1 | /*
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2 | * Copyright 2006-2016 The OpenSSL Project Authors. All Rights Reserved.
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3 | *
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4 | * Licensed under the OpenSSL license (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 <stdio.h>
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11 | #include "internal/cryptlib.h"
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12 | #include <openssl/x509.h>
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13 | #include <openssl/ec.h>
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14 | #include <openssl/rand.h>
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15 | #include "internal/asn1_int.h"
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16 | #include "internal/evp_int.h"
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17 | #include "ec_lcl.h"
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18 |
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19 | #define X25519_KEYLEN 32
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20 | #define X25519_BITS 253
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21 | #define X25519_SECURITY_BITS 128
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22 |
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23 | typedef struct {
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24 | unsigned char pubkey[X25519_KEYLEN];
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25 | unsigned char *privkey;
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26 | } X25519_KEY;
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27 |
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28 | typedef enum {
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29 | X25519_PUBLIC,
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30 | X25519_PRIVATE,
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31 | X25519_KEYGEN
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32 | } ecx_key_op_t;
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33 |
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34 | /* Setup EVP_PKEY using public, private or generation */
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35 | static int ecx_key_op(EVP_PKEY *pkey, const X509_ALGOR *palg,
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36 | const unsigned char *p, int plen, ecx_key_op_t op)
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37 | {
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38 | X25519_KEY *xkey;
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39 |
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40 | if (op != X25519_KEYGEN) {
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41 | if (palg != NULL) {
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42 | int ptype;
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43 |
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44 | /* Algorithm parameters must be absent */
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45 | X509_ALGOR_get0(NULL, &ptype, NULL, palg);
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46 | if (ptype != V_ASN1_UNDEF) {
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47 | ECerr(EC_F_ECX_KEY_OP, EC_R_INVALID_ENCODING);
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48 | return 0;
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49 | }
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50 | }
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51 |
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52 | if (p == NULL || plen != X25519_KEYLEN) {
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53 | ECerr(EC_F_ECX_KEY_OP, EC_R_INVALID_ENCODING);
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54 | return 0;
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55 | }
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56 | }
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57 |
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58 | xkey = OPENSSL_zalloc(sizeof(*xkey));
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59 | if (xkey == NULL) {
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60 | ECerr(EC_F_ECX_KEY_OP, ERR_R_MALLOC_FAILURE);
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61 | return 0;
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62 | }
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63 |
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64 | if (op == X25519_PUBLIC) {
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65 | memcpy(xkey->pubkey, p, plen);
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66 | } else {
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67 | xkey->privkey = OPENSSL_secure_malloc(X25519_KEYLEN);
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68 | if (xkey->privkey == NULL) {
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69 | ECerr(EC_F_ECX_KEY_OP, ERR_R_MALLOC_FAILURE);
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70 | OPENSSL_free(xkey);
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71 | return 0;
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72 | }
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73 | if (op == X25519_KEYGEN) {
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74 | if (RAND_bytes(xkey->privkey, X25519_KEYLEN) <= 0) {
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75 | OPENSSL_secure_free(xkey->privkey);
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76 | OPENSSL_free(xkey);
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77 | return 0;
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78 | }
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79 | xkey->privkey[0] &= 248;
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80 | xkey->privkey[31] &= 127;
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81 | xkey->privkey[31] |= 64;
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82 | } else {
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83 | memcpy(xkey->privkey, p, X25519_KEYLEN);
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84 | }
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85 | X25519_public_from_private(xkey->pubkey, xkey->privkey);
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86 | }
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87 |
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88 | EVP_PKEY_assign(pkey, NID_X25519, xkey);
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89 | return 1;
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90 | }
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91 |
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92 | static int ecx_pub_encode(X509_PUBKEY *pk, const EVP_PKEY *pkey)
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93 | {
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94 | const X25519_KEY *xkey = pkey->pkey.ptr;
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95 | unsigned char *penc;
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96 |
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97 | if (xkey == NULL) {
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98 | ECerr(EC_F_ECX_PUB_ENCODE, EC_R_INVALID_KEY);
