text: /*
   * Copyright 2006-2016 The OpenSSL Project Authors. All Rights Reserved.
   *
   * Licensed under the OpenSSL license (the "License").  You may not use
   * this file except in compliance with the License.  You can obtain a copy
   * in the file LICENSE in the source distribution or at
   * https://www.openssl.org/source/license.html
   */
  
  #include <stdio.h>
  #include "internal/cryptlib.h"
  #include <openssl/x509.h>
  #include <openssl/asn1.h>
  #include "dh_locl.h"
  #include <openssl/bn.h>
  #include "internal/asn1_int.h"
  #include "internal/evp_int.h"
  #include <openssl/cms.h>
  
  /*
   * i2d/d2i like DH parameter functions which use the appropriate routine for
   * PKCS#3 DH or X9.42 DH.
   */
  
  static DH *d2i_dhp(const EVP_PKEY *pkey, const unsigned char **pp,
                     long length)
  {
      if (pkey->ameth == &dhx_asn1_meth)
          return d2i_DHxparams(NULL, pp, length);
      return d2i_DHparams(NULL, pp, length);
  }
  
  static int i2d_dhp(const EVP_PKEY *pkey, const DH *a, unsigned char **pp)
  {
      if (pkey->ameth == &dhx_asn1_meth)
          return i2d_DHxparams(a, pp);
      return i2d_DHparams(a, pp);
  }
  
  static void int_dh_free(EVP_PKEY *pkey)
  {
      DH_free(pkey->pkey.dh);
  }
  
  static int dh_pub_decode(EVP_PKEY *pkey, X509_PUBKEY *pubkey)
  {
      const unsigned char *p, *pm;
      int pklen, pmlen;
      int ptype;
      const void *pval;
      const ASN1_STRING *pstr;
      X509_ALGOR *palg;
      ASN1_INTEGER *public_key = NULL;
  
      DH *dh = NULL;
  
      if (!X509_PUBKEY_get0_param(NULL, &p, &pklen, &palg, pubkey))
          return 0;
      X509_ALGOR_get0(NULL, &ptype, &pval, palg);
  
      if (ptype != V_ASN1_SEQUENCE) {
          DHerr(DH_F_DH_PUB_DECODE, DH_R_PARAMETER_ENCODING_ERROR);
          goto err;
      }
  
      pstr = pval;
      pm = pstr->data;
      pmlen = pstr->length;
  
      if ((dh = d2i_dhp(pkey, &pm, pmlen)) == NULL) {
          DHerr(DH_F_DH_PUB_DECODE, DH_R_DECODE_ERROR);
          goto err;
      }
  
      if ((public_key = d2i_ASN1_INTEGER(NULL, &p, pklen)) == NULL) {
          DHerr(DH_F_DH_PUB_DECODE, DH_R_DECODE_ERROR);
          goto err;
      }
  
      /* We have parameters now set public key */
      if ((dh->pub_key = ASN1_INTEGER_to_BN(public_key, NULL)) == NULL) {
          DHerr(DH_F_DH_PUB_DECODE, DH_R_BN_DECODE_ERROR);
          goto err;
      }
  
      ASN1_INTEGER_free(public_key);
      EVP_PKEY_assign(pkey, pkey->ameth->pkey_id, dh);
      return 1;
  
   err:
      ASN1_INTEGER_free(public_key);
      DH_free(dh);
      return 0;
  
