grisp_cryptoauth

#define STATIC_ERLANG_NIF 1

#include <cryptoauthlib/atca_basic.h>

#include <erl_nif.h>
#include <fcntl.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/ioctl.h>
#include <unistd.h>


/*
 * Device Configuration, shamelessly stolen from Microchip's ATECC608B-TFLXTLSS. This configuration
 * is supposed to support all our envisioned usecases based on the TrustFLEX configuration, in
 * particular a custom Public Key Infrastructure (PKI) is supported.
 *
 * There are way more supported usecases, you can checkout the Trust Platform for explanations.
 * In the following the supposed usage and purpose of each slot is explained: 
 *
 *
 * Slot 0   Primary private key; Primary authentication key; Permanent, Ext Sign, ECDH
 * Slot 1   Internal sign private key; Private key that can only be used to attest internal keys and
 *          state of the a device; Can't be used to sign arbitrary messages; Permanent, Int Sign
 * Slot 2   Secondary private key 1; Secondary private key for other uses; Updatable, Ext Sign, ECDH, Lockable
 * Slot 3   Secondary private key 2; Secondary private key for other uses; Updatable, Ext Sign, ECDH, Lockable
 * Slot 4   Secondary private key 3; Secondary private key for other uses; Updatable, Ext Sign, ECDH, Lockable
 * Slot 5   Secret key; Storage for a secret key; No Read, Encrypted write(6), Lockable, AES key
 * Slot 6   IO protection key; Key used to protect the I2C bus communication (IO) of certain commands;
 *          Requires setup before use; No read, Clear write, Lockable
 * Slot 7   Secure boot digest; Storage location for secureboot digest; This is an internal function, so no
 *          reads or writes are enabled; No read, No write
 * Slot 8   General data; General public data storage (416 bytes); Clear read, Always write, Lockable
 * Slot 9   AES key; Intermediate key storage for ECDH and KDF output; No read, Always write, AES key
 * Slot 10  Device compressed certificate; Certificate primary public key in the Crypto Authentication
 *          compressed format; Clear read, No write or writable depending on access policies set.
 * Slot 11  Signer public key; Public key for the CA (signer) that signed the device cert; Clear read, No write
 *          or writable depending on access policies set.
 * Slot 12  Signer compressed certificate; Certificate for the CA (signer) certificate for the device
 *          certificate in the CryptoAuthentication compressed format; Clear read, No write or writable
 *          depending on access policies set.
 * Slot 13  Parent public key or general data; Parent public key for validating/invalidating the validated
 *          public key; Can also be used just as a public key or general data storage (72 bytes);
 *          Clear read, Always write, Lockable
 * Slot 14  Validated public key; Validated public key cannot be used (Verify command) or changed without
 *          authorization via the parent public key; Clear read, Always write, Validated (13)
 * Slot 15  Secure boot public key; Secure boot public key; Clear read, Always write, Lockable
 *
 * Check out e.g. https://www.microchip.com/en-us/product/ATECC608B-TFLXTLS for a complete data sheet.
 *
 * The following configuration can be written at the very beginning of the provisioning process onto an
 * unconfigured device. Don't touch this without informing yourself, be very careful. Note that Slot
 * 10-12 are configured to be writable and lockable, so certificates can be customized after config and
 * data are locked.
 */
static const uint8_t grisp_device_default_config[] = {
    0x01, 0x23, 0x00, 0x00, 0x00, 0x00, 0x60, 0x01,  // 0   - 7      ignored on write (dummy data)
    0x00, 0x00, 0x00, 0x00, 0xEE, 0x01, 0x01, 0x00,  // 8   - 15     ignored on write (dummy data)
    0x6C, 0x00, 0x00, 0x01,                          // 16  - 19     16: I2C address; 19: ChipMode
    // Start of Slot configuration, two bytes per slot
    0x85, 0x00, 0x82, 0x00, 0x85, 0x20, 0x85, 0x20,  // 20  - 27     Slots 0  - 3
    0x85, 0x20, 0x8F, 0x46, 0x8F, 0x0F, 0x9F, 0x8F,  // 28  - 35     Slots 4  - 7
    0x0F, 0x0F, 0x8F, 0x0F, 0x0F, 0x0F, 0x0F, 0x0F,  // 36  - 43     Slots 8  - 11
    0x0F, 0x0F, 0x0F, 0x0F, 0x0D, 0x1F, 0x0F, 0x0F,  // 44  - 51     Slots 12 - 15
    // End of Slot configuration, next comes more general stuff
    0xFF, 0xFF, 0xFF, 0xFF, 0x00, 0x00, 0x00, 0x00,  // 52  - 59     Monotonic Counter connected to keys
    0xFF, 0xFF, 0xFF, 0xFF, 0x00, 0x00, 0x00, 0x00,  // 60  - 67     Monotonic Counter (not connected to keys)
    0x00, 0x00, 0x03, 0xF7, 0x00, 0x69, 0x76, 0x00,  // 68  - 75     UseLock, VolatileKey, SecureBoot, KDF
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,  // 76  - 83     unknown
    0x00, 0x00, 0x00, 0x00, 0xFF, 0xFF, 0x0E, 0x60,  // 84  - 91     85: UserExtraAdd; Lock Bytes
    0x00, 0x00, 0x00, 0x00,                          // 92  - 95     X.509 certificate formatting
    // Slot Key configuration, two bytes per slot
    0x53, 0x00, 0x53, 0x00, 0x73, 0x00, 0x73, 0x00,  // 96  - 103    Slots 0  - 3
    0x73, 0x00, 0x38, 0x00, 0x7C, 0x00, 0x1C, 0x00,  // 104 - 111    Slots 4  - 7
    0x3C, 0x00, 0x1A, 0x00, 0x3C, 0x00, 0x30, 0x00,  // 112 - 119    Slots 8  - 11
    0x3C, 0x00, 0x30, 0x00, 0x12, 0x00, 0x30, 0x00,  // 120 - 127    Slots 12 - 15
};