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99 | return 0;
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100 | }
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101 |
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102 | penc = OPENSSL_memdup(xkey->pubkey, X25519_KEYLEN);
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103 | if (penc == NULL) {
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104 | ECerr(EC_F_ECX_PUB_ENCODE, ERR_R_MALLOC_FAILURE);
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105 | return 0;
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106 | }
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107 |
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108 | if (!X509_PUBKEY_set0_param(pk, OBJ_nid2obj(NID_X25519), V_ASN1_UNDEF,
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109 | NULL, penc, X25519_KEYLEN)) {
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110 | OPENSSL_free(penc);
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111 | ECerr(EC_F_ECX_PUB_ENCODE, ERR_R_MALLOC_FAILURE);
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112 | return 0;
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113 | }
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114 | return 1;
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115 | }
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116 |
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117 | static int ecx_pub_decode(EVP_PKEY *pkey, X509_PUBKEY *pubkey)
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118 | {
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119 | const unsigned char *p;
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120 | int pklen;
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121 | X509_ALGOR *palg;
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122 |
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123 | if (!X509_PUBKEY_get0_param(NULL, &p, &pklen, &palg, pubkey))
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124 | return 0;
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125 | return ecx_key_op(pkey, palg, p, pklen, X25519_PUBLIC);
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126 | }
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127 |
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128 | static int ecx_pub_cmp(const EVP_PKEY *a, const EVP_PKEY *b)
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129 | {
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130 | const X25519_KEY *akey = a->pkey.ptr;
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131 | const X25519_KEY *bkey = b->pkey.ptr;
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132 |
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133 | if (akey == NULL || bkey == NULL)
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134 | return -2;
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135 | return !CRYPTO_memcmp(akey->pubkey, bkey->pubkey, X25519_KEYLEN);
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136 | }
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137 |
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138 | static int ecx_priv_decode(EVP_PKEY *pkey, const PKCS8_PRIV_KEY_INFO *p8)
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139 | {
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140 | const unsigned char *p;
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141 | int plen;
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142 | ASN1_OCTET_STRING *oct = NULL;
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143 | const X509_ALGOR *palg;
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144 | int rv;
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145 |
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146 | if (!PKCS8_pkey_get0(NULL, &p, &plen, &palg, p8))
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147 | return 0;
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148 |
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149 | oct = d2i_ASN1_OCTET_STRING(NULL, &p, plen);
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150 | if (oct == NULL) {
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151 | p = NULL;
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152 | plen = 0;
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153 | } else {
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154 | p = ASN1_STRING_get0_data(oct);
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155 | plen = ASN1_STRING_length(oct);
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156 | }
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157 |
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158 | rv = ecx_key_op(pkey, palg, p, plen, X25519_PRIVATE);
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159 | ASN1_OCTET_STRING_free(oct);
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160 | return rv;
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161 | }
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162 |
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163 | static int ecx_priv_encode(PKCS8_PRIV_KEY_INFO *p8, const EVP_PKEY *pkey)
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164 | {
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165 | const X25519_KEY *xkey = pkey->pkey.ptr;
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166 | ASN1_OCTET_STRING oct;
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167 | unsigned char *penc = NULL;
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168 | int penclen;
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169 |
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170 | if (xkey == NULL || xkey->privkey == NULL) {
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171 | ECerr(EC_F_ECX_PRIV_ENCODE, EC_R_INVALID_PRIVATE_KEY);
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172 | return 0;
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173 | }
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174 |
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175 | oct.data = xkey->privkey;
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176 | oct.length = X25519_KEYLEN;
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177 | oct.flags = 0;
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178 |
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179 | penclen = i2d_ASN1_OCTET_STRING(&oct, &penc);
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180 | if (penclen < 0) {
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181 | ECerr(EC_F_ECX_PRIV_ENCODE, ERR_R_MALLOC_FAILURE);
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182 | return 0;
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183 | }
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184 |
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185 | if (!PKCS8_pkey_set0(p8, OBJ_nid2obj(NID_X25519), 0,
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186 | V_ASN1_UNDEF, NULL, penc, penclen)) {
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187 | OPENSSL_clear_free(penc, penclen);
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188 | ECerr(EC_F_ECX_PRIV_ENCODE, ERR_R_MALLOC_FAILURE);
