1/* $NetBSD: kex.h,v 1.24 2023/12/20 17:15:20 christos Exp $ */ 2/* $OpenBSD: kex.h,v 1.121 2023/12/18 14:45:49 djm Exp $ */ 3 4/* 5 * Copyright (c) 2000, 2001 Markus Friedl. All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 17 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 18 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 19 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 21 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 22 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 23 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 25 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 26 */ 27#ifndef KEX_H 28#define KEX_H 29 30#include "mac.h" 31#include "crypto_api.h" 32 33#ifdef WITH_OPENSSL 34#include <openssl/bn.h> 35#include <openssl/dh.h> 36#include <openssl/ec.h> 37#include <openssl/ecdsa.h> 38#else /* OPENSSL */ 39#define BIGNUM void 40#define DH void 41#define EC_KEY void 42#define EC_GROUP void 43#endif /* WITH_OPENSSL */ 44 45#define KEX_COOKIE_LEN 16 46 47#define KEX_DH1 "diffie-hellman-group1-sha1" 48#define KEX_DH14_SHA1 "diffie-hellman-group14-sha1" 49#define KEX_DH14_SHA256 "diffie-hellman-group14-sha256" 50#define KEX_DH16_SHA512 "diffie-hellman-group16-sha512" 51#define KEX_DH18_SHA512 "diffie-hellman-group18-sha512" 52#define KEX_DHGEX_SHA1 "diffie-hellman-group-exchange-sha1" 53#define KEX_DHGEX_SHA256 "diffie-hellman-group-exchange-sha256" 54#define KEX_ECDH_SHA2_NISTP256 "ecdh-sha2-nistp256" 55#define KEX_ECDH_SHA2_NISTP384 "ecdh-sha2-nistp384" 56#define KEX_ECDH_SHA2_NISTP521 "ecdh-sha2-nistp521" 57#define KEX_CURVE25519_SHA256 "curve25519-sha256" 58#define KEX_CURVE25519_SHA256_OLD "curve25519-sha256@libssh.org" 59#define KEX_SNTRUP761X25519_SHA512 "sntrup761x25519-sha512@openssh.com" 60 61#define COMP_NONE 0 62/* pre-auth compression (COMP_ZLIB) is only supported in the client */ 63#define COMP_ZLIB 1 64#define COMP_DELAYED 2 65 66#define CURVE25519_SIZE 32 67 68enum kex_init_proposals { 69 PROPOSAL_KEX_ALGS, 70 PROPOSAL_SERVER_HOST_KEY_ALGS, 71 PROPOSAL_ENC_ALGS_CTOS, 72 PROPOSAL_ENC_ALGS_STOC, 73 PROPOSAL_MAC_ALGS_CTOS, 74 PROPOSAL_MAC_ALGS_STOC, 75 PROPOSAL_COMP_ALGS_CTOS, 76 PROPOSAL_COMP_ALGS_STOC, 77 PROPOSAL_LANG_CTOS, 78 PROPOSAL_LANG_STOC, 79 PROPOSAL_MAX 80}; 81 82enum kex_modes { 83 MODE_IN, 84 MODE_OUT, 85 MODE_MAX 86}; 87 88enum kex_exchange { 89 KEX_DH_GRP1_SHA1, 90 KEX_DH_GRP14_SHA1, 91 KEX_DH_GRP14_SHA256, 92 KEX_DH_GRP16_SHA512, 93 KEX_DH_GRP18_SHA512, 94 KEX_DH_GEX_SHA1, 95 KEX_DH_GEX_SHA256, 96 KEX_ECDH_SHA2, 97 KEX_C25519_SHA256, 98 KEX_KEM_SNTRUP761X25519_SHA512, 99 KEX_MAX 100}; 101 102/* kex->flags */ 103#define KEX_INIT_SENT 0x0001 104#define KEX_INITIAL 0x0002 105#define KEX_HAS_PUBKEY_HOSTBOUND 0x0004 106#define KEX_RSA_SHA2_256_SUPPORTED 0x0008 /* only set in server for now */ 107#define KEX_RSA_SHA2_512_SUPPORTED 0x0010 /* only set in server for now */ 108#define KEX_HAS_PING 0x0020 109#define KEX_HAS_EXT_INFO_IN_AUTH 0x0040 110 111struct sshenc { 112 char *name; 113 const struct sshcipher *cipher; 114 int enabled; 115 u_int key_len; 116 u_int iv_len; 117 u_int block_size; 118 u_char *key; 119 u_char *iv; 120}; 121struct sshcomp { 122 u_int type; 123 int enabled; 124 char *name; 125}; 126struct newkeys { 127 struct sshenc enc; 128 struct sshmac mac; 129 struct sshcomp comp; 130}; 131 132struct ssh; 133struct sshbuf; 134 135struct kex { 136 struct newkeys *newkeys[MODE_MAX]; 137 u_int we_need; 138 u_int dh_need; 139 int server; 140 char *name; 141 char *hostkey_alg; 142 int hostkey_type; 143 int hostkey_nid; 144 u_int kex_type; 145 char *server_sig_algs; 146 int ext_info_c; 147 int ext_info_s; 148 int kex_strict; 149 int ext_info_received; 150 struct sshbuf *my; 151 struct sshbuf *peer; 152 struct sshbuf *client_version; 153 struct sshbuf *server_version; 154 struct sshbuf *session_id; 155 struct sshbuf *initial_sig; 156 struct sshkey *initial_hostkey; 157 sig_atomic_t done; 158 u_int flags; 159 int hash_alg; 160 int ec_nid; 161 char *failed_choice; 162 int (*verify_host_key)(struct sshkey *, struct ssh *); 163 struct sshkey *(*load_host_public_key)(int, int, struct ssh *); 164 struct sshkey *(*load_host_private_key)(int, int, struct ssh *); 165 int (*host_key_index)(struct sshkey *, int, struct ssh *); 166 int (*sign)(struct ssh *, struct sshkey *, struct sshkey *, 167 u_char **, size_t *, const u_char *, size_t, const char *); 168 int (*kex[KEX_MAX])(struct ssh *); 169 /* kex specific state */ 170 DH *dh; /* DH */ 171 u_int min, max, nbits; /* GEX */ 172 EC_KEY *ec_client_key; /* ECDH */ 173 const EC_GROUP *ec_group; /* ECDH */ 174 u_char c25519_client_key[CURVE25519_SIZE]; /* 25519 + KEM */ 175 u_char c25519_client_pubkey[CURVE25519_SIZE]; /* 25519 */ 176 u_char sntrup761_client_key[crypto_kem_sntrup761_SECRETKEYBYTES]; /* KEM */ 177 struct sshbuf *client_pub; 178}; 179 180int kex_names_valid(const char *); 181char *kex_alg_list(char); 182char *kex_names_cat(const char *, const char *); 183int kex_assemble_names(char **, const char *, const char *); 184void kex_proposal_populate_entries(struct ssh *, char *prop[PROPOSAL_MAX], 185 const char *, const char *, const char *, const char *, const char *); 186void kex_proposal_free_entries(char *prop[PROPOSAL_MAX]); 187 188int kex_exchange_identification(struct ssh *, int, const char *); 189 190struct kex *kex_new(void); 191int kex_ready(struct ssh *, char *[PROPOSAL_MAX]); 192int kex_setup(struct ssh *, char *[PROPOSAL_MAX]); 193void kex_free_newkeys(struct newkeys *); 194void kex_free(struct kex *); 195 196int kex_buf2prop(struct sshbuf *, int *, char ***); 197int kex_prop2buf(struct sshbuf *, char *proposal[PROPOSAL_MAX]); 198void kex_prop_free(char **); 199int kex_load_hostkey(struct ssh *, struct sshkey **, struct sshkey **); 200int kex_verify_host_key(struct ssh *, struct sshkey *); 201 202int kex_send_kexinit(struct ssh *); 203int kex_input_kexinit(int, u_int32_t, struct ssh *); 204int kex_input_ext_info(int, u_int32_t, struct ssh *); 205int kex_protocol_error(int, u_int32_t, struct ssh *); 206int kex_derive_keys(struct ssh *, u_char *, u_int, const struct sshbuf *); 207int kex_send_newkeys(struct ssh *); 208int kex_start_rekex(struct ssh *); 209int kex_server_update_ext_info(struct ssh *); 210void kex_set_server_sig_algs(struct ssh *, const char *); 211 212int kexgex_client(struct ssh *); 213int kexgex_server(struct ssh *); 214int kex_gen_client(struct ssh *); 215int kex_gen_server(struct ssh *); 216 217int kex_dh_keypair(struct kex *); 218int kex_dh_enc(struct kex *, const struct sshbuf *, struct sshbuf **, 219 struct sshbuf **); 220int kex_dh_dec(struct kex *, const struct sshbuf *, struct sshbuf **); 221 222int kex_ecdh_keypair(struct kex *); 223int kex_ecdh_enc(struct kex *, const struct sshbuf *, struct sshbuf **, 224 struct sshbuf **); 225int kex_ecdh_dec(struct kex *, const struct sshbuf *, struct sshbuf **); 226 227int kex_c25519_keypair(struct kex *); 228int kex_c25519_enc(struct kex *, const struct sshbuf *, struct sshbuf **, 229 struct sshbuf **); 230int kex_c25519_dec(struct kex *, const struct sshbuf *, struct sshbuf **); 231 232int kex_kem_sntrup761x25519_keypair(struct kex *); 233int kex_kem_sntrup761x25519_enc(struct kex *, const struct sshbuf *, 234 struct sshbuf **, struct sshbuf **); 235int kex_kem_sntrup761x25519_dec(struct kex *, const struct sshbuf *, 236 struct sshbuf **); 237 238int kex_dh_keygen(struct kex *); 239int kex_dh_compute_key(struct kex *, BIGNUM *, struct sshbuf *); 240 241int kexgex_hash(int, const struct sshbuf *, const struct sshbuf *, 242 const struct sshbuf *, const struct sshbuf *, const struct sshbuf *, 243 int, int, int, 244 const BIGNUM *, const BIGNUM *, const BIGNUM *, 245 const BIGNUM *, const u_char *, size_t, 246 u_char *, size_t *); 247 248void kexc25519_keygen(u_char key[CURVE25519_SIZE], u_char pub[CURVE25519_SIZE]) 249 __attribute__((__bounded__(__minbytes__, 1, CURVE25519_SIZE))) 250 __attribute__((__bounded__(__minbytes__, 2, CURVE25519_SIZE))); 251int kexc25519_shared_key(const u_char key[CURVE25519_SIZE], 252 const u_char pub[CURVE25519_SIZE], struct sshbuf *out) 253 __attribute__((__bounded__(__minbytes__, 1, CURVE25519_SIZE))) 254 __attribute__((__bounded__(__minbytes__, 2, CURVE25519_SIZE))); 255int kexc25519_shared_key_ext(const u_char key[CURVE25519_SIZE], 256 const u_char pub[CURVE25519_SIZE], struct sshbuf *out, int) 257 __attribute__((__bounded__(__minbytes__, 1, CURVE25519_SIZE))) 258 __attribute__((__bounded__(__minbytes__, 2, CURVE25519_SIZE))); 259 260#if defined(DEBUG_KEX) || defined(DEBUG_KEXDH) || defined(DEBUG_KEXECDH