crypto/cms/cms_dh.c

   1 /*
   2  * Copyright 2006-2021 The OpenSSL Project Authors. All Rights Reserved.
   3  *
   4  * Licensed under the Apache License 2.0 (the "License").  You may not use
   5  * this file except in compliance with the License.  You can obtain a copy
   6  * in the file LICENSE in the source distribution or at
   7  * https://www.openssl.org/source/license.html
   8  */
   9
  10 #include <assert.h>
  11 #include <openssl/cms.h>
  12 #include <openssl/dh.h>
  13 #include <openssl/err.h>
  14 #include <openssl/core_names.h>
  15 #include "internal/sizes.h"
  16 #include "crypto/evp.h"
  17 #include "cms_local.h"
  18
  19 static int dh_cms_set_peerkey(EVP_PKEY_CTX *pctx,
  20                               X509_ALGOR *alg, ASN1_BIT_STRING *pubkey)
  21 {
  22     const ASN1_OBJECT *aoid;
  23     int atype;
  24     const void *aval;
  25     ASN1_INTEGER *public_key = NULL;
  26     int rv = 0;
  27     EVP_PKEY *pkpeer = NULL, *pk = NULL;
  28     BIGNUM *bnpub = NULL;
  29     const unsigned char *p;
  30     unsigned char *buf = NULL;
  31     int plen;
  32
  33     X509_ALGOR_get0(&aoid, &atype, &aval, alg);
  34     if (OBJ_obj2nid(aoid) != NID_dhpublicnumber)
  35         goto err;
  36     /* Only absent parameters allowed in RFC XXXX */
  37     if (atype != V_ASN1_UNDEF && atype == V_ASN1_NULL)
  38         goto err;
  39
  40     pk = EVP_PKEY_CTX_get0_pkey(pctx);
  41     if (pk == NULL || !EVP_PKEY_is_a(pk, "DHX"))
  42         goto err;
  43
  44     /* Get public key */
  45     plen = ASN1_STRING_length(pubkey);
  46     p = ASN1_STRING_get0_data(pubkey);
  47     if (p == NULL || plen == 0)
  48         goto err;
  49
  50     if ((public_key = d2i_ASN1_INTEGER(NULL, &p, plen)) == NULL)
  51         goto err;
  52     /*
  53      * Pad to full p parameter size as that is checked by
  54      * EVP_PKEY_set1_encoded_public_key()
  55      */
  56     plen = EVP_PKEY_get_size(pk);
  57     if ((bnpub = ASN1_INTEGER_to_BN(public_key, NULL)) == NULL)
  58         goto err;
  59     if ((buf = OPENSSL_malloc(plen)) == NULL)
  60         goto err;
  61     if (BN_bn2binpad(bnpub, buf, plen) < 0)
  62         goto err;
  63
  64     pkpeer = EVP_PKEY_new();
  65     if (pkpeer == NULL
  66             || !EVP_PKEY_copy_parameters(pkpeer, pk)
  67             || !EVP_PKEY_set1_encoded_public_key(pkpeer, buf, plen))
  68         goto err;
  69
  70     if (EVP_PKEY_derive_set_peer(pctx, pkpeer) > 0)
  71         rv = 1;
  72  err:
  73     ASN1_INTEGER_free(public_key);
  74     BN_free(bnpub);
  75     OPENSSL_free(buf);
  76     EVP_PKEY_free(pkpeer);
  77     return rv;
  78 }
  79
  80 static int dh_cms_set_shared_info(EVP_PKEY_CTX *pctx, CMS_RecipientInfo *ri)
  81 {
  82     int rv = 0;
  83     X509_ALGOR *alg, *kekalg = NULL;
  84     ASN1_OCTET_STRING *ukm;
  85     const unsigned char *p;
  86     unsigned char *dukm = NULL;
  87     size_t dukmlen = 0;
  88     int keylen, plen;
  89     EVP_CIPHER *kekcipher = NULL;
  90     EVP_CIPHER_CTX *kekctx;
  91     char name[OSSL_MAX_NAME_SIZE];
  92
  93     if (!CMS_RecipientInfo_kari_get0_alg(ri, &alg, &ukm))
  94         goto err;
  95
  96     /*
  97      * For DH we only have one OID permissible. If ever any more get defined
  98      * we will need something cleverer.