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189 | return 0;
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190 | }
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191 |
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192 | return 1;
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193 | }
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194 |
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195 | static int ecx_size(const EVP_PKEY *pkey)
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196 | {
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197 | return X25519_KEYLEN;
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198 | }
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199 |
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200 | static int ecx_bits(const EVP_PKEY *pkey)
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201 | {
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202 | return X25519_BITS;
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203 | }
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204 |
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205 | static int ecx_security_bits(const EVP_PKEY *pkey)
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206 | {
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207 | return X25519_SECURITY_BITS;
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208 | }
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209 |
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210 | static void ecx_free(EVP_PKEY *pkey)
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211 | {
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212 | X25519_KEY *xkey = pkey->pkey.ptr;
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213 |
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214 | if (xkey)
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215 | OPENSSL_secure_free(xkey->privkey);
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216 | OPENSSL_free(xkey);
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217 | }
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218 |
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219 | /* "parameters" are always equal */
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220 | static int ecx_cmp_parameters(const EVP_PKEY *a, const EVP_PKEY *b)
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221 | {
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222 | return 1;
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223 | }
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224 |
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225 | static int ecx_key_print(BIO *bp, const EVP_PKEY *pkey, int indent,
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226 | ASN1_PCTX *ctx, ecx_key_op_t op)
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227 | {
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228 | const X25519_KEY *xkey = pkey->pkey.ptr;
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229 |
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230 | if (op == X25519_PRIVATE) {
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231 | if (xkey == NULL || xkey->privkey == NULL) {
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232 | if (BIO_printf(bp, "%*s<INVALID PRIVATE KEY>\n", indent, "") <= 0)
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233 | return 0;
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234 | return 1;
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235 | }
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236 | if (BIO_printf(bp, "%*sX25519 Private-Key:\n", indent, "") <= 0)
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237 | return 0;
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238 | if (BIO_printf(bp, "%*spriv:\n", indent, "") <= 0)
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239 | return 0;
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240 | if (ASN1_buf_print(bp, xkey->privkey, X25519_KEYLEN, indent + 4) == 0)
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241 | return 0;
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242 | } else {
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243 | if (xkey == NULL) {
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244 | if (BIO_printf(bp, "%*s<INVALID PUBLIC KEY>\n", indent, "") <= 0)
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245 | return 0;
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246 | return 1;
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247 | }
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248 | if (BIO_printf(bp, "%*sX25519 Public-Key:\n", indent, "") <= 0)
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249 | return 0;
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250 | }
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251 | if (BIO_printf(bp, "%*spub:\n", indent, "") <= 0)
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252 | return 0;
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253 | if (ASN1_buf_print(bp, xkey->pubkey, X25519_KEYLEN, indent + 4) == 0)
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254 | return 0;
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255 | return 1;
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256 | }
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257 |
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258 | static int ecx_priv_print(BIO *bp, const EVP_PKEY *pkey, int indent,
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259 | ASN1_PCTX *ctx)
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260 | {
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261 | return ecx_key_print(bp, pkey, indent, ctx, X25519_PRIVATE);
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262 | }
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263 |
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264 | static int ecx_pub_print(BIO *bp, const EVP_PKEY *pkey, int indent,
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265 | ASN1_PCTX *ctx)
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266 | {
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267 | return ecx_key_print(bp, pkey, indent, ctx, X25519_PUBLIC);
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268 | }
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269 |
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270 | static int ecx_ctrl(EVP_PKEY *pkey, int op, long arg1, void *arg2)
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271 | {
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272 | switch (op) {
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273 |
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274 | case ASN1_PKEY_CTRL_SET1_TLS_ENCPT:
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275 | return ecx_key_op(pkey, NULL, arg2, arg1, X25519_PUBLIC);
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276 |
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277 | case ASN1_PKEY_CTRL_GET1_TLS_ENCPT:
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278 | if (pkey->pkey.ptr != NULL) {
