1 | /*
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2 | * Copyright 2006-2023 The OpenSSL Project Authors. All Rights Reserved.
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3 | *
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4 | * Licensed under the Apache License 2.0 (the "License"). You may not use
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5 | * this file except in compliance with the License. You can obtain a copy
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6 | * in the file LICENSE in the source distribution or at
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7 | * https://www.openssl.org/source/license.html
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8 | */
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9 |
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10 | #include <assert.h>
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11 | #include <limits.h>
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12 | #include <openssl/cms.h>
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13 | #include <openssl/err.h>
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14 | #include <openssl/decoder.h>
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15 | #include "internal/sizes.h"
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16 | #include "crypto/evp.h"
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17 | #include "cms_local.h"
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18 |
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19 | static EVP_PKEY *pkey_type2param(int ptype, const void *pval,
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20 | OSSL_LIB_CTX *libctx, const char *propq)
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21 | {
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22 | EVP_PKEY *pkey = NULL;
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23 | EVP_PKEY_CTX *pctx = NULL;
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24 | OSSL_DECODER_CTX *ctx = NULL;
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25 |
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26 | if (ptype == V_ASN1_SEQUENCE) {
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27 | const ASN1_STRING *pstr = pval;
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28 | const unsigned char *pm = pstr->data;
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29 | size_t pmlen = (size_t)pstr->length;
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30 | int selection = OSSL_KEYMGMT_SELECT_ALL_PARAMETERS;
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31 |
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32 | ctx = OSSL_DECODER_CTX_new_for_pkey(&pkey, "DER", NULL, "EC",
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33 | selection, libctx, propq);
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34 | if (ctx == NULL)
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35 | goto err;
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36 |
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37 | if (!OSSL_DECODER_from_data(ctx, &pm, &pmlen)) {
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38 | ERR_raise(ERR_LIB_CMS, CMS_R_DECODE_ERROR);
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39 | goto err;
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40 | }
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41 | OSSL_DECODER_CTX_free(ctx);
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42 | return pkey;
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43 | } else if (ptype == V_ASN1_OBJECT) {
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44 | const ASN1_OBJECT *poid = pval;
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45 | char groupname[OSSL_MAX_NAME_SIZE];
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46 |
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47 | /* type == V_ASN1_OBJECT => the parameters are given by an asn1 OID */
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48 | pctx = EVP_PKEY_CTX_new_from_name(libctx, "EC", propq);
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49 | if (pctx == NULL || EVP_PKEY_paramgen_init(pctx) <= 0)
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50 | goto err;
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51 | if (OBJ_obj2txt(groupname, sizeof(groupname), poid, 0) <= 0
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52 | || EVP_PKEY_CTX_set_group_name(pctx, groupname) <= 0) {
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53 | ERR_raise(ERR_LIB_CMS, CMS_R_DECODE_ERROR);
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54 | goto err;
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55 | }
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56 | if (EVP_PKEY_paramgen(pctx, &pkey) <= 0)
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57 | goto err;
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58 | EVP_PKEY_CTX_free(pctx);
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59 | return pkey;
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60 | }
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61 |
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62 | ERR_raise(ERR_LIB_CMS, CMS_R_DECODE_ERROR);
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63 | return NULL;
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64 |
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65 | err:
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66 | EVP_PKEY_free(pkey);
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67 | EVP_PKEY_CTX_free(pctx);
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68 | OSSL_DECODER_CTX_free(ctx);
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69 | return NULL;
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70 | }
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71 |
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72 | static int ecdh_cms_set_peerkey(EVP_PKEY_CTX *pctx,
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73 | X509_ALGOR *alg, ASN1_BIT_STRING *pubkey)
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74 | {
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75 | const ASN1_OBJECT *aoid;
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76 | int atype;
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77 | const void *aval;
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78 | int rv = 0;
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79 | EVP_PKEY *pkpeer = NULL;
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80 | const unsigned char *p;
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81 | int plen;
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82 |
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83 | X509_ALGOR_get0(&aoid, &atype, &aval, alg);
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84 | if (OBJ_obj2nid(aoid) != NID_X9_62_id_ecPublicKey)
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85 | goto err;
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86 |
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87 | /* If absent parameters get group from main key */
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88 | if (atype == V_ASN1_UNDEF || atype == V_ASN1_NULL) {
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89 | EVP_PKEY *pk;
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90 |
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91 | pk = EVP_PKEY_CTX_get0_pkey(pctx);
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92 | if (pk == NULL)
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93 | goto err;
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94 |
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95 | pkpeer = EVP_PKEY_new();
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96 | if (pkpeer == NULL)
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97 | goto err;
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98 | if (!EVP_PKEY_copy_parameters(pkpeer, pk))
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99 | goto err;
