text: /*
   * 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 <stdio.h>
  #include "cryptlib.h"
  #include <openssl/asn1t.h>
  #include <openssl/x509.h>
  #include <openssl/ec.h>
  #include "ec_lcl.h"
  #include <openssl/ecdsa.h>
  #include <openssl/evp.h>
  #include "evp_locl.h"
  
  /* EC pkey context structure */
  
  typedef struct {
      /* Key and paramgen group */
      EC_GROUP *gen_group;
      /* message digest */
      const EVP_MD *md;
      /* Duplicate key if custom cofactor needed */
      EC_KEY *co_key;
      /* Cofactor mode */
      signed char cofactor_mode;
      /* KDF (if any) to use for ECDH */
      char kdf_type;
      /* Message digest to use for key derivation */
      const EVP_MD *kdf_md;
      /* User key material */
      unsigned char *kdf_ukm;
      size_t kdf_ukmlen;
      /* KDF output length */
      size_t kdf_outlen;
  } EC_PKEY_CTX;
  
  static int pkey_ec_init(EVP_PKEY_CTX *ctx)
  {
      EC_PKEY_CTX *dctx;
      dctx = OPENSSL_malloc(sizeof(EC_PKEY_CTX));
      if (!dctx)
          return 0;
      dctx->gen_group = NULL;
      dctx->md = NULL;
  
      dctx->cofactor_mode = -1;
      dctx->co_key = NULL;
      dctx->kdf_type = EVP_PKEY_ECDH_KDF_NONE;
      dctx->kdf_md = NULL;
      dctx->kdf_outlen = 0;
      dctx->kdf_ukm = NULL;
      dctx->kdf_ukmlen = 0;
  
      ctx->data = dctx;
  
      return 1;
  }
  
  static int pkey_ec_copy(EVP_PKEY_CTX *dst, EVP_PKEY_CTX *src)
  {
      EC_PKEY_CTX *dctx, *sctx;
      if (!pkey_ec_init(dst))
          return 0;
      sctx = src->data;
      dctx = dst->data;
      if (sctx->gen_group) {
          dctx->gen_group = EC_GROUP_dup(sctx->gen_group);
          if (!dctx->gen_group)
              return 0;
      }
      dctx->md = sctx->md;
  
      if (sctx->co_key) {
          dctx->co_key = EC_KEY_dup(sctx->co_key);
          if (!dctx->co_key)
              return 0;
      }
      dctx->kdf_type = sctx->kdf_type;
      dctx->kdf_md = sctx->kdf_md;
      dctx->kdf_outlen = sctx->kdf_outlen;
      if (sctx->kdf_ukm) {
          dctx->kdf_ukm = BUF_memdup(sctx->kdf_ukm, sctx->kdf_ukmlen);
          if (!dctx->kdf_ukm)
              return 0;
      } else
          dctx->kdf_ukm = NULL;
      dctx->kdf_ukmlen = sctx->kdf_ukmlen;
      return 1;
  }
  
  static void pkey_ec_cleanup(EVP_PKEY_CTX *ctx)
  {
      EC_PKEY_CTX *dctx = ctx->data;
      if (dctx) {
          if (dctx->gen_group)
              EC_GROUP_free(dctx->gen_group);
          if (dctx->co_key)
              EC_KEY_free(dctx->co_key);
          if (dctx->kdf_ukm)
              OPENSSL_free(dctx->kdf_ukm);
          OPENSSL_free(dctx);
      }
  }
  
  static int pkey_ec_sign(EVP_PKEY_CTX *ctx, unsigned char *sig, size_t *siglen,
                          const unsigned char *tbs, size_t tbslen)
  {
      int ret, type;
      unsigned int sltmp;
      EC_PKEY_CTX *dctx = ctx->data;
      EC_KEY *ec = ctx->pkey->pkey.ec;
  
      if (!sig) {
          *siglen = ECDSA_size(ec);
          return 1;
      } else if (*siglen < (size_t)ECDSA_size(ec)) {
          ECerr(EC_F_PKEY_EC_SIGN, EC_R_BUFFER_TOO_SMALL);
          return 0;
      }
  
      if (dctx->md)
          type = EVP_MD_type(dctx->md);
      else
          type = NID_sha1;
  