  }
  
  static int dh_pub_encode(X509_PUBKEY *pk, const EVP_PKEY *pkey)
  {
      DH *dh;
      int ptype;
      unsigned char *penc = NULL;
      int penclen;
      ASN1_STRING *str;
      ASN1_INTEGER *pub_key = NULL;
  
      dh = pkey->pkey.dh;
  
      str = ASN1_STRING_new();
      if (str == NULL) {
          DHerr(DH_F_DH_PUB_ENCODE, ERR_R_MALLOC_FAILURE);
          goto err;
      }
      str->length = i2d_dhp(pkey, dh, &str->data);
      if (str->length <= 0) {
          DHerr(DH_F_DH_PUB_ENCODE, ERR_R_MALLOC_FAILURE);
          goto err;
      }
      ptype = V_ASN1_SEQUENCE;
  
      pub_key = BN_to_ASN1_INTEGER(dh->pub_key, NULL);
      if (!pub_key)
          goto err;
  
      penclen = i2d_ASN1_INTEGER(pub_key, &penc);
  
      ASN1_INTEGER_free(pub_key);
  
      if (penclen <= 0) {
          DHerr(DH_F_DH_PUB_ENCODE, ERR_R_MALLOC_FAILURE);
          goto err;
      }
  
      if (X509_PUBKEY_set0_param(pk, OBJ_nid2obj(pkey->ameth->pkey_id),
                                 ptype, str, penc, penclen))
          return 1;
  
   err:
      OPENSSL_free(penc);
      ASN1_STRING_free(str);
  
      return 0;
  }
  
  /*
   * PKCS#8 DH is defined in PKCS#11 of all places. It is similar to DH in that
   * the AlgorithmIdentifier contains the parameters, the private key is
   * explicitly included and the pubkey must be recalculated.
   */
  
  static int dh_priv_decode(EVP_PKEY *pkey, const PKCS8_PRIV_KEY_INFO *p8)
  {
      const unsigned char *p, *pm;
      int pklen, pmlen;
      int ptype;
      const void *pval;
      const ASN1_STRING *pstr;
      const X509_ALGOR *palg;
      ASN1_INTEGER *privkey = NULL;
  
      DH *dh = NULL;
  
      if (!PKCS8_pkey_get0(NULL, &p, &pklen, &palg, p8))
          return 0;
  
      X509_ALGOR_get0(NULL, &ptype, &pval, palg);
  
      if (ptype != V_ASN1_SEQUENCE)
          goto decerr;
      if ((privkey = d2i_ASN1_INTEGER(NULL, &p, pklen)) == NULL)
          goto decerr;
  
      pstr = pval;
      pm = pstr->data;
      pmlen = pstr->length;
      if ((dh = d2i_dhp(pkey, &pm, pmlen)) == NULL)
          goto decerr;
  
      /* We have parameters now set private key */
      if ((dh->priv_key = BN_secure_new()) == NULL
          || !ASN1_INTEGER_to_BN(privkey, dh->priv_key)) {
          DHerr(DH_F_DH_PRIV_DECODE, DH_R_BN_ERROR);
          goto dherr;
      }
      /* Calculate public key */
      if (!DH_generate_key(dh))
          goto dherr;
  
      EVP_PKEY_assign(pkey, pkey->ameth->pkey_id, dh);
  
      ASN1_STRING_clear_free(privkey);
  
      return 1;
  
   decerr:
      DHerr(DH_F_DH_PRIV_DECODE, EVP_R_DECODE_ERROR);
   dherr:
      DH_free(dh);
      ASN1_STRING_clear_free(privkey);
      return 0;
  }
  
  static int dh_priv_encode(PKCS8_PRIV_KEY_INFO *p8, const EVP_PKEY *pkey)
  {
      ASN1_STRING *params = NULL;
      ASN1_INTEGER *prkey = NULL;
      unsigned char *dp = NULL;
      int dplen;
  
      params = ASN1_STRING_new();
  
      if (params == NULL) {
          DHerr(DH_F_DH_PRIV_ENCODE, ERR_R_MALLOC_FAILURE);
          goto err;
      }
  
      params->length = i2d_dhp(pkey, pkey->pkey.dh, &params->data);
      if (params->length <= 0) {
          DHerr(DH_F_DH_PRIV_ENCODE, ERR_R_MALLOC_FAILURE);
          goto err;
      }
      params->type = V_ASN1_SEQUENCE;
  