#define CONFIG_DEVICE_TYPE_KEY "type"
#define CONFIG_I2C_BUS_KEY "i2c_bus"
#define CONFIG_I2C_ADDRESS_KEY "i2c_address"

/* Helpers, don't use these directly */
#define EXEC_CA_FUN_STATUS(STATUS, fun, args...) { \
    ATCA_STATUS STATUS = fun(args); \
    if (STATUS != ATCA_SUCCESS) \
        return MK_ERROR_STATUS(env, #fun, STATUS); \
    }
#define UNIQ_CA_STATUS __func__##__LINE__##_status

/* Execute atcab_* functions */
#define EXEC_CA_FUN(fun, args...) EXEC_CA_FUN_STATUS(UNIQ_CA_STATUS, fun, args)

/* Init device context */
#define INIT_DEVICE \
    struct device_context_t *DEVICE_CONTEXT; \
    if(!enif_get_resource(env, argv[0], device_resource_type, (void**) &DEVICE_CONTEXT)){ \
	    return enif_make_badarg(env); \
    } \
    ATCADevice DEVICE = DEVICE_CONTEXT->device; \

/* Return value macros */
#define MK_OK(env) mk_atom(env, "ok")
#define MK_ERROR(env, msg) enif_make_tuple2(env, mk_atom(env, "error"), mk_atom(env, msg))
#define MK_ERROR_STATUS(env, msg, status) enif_make_tuple3(env, mk_atom(env, "error"), mk_atom(env, msg), enif_make_int(env, status))
#define MK_SUCCESS(env, term) enif_make_tuple2(env, mk_atom(env, "ok"), term)
#define MK_SUCCESS_ATOM(env, msg) enif_make_tuple2(env, mk_atom(env, "ok"), mk_atom(env, msg))

#define BINARY_FROM_RAW(env, bin_term, raw, size) memcpy(enif_make_new_binary(env, size, &bin_term), raw, size)


static ATCAIfaceCfg grisp_atcab_default_config = {
    .iface_type                 = ATCA_I2C_IFACE,
    .devtype                    = ATECC608,
    {
        /*
         * ATECC608B-TFLXTLSS default address;
         * unconfigured chips usually have 0xCO
         */
        .atcai2c.address        = 0x6C,
        .atcai2c.bus            = 0,
        .atcai2c.baud           = 100000,
    },
    .wake_delay                 = 1500,
    .rx_retries                 = 20
};


ErlNifResourceType *device_resource_type;

struct device_context_t {
    ATCAIfaceCfg config;
    ATCADevice device;
};


struct device_type_nif {
    ATCADeviceType type;
    const char *name;
};


static ERL_NIF_TERM mk_atom(ErlNifEnv* env, const char* atom)
{
    ERL_NIF_TERM ret;

    if (!enif_make_existing_atom(env, atom, &ret, ERL_NIF_LATIN1))
        return enif_make_atom(env, atom);

    return ret;
}


static void build_atcab_config(ErlNifEnv* env, ATCAIfaceCfg *atcab_config, ERL_NIF_TERM config_map)
{
    int i2c_bus, i2c_address;
    bool device_type_present, i2c_bus_present, i2c_address_present;
    ERL_NIF_TERM device_type_value, i2c_bus_value, i2c_address_value;