      ret = ECDSA_sign(type, tbs, tbslen, sig, &sltmp, ec);
  
      if (ret <= 0)
          return ret;
      *siglen = (size_t)sltmp;
      return 1;
  }
  
  static int pkey_ec_verify(EVP_PKEY_CTX *ctx,
                            const unsigned char *sig, size_t siglen,
                            const unsigned char *tbs, size_t tbslen)
  {
      int ret, type;
      EC_PKEY_CTX *dctx = ctx->data;
      EC_KEY *ec = ctx->pkey->pkey.ec;
  
      if (dctx->md)
          type = EVP_MD_type(dctx->md);
      else
          type = NID_sha1;
  
      ret = ECDSA_verify(type, tbs, tbslen, sig, siglen, ec);
  
      return ret;
  }
  
  #ifndef OPENSSL_NO_ECDH
  static int pkey_ec_derive(EVP_PKEY_CTX *ctx, unsigned char *key,
                            size_t *keylen)
  {
      int ret;
      size_t outlen;
      const EC_POINT *pubkey = NULL;
      EC_KEY *eckey;
      EC_PKEY_CTX *dctx = ctx->data;
      if (!ctx->pkey || !ctx->peerkey) {
          ECerr(EC_F_PKEY_EC_DERIVE, EC_R_KEYS_NOT_SET);
          return 0;
      }
  
      eckey = dctx->co_key ? dctx->co_key : ctx->pkey->pkey.ec;
  
      if (!key) {
          const EC_GROUP *group;
          group = EC_KEY_get0_group(eckey);
          *keylen = (EC_GROUP_get_degree(group) + 7) / 8;
          return 1;
      }
      pubkey = EC_KEY_get0_public_key(ctx->peerkey->pkey.ec);
  
      /*
       * NB: unlike PKCS#3 DH, if *outlen is less than maximum size this is not
       * an error, the result is truncated.
       */
  
      outlen = *keylen;
  
      ret = ECDH_compute_key(key, outlen, pubkey, eckey, 0);
      if (ret <= 0)
          return 0;
      *keylen = ret;
      return 1;
  }
  
  static int pkey_ec_kdf_derive(EVP_PKEY_CTX *ctx,
                                unsigned char *key, size_t *keylen)
  {
      EC_PKEY_CTX *dctx = ctx->data;
      unsigned char *ktmp = NULL;
      size_t ktmplen;
      int rv = 0;
      if (dctx->kdf_type == EVP_PKEY_ECDH_KDF_NONE)
          return pkey_ec_derive(ctx, key, keylen);
      if (!key) {
          *keylen = dctx->kdf_outlen;
          return 1;
      }
      if (*keylen != dctx->kdf_outlen)
          return 0;
      if (!pkey_ec_derive(ctx, NULL, &ktmplen))
          return 0;
      ktmp = OPENSSL_malloc(ktmplen);
      if (!ktmp)
          return 0;
      if (!pkey_ec_derive(ctx, ktmp, &ktmplen))
          goto err;
      /* Do KDF stuff */
      if (!ECDH_KDF_X9_62(key, *keylen, ktmp, ktmplen,
                          dctx->kdf_ukm, dctx->kdf_ukmlen, dctx->kdf_md))
          goto err;
      rv = 1;
  
   err:
      if (ktmp) {
          OPENSSL_cleanse(ktmp, ktmplen);
          OPENSSL_free(ktmp);
      }
      return rv;
  }
  #endif
  
  static int pkey_ec_ctrl(EVP_PKEY_CTX *ctx, int type, int p1, void *p2)
  {
      EC_PKEY_CTX *dctx = ctx->data;
      EC_GROUP *group;
      switch (type) {
      case EVP_PKEY_CTRL_EC_PARAMGEN_CURVE_NID:
          group = EC_GROUP_new_by_curve_name(p1);
          if (group == NULL) {
              ECerr(EC_F_PKEY_EC_CTRL, EC_R_INVALID_CURVE);
              return 0;
          }
          if (dctx->gen_group)
              EC_GROUP_free(dctx->gen_group);
          dctx->gen_group = group;
          return 1;
  
      case EVP_PKEY_CTRL_EC_PARAM_ENC:
          if (!dctx->gen_group) {
              ECerr(EC_F_PKEY_EC_CTRL, EC_R_NO_PARAMETERS_SET);
              return 0;
          }
          EC_GROUP_set_asn1_flag(dctx->gen_group, p1);
          return 1;
  