      /* Get private key into integer */
      prkey = BN_to_ASN1_INTEGER(pkey->pkey.dh->priv_key, NULL);
  
      if (!prkey) {
          DHerr(DH_F_DH_PRIV_ENCODE, DH_R_BN_ERROR);
          goto err;
      }
  
      dplen = i2d_ASN1_INTEGER(prkey, &dp);
  
      ASN1_STRING_clear_free(prkey);
      prkey = NULL;
  
      if (!PKCS8_pkey_set0(p8, OBJ_nid2obj(pkey->ameth->pkey_id), 0,
                           V_ASN1_SEQUENCE, params, dp, dplen))
          goto err;
  
      return 1;
  
   err:
      OPENSSL_free(dp);
      ASN1_STRING_free(params);
      ASN1_STRING_clear_free(prkey);
      return 0;
  }
  
  static int dh_param_decode(EVP_PKEY *pkey,
                             const unsigned char **pder, int derlen)
  {
      DH *dh;
  
      if ((dh = d2i_dhp(pkey, pder, derlen)) == NULL) {
          DHerr(DH_F_DH_PARAM_DECODE, ERR_R_DH_LIB);
          return 0;
      }
      EVP_PKEY_assign(pkey, pkey->ameth->pkey_id, dh);
      return 1;
  }
  
  static int dh_param_encode(const EVP_PKEY *pkey, unsigned char **pder)
  {
      return i2d_dhp(pkey, pkey->pkey.dh, pder);
  }
  
  static int do_dh_print(BIO *bp, const DH *x, int indent, int ptype)
  {
      int reason = ERR_R_BUF_LIB;
      const char *ktype = NULL;
      BIGNUM *priv_key, *pub_key;
  
      if (ptype == 2)
          priv_key = x->priv_key;
      else
          priv_key = NULL;
  
      if (ptype > 0)
          pub_key = x->pub_key;
      else
          pub_key = NULL;
  
      if (x->p == NULL || (ptype == 2 && priv_key == NULL)
              || (ptype > 0 && pub_key == NULL)) {
          reason = ERR_R_PASSED_NULL_PARAMETER;
          goto err;
      }
  
      if (ptype == 2)
          ktype = "DH Private-Key";
      else if (ptype == 1)
          ktype = "DH Public-Key";
      else
          ktype = "DH Parameters";
  
      BIO_indent(bp, indent, 128);
      if (BIO_printf(bp, "%s: (%d bit)\n", ktype, BN_num_bits(x->p)) <= 0)
          goto err;
      indent += 4;
  
      if (!ASN1_bn_print(bp, "private-key:", priv_key, NULL, indent))
          goto err;
      if (!ASN1_bn_print(bp, "public-key:", pub_key, NULL, indent))
          goto err;
  
      if (!ASN1_bn_print(bp, "prime:", x->p, NULL, indent))
          goto err;
      if (!ASN1_bn_print(bp, "generator:", x->g, NULL, indent))
          goto err;
      if (x->q && !ASN1_bn_print(bp, "subgroup order:", x->q, NULL, indent))
          goto err;
      if (x->j && !ASN1_bn_print(bp, "subgroup factor:", x->j, NULL, indent))
          goto err;
      if (x->seed) {
          int i;
          BIO_indent(bp, indent, 128);
          BIO_puts(bp, "seed:");
          for (i = 0; i < x->seedlen; i++) {
              if ((i % 15) == 0) {
                  if (BIO_puts(bp, "\n") <= 0
                      || !BIO_indent(bp, indent + 4, 128))
                      goto err;
              }
              if (BIO_printf(bp, "%02x%s", x->seed[i],
                             ((i + 1) == x->seedlen) ? "" : ":") <= 0)
                  goto err;
          }
          if (BIO_write(bp, "\n", 1) <= 0)
              return (0);
      }
      if (x->counter && !ASN1_bn_print(bp, "counter:", x->counter, NULL, indent))
          goto err;
      if (x->length != 0) {
          BIO_indent(bp, indent, 128);
          if (BIO_printf(bp, "recommended-private-length: %d bits\n",
                         (int)x->length) <= 0)
              goto err;
      }
  
