i];
            }

            err = bt_mesh_encrypt_be(key, pmsg, Xn);
            if (err) {
                return err;
            }

            /* C_1 = e(AppKey, 0x01 || nonce || 0x0001) */
            pmsg[0] = 0x01;
            memcpy(pmsg + 1, nonce, 13);
            sys_put_be16(j + 1, pmsg + 14);

            err = bt_mesh_encrypt_be(key, pmsg, cmsg);
            if (err) {
                return err;
            }

            /* Encrypted = Payload[0-15] ^ C_N */
            for (i = 0; i < 16; i++) {
                out_msg[(j * 16) + i] =
                    msg[(j * 16) + i] ^ cmsg[i];
            }

        }
    }

    memcpy(out_msg + msg_len, mic, mic_size);

    return 0;
}

#if defined(CONFIG_BLE_MESH_PROXY)
static void create_proxy_nonce(u8_t nonce[13], const u8_t *pdu,
                               u32_t iv_index)
{
    /* Nonce Type */
    nonce[0] = 0x03;

    /* Pad */
    nonce[1] = 0x00;

    /* Sequence Number */
    nonce[2] = pdu[2];
    nonce[3] = pdu[3];
    nonce[4] = pdu[4];

    /* Source Address */
    nonce[5] = pdu[5];
    nonce[6] = pdu[6];

    /* Pad */
    nonce[7] = 0U;
    nonce[8] = 0U;

    /* IV Index */
    sys_put_be32(iv_index, &nonce[9]);
}
#endif /* PROXY */

static void create_net_nonce(u8_t nonce[13], const u8_t *pdu,
                             u32_t iv_index)
{
    /* Nonce Type */
    nonce[0] = 0x00;

    /* FRND + TTL */
    nonce[1] = pdu[1];

    /* Sequence Number */
    nonce[2] = pdu[2];
    nonce[3] = pdu[3];
    nonce[4] = pdu[4];

    /* Source Address */
    nonce[5] = pdu[5];
    nonce[6] = pdu[6];

    /* Pad */
    nonce[7] = 0U;
    nonce[8] = 0U;

    /* IV Index */
    sys_put_be32(iv_index, &nonce[9]);
}

int bt_mesh_net_obfuscate(u8_t *pdu, u32_t iv_index,
                          const u8_t privacy_key[16])
{
    u8_t priv_rand[16] = { 0x00, 0x00, 0x00, 0x00, 0x00, };
    u8_t tmp[16] = {0};
    int err = 0, i;

    BT_DBG("IVIndex %u, PrivacyKey %s", iv_index, bt_hex(privacy_key, 16));

    sys_put_be32(iv_index, &priv_rand[5]);
    memcpy(&priv_rand[9], &pdu[7], 7);

    BT_DBG("PrivacyRandom %s", bt_hex(priv_rand, 16));

    err = bt_mesh_encrypt_be(privacy_key, priv_rand, tmp);
    if (err) {
        return err;
    }

    for (i = 0; i < 6; i++) {
        pdu[1 + i] ^= tmp[i];
    }

    return 0;
}

int bt_mesh_net_encrypt(const u8_t key[16], struct net_buf_simple *buf,
                        u32_t iv_index, bool proxy)
{
    u8_t mic_len = NET_MIC_LEN(buf->data);
    u8_t nonce[13] = {0};
    int err = 0;

    BT_DBG("IVIndex %u EncKey %s mic_len %u", iv_index, bt_hex(key, 16),
           mic_len);
    BT_DBG("PDU (len %u) %s", buf->len, bt_hex(buf->data, buf->len));

#if defined(CONFIG_BLE_MESH_PROXY)
    if (proxy) {
        create_proxy_nonce(nonce, buf->data, iv_index);
    } else {
        create_net_nonce(nonce, buf->data, iv_index);
    }
#else
    create_net_nonce(nonce, buf->data, iv_index);
#endif