    ERL_NIF_TERM device_type_key = mk_atom(env, CONFIG_DEVICE_TYPE_KEY);
    ERL_NIF_TERM i2c_bus_key = mk_atom(env, CONFIG_I2C_BUS_KEY);
    ERL_NIF_TERM i2c_address_key = mk_atom(env, CONFIG_I2C_ADDRESS_KEY);

    device_type_present = enif_get_map_value(env, config_map, device_type_key, &device_type_value);
    i2c_bus_present = enif_get_map_value(env, config_map, i2c_bus_key, &i2c_bus_value);
    i2c_address_present = enif_get_map_value(env, config_map, i2c_address_key, &i2c_address_value);

    if (i2c_bus_present) {
        enif_get_int(env, i2c_bus_value, &i2c_bus);
        atcab_config->atcai2c.bus = (uint16_t) i2c_bus;
    }
    if (i2c_address_present) {
        enif_get_int(env, i2c_address_value, &i2c_address);
        atcab_config->atcai2c.address = (uint16_t) i2c_address;
    }
    if (device_type_present) {
        if (enif_compare(mk_atom(env, "ATECC508A"), device_type_value))
            atcab_config->devtype = ATECC508A;
        if (enif_compare(mk_atom(env, "ATECC608A"), device_type_value))
            atcab_config->devtype = ATECC608A;
        if (enif_compare(mk_atom(env, "ATECC608B"), device_type_value))
            atcab_config->devtype = ATECC608B;
        if (enif_compare(mk_atom(env, "ATECC608"), device_type_value))
            atcab_config->devtype = ATECC608;
    }
}


int load_ca_drv(ErlNifEnv* env, void** priv_data, ERL_NIF_TERM load_info)
{
    /*
     * TODO: Destructor missing
     * https://github.com/MicrochipTech/cryptoauthlib/issues/240
     * --> wait for release 3.3.3
     */
    device_resource_type =
        enif_open_resource_type(env, NULL, "device_resource",
                                NULL, ERL_NIF_RT_CREATE, NULL);

    return 0;
}


static ERL_NIF_TERM init_device_nif(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
{
    struct device_context_t *device_context;
    ERL_NIF_TERM device_context_term;

    device_context = enif_alloc_resource(device_resource_type, sizeof(struct device_context_t));

    device_context->device = NULL;
    device_context->config = grisp_atcab_default_config;

    build_atcab_config(env, &device_context->config, argv[0]);

    EXEC_CA_FUN(atcab_init_ext, &device_context->device, &device_context->config);

    device_context_term = enif_make_resource(env, device_context);
    enif_release_resource(device_context);

    return MK_SUCCESS(env, device_context_term);
}


static ERL_NIF_TERM sleep_device_nif(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
{
    INIT_DEVICE;

    EXEC_CA_FUN(calib_sleep, DEVICE);

    return MK_OK(env);
}


static ERL_NIF_TERM device_info_nif(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
{
    INIT_DEVICE;

    ATCADeviceType dt = atcab_get_device_type_ext(DEVICE);

    if (dt == ATECC508A)
        return MK_SUCCESS_ATOM(env, "ATECC508A");

    if (dt == ATECC608)
        return MK_SUCCESS_ATOM(env, "ATECC608");

    return MK_ERROR(env, "unknown_device");
}


static ERL_NIF_TERM config_locked_nif(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
{
    INIT_DEVICE;

    bool is_locked = false;
    EXEC_CA_FUN(calib_is_locked, DEVICE, LOCK_ZONE_CONFIG, &is_locked);

    return MK_SUCCESS_ATOM(env, is_locked ? "true" : "false");
}


static ERL_NIF_TERM data_locked_nif(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
{
    INIT_DEVICE;

    bool is_locked = false;
    EXEC_CA_FUN(calib_is_locked, DEVICE, LOCK_ZONE_DATA, &is_locked);

    return MK_SUCCESS_ATOM(env, is_locked ? "true" : "false");
}


static ERL_NIF_TERM slot_locked_nif(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
{
    INIT_DEVICE;

    int slot_idx;
    bool is_locked = false;

    if (!enif_get_int(env, argv[1], &slot_idx))
	    return enif_make_badarg(env);

    EXEC_CA_FUN(calib_is_slot_locked, DEVICE, (uint16_t) slot_idx, &is_locked);

    return MK_SUCCESS_ATOM(env, is_locked ? "true" : "false");
}


static ERL_NIF_TERM serial_number_nif(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
{
    INIT_DEVICE;

    uint8_t sn[9];
    EXEC_CA_FUN(calib_read_serial_number, DEVICE, sn);