      return 1;
  
   err:
      DHerr(DH_F_DO_DH_PRINT, reason);
      return 0;
  }
  
  static int int_dh_size(const EVP_PKEY *pkey)
  {
      return (DH_size(pkey->pkey.dh));
  }
  
  static int dh_bits(const EVP_PKEY *pkey)
  {
      return BN_num_bits(pkey->pkey.dh->p);
  }
  
  static int dh_security_bits(const EVP_PKEY *pkey)
  {
      return DH_security_bits(pkey->pkey.dh);
  }
  
  static int dh_cmp_parameters(const EVP_PKEY *a, const EVP_PKEY *b)
  {
      if (BN_cmp(a->pkey.dh->p, b->pkey.dh->p) ||
          BN_cmp(a->pkey.dh->g, b->pkey.dh->g))
          return 0;
      else if (a->ameth == &dhx_asn1_meth) {
          if (BN_cmp(a->pkey.dh->q, b->pkey.dh->q))
              return 0;
      }
      return 1;
  }
  
  static int int_dh_bn_cpy(BIGNUM **dst, const BIGNUM *src)
  {
      BIGNUM *a;
      if (src) {
          a = BN_dup(src);
          if (!a)
              return 0;
      } else
          a = NULL;
      BN_free(*dst);
      *dst = a;
      return 1;
  }
  
  static int int_dh_param_copy(DH *to, const DH *from, int is_x942)
  {
      if (is_x942 == -1)
          is_x942 = ! !from->q;
      if (!int_dh_bn_cpy(&to->p, from->p))
          return 0;
      if (!int_dh_bn_cpy(&to->g, from->g))
          return 0;
      if (is_x942) {
          if (!int_dh_bn_cpy(&to->q, from->q))
              return 0;
          if (!int_dh_bn_cpy(&to->j, from->j))
              return 0;
          OPENSSL_free(to->seed);
          to->seed = NULL;
          to->seedlen = 0;
          if (from->seed) {
              to->seed = OPENSSL_memdup(from->seed, from->seedlen);
              if (!to->seed)
                  return 0;
              to->seedlen = from->seedlen;
          }
      } else
          to->length = from->length;
      return 1;
  }
  
  DH *DHparams_dup(DH *dh)
  {
      DH *ret;
      ret = DH_new();
      if (ret == NULL)
          return NULL;
      if (!int_dh_param_copy(ret, dh, -1)) {
          DH_free(ret);
          return NULL;
      }
      return ret;
  }
  
  static int dh_copy_parameters(EVP_PKEY *to, const EVP_PKEY *from)
  {
      if (to->pkey.dh == NULL) {
          to->pkey.dh = DH_new();
          if (to->pkey.dh == NULL)
              return 0;
      }
      return int_dh_param_copy(to->pkey.dh, from->pkey.dh,
                               from->ameth == &dhx_asn1_meth);
  }
  
  static int dh_missing_parameters(const EVP_PKEY *a)
  {
      if (a->pkey.dh == NULL || a->pkey.dh->p == NULL || a->pkey.dh->g == NULL)
          return 1;
      return 0;
  }
  
  static int dh_pub_cmp(const EVP_PKEY *a, const EVP_PKEY *b)
  {
      if (dh_cmp_parameters(a, b) == 0)
          return 0;
      if (BN_cmp(b->pkey.dh->pub_key, a->pkey.dh->pub_key) != 0)
          return 0;
      else
          return 1;
  }
  
  static int dh_param_print(BIO *bp, const EVP_PKEY *pkey, int indent,
                            ASN1_PCTX *ctx)
  {
      return do_dh_print(bp, pkey->pkey.dh, indent, 0);
  }
  