  99      */
 100     if (OBJ_obj2nid(alg->algorithm) != NID_id_smime_alg_ESDH) {
 101         ERR_raise(ERR_LIB_CMS, CMS_R_KDF_PARAMETER_ERROR);
 102         goto err;
 103     }
 104
 105     if (EVP_PKEY_CTX_set_dh_kdf_type(pctx, EVP_PKEY_DH_KDF_X9_42) <= 0
 106             || EVP_PKEY_CTX_set_dh_kdf_md(pctx, EVP_sha1()) <= 0)
 107         goto err;
 108
 109     if (alg->parameter->type != V_ASN1_SEQUENCE)
 110         goto err;
 111
 112     p = alg->parameter->value.sequence->data;
 113     plen = alg->parameter->value.sequence->length;
 114     kekalg = d2i_X509_ALGOR(NULL, &p, plen);
 115     if (kekalg == NULL)
 116         goto err;
 117     kekctx = CMS_RecipientInfo_kari_get0_ctx(ri);
 118     if (kekctx == NULL)
 119         goto err;
 120
 121     if (!OBJ_obj2txt(name, sizeof(name), kekalg->algorithm, 0))
 122         goto err;
 123
 124     kekcipher = EVP_CIPHER_fetch(pctx->libctx, name, pctx->propquery);
 125     if (kekcipher == NULL
 126         || EVP_CIPHER_get_mode(kekcipher) != EVP_CIPH_WRAP_MODE)
 127         goto err;
 128     if (!EVP_EncryptInit_ex(kekctx, kekcipher, NULL, NULL, NULL))
 129         goto err;
 130     if (EVP_CIPHER_asn1_to_param(kekctx, kekalg->parameter) <= 0)
 131         goto err;
 132
 133     keylen = EVP_CIPHER_CTX_get_key_length(kekctx);
 134     if (EVP_PKEY_CTX_set_dh_kdf_outlen(pctx, keylen) <= 0)
 135         goto err;
 136     /* Use OBJ_nid2obj to ensure we use built in OID that isn't freed */
 137     if (EVP_PKEY_CTX_set0_dh_kdf_oid(pctx,
 138                                      OBJ_nid2obj(EVP_CIPHER_get_type(kekcipher)))
 139         <= 0)
 140         goto err;
 141
 142     if (ukm != NULL) {
 143         dukmlen = ASN1_STRING_length(ukm);
 144         dukm = OPENSSL_memdup(ASN1_STRING_get0_data(ukm), dukmlen);
 145         if (dukm == NULL)
 146             goto err;
 147     }
 148
 149     if (EVP_PKEY_CTX_set0_dh_kdf_ukm(pctx, dukm, dukmlen) <= 0)
 150         goto err;
 151     dukm = NULL;
 152
 153     rv = 1;
 154  err:
 155     X509_ALGOR_free(kekalg);
 156     EVP_CIPHER_free(kekcipher);
 157     OPENSSL_free(dukm);
 158     return rv;
 159 }
 160
 161 static int dh_cms_decrypt(CMS_RecipientInfo *ri)
 162 {
 163     EVP_PKEY_CTX *pctx = CMS_RecipientInfo_get0_pkey_ctx(ri);
 164
 165     if (pctx == NULL)
 166         return 0;
 167     /* See if we need to set peer key */
 168     if (!EVP_PKEY_CTX_get0_peerkey(pctx)) {
 169         X509_ALGOR *alg;
 170         ASN1_BIT_STRING *pubkey;
 171
 172         if (!CMS_RecipientInfo_kari_get0_orig_id(ri, &alg, &pubkey,
 173                                                  NULL, NULL, NULL))
 174             return 0;
 175         if (alg ==  NULL || pubkey == NULL)
 176             return 0;
 177         if (!dh_cms_set_peerkey(pctx, alg, pubkey)) {
