[331] | 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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