  static int dh_public_print(BIO *bp, const EVP_PKEY *pkey, int indent,
                             ASN1_PCTX *ctx)
  {
      return do_dh_print(bp, pkey->pkey.dh, indent, 1);
  }
  
  static int dh_private_print(BIO *bp, const EVP_PKEY *pkey, int indent,
                              ASN1_PCTX *ctx)
  {
      return do_dh_print(bp, pkey->pkey.dh, indent, 2);
  }
  
  int DHparams_print(BIO *bp, const DH *x)
  {
      return do_dh_print(bp, x, 4, 0);
  }
  
  #ifndef OPENSSL_NO_CMS
  static int dh_cms_decrypt(CMS_RecipientInfo *ri);
  static int dh_cms_encrypt(CMS_RecipientInfo *ri);
  #endif
  
  static int dh_pkey_ctrl(EVP_PKEY *pkey, int op, long arg1, void *arg2)
  {
      switch (op) {
  #ifndef OPENSSL_NO_CMS
  
      case ASN1_PKEY_CTRL_CMS_ENVELOPE:
          if (arg1 == 1)
              return dh_cms_decrypt(arg2);
          else if (arg1 == 0)
              return dh_cms_encrypt(arg2);
          return -2;
  
      case ASN1_PKEY_CTRL_CMS_RI_TYPE:
          *(int *)arg2 = CMS_RECIPINFO_AGREE;
          return 1;
  #endif
      default:
          return -2;
      }
  
  }
  
  const EVP_PKEY_ASN1_METHOD dh_asn1_meth = {
      EVP_PKEY_DH,
      EVP_PKEY_DH,
      0,
  
      "DH",
      "OpenSSL PKCS#3 DH method",
  
      dh_pub_decode,
      dh_pub_encode,
      dh_pub_cmp,
      dh_public_print,
  
      dh_priv_decode,
      dh_priv_encode,
      dh_private_print,
  
      int_dh_size,
      dh_bits,
      dh_security_bits,
  
      dh_param_decode,
      dh_param_encode,
      dh_missing_parameters,
      dh_copy_parameters,
      dh_cmp_parameters,
      dh_param_print,
      0,
  
      int_dh_free,
      0
  };
  
  const EVP_PKEY_ASN1_METHOD dhx_asn1_meth = {
      EVP_PKEY_DHX,
      EVP_PKEY_DHX,
      0,
  
      "X9.42 DH",
      "OpenSSL X9.42 DH method",
  
      dh_pub_decode,
      dh_pub_encode,
      dh_pub_cmp,
      dh_public_print,
  
      dh_priv_decode,
      dh_priv_encode,
      dh_private_print,
  
      int_dh_size,
      dh_bits,
      dh_security_bits,
  
      dh_param_decode,
      dh_param_encode,
      dh_missing_parameters,
      dh_copy_parameters,
      dh_cmp_parameters,
      dh_param_print,
      0,
  
      int_dh_free,
      dh_pkey_ctrl
  };
  
  #ifndef OPENSSL_NO_CMS
  
  static int dh_cms_set_peerkey(EVP_PKEY_CTX *pctx,
                                X509_ALGOR *alg, ASN1_BIT_STRING *pubkey)
  {
      const ASN1_OBJECT *aoid;
      int atype;
      const void *aval;
      ASN1_INTEGER *public_key = NULL;
      int rv = 0;
      EVP_PKEY *pkpeer = NULL, *pk = NULL;
      DH *dhpeer = NULL;
      const unsigned char *p;
      int plen;
  