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100 | } else {
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101 | pkpeer = pkey_type2param(atype, aval,
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102 | EVP_PKEY_CTX_get0_libctx(pctx),
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103 | EVP_PKEY_CTX_get0_propq(pctx));
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104 | if (pkpeer == NULL)
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105 | goto err;
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106 | }
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107 | /* We have parameters now set public key */
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108 | plen = ASN1_STRING_length(pubkey);
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109 | p = ASN1_STRING_get0_data(pubkey);
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110 | if (p == NULL || plen == 0)
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111 | goto err;
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112 |
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113 | if (!EVP_PKEY_set1_encoded_public_key(pkpeer, p, plen))
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114 | goto err;
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115 |
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116 | if (EVP_PKEY_derive_set_peer(pctx, pkpeer) > 0)
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117 | rv = 1;
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118 | err:
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119 | EVP_PKEY_free(pkpeer);
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120 | return rv;
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121 | }
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122 |
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123 | /* Set KDF parameters based on KDF NID */
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124 | static int ecdh_cms_set_kdf_param(EVP_PKEY_CTX *pctx, int eckdf_nid)
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125 | {
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126 | int kdf_nid, kdfmd_nid, cofactor;
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127 | const EVP_MD *kdf_md;
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128 |
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129 | if (eckdf_nid == NID_undef)
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130 | return 0;
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131 |
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132 | /* Lookup KDF type, cofactor mode and digest */
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133 | if (!OBJ_find_sigid_algs(eckdf_nid, &kdfmd_nid, &kdf_nid))
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134 | return 0;
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135 |
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136 | if (kdf_nid == NID_dh_std_kdf)
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137 | cofactor = 0;
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138 | else if (kdf_nid == NID_dh_cofactor_kdf)
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139 | cofactor = 1;
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140 | else
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141 | return 0;
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142 |
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143 | if (EVP_PKEY_CTX_set_ecdh_cofactor_mode(pctx, cofactor) <= 0)
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144 | return 0;
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145 |
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146 | if (EVP_PKEY_CTX_set_ecdh_kdf_type(pctx, EVP_PKEY_ECDH_KDF_X9_63) <= 0)
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147 | return 0;
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148 |
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149 | kdf_md = EVP_get_digestbynid(kdfmd_nid);
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150 | if (!kdf_md)
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151 | return 0;
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152 |
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153 | if (EVP_PKEY_CTX_set_ecdh_kdf_md(pctx, kdf_md) <= 0)
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154 | return 0;
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155 | return 1;
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156 | }
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157 |
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158 | static int ecdh_cms_set_shared_info(EVP_PKEY_CTX *pctx, CMS_RecipientInfo *ri)
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159 | {
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160 | int rv = 0;
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161 | X509_ALGOR *alg, *kekalg = NULL;
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162 | ASN1_OCTET_STRING *ukm;
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163 | const unsigned char *p;
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164 | unsigned char *der = NULL;
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165 | int plen, keylen;
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166 | EVP_CIPHER *kekcipher = NULL;
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167 | EVP_CIPHER_CTX *kekctx;
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168 | char name[OSSL_MAX_NAME_SIZE];
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169 |
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170 | if (!CMS_RecipientInfo_kari_get0_alg(ri, &alg, &ukm))
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171 | return 0;
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172 |
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173 | if (!ecdh_cms_set_kdf_param(pctx, OBJ_obj2nid(alg->algorithm))) {
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174 | ERR_raise(ERR_LIB_CMS, CMS_R_KDF_PARAMETER_ERROR);
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175 | return 0;
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176 | }
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177 |
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178 | if (alg->parameter->type != V_ASN1_SEQUENCE)
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179 | return 0;
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180 |
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181 | p = alg->parameter->value.sequence->data;
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182 | plen = alg->parameter->value.sequence->length;
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183 | kekalg = d2i_X509_ALGOR(NULL, &p, plen);
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184 | if (kekalg == NULL)
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185 | goto err;
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186 | kekctx = CMS_RecipientInfo_kari_get0_ctx(ri);
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187 | if (kekctx == NULL)
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188 | goto err;
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189 | OBJ_obj2txt(name, sizeof(name), kekalg->algorithm, 0);
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190 | kekcipher = EVP_CIPHER_fetch(pctx->libctx, name, pctx->propquery);
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191 | if (kekcipher == NULL || EVP_CIPHER_get_mode(kekcipher) != EVP_CIPH_WRAP_MODE)
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192 | goto err;
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193 | if (!EVP_EncryptInit_ex(kekctx, kekcipher, NULL, NULL, NULL))
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194 | goto err;
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195 | if (EVP_CIPHER_asn1_to_param(kekctx, kekalg->parameter) <= 0)
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196 | goto err;
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197 |