    BT_DBG("Nonce %s", bt_hex(nonce, 13));

    err = bt_mesh_ccm_encrypt(key, nonce, &buf->data[7], buf->len - 7,
                              NULL, 0, &buf->data[7], mic_len);
    if (!err) {
        net_buf_simple_add(buf, mic_len);
    }

    return err;
}

int bt_mesh_net_decrypt(const u8_t key[16], struct net_buf_simple *buf,
                        u32_t iv_index, bool proxy)
{
    u8_t mic_len = NET_MIC_LEN(buf->data);
    u8_t nonce[13] = {0};

    BT_DBG("PDU (%u bytes) %s", buf->len, bt_hex(buf->data, buf->len));
    BT_DBG("iv_index %u, key %s mic_len %u", iv_index, bt_hex(key, 16),
           mic_len);

#if defined(CONFIG_BLE_MESH_PROXY)
    if (proxy) {
        create_proxy_nonce(nonce, buf->data, iv_index);
    } else {
        create_net_nonce(nonce, buf->data, iv_index);
    }
#else
    create_net_nonce(nonce, buf->data, iv_index);
#endif

    BT_DBG("Nonce %s", bt_hex(nonce, 13));

    buf->len -= mic_len;

    return bt_mesh_ccm_decrypt(key, nonce, &buf->data[7], buf->len - 7,
                               NULL, 0, &buf->data[7], mic_len);
}

static void create_app_nonce(u8_t nonce[13], bool dev_key, u8_t aszmic,
                             u16_t src, u16_t dst, u32_t seq_num,
                             u32_t iv_index)
{
    if (dev_key) {
        nonce[0] = 0x02;
    } else {
        nonce[0] = 0x01;
    }

    sys_put_be32((seq_num | ((u32_t)aszmic << 31)), &nonce[1]);

    sys_put_be16(src, &nonce[5]);
    sys_put_be16(dst, &nonce[7]);

    sys_put_be32(iv_index, &nonce[9]);
}

int bt_mesh_app_encrypt(const u8_t key[16], bool dev_key, u8_t aszmic,
                        struct net_buf_simple *buf, const u8_t *ad,
                        u16_t src, u16_t dst, u32_t seq_num, u32_t iv_index)
{
    u8_t nonce[13] = {0};
    int err = 0;

    BT_DBG("AppKey %s", bt_hex(key, 16));
    BT_DBG("dev_key %u src 0x%04x dst 0x%04x", dev_key, src, dst);
    BT_DBG("seq_num 0x%08x iv_index 0x%08x", seq_num, iv_index);
    BT_DBG("Clear: %s", bt_hex(buf->data, buf->len));

    create_app_nonce(nonce, dev_key, aszmic, src, dst, seq_num, iv_index);

    BT_DBG("Nonce  %s", bt_hex(nonce, 13));

    err = bt_mesh_ccm_encrypt(key, nonce, buf->data, buf->len, ad,
                              ad ? 16 : 0, buf->data, APP_MIC_LEN(aszmic));
    if (!err) {
        net_buf_simple_add(buf, APP_MIC_LEN(aszmic));
        BT_DBG("Encr: %s", bt_hex(buf->data, buf->len));
    }

    return err;
}

int bt_mesh_app_decrypt(const u8_t key[16], bool dev_key, u8_t aszmic,
                        struct net_buf_simple *buf, struct net_buf_simple *out,
                        const u8_t *ad, u16_t src, u16_t dst, u32_t seq_num,
                        u32_t iv_index)
{
    u8_t nonce[13] = {0};
    int err = 0;

    BT_DBG("EncData (len %u) %s", buf->len, bt_hex(buf->data, buf->len));

    create_app_nonce(nonce, dev_key, aszmic, src, dst, seq_num, iv_index);