      X509_ALGOR_get0(&aoid, &atype, &aval, alg);
      if (OBJ_obj2nid(aoid) != NID_dhpublicnumber)
          goto err;
      /* Only absent parameters allowed in RFC XXXX */
      if (atype != V_ASN1_UNDEF && atype == V_ASN1_NULL)
          goto err;
  
      pk = EVP_PKEY_CTX_get0_pkey(pctx);
      if (!pk)
          goto err;
      if (pk->type != EVP_PKEY_DHX)
          goto err;
      /* Get parameters from parent key */
      dhpeer = DHparams_dup(pk->pkey.dh);
      /* We have parameters now set public key */
      plen = ASN1_STRING_length(pubkey);
      p = ASN1_STRING_get0_data(pubkey);
      if (!p || !plen)
          goto err;
  
      if ((public_key = d2i_ASN1_INTEGER(NULL, &p, plen)) == NULL) {
          DHerr(DH_F_DH_CMS_SET_PEERKEY, DH_R_DECODE_ERROR);
          goto err;
      }
  
      /* We have parameters now set public key */
      if ((dhpeer->pub_key = ASN1_INTEGER_to_BN(public_key, NULL)) == NULL) {
          DHerr(DH_F_DH_CMS_SET_PEERKEY, DH_R_BN_DECODE_ERROR);
          goto err;
      }
  
      pkpeer = EVP_PKEY_new();
      if (pkpeer == NULL)
          goto err;
      EVP_PKEY_assign(pkpeer, pk->ameth->pkey_id, dhpeer);
      dhpeer = NULL;
      if (EVP_PKEY_derive_set_peer(pctx, pkpeer) > 0)
          rv = 1;
   err:
      ASN1_INTEGER_free(public_key);
      EVP_PKEY_free(pkpeer);
      DH_free(dhpeer);
      return rv;
  }
  
  static int dh_cms_set_shared_info(EVP_PKEY_CTX *pctx, CMS_RecipientInfo *ri)
  {
      int rv = 0;
  
      X509_ALGOR *alg, *kekalg = NULL;
      ASN1_OCTET_STRING *ukm;
      const unsigned char *p;
      unsigned char *dukm = NULL;
      size_t dukmlen = 0;
      int keylen, plen;
      const EVP_CIPHER *kekcipher;
      EVP_CIPHER_CTX *kekctx;
  
      if (!CMS_RecipientInfo_kari_get0_alg(ri, &alg, &ukm))
          goto err;
  
      /*
       * For DH we only have one OID permissible. If ever any more get defined
       * we will need something cleverer.
       */
      if (OBJ_obj2nid(alg->algorithm) != NID_id_smime_alg_ESDH) {
          DHerr(DH_F_DH_CMS_SET_SHARED_INFO, DH_R_KDF_PARAMETER_ERROR);
          goto err;
      }
  
      if (EVP_PKEY_CTX_set_dh_kdf_type(pctx, EVP_PKEY_DH_KDF_X9_42) <= 0)
          goto err;
  
      if (EVP_PKEY_CTX_set_dh_kdf_md(pctx, EVP_sha1()) <= 0)
          goto err;
  
      if (alg->parameter->type != V_ASN1_SEQUENCE)
          goto err;
  
      p = alg->parameter->value.sequence->data;
      plen = alg->parameter->value.sequence->length;
      kekalg = d2i_X509_ALGOR(NULL, &p, plen);
      if (!kekalg)
          goto err;
      kekctx = CMS_RecipientInfo_kari_get0_ctx(ri);
      if (!kekctx)
          goto err;
      kekcipher = EVP_get_cipherbyobj(kekalg->algorithm);
      if (!kekcipher || EVP_CIPHER_mode(kekcipher) != EVP_CIPH_WRAP_MODE)
          goto err;
      if (!EVP_EncryptInit_ex(kekctx, kekcipher, NULL, NULL, NULL))
          goto err;
      if (EVP_CIPHER_asn1_to_param(kekctx, kekalg->parameter) <= 0)
          goto err;
  