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198 | keylen = EVP_CIPHER_CTX_get_key_length(kekctx);
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199 | if (EVP_PKEY_CTX_set_ecdh_kdf_outlen(pctx, keylen) <= 0)
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200 | goto err;
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201 |
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202 | plen = CMS_SharedInfo_encode(&der, kekalg, ukm, keylen);
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203 |
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204 | if (plen <= 0)
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205 | goto err;
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206 |
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207 | if (EVP_PKEY_CTX_set0_ecdh_kdf_ukm(pctx, der, plen) <= 0)
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208 | goto err;
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209 | der = NULL;
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210 |
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211 | rv = 1;
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212 | err:
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213 | EVP_CIPHER_free(kekcipher);
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214 | X509_ALGOR_free(kekalg);
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215 | OPENSSL_free(der);
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216 | return rv;
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217 | }
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218 |
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219 | static int ecdh_cms_decrypt(CMS_RecipientInfo *ri)
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220 | {
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221 | EVP_PKEY_CTX *pctx;
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222 |
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223 | pctx = CMS_RecipientInfo_get0_pkey_ctx(ri);
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224 | if (pctx == NULL)
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225 | return 0;
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226 | /* See if we need to set peer key */
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227 | if (!EVP_PKEY_CTX_get0_peerkey(pctx)) {
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228 | X509_ALGOR *alg;
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229 | ASN1_BIT_STRING *pubkey;
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230 |
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231 | if (!CMS_RecipientInfo_kari_get0_orig_id(ri, &alg, &pubkey,
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232 | NULL, NULL, NULL))
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233 | return 0;
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234 | if (alg == NULL || pubkey == NULL)
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235 | return 0;
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236 | if (!ecdh_cms_set_peerkey(pctx, alg, pubkey)) {
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237 | ERR_raise(ERR_LIB_CMS, CMS_R_PEER_KEY_ERROR);
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238 | return 0;
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239 | }
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240 | }
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241 | /* Set ECDH derivation parameters and initialise unwrap context */
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242 | if (!ecdh_cms_set_shared_info(pctx, ri)) {
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243 | ERR_raise(ERR_LIB_CMS, CMS_R_SHARED_INFO_ERROR);
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244 | return 0;
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245 | }
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246 | return 1;
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247 | }
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248 |
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249 | static int ecdh_cms_encrypt(CMS_RecipientInfo *ri)
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250 | {
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251 | EVP_PKEY_CTX *pctx;
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252 | EVP_PKEY *pkey;
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253 | EVP_CIPHER_CTX *ctx;
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254 | int keylen;
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255 | X509_ALGOR *talg, *wrap_alg = NULL;
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256 | const ASN1_OBJECT *aoid;
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257 | ASN1_BIT_STRING *pubkey;
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258 | ASN1_STRING *wrap_str;
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259 | ASN1_OCTET_STRING *ukm;
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260 | unsigned char *penc = NULL;
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261 | int penclen;
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262 | int rv = 0;
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263 | int ecdh_nid, kdf_type, kdf_nid, wrap_nid;
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264 | const EVP_MD *kdf_md;
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265 |
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266 | pctx = CMS_RecipientInfo_get0_pkey_ctx(ri);
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267 | if (pctx == NULL)
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268 | return 0;
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269 | /* Get ephemeral key */
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270 | pkey = EVP_PKEY_CTX_get0_pkey(pctx);
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271 | if (!CMS_RecipientInfo_kari_get0_orig_id(ri, &talg, &pubkey,
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272 | NULL, NULL, NULL))
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273 | goto err;
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274 | X509_ALGOR_get0(&aoid, NULL, NULL, talg);
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275 | /* Is everything uninitialised? */
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276 | if (aoid == OBJ_nid2obj(NID_undef)) {
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277 | /* Set the key */
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278 | size_t enckeylen;
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279 |
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280 | enckeylen = EVP_PKEY_get1_encoded_public_key(pkey, &penc);
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281 | if (enckeylen > INT_MAX || enckeylen == 0)
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282 | goto err;
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283 | ASN1_STRING_set0(pubkey, penc, (int)enckeylen);
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284 | pubkey->flags &= ~(ASN1_STRING_FLAG_BITS_LEFT | 0x07);
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285 | pubkey->flags |= ASN1_STRING_FLAG_BITS_LEFT;
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286 |
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287 | penc = NULL;
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288 | (void)X509_ALGOR_set0(talg, OBJ_nid2obj(NID_X9_62_id_ecPublicKey),
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289 | V_ASN1_UNDEF, NULL); /* cannot fail */
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290 | }
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291 |
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292 | /* See if custom parameters set */
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293 | kdf_type = EVP_PKEY_CTX_get_ecdh_kdf_type(pctx);
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294 | if (kdf_type <= 0)
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295 | goto err;
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296 | if (EVP_PKEY_CTX_get_ecdh_kdf_md(pctx, &kdf_md) <= 0)