 178             ERR_raise(ERR_LIB_CMS, CMS_R_PEER_KEY_ERROR);
 179             return 0;
 180         }
 181     }
 182     /* Set DH derivation parameters and initialise unwrap context */
 183     if (!dh_cms_set_shared_info(pctx, ri)) {
 184         ERR_raise(ERR_LIB_CMS, CMS_R_SHARED_INFO_ERROR);
 185         return 0;
 186     }
 187     return 1;
 188 }
 189
 190 static int dh_cms_encrypt(CMS_RecipientInfo *ri)
 191 {
 192     EVP_PKEY_CTX *pctx;
 193     EVP_PKEY *pkey;
 194     EVP_CIPHER_CTX *ctx;
 195     int keylen;
 196     X509_ALGOR *talg, *wrap_alg = NULL;
 197     const ASN1_OBJECT *aoid;
 198     ASN1_BIT_STRING *pubkey;
 199     ASN1_STRING *wrap_str;
 200     ASN1_OCTET_STRING *ukm;
 201     unsigned char *penc = NULL, *dukm = NULL;
 202     int penclen;
 203     size_t dukmlen = 0;
 204     int rv = 0;
 205     int kdf_type, wrap_nid;
 206     const EVP_MD *kdf_md;
 207
 208     pctx = CMS_RecipientInfo_get0_pkey_ctx(ri);
 209     if (pctx == NULL)
 210         return 0;
 211     /* Get ephemeral key */
 212     pkey = EVP_PKEY_CTX_get0_pkey(pctx);
 213     if (!CMS_RecipientInfo_kari_get0_orig_id(ri, &talg, &pubkey,
 214                                              NULL, NULL, NULL))
 215         goto err;
 216
 217     /* Is everything uninitialised? */
 218     X509_ALGOR_get0(&aoid, NULL, NULL, talg);
 219     if (aoid == OBJ_nid2obj(NID_undef)) {
 220         BIGNUM *bn_pub_key = NULL;
 221         ASN1_INTEGER *pubk;
 222
 223         if (!EVP_PKEY_get_bn_param(pkey, OSSL_PKEY_PARAM_PUB_KEY, &bn_pub_key))
 224             goto err;
 225
 226         pubk = BN_to_ASN1_INTEGER(bn_pub_key, NULL);
 227         BN_free(bn_pub_key);
 228         if (pubk == NULL)
 229             goto err;
 230
 231         /* Set the key */
 232         penclen = i2d_ASN1_INTEGER(pubk, &penc);
 233         ASN1_INTEGER_free(pubk);
 234         if (penclen <= 0)
 235             goto err;
 236         ASN1_STRING_set0(pubkey, penc, penclen);
 237         pubkey->flags &= ~(ASN1_STRING_FLAG_BITS_LEFT | 0x07);
 238         pubkey->flags |= ASN1_STRING_FLAG_BITS_LEFT;
 239
 240         penc = NULL;
 241         X509_ALGOR_set0(talg, OBJ_nid2obj(NID_dhpublicnumber),
 242                         V_ASN1_UNDEF, NULL);
 243     }
 244
 245     /* See if custom parameters set */
 246     kdf_type = EVP_PKEY_CTX_get_dh_kdf_type(pctx);
 247     if (kdf_type <= 0 || !EVP_PKEY_CTX_get_dh_kdf_md(pctx, &kdf_md))
 248         goto err;
 249
 250     if (kdf_type == EVP_PKEY_DH_KDF_NONE) {
 251         kdf_type = EVP_PKEY_DH_KDF_X9_42;
 252         if (EVP_PKEY_CTX_set_dh_kdf_type(pctx, kdf_type) <= 0)
 253             goto err;
 254     } else if (kdf_type != EVP_PKEY_DH_KDF_X9_42)
 255         /* Unknown KDF */
 256         goto err;
 257     if (kdf_md == NULL) {