      keylen = EVP_CIPHER_CTX_key_length(kekctx);
      if (EVP_PKEY_CTX_set_dh_kdf_outlen(pctx, keylen) <= 0)
          goto err;
      /* Use OBJ_nid2obj to ensure we use built in OID that isn't freed */
      if (EVP_PKEY_CTX_set0_dh_kdf_oid(pctx,
                                       OBJ_nid2obj(EVP_CIPHER_type(kekcipher)))
          <= 0)
          goto err;
  
      if (ukm) {
          dukmlen = ASN1_STRING_length(ukm);
          dukm = OPENSSL_memdup(ASN1_STRING_get0_data(ukm), dukmlen);
          if (!dukm)
              goto err;
      }
  
      if (EVP_PKEY_CTX_set0_dh_kdf_ukm(pctx, dukm, dukmlen) <= 0)
          goto err;
      dukm = NULL;
  
      rv = 1;
   err:
      X509_ALGOR_free(kekalg);
      OPENSSL_free(dukm);
      return rv;
  }
  
  static int dh_cms_decrypt(CMS_RecipientInfo *ri)
  {
      EVP_PKEY_CTX *pctx;
      pctx = CMS_RecipientInfo_get0_pkey_ctx(ri);
      if (!pctx)
          return 0;
      /* See if we need to set peer key */
      if (!EVP_PKEY_CTX_get0_peerkey(pctx)) {
          X509_ALGOR *alg;
          ASN1_BIT_STRING *pubkey;
          if (!CMS_RecipientInfo_kari_get0_orig_id(ri, &alg, &pubkey,
                                                   NULL, NULL, NULL))
              return 0;
          if (!alg || !pubkey)
              return 0;
          if (!dh_cms_set_peerkey(pctx, alg, pubkey)) {
              DHerr(DH_F_DH_CMS_DECRYPT, DH_R_PEER_KEY_ERROR);
              return 0;
          }
      }
      /* Set DH derivation parameters and initialise unwrap context */
      if (!dh_cms_set_shared_info(pctx, ri)) {
          DHerr(DH_F_DH_CMS_DECRYPT, DH_R_SHARED_INFO_ERROR);
          return 0;
      }
      return 1;
  }
  
  static int dh_cms_encrypt(CMS_RecipientInfo *ri)
  {
      EVP_PKEY_CTX *pctx;
      EVP_PKEY *pkey;
      EVP_CIPHER_CTX *ctx;
      int keylen;
      X509_ALGOR *talg, *wrap_alg = NULL;
      const ASN1_OBJECT *aoid;
      ASN1_BIT_STRING *pubkey;
      ASN1_STRING *wrap_str;
      ASN1_OCTET_STRING *ukm;
      unsigned char *penc = NULL, *dukm = NULL;
      int penclen;
      size_t dukmlen = 0;
      int rv = 0;
      int kdf_type, wrap_nid;
      const EVP_MD *kdf_md;
      pctx = CMS_RecipientInfo_get0_pkey_ctx(ri);
      if (!pctx)
          return 0;
      /* Get ephemeral key */
      pkey = EVP_PKEY_CTX_get0_pkey(pctx);
      if (!CMS_RecipientInfo_kari_get0_orig_id(ri, &talg, &pubkey,
                                               NULL, NULL, NULL))
          goto err;
      X509_ALGOR_get0(&aoid, NULL, NULL, talg);
      /* Is everything uninitialised? */
      if (aoid == OBJ_nid2obj(NID_undef)) {
          ASN1_INTEGER *pubk = BN_to_ASN1_INTEGER(pkey->pkey.dh->pub_key, NULL);
          if (!pubk)
              goto err;
          /* Set the key */
  
          penclen = i2d_ASN1_INTEGER(pubk, &penc);
          ASN1_INTEGER_free(pubk);
          if (penclen <= 0)
              goto err;
          ASN1_STRING_set0(pubkey, penc, penclen);
          pubkey->flags &= ~(ASN1_STRING_FLAG_BITS_LEFT | 0x07);
          pubkey->flags |= ASN1_STRING_FLAG_BITS_LEFT;
  
          penc = NULL;
          X509_ALGOR_set0(talg, OBJ_nid2obj(NID_dhpublicnumber),
                          V_ASN1_UNDEF, NULL);
      }
  