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297 | goto err;
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298 | ecdh_nid = EVP_PKEY_CTX_get_ecdh_cofactor_mode(pctx);
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299 | if (ecdh_nid < 0)
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300 | goto err;
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301 | else if (ecdh_nid == 0)
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302 | ecdh_nid = NID_dh_std_kdf;
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303 | else if (ecdh_nid == 1)
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304 | ecdh_nid = NID_dh_cofactor_kdf;
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305 |
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306 | if (kdf_type == EVP_PKEY_ECDH_KDF_NONE) {
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307 | kdf_type = EVP_PKEY_ECDH_KDF_X9_63;
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308 | if (EVP_PKEY_CTX_set_ecdh_kdf_type(pctx, kdf_type) <= 0)
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309 | goto err;
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310 | } else
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311 | /* Unknown KDF */
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312 | goto err;
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313 | if (kdf_md == NULL) {
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314 | /* Fixme later for better MD */
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315 | kdf_md = EVP_sha1();
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316 | if (EVP_PKEY_CTX_set_ecdh_kdf_md(pctx, kdf_md) <= 0)
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317 | goto err;
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318 | }
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319 |
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320 | if (!CMS_RecipientInfo_kari_get0_alg(ri, &talg, &ukm))
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321 | goto err;
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322 |
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323 | /* Lookup NID for KDF+cofactor+digest */
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324 |
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325 | if (!OBJ_find_sigid_by_algs(&kdf_nid, EVP_MD_get_type(kdf_md), ecdh_nid))
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326 | goto err;
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327 | /* Get wrap NID */
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328 | ctx = CMS_RecipientInfo_kari_get0_ctx(ri);
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329 | wrap_nid = EVP_CIPHER_CTX_get_type(ctx);
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330 | keylen = EVP_CIPHER_CTX_get_key_length(ctx);
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331 |
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332 | /* Package wrap algorithm in an AlgorithmIdentifier */
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333 |
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334 | wrap_alg = X509_ALGOR_new();
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335 | if (wrap_alg == NULL)
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336 | goto err;
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337 | wrap_alg->algorithm = OBJ_nid2obj(wrap_nid);
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338 | wrap_alg->parameter = ASN1_TYPE_new();
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339 | if (wrap_alg->parameter == NULL)
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340 | goto err;
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341 | if (EVP_CIPHER_param_to_asn1(ctx, wrap_alg->parameter) <= 0)
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342 | goto err;
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343 | if (ASN1_TYPE_get(wrap_alg->parameter) == NID_undef) {
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344 | ASN1_TYPE_free(wrap_alg->parameter);
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345 | wrap_alg->parameter = NULL;
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346 | }
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347 |
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348 | if (EVP_PKEY_CTX_set_ecdh_kdf_outlen(pctx, keylen) <= 0)
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349 | goto err;
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350 |
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351 | penclen = CMS_SharedInfo_encode(&penc, wrap_alg, ukm, keylen);
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352 |
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353 | if (penclen <= 0)
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354 | goto err;
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355 |
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356 | if (EVP_PKEY_CTX_set0_ecdh_kdf_ukm(pctx, penc, penclen) <= 0)
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357 | goto err;
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358 | penc = NULL;
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359 |
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360 | /*
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361 | * Now need to wrap encoding of wrap AlgorithmIdentifier into parameter
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362 | * of another AlgorithmIdentifier.
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363 | */
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364 | penclen = i2d_X509_ALGOR(wrap_alg, &penc);
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365 | if (penclen <= 0)
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366 | goto err;
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367 | wrap_str = ASN1_STRING_new();
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368 | if (wrap_str == NULL)
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369 | goto err;
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370 | ASN1_STRING_set0(wrap_str, penc, penclen);
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371 | penc = NULL;
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372 | X509_ALGOR_set0(talg, OBJ_nid2obj(kdf_nid), V_ASN1_SEQUENCE, wrap_str);
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373 |
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374 | rv = 1;
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375 |
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376 | err:
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377 | OPENSSL_free(penc);
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378 | X509_ALGOR_free(wrap_alg);
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379 | return rv;
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380 | }
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381 |
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382 | int ossl_cms_ecdh_envelope(CMS_RecipientInfo *ri, int decrypt)
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383 | {
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384 | assert(decrypt == 0 || decrypt == 1);
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385 |
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386 | if (decrypt == 1)
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387 | return ecdh_cms_decrypt(ri);
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388 |
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389 | if (decrypt == 0)
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390 | return ecdh_cms_encrypt(ri);
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391 |
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392 | ERR_raise(ERR_LIB_CMS, CMS_R_NOT_SUPPORTED_FOR_THIS_KEY_TYPE);
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393 | return 0;
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394 | }
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