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279 | const X25519_KEY *xkey = pkey->pkey.ptr;
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280 | unsigned char **ppt = arg2;
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281 | *ppt = OPENSSL_memdup(xkey->pubkey, X25519_KEYLEN);
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282 | if (*ppt != NULL)
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283 | return X25519_KEYLEN;
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284 | }
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285 | return 0;
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286 |
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287 | case ASN1_PKEY_CTRL_DEFAULT_MD_NID:
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288 | *(int *)arg2 = NID_sha256;
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289 | return 2;
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290 |
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291 | default:
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292 | return -2;
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293 |
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294 | }
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295 | }
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296 |
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297 | const EVP_PKEY_ASN1_METHOD ecx25519_asn1_meth = {
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298 | NID_X25519,
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299 | NID_X25519,
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300 | 0,
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301 | "X25519",
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302 | "OpenSSL X25519 algorithm",
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303 |
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304 | ecx_pub_decode,
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305 | ecx_pub_encode,
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306 | ecx_pub_cmp,
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307 | ecx_pub_print,
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308 |
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309 | ecx_priv_decode,
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310 | ecx_priv_encode,
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311 | ecx_priv_print,
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312 |
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313 | ecx_size,
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314 | ecx_bits,
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315 | ecx_security_bits,
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316 |
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317 | 0, 0, 0, 0,
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318 | ecx_cmp_parameters,
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319 | 0, 0,
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320 |
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321 | ecx_free,
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322 | ecx_ctrl,
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323 | NULL,
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324 | NULL
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325 | };
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326 |
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327 | static int pkey_ecx_keygen(EVP_PKEY_CTX *ctx, EVP_PKEY *pkey)
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328 | {
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329 | return ecx_key_op(pkey, NULL, NULL, 0, X25519_KEYGEN);
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330 | }
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331 |
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332 | static int pkey_ecx_derive(EVP_PKEY_CTX *ctx, unsigned char *key,
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333 | size_t *keylen)
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334 | {
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335 | const X25519_KEY *pkey, *peerkey;
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336 |
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337 | if (ctx->pkey == NULL || ctx->peerkey == NULL) {
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338 | ECerr(EC_F_PKEY_ECX_DERIVE, EC_R_KEYS_NOT_SET);
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339 | return 0;
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340 | }
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341 | pkey = ctx->pkey->pkey.ptr;
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342 | peerkey = ctx->peerkey->pkey.ptr;
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343 | if (pkey == NULL || pkey->privkey == NULL) {
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344 | ECerr(EC_F_PKEY_ECX_DERIVE, EC_R_INVALID_PRIVATE_KEY);
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345 | return 0;
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346 | }
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347 | if (peerkey == NULL) {
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348 | ECerr(EC_F_PKEY_ECX_DERIVE, EC_R_INVALID_PEER_KEY);
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349 | return 0;
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350 | }
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351 | *keylen = X25519_KEYLEN;
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352 | if (key != NULL && X25519(key, pkey->privkey, peerkey->pubkey) == 0)
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353 | return 0;
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354 | return 1;
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355 | }
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356 |
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357 | static int pkey_ecx_ctrl(EVP_PKEY_CTX *ctx, int type, int p1, void *p2)
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358 | {
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359 | /* Only need to handle peer key for derivation */
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360 | if (type == EVP_PKEY_CTRL_PEER_KEY)
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361 | return 1;
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362 | return -2;
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363 | }
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364 |
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365 | const EVP_PKEY_METHOD ecx25519_pkey_meth = {
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366 | NID_X25519,
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367 | 0, 0, 0, 0, 0, 0, 0,
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368 | pkey_ecx_keygen,
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369 | 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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370 | pkey_ecx_derive,
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371 | pkey_ecx_ctrl,
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372 | 0
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373 | };
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