  #ifndef OPENSSL_NO_ECDH
      case EVP_PKEY_CTRL_EC_ECDH_COFACTOR:
          if (p1 == -2) {
              if (dctx->cofactor_mode != -1)
                  return dctx->cofactor_mode;
              else {
                  EC_KEY *ec_key = ctx->pkey->pkey.ec;
                  return EC_KEY_get_flags(ec_key) & EC_FLAG_COFACTOR_ECDH ? 1 :
                      0;
              }
          } else if (p1 < -1 || p1 > 1)
              return -2;
          dctx->cofactor_mode = p1;
          if (p1 != -1) {
              EC_KEY *ec_key = ctx->pkey->pkey.ec;
              if (!ec_key->group)
                  return -2;
              /* If cofactor is 1 cofactor mode does nothing */
              if (BN_is_one(&ec_key->group->cofactor))
                  return 1;
              if (!dctx->co_key) {
                  dctx->co_key = EC_KEY_dup(ec_key);
                  if (!dctx->co_key)
                      return 0;
              }
              if (p1)
                  EC_KEY_set_flags(dctx->co_key, EC_FLAG_COFACTOR_ECDH);
              else
                  EC_KEY_clear_flags(dctx->co_key, EC_FLAG_COFACTOR_ECDH);
          } else if (dctx->co_key) {
              EC_KEY_free(dctx->co_key);
              dctx->co_key = NULL;
          }
          return 1;
  #endif
  
      case EVP_PKEY_CTRL_EC_KDF_TYPE:
          if (p1 == -2)
              return dctx->kdf_type;
          if (p1 != EVP_PKEY_ECDH_KDF_NONE && p1 != EVP_PKEY_ECDH_KDF_X9_62)
              return -2;
          dctx->kdf_type = p1;
          return 1;
  
      case EVP_PKEY_CTRL_EC_KDF_MD:
          dctx->kdf_md = p2;
          return 1;
  
      case EVP_PKEY_CTRL_GET_EC_KDF_MD:
          *(const EVP_MD **)p2 = dctx->kdf_md;
          return 1;
  
      case EVP_PKEY_CTRL_EC_KDF_OUTLEN:
          if (p1 <= 0)
              return -2;
          dctx->kdf_outlen = (size_t)p1;
          return 1;
  
      case EVP_PKEY_CTRL_GET_EC_KDF_OUTLEN:
          *(int *)p2 = dctx->kdf_outlen;
          return 1;
  
      case EVP_PKEY_CTRL_EC_KDF_UKM:
          if (dctx->kdf_ukm)
              OPENSSL_free(dctx->kdf_ukm);
          dctx->kdf_ukm = p2;
          if (p2)
              dctx->kdf_ukmlen = p1;
          else
              dctx->kdf_ukmlen = 0;
          return 1;
  
      case EVP_PKEY_CTRL_GET_EC_KDF_UKM:
          *(unsigned char **)p2 = dctx->kdf_ukm;
          return dctx->kdf_ukmlen;
  
      case EVP_PKEY_CTRL_MD:
          if (EVP_MD_type((const EVP_MD *)p2) != NID_sha1 &&
              EVP_MD_type((const EVP_MD *)p2) != NID_ecdsa_with_SHA1 &&
              EVP_MD_type((const EVP_MD *)p2) != NID_sha224 &&
              EVP_MD_type((const EVP_MD *)p2) != NID_sha256 &&
              EVP_MD_type((const EVP_MD *)p2) != NID_sha384 &&
              EVP_MD_type((const EVP_MD *)p2) != NID_sha512) {
              ECerr(EC_F_PKEY_EC_CTRL, EC_R_INVALID_DIGEST_TYPE);
              return 0;
          }
          dctx->md = p2;
          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 */
      case EVP_PKEY_CTRL_DIGESTINIT:
      case EVP_PKEY_CTRL_PKCS7_SIGN:
      case EVP_PKEY_CTRL_CMS_SIGN:
          return 1;
  
      default:
          return -2;
  