    ERL_NIF_TERM bin_sn;
    BINARY_FROM_RAW(env, bin_sn, sn, 9);

    return MK_SUCCESS(env, bin_sn);
}

static ERL_NIF_TERM read_config_nif(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
{
    INIT_DEVICE;

    uint8_t config_zone[ATCA_ECC_CONFIG_SIZE];
    EXEC_CA_FUN(calib_read_config_zone, DEVICE, config_zone);

    ERL_NIF_TERM bin_config_zone;
    BINARY_FROM_RAW(env, bin_config_zone, config_zone, ATCA_ECC_CONFIG_SIZE);

    return MK_SUCCESS(env, bin_config_zone);
}


static ERL_NIF_TERM write_config_nif(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
{
    INIT_DEVICE;

    EXEC_CA_FUN(calib_write_config_zone, DEVICE, grisp_device_default_config);

    return MK_OK(env);
}


static ERL_NIF_TERM lock_config_nif(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
{
    INIT_DEVICE;

    EXEC_CA_FUN(calib_lock_config_zone, DEVICE);

    return MK_OK(env);
}


static ERL_NIF_TERM lock_data_nif(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
{
    INIT_DEVICE;

    EXEC_CA_FUN(calib_lock_data_zone, DEVICE);

    return MK_OK(env);
}


static ERL_NIF_TERM lock_slot_nif(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
{
    INIT_DEVICE;

    int slot_idx;

    if (!enif_get_int(env, argv[1], &slot_idx))
	    return enif_make_badarg(env);

    EXEC_CA_FUN(calib_lock_data_slot, DEVICE, (uint16_t) slot_idx);

    return MK_OK(env);
}


static ERL_NIF_TERM gen_private_key_nif(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
{
    INIT_DEVICE;

    int slot_idx;

    if (!enif_get_int(env, argv[1], &slot_idx))
	    return enif_make_badarg(env);

    uint8_t pubkey[ATCA_ECCP256_PUBKEY_SIZE];
    EXEC_CA_FUN(calib_genkey, DEVICE, (uint16_t) slot_idx, pubkey);

    ERL_NIF_TERM bin_pubkey;
    BINARY_FROM_RAW(env, bin_pubkey, pubkey, ATCA_ECCP256_PUBKEY_SIZE);

    return MK_SUCCESS(env, bin_pubkey);
}


static ERL_NIF_TERM gen_public_key_nif(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
{
    INIT_DEVICE;

    int slot_idx;

    if (!enif_get_int(env, argv[1], &slot_idx))
	    return enif_make_badarg(env);

    uint8_t pubkey[ATCA_ECCP256_PUBKEY_SIZE];
    EXEC_CA_FUN(atcab_get_pubkey_ext, DEVICE, (uint16_t) slot_idx, pubkey);

    ERL_NIF_TERM bin_pubkey;
    BINARY_FROM_RAW(env, bin_pubkey, pubkey, ATCA_ECCP256_PUBKEY_SIZE);

    return MK_SUCCESS(env, bin_pubkey);
}


static ERL_NIF_TERM sign_nif(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
{
    INIT_DEVICE;

    int slot_idx;
    ErlNifBinary bin_msg;

    if (!enif_get_int(env, argv[1], &slot_idx))
	    return enif_make_badarg(env);

    if (!enif_inspect_binary(env, argv[2], &bin_msg) || (bin_msg.size != ATCA_SHA256_DIGEST_SIZE))
        return enif_make_badarg(env);

    uint8_t sig[ATCA_ECCP256_SIG_SIZE];
    EXEC_CA_FUN(atcab_sign_ext, DEVICE, (uint16_t) slot_idx, (uint8_t *) bin_msg.data, sig);

    ERL_NIF_TERM bin_sig;
    BINARY_FROM_RAW(env, bin_sig, sig, ATCA_ECCP256_SIG_SIZE);

    return MK_SUCCESS(env, bin_sig);
}


static ERL_NIF_TERM verify_extern_nif(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
{
    INIT_DEVICE;

