/*

 * Copyright (c) 2019-2021 Yubico AB. All rights reserved.

 * Use of this source code is governed by a BSD-style

 * license that can be found in the LICENSE file.

 * SPDX-License-Identifier: BSD-2-Clause

 */

#include <openssl/bn.h>

#include <openssl/obj_mac.h>

#include "fido.h"

#include "fido/eddsa.h"

#if defined(LIBRESSL_VERSION_NUMBER) && LIBRESSL_VERSION_NUMBER < 0x3070000f

EVP_PKEY *

EVP_PKEY_new_raw_public_key(int type, ENGINE *e, const unsigned char *key,

    size_t keylen)

{

        (void)type;

        (void)e;

        (void)key;

        (void)keylen;

        fido_log_debug("%s: unimplemented", __func__);

        return (NULL);

}

int

EVP_PKEY_get_raw_public_key(const EVP_PKEY *pkey, unsigned char *pub,

    size_t *len)

{

        (void)pkey;

        (void)pub;

        (void)len;

        fido_log_debug("%s: unimplemented", __func__);

        return (0);

}

#endif /* LIBRESSL_VERSION_NUMBER */

#if defined(LIBRESSL_VERSION_NUMBER) && LIBRESSL_VERSION_NUMBER < 0x3040000f

int

EVP_DigestVerify(EVP_MD_CTX *ctx, const unsigned char *sigret, size_t siglen,

    const unsigned char *tbs, size_t tbslen)

{

        (void)ctx;

        (void)sigret;

        (void)siglen;

        (void)tbs;

        (void)tbslen;

        fido_log_debug("%s: unimplemented", __func__);

        return (0);

}

#endif /* LIBRESSL_VERSION_NUMBER < 0x3040000f */

static int

decode_coord(const cbor_item_t *item, void *xy, size_t xy_len)

{

        if (cbor_isa_bytestring(item) == false ||

            cbor_bytestring_is_definite(item) == false ||

            cbor_bytestring_length(item) != xy_len) {

                fido_log_debug("%s: cbor type", __func__);

                return (-1);

        }

        memcpy(xy, cbor_bytestring_handle(item), xy_len);

        return (0);

}

static int

decode_pubkey_point(const cbor_item_t *key, const cbor_item_t *val, void *arg)

{

        eddsa_pk_t *k = arg;

        if (cbor_isa_negint(key) == false ||

            cbor_int_get_width(key) != CBOR_INT_8)

                return (0); /* ignore */

        switch (cbor_get_uint8(key)) {

        case 1: /* x coordinate */

                return (decode_coord(val, &k->x, sizeof(k->x)));

        }

        return (0); /* ignore */

}

int

eddsa_pk_decode(const cbor_item_t *item, eddsa_pk_t *k)

{

        if (cbor_isa_map(item) == false ||

            cbor_map_is_definite(item) == false ||

            cbor_map_iter(item, k, decode_pubkey_point) < 0) {

                fido_log_debug("%s: cbor type", __func__);

                return (-1);

        }

        return (0);

}

eddsa_pk_t *

eddsa_pk_new(void)

{

        return (calloc(1, sizeof(eddsa_pk_t)));

}

void

eddsa_pk_free(eddsa_pk_t **pkp)

{

        eddsa_pk_t *pk;

        if (pkp == NULL || (pk = *pkp) == NULL)

                return;

        freezero(pk, sizeof(*pk));

        *pkp = NULL;

}

int

eddsa_pk_from_ptr(eddsa_pk_t *pk, const void *ptr, size_t len)

{

        EVP_PKEY *pkey;

        if (len < sizeof(*pk))

                return (FIDO_ERR_INVALID_ARGUMENT);

        memcpy(pk, ptr, sizeof(*pk));

        if ((pkey = eddsa_pk_to_EVP_PKEY(pk)) == NULL) {

                fido_log_debug("%s: eddsa_pk_to_EVP_PKEY", __func__);

                return (FIDO_ERR_INVALID_ARGUMENT);

        }

        EVP_PKEY_free(pkey);

        return (FIDO_OK);

}

EVP_PKEY *

eddsa_pk_to_EVP_PKEY(const eddsa_pk_t *k)

{

        EVP_PKEY *pkey = NULL;

        if ((pkey = EVP_PKEY_new_raw_public_key(EVP_PKEY_ED25519, NULL, k->x,

            sizeof(k->x))) == NULL)

                fido_log_debug("%s: EVP_PKEY_new_raw_public_key", __func__);

        return (pkey);

}

int

eddsa_pk_from_EVP_PKEY(eddsa_pk_t *pk, const EVP_PKEY *pkey)

{

        size_t len = 0;

        if (EVP_PKEY_base_id(pkey) != EVP_PKEY_ED25519)

                return (FIDO_ERR_INVALID_ARGUMENT);

        if (EVP_PKEY_get_raw_public_key(pkey, NULL, &len) != 1 ||

            len != sizeof(pk->x))

                return (FIDO_ERR_INTERNAL);

        if (EVP_PKEY_get_raw_public_key(pkey, pk->x, &len) != 1 ||

            len != sizeof(pk->x))

                return (FIDO_ERR_INTERNAL);

        return (FIDO_OK);

}

int

eddsa_verify_sig(const fido_blob_t *dgst, EVP_PKEY *pkey,

    const fido_blob_t *sig)

{

        EVP_MD_CTX      *mdctx = NULL;

        int              ok = -1;

        if (EVP_PKEY_base_id(pkey) != EVP_PKEY_ED25519) {

                fido_log_debug("%s: EVP_PKEY_base_id", __func__);

                goto fail;

        }

        /* EVP_DigestVerify needs ints */

        if (dgst->len > INT_MAX || sig->len > INT_MAX) {

                fido_log_debug("%s: dgst->len=%zu, sig->len=%zu", __func__,

                    dgst->len, sig->len);

                return (-1);

        }

        if ((mdctx = EVP_MD_CTX_new()) == NULL) {

                fido_log_debug("%s: EVP_MD_CTX_new", __func__);

                goto fail;

        }

        if (EVP_DigestVerifyInit(mdctx, NULL, NULL, NULL, pkey) != 1) {

                fido_log_debug("%s: EVP_DigestVerifyInit", __func__);

                goto fail;

        }

        if (EVP_DigestVerify(mdctx, sig->ptr, sig->len, dgst->ptr,

            dgst->len) != 1) {

                fido_log_debug("%s: EVP_DigestVerify", __func__);

                goto fail;

        }

        ok = 0;

fail:

        EVP_MD_CTX_free(mdctx);

        return (ok);

}

int

eddsa_pk_verify_sig(const fido_blob_t *dgst, const eddsa_pk_t *pk,

    const fido_blob_t *sig)

{

        EVP_PKEY        *pkey;

        int              ok = -1;

        if ((pkey = eddsa_pk_to_EVP_PKEY(pk)) == NULL ||

            eddsa_verify_sig(dgst, pkey, sig) < 0) {

                fido_log_debug("%s: eddsa_verify_sig", __func__);

                goto fail;

        }

        ok = 0;

fail:

        EVP_PKEY_free(pkey);

        return (ok);

}