 258         /* Only SHA1 supported */
 259         kdf_md = EVP_sha1();
 260         if (EVP_PKEY_CTX_set_dh_kdf_md(pctx, kdf_md) <= 0)
 261             goto err;
 262     } else if (EVP_MD_get_type(kdf_md) != NID_sha1)
 263         /* Unsupported digest */
 264         goto err;
 265
 266     if (!CMS_RecipientInfo_kari_get0_alg(ri, &talg, &ukm))
 267         goto err;
 268
 269     /* Get wrap NID */
 270     ctx = CMS_RecipientInfo_kari_get0_ctx(ri);
 271     wrap_nid = EVP_CIPHER_CTX_get_type(ctx);
 272     if (EVP_PKEY_CTX_set0_dh_kdf_oid(pctx, OBJ_nid2obj(wrap_nid)) <= 0)
 273         goto err;
 274     keylen = EVP_CIPHER_CTX_get_key_length(ctx);
 275
 276     /* Package wrap algorithm in an AlgorithmIdentifier */
 277
 278     wrap_alg = X509_ALGOR_new();
 279     if (wrap_alg == NULL)
 280         goto err;
 281     wrap_alg->algorithm = OBJ_nid2obj(wrap_nid);
 282     wrap_alg->parameter = ASN1_TYPE_new();
 283     if (wrap_alg->parameter == NULL)
 284         goto err;
 285     if (EVP_CIPHER_param_to_asn1(ctx, wrap_alg->parameter) <= 0)
 286         goto err;
 287     if (ASN1_TYPE_get(wrap_alg->parameter) == NID_undef) {
 288         ASN1_TYPE_free(wrap_alg->parameter);
 289         wrap_alg->parameter = NULL;
 290     }
 291
 292     if (EVP_PKEY_CTX_set_dh_kdf_outlen(pctx, keylen) <= 0)
 293         goto err;
 294
 295     if (ukm != NULL) {
 296         dukmlen = ASN1_STRING_length(ukm);
 297         dukm = OPENSSL_memdup(ASN1_STRING_get0_data(ukm), dukmlen);
 298         if (dukm == NULL)
 299             goto err;
 300     }
 301
 302     if (EVP_PKEY_CTX_set0_dh_kdf_ukm(pctx, dukm, dukmlen) <= 0)
 303         goto err;
 304     dukm = NULL;
 305
 306     /*
 307      * Now need to wrap encoding of wrap AlgorithmIdentifier into parameter
 308      * of another AlgorithmIdentifier.
 309      */
 310     penc = NULL;
 311     penclen = i2d_X509_ALGOR(wrap_alg, &penc);
 312     if (penc == NULL || penclen == 0)
 313         goto err;
 314     wrap_str = ASN1_STRING_new();
 315     if (wrap_str == NULL)
 316         goto err;
 317     ASN1_STRING_set0(wrap_str, penc, penclen);
 318     penc = NULL;
 319     X509_ALGOR_set0(talg, OBJ_nid2obj(NID_id_smime_alg_ESDH),
 320                     V_ASN1_SEQUENCE, wrap_str);
 321
 322     rv = 1;
 323
 324  err:
 325     OPENSSL_free(penc);
 326     X509_ALGOR_free(wrap_alg);
 327     OPENSSL_free(dukm);
 328     return rv;
 329 }
 330
 331 int ossl_cms_dh_envelope(CMS_RecipientInfo *ri, int decrypt)
 332 {
 333     assert(decrypt == 0 || decrypt == 1);
 334
 335     if (decrypt == 1)
 336         return dh_cms_decrypt(ri);
 337
 338     if (decrypt == 0)
 339         return dh_cms_encrypt(ri);
 340
 341     ERR_raise(ERR_LIB_CMS, CMS_R_NOT_SUPPORTED_FOR_THIS_KEY_TYPE);
 342     return 0;
 343 }