    ErlNifBinary bin_pubkey;
    ErlNifBinary bin_msg;
    ErlNifBinary bin_sig;

    if (!enif_inspect_binary(env, argv[1], &bin_pubkey) || (bin_pubkey.size != ATCA_ECCP256_PUBKEY_SIZE))
        return enif_make_badarg(env);

    if (!enif_inspect_binary(env, argv[2], &bin_msg) || (bin_msg.size != ATCA_SHA256_DIGEST_SIZE))
        return enif_make_badarg(env);

    if (!enif_inspect_binary(env, argv[3], &bin_sig) || (bin_sig.size != ATCA_ECCP256_SIG_SIZE))
        return enif_make_badarg(env);

    bool is_verified;
    EXEC_CA_FUN(atcab_verify_extern_ext, DEVICE, (uint8_t *) bin_msg.data,
                (uint8_t *) bin_sig.data, (uint8_t *) bin_pubkey.data, &is_verified);

    return MK_SUCCESS_ATOM(env, is_verified ? "true" : "false");
}


static ERL_NIF_TERM verify_stored_nif(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
{
    INIT_DEVICE;

    int slot_idx;
    ErlNifBinary bin_msg;
    ErlNifBinary bin_sig;

    if (!enif_get_int(env, argv[1], &slot_idx))
	    return enif_make_badarg(env);

    if (!enif_inspect_binary(env, argv[2], &bin_msg) || (bin_msg.size != ATCA_SHA256_DIGEST_SIZE))
        return enif_make_badarg(env);

    if (!enif_inspect_binary(env, argv[3], &bin_sig) || (bin_msg.size != ATCA_ECCP256_SIG_SIZE))
        return enif_make_badarg(env);

    bool is_verified;
    EXEC_CA_FUN(atcab_verify_stored_ext, DEVICE, (uint8_t *) bin_msg.data,
                (uint8_t *) bin_sig.data, (uint16_t) slot_idx, &is_verified);

    return MK_SUCCESS_ATOM(env, is_verified ? "true" : "false");
}


static ERL_NIF_TERM write_comp_cert_nif(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
{
    INIT_DEVICE;

    int slot_idx;
    ErlNifBinary bin_cert;

    if (!enif_get_int(env, argv[1], &slot_idx))
	    return enif_make_badarg(env);

    if (!enif_inspect_binary(env, argv[2], &bin_cert) || bin_cert.size != 72)
        return enif_make_badarg(env);

    EXEC_CA_FUN(calib_write_bytes_zone, DEVICE, ATCA_ZONE_DATA, (uint16_t) slot_idx, 0,
                (uint8_t *) bin_cert.data, bin_cert.size);

    return MK_OK(env);
}


static ERL_NIF_TERM read_comp_cert_nif(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
{
    INIT_DEVICE;

    int slot_idx;

    if (!enif_get_int(env, argv[1], &slot_idx))
	    return enif_make_badarg(env);

    uint8_t comp_cert[72];
    EXEC_CA_FUN(calib_read_bytes_zone, DEVICE, ATCA_ZONE_DATA, (uint16_t) slot_idx, 0,
                (uint8_t *) comp_cert, 72);

    ERL_NIF_TERM bin_comp_cert;
    BINARY_FROM_RAW(env, bin_comp_cert, comp_cert, 72);

    return MK_SUCCESS(env, bin_comp_cert);
}


static ERL_NIF_TERM gen_random_bytes_nif(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
{
    INIT_DEVICE;

    uint8_t random_bytes[32];
    EXEC_CA_FUN(atcab_random_ext, DEVICE, (uint8_t *) &random_bytes);

    ERL_NIF_TERM bin_random_bytes;
    BINARY_FROM_RAW(env, bin_random_bytes, random_bytes, 32);

    return MK_SUCCESS(env, bin_random_bytes);
}


static ErlNifFunc nif_funcs[] = {
    {"init_device",         1, init_device_nif},
    {"sleep_device",        1, sleep_device_nif},
    {"device_info",         1, device_info_nif},
    {"config_locked",       1, config_locked_nif},
    {"data_locked",         1, data_locked_nif},
    {"slot_locked",         2, slot_locked_nif},
    {"serial_number",       1, serial_number_nif},
    {"read_config",         1, read_config_nif},
    {"write_config",        1, write_config_nif},
    {"lock_config",         1, lock_config_nif},
    {"lock_data",           1, lock_data_nif},
    {"lock_slot",           2, lock_slot_nif},
    {"gen_private_key",     2, gen_private_key_nif},
    {"gen_public_key",      2, gen_public_key_nif},
    {"sign",                3, sign_nif},
    {"verify_extern",       4, verify_extern_nif},
    {"verify_stored",       4, verify_stored_nif},
    {"write_comp_cert",     3, write_comp_cert_nif},
    {"read_comp_cert",      2, read_comp_cert_nif},
    {"gen_random_bytes",    1, gen_random_bytes_nif},
};

ERL_NIF_INIT(grisp_cryptoauth_drv, nif_funcs, &load_ca_drv, NULL, NULL, NULL);