    BT_DBG("AppKey %s", bt_hex(key, 16));
    BT_DBG("Nonce  %s", bt_hex(nonce, 13));

    err = bt_mesh_ccm_decrypt(key, nonce, buf->data, buf->len, ad,
                              ad ? 16 : 0, out->data, APP_MIC_LEN(aszmic));
    if (!err) {
        net_buf_simple_add(out, buf->len);
    }

    return err;
}

/* reversed, 8-bit, poly=0x07 */
static const u8_t crc_table[256] = {
    0x00, 0x91, 0xe3, 0x72, 0x07, 0x96, 0xe4, 0x75,
    0x0e, 0x9f, 0xed, 0x7c, 0x09, 0x98, 0xea, 0x7b,
    0x1c, 0x8d, 0xff, 0x6e, 0x1b, 0x8a, 0xf8, 0x69,
    0x12, 0x83, 0xf1, 0x60, 0x15, 0x84, 0xf6, 0x67,

    0x38, 0xa9, 0xdb, 0x4a, 0x3f, 0xae, 0xdc, 0x4d,
    0x36, 0xa7, 0xd5, 0x44, 0x31, 0xa0, 0xd2, 0x43,
    0x24, 0xb5, 0xc7, 0x56, 0x23, 0xb2, 0xc0, 0x51,
    0x2a, 0xbb, 0xc9, 0x58, 0x2d, 0xbc, 0xce, 0x5f,

    0x70, 0xe1, 0x93, 0x02, 0x77, 0xe6, 0x94, 0x05,
    0x7e, 0xef, 0x9d, 0x0c, 0x79, 0xe8, 0x9a, 0x0b,
    0x6c, 0xfd, 0x8f, 0x1e, 0x6b, 0xfa, 0x88, 0x19,
    0x62, 0xf3, 0x81, 0x10, 0x65, 0xf4, 0x86, 0x17,

    0x48, 0xd9, 0xab, 0x3a, 0x4f, 0xde, 0xac, 0x3d,
    0x46, 0xd7, 0xa5, 0x34, 0x41, 0xd0, 0xa2, 0x33,
    0x54, 0xc5, 0xb7, 0x26, 0x53, 0xc2, 0xb0, 0x21,
    0x5a, 0xcb, 0xb9, 0x28, 0x5d, 0xcc, 0xbe, 0x2f,

    0xe0, 0x71, 0x03, 0x92, 0xe7, 0x76, 0x04, 0x95,
    0xee, 0x7f, 0x0d, 0x9c, 0xe9, 0x78, 0x0a, 0x9b,
    0xfc, 0x6d, 0x1f, 0x8e, 0xfb, 0x6a, 0x18, 0x89,
    0xf2, 0x63, 0x11, 0x80, 0xf5, 0x64, 0x16, 0x87,

    0xd8, 0x49, 0x3b, 0xaa, 0xdf, 0x4e, 0x3c, 0xad,
    0xd6, 0x47, 0x35, 0xa4, 0xd1, 0x40, 0x32, 0xa3,
    0xc4, 0x55, 0x27, 0xb6, 0xc3, 0x52, 0x20, 0xb1,
    0xca, 0x5b, 0x29, 0xb8, 0xcd, 0x5c, 0x2e, 0xbf,

    0x90, 0x01, 0x73, 0xe2, 0x97, 0x06, 0x74, 0xe5,
    0x9e, 0x0f, 0x7d, 0xec, 0x99, 0x08, 0x7a, 0xeb,
    0x8c, 0x1d, 0x6f, 0xfe, 0x8b, 0x1a, 0x68, 0xf9,
    0x82, 0x13, 0x61, 0xf0, 0x85, 0x14, 0x66, 0xf7,