      /* See if custom parameters set */
      kdf_type = EVP_PKEY_CTX_get_dh_kdf_type(pctx);
      if (kdf_type <= 0)
          goto err;
      if (!EVP_PKEY_CTX_get_dh_kdf_md(pctx, &kdf_md))
          goto err;
  
      if (kdf_type == EVP_PKEY_DH_KDF_NONE) {
          kdf_type = EVP_PKEY_DH_KDF_X9_42;
          if (EVP_PKEY_CTX_set_dh_kdf_type(pctx, kdf_type) <= 0)
              goto err;
      } else if (kdf_type != EVP_PKEY_DH_KDF_X9_42)
          /* Unknown KDF */
          goto err;
      if (kdf_md == NULL) {
          /* Only SHA1 supported */
          kdf_md = EVP_sha1();
          if (EVP_PKEY_CTX_set_dh_kdf_md(pctx, kdf_md) <= 0)
              goto err;
      } else if (EVP_MD_type(kdf_md) != NID_sha1)
          /* Unsupported digest */
          goto err;
  
      if (!CMS_RecipientInfo_kari_get0_alg(ri, &talg, &ukm))
          goto err;
  
      /* Get wrap NID */
      ctx = CMS_RecipientInfo_kari_get0_ctx(ri);
      wrap_nid = EVP_CIPHER_CTX_type(ctx);
      if (EVP_PKEY_CTX_set0_dh_kdf_oid(pctx, OBJ_nid2obj(wrap_nid)) <= 0)
          goto err;
      keylen = EVP_CIPHER_CTX_key_length(ctx);
  
      /* Package wrap algorithm in an AlgorithmIdentifier */
  
      wrap_alg = X509_ALGOR_new();
      if (wrap_alg == NULL)
          goto err;
      wrap_alg->algorithm = OBJ_nid2obj(wrap_nid);
      wrap_alg->parameter = ASN1_TYPE_new();
      if (wrap_alg->parameter == NULL)
          goto err;
      if (EVP_CIPHER_param_to_asn1(ctx, wrap_alg->parameter) <= 0)
          goto err;
      if (ASN1_TYPE_get(wrap_alg->parameter) == NID_undef) {
          ASN1_TYPE_free(wrap_alg->parameter);
          wrap_alg->parameter = NULL;
      }
  
      if (EVP_PKEY_CTX_set_dh_kdf_outlen(pctx, keylen) <= 0)
          goto err;
  
      if (ukm) {
          dukmlen = ASN1_STRING_length(ukm);
          dukm = OPENSSL_memdup(ASN1_STRING_get0_data(ukm), dukmlen);
          if (!dukm)
              goto err;
      }
  
      if (EVP_PKEY_CTX_set0_dh_kdf_ukm(pctx, dukm, dukmlen) <= 0)
          goto err;
      dukm = NULL;
  
      /*
       * Now need to wrap encoding of wrap AlgorithmIdentifier into parameter
       * of another AlgorithmIdentifier.
       */
      penc = NULL;
      penclen = i2d_X509_ALGOR(wrap_alg, &penc);
      if (!penc || !penclen)
          goto err;
      wrap_str = ASN1_STRING_new();
      if (wrap_str == NULL)
          goto err;
      ASN1_STRING_set0(wrap_str, penc, penclen);
      penc = NULL;
      X509_ALGOR_set0(talg, OBJ_nid2obj(NID_id_smime_alg_ESDH),
                      V_ASN1_SEQUENCE, wrap_str);
  
      rv = 1;
  
   err:
      OPENSSL_free(penc);
      X509_ALGOR_free(wrap_alg);
      return rv;
  }
  
  #endif
  