/* Written by Dr Stephen N Henson (steve@openssl.org) for the OpenSSL

 * project 2006.

 */

/* ====================================================================

 * Copyright (c) 2006 The OpenSSL Project.  All rights reserved.

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions

 * are met:

 *

 * 1. Redistributions of source code must retain the above copyright

 *    notice, this list of conditions and the following disclaimer.

 *

 * 2. Redistributions in binary form must reproduce the above copyright

 *    notice, this list of conditions and the following disclaimer in

 *    the documentation and/or other materials provided with the

 *    distribution.

 *

 * 3. All advertising materials mentioning features or use of this

 *    software must display the following acknowledgment:

 *    "This product includes software developed by the OpenSSL Project

 *    for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)"

 *

 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to

 *    endorse or promote products derived from this software without

 *    prior written permission. For written permission, please contact

 *    licensing@OpenSSL.org.

 *

 * 5. Products derived from this software may not be called "OpenSSL"

 *    nor may "OpenSSL" appear in their names without prior written

 *    permission of the OpenSSL Project.

 *

 * 6. Redistributions of any form whatsoever must retain the following

 *    acknowledgment:

 *    "This product includes software developed by the OpenSSL Project

 *    for use in the OpenSSL Toolkit (http://www.OpenSSL.org/)"

 *

 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY

 * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE

 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR

 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR

 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,

 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT

 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;

 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)

 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,

 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)

 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED

 * OF THE POSSIBILITY OF SUCH DAMAGE.

 * ====================================================================

 *

 * This product includes cryptographic software written by Eric Young

 * (eay@cryptsoft.com).  This product includes software written by Tim

 * Hudson (tjh@cryptsoft.com). */

#include <openssl/evp.h>

#include <string.h>

#include <openssl/bn.h>

#include <openssl/digest.h>

#include <openssl/ec.h>

#include <openssl/ec_key.h>

#include <openssl/ecdh.h>

#include <openssl/ecdsa.h>

#include <openssl/err.h>

#include <openssl/mem.h>

#include <openssl/nid.h>

#include "internal.h"

#include "../fipsmodule/ec/internal.h"

#include "../internal.h"

typedef struct {

  // message digest

  const EVP_MD *md;

  const EC_GROUP *gen_group;

} EC_PKEY_CTX;

static int pkey_ec_init(EVP_PKEY_CTX *ctx) {

  EC_PKEY_CTX *dctx = OPENSSL_zalloc(sizeof(EC_PKEY_CTX));

  if (!dctx) {

    return 0;

  }

  ctx->data = dctx;

  return 1;

}

static int pkey_ec_copy(EVP_PKEY_CTX *dst, EVP_PKEY_CTX *src) {

  if (!pkey_ec_init(dst)) {

    return 0;

  }

  const EC_PKEY_CTX *sctx = src->data;

  EC_PKEY_CTX *dctx = dst->data;

  dctx->md = sctx->md;

  dctx->gen_group = sctx->gen_group;

  return 1;

}

static void pkey_ec_cleanup(EVP_PKEY_CTX *ctx) {

  EC_PKEY_CTX *dctx = ctx->data;

  if (!dctx) {

    return;

  }

  OPENSSL_free(dctx);

}

static int pkey_ec_sign(EVP_PKEY_CTX *ctx, uint8_t *sig, size_t *siglen,

                        const uint8_t *tbs, size_t tbslen) {

  const EC_KEY *ec = ctx->pkey->pkey;

  if (!sig) {

    *siglen = ECDSA_size(ec);

    return 1;

  } else if (*siglen < (size_t)ECDSA_size(ec)) {

    OPENSSL_PUT_ERROR(EVP, EVP_R_BUFFER_TOO_SMALL);

    return 0;

  }

  unsigned int sltmp;

  if (!ECDSA_sign(0, tbs, tbslen, sig, &sltmp, ec)) {

    return 0;

  }

  *siglen = (size_t)sltmp;

  return 1;

}

static int pkey_ec_verify(EVP_PKEY_CTX *ctx, const uint8_t *sig, size_t siglen,

                          const uint8_t *tbs, size_t tbslen) {

  const EC_KEY *ec_key = ctx->pkey->pkey;

  return ECDSA_verify(0, tbs, tbslen, sig, siglen, ec_key);

}

static int pkey_ec_derive(EVP_PKEY_CTX *ctx, uint8_t *key,

                          size_t *keylen) {

  if (!ctx->pkey || !ctx->peerkey) {

    OPENSSL_PUT_ERROR(EVP, EVP_R_KEYS_NOT_SET);

    return 0;

  }

  const EC_KEY *eckey = ctx->pkey->pkey;

  if (!key) {

    const EC_GROUP *group;

    group = EC_KEY_get0_group(eckey);