      }
  }
  
  static int pkey_ec_ctrl_str(EVP_PKEY_CTX *ctx,
                              const char *type, const char *value)
  {
      if (!strcmp(type, "ec_paramgen_curve")) {
          int nid;
          nid = EC_curve_nist2nid(value);
          if (nid == NID_undef)
              nid = OBJ_sn2nid(value);
          if (nid == NID_undef)
              nid = OBJ_ln2nid(value);
          if (nid == NID_undef) {
              ECerr(EC_F_PKEY_EC_CTRL_STR, EC_R_INVALID_CURVE);
              return 0;
          }
          return EVP_PKEY_CTX_set_ec_paramgen_curve_nid(ctx, nid);
      } else if (!strcmp(type, "ec_param_enc")) {
          int param_enc;
          if (!strcmp(value, "explicit"))
              param_enc = 0;
          else if (!strcmp(value, "named_curve"))
              param_enc = OPENSSL_EC_NAMED_CURVE;
          else
              return -2;
          return EVP_PKEY_CTX_set_ec_param_enc(ctx, param_enc);
      } else if (!strcmp(type, "ecdh_kdf_md")) {
          const EVP_MD *md;
          if (!(md = EVP_get_digestbyname(value))) {
              ECerr(EC_F_PKEY_EC_CTRL_STR, EC_R_INVALID_DIGEST);
              return 0;
          }
          return EVP_PKEY_CTX_set_ecdh_kdf_md(ctx, md);
      } else if (!strcmp(type, "ecdh_cofactor_mode")) {
          int co_mode;
          co_mode = atoi(value);
          return EVP_PKEY_CTX_set_ecdh_cofactor_mode(ctx, co_mode);
      }
  
      return -2;
  }
  
  static int pkey_ec_paramgen(EVP_PKEY_CTX *ctx, EVP_PKEY *pkey)
  {
      EC_KEY *ec = NULL;
      EC_PKEY_CTX *dctx = ctx->data;
      int ret = 0;
      if (dctx->gen_group == NULL) {
          ECerr(EC_F_PKEY_EC_PARAMGEN, EC_R_NO_PARAMETERS_SET);
          return 0;
      }
      ec = EC_KEY_new();
      if (!ec)
          return 0;
      ret = EC_KEY_set_group(ec, dctx->gen_group);
      if (ret)
          EVP_PKEY_assign_EC_KEY(pkey, ec);
      else
          EC_KEY_free(ec);
      return ret;
  }
  
  static int pkey_ec_keygen(EVP_PKEY_CTX *ctx, EVP_PKEY *pkey)
  {
      EC_KEY *ec = NULL;
      EC_PKEY_CTX *dctx = ctx->data;
      if (ctx->pkey == NULL && dctx->gen_group == NULL) {
          ECerr(EC_F_PKEY_EC_KEYGEN, EC_R_NO_PARAMETERS_SET);
          return 0;
      }
      ec = EC_KEY_new();
      if (!ec)
          return 0;
      EVP_PKEY_assign_EC_KEY(pkey, ec);
      if (ctx->pkey) {
          /* Note: if error return, pkey is freed by parent routine */
          if (!EVP_PKEY_copy_parameters(pkey, ctx->pkey))
              return 0;
      } else {
          if (!EC_KEY_set_group(ec, dctx->gen_group))
              return 0;
      }
      return EC_KEY_generate_key(pkey->pkey.ec);
  }
  
  const EVP_PKEY_METHOD ec_pkey_meth = {
      EVP_PKEY_EC,
      0,
      pkey_ec_init,
      pkey_ec_copy,
      pkey_ec_cleanup,
  
      0,
      pkey_ec_paramgen,
  
      0,
      pkey_ec_keygen,
  
      0,
      pkey_ec_sign,
  
      0,
      pkey_ec_verify,
  
      0, 0,
  
      0, 0, 0, 0,
  
      0, 0,
  
      0, 0,
  
      0,
  #ifndef OPENSSL_NO_ECDH
      pkey_ec_kdf_derive,
  #else
      0,
  #endif
  
      pkey_ec_ctrl,
      pkey_ec_ctrl_str
  };
  