    0xa8, 0x39, 0x4b, 0xda, 0xaf, 0x3e, 0x4c, 0xdd,
    0xa6, 0x37, 0x45, 0xd4, 0xa1, 0x30, 0x42, 0xd3,
    0xb4, 0x25, 0x57, 0xc6, 0xb3, 0x22, 0x50, 0xc1,
    0xba, 0x2b, 0x59, 0xc8, 0xbd, 0x2c, 0x5e, 0xcf
};

u8_t bt_mesh_fcs_calc(const u8_t *data, u8_t data_len)
{
    u8_t fcs = 0xff;

    while (data_len--) {
        fcs = crc_table[fcs ^ *data++];
    }

    BT_DBG("fcs 0x%02x", 0xff - fcs);

    return 0xff - fcs;
}

bool bt_mesh_fcs_check(struct net_buf_simple *buf, u8_t received_fcs)
{
    const u8_t *data = buf->data;
    u16_t data_len = buf->len;
    u8_t fcs = 0xff;

    while (data_len--) {
        fcs = crc_table[fcs ^ *data++];
    }

    return crc_table[fcs ^ received_fcs] == 0xcf;
}

int bt_mesh_virtual_addr(const u8_t virtual_label[16], u16_t *addr)
{
    u8_t salt[16] = {0};
    u8_t tmp[16] = {0};
    int err = 0;

    err = bt_mesh_s1("vtad", salt);
    if (err) {
        return err;
    }

    err = bt_mesh_aes_cmac_one(salt, virtual_label, 16, tmp);
    if (err) {
        return err;
    }

    *addr = (sys_get_be16(&tmp[14]) & 0x3fff) | 0x8000;

    return 0;
}

int bt_mesh_prov_conf_salt(const u8_t conf_inputs[145], u8_t salt[16])
{
    const u8_t conf_salt_key[16] = { 0 };

    return bt_mesh_aes_cmac_one(conf_salt_key, conf_inputs, 145, salt);
}

int bt_mesh_prov_conf_key(const u8_t dhkey[32], const u8_t conf_salt[16],
                          u8_t conf_key[16])
{
    return bt_mesh_k1(dhkey, 32, conf_salt, "prck", conf_key);
}

int bt_mesh_prov_conf(const u8_t conf_key[16], const u8_t rand[16],
                      const u8_t auth[16], u8_t conf[16])
{
    struct bt_mesh_sg sg[] = { { rand, 16 }, { auth, 16 } };

    BT_DBG("ConfirmationKey %s", bt_hex(conf_key, 16));
    BT_DBG("RandomDevice %s", bt_hex(rand, 16));
    BT_DBG("AuthValue %s", bt_hex(auth, 16));

    return bt_mesh_aes_cmac(conf_key, sg, ARRAY_SIZE(sg), conf);
}

int bt_mesh_prov_decrypt(const u8_t key[16], u8_t nonce[13],
                         const u8_t data[25 + 8], u8_t out[25])
{
    return bt_mesh_ccm_decrypt(key, nonce, data, 25, NULL, 0, out, 8);
}

#if CONFIG_BLE_MESH_PROVISIONER
int bt_mesh_prov_encrypt(const u8_t key[16], u8_t nonce[13],
                         const u8_t data[25], u8_t out[33])
{
    return bt_mesh_ccm_encrypt(key, nonce, data, 25, NULL, 0, out, 8);
}
#endif

int bt_mesh_beacon_auth(const u8_t beacon_key[16], u8_t flags,
                        const u8_t net_id[8], u32_t iv_index,
                        u8_t auth[8])
{
    u8_t msg[13] = {0}, tmp[16] = {0};
    int err = 0;

    BT_DBG("BeaconKey %s", bt_hex(beacon_key, 16));
    BT_DBG("NetId %s", bt_hex(net_id, 8));
    BT_DBG("IV Index 0x%08x", iv_index);

    msg[0] = flags;
    memcpy(&msg[1], net_id, 8);
    sys_put_be32(iv_index, &msg[9]);

    BT_DBG("BeaconMsg %s", bt_hex(msg, sizeof(msg)));

    err = bt_mesh_aes_cmac_one(beacon_key, msg, sizeof(msg), tmp);
    if (!err) {
        memcpy(auth, tmp, 8);
    }

    return err;
}