    *keylen = (EC_GROUP_get_degree(group) + 7) / 8;

    return 1;

  }

  const EC_KEY *eckey_peer = ctx->peerkey->pkey;

  const EC_POINT *pubkey = EC_KEY_get0_public_key(eckey_peer);

  // NB: unlike PKCS#3 DH, if *outlen is less than maximum size this is

  // not an error, the result is truncated.

  size_t outlen = *keylen;

  int ret = ECDH_compute_key(key, outlen, pubkey, eckey, 0);

  if (ret < 0) {

    return 0;

  }

  *keylen = ret;

  return 1;

}

static int pkey_ec_ctrl(EVP_PKEY_CTX *ctx, int type, int p1, void *p2) {

  EC_PKEY_CTX *dctx = ctx->data;

  switch (type) {

    case EVP_PKEY_CTRL_MD: {

      const EVP_MD *md = p2;

      int md_type = EVP_MD_type(md);

      if (md_type != NID_sha1 && md_type != NID_sha224 &&

          md_type != NID_sha256 && md_type != NID_sha384 &&

          md_type != NID_sha512) {

        OPENSSL_PUT_ERROR(EVP, EVP_R_INVALID_DIGEST_TYPE);

        return 0;

      }

      dctx->md = md;

      return 1;

    }

    case EVP_PKEY_CTRL_GET_MD:

      *(const EVP_MD **)p2 = dctx->md;

      return 1;

    case EVP_PKEY_CTRL_PEER_KEY:

      // Default behaviour is OK

      return 1;

    case EVP_PKEY_CTRL_EC_PARAMGEN_CURVE_NID: {

      const EC_GROUP *group = EC_GROUP_new_by_curve_name(p1);

      if (group == NULL) {

        return 0;

      }

      dctx->gen_group = group;

      return 1;

    }

    default:

      OPENSSL_PUT_ERROR(EVP, EVP_R_COMMAND_NOT_SUPPORTED);

      return 0;

  }

}

static int pkey_ec_keygen(EVP_PKEY_CTX *ctx, EVP_PKEY *pkey) {

  EC_PKEY_CTX *dctx = ctx->data;

  const EC_GROUP *group = dctx->gen_group;

  if (group == NULL) {

    if (ctx->pkey == NULL) {

      OPENSSL_PUT_ERROR(EVP, EVP_R_NO_PARAMETERS_SET);

      return 0;

    }

    group = EC_KEY_get0_group(ctx->pkey->pkey);

  }

  EC_KEY *ec = EC_KEY_new();

  if (ec == NULL ||

      !EC_KEY_set_group(ec, group) ||

      !EC_KEY_generate_key(ec)) {

    EC_KEY_free(ec);

    return 0;

  }

  EVP_PKEY_assign_EC_KEY(pkey, ec);

  return 1;

}

static int pkey_ec_paramgen(EVP_PKEY_CTX *ctx, EVP_PKEY *pkey) {

  EC_PKEY_CTX *dctx = ctx->data;

  if (dctx->gen_group == NULL) {

    OPENSSL_PUT_ERROR(EVP, EVP_R_NO_PARAMETERS_SET);

    return 0;

  }

  EC_KEY *ec = EC_KEY_new();

  if (ec == NULL ||

      !EC_KEY_set_group(ec, dctx->gen_group)) {

    EC_KEY_free(ec);

    return 0;

  }

  EVP_PKEY_assign_EC_KEY(pkey, ec);

  return 1;

}

const EVP_PKEY_METHOD ec_pkey_meth = {

    EVP_PKEY_EC,

    pkey_ec_init,

    pkey_ec_copy,

    pkey_ec_cleanup,

    pkey_ec_keygen,

    pkey_ec_sign,

    NULL /* sign_message */,

    pkey_ec_verify,

    NULL /* verify_message */,

    NULL /* verify_recover */,

    NULL /* encrypt */,

    NULL /* decrypt */,

    pkey_ec_derive,

    pkey_ec_paramgen,

    pkey_ec_ctrl,

};

int EVP_PKEY_CTX_set_ec_paramgen_curve_nid(EVP_PKEY_CTX *ctx, int nid) {

  return EVP_PKEY_CTX_ctrl(ctx, EVP_PKEY_EC, EVP_PKEY_OP_TYPE_GEN,

                           EVP_PKEY_CTRL_EC_PARAMGEN_CURVE_NID, nid, NULL);

}

int EVP_PKEY_CTX_set_ec_param_enc(EVP_PKEY_CTX *ctx, int encoding) {

  // BoringSSL only supports named curve syntax.

  if (encoding != OPENSSL_EC_NAMED_CURVE) {

    OPENSSL_PUT_ERROR(EVP, EVP_R_INVALID_PARAMETERS);

    return 0;

  }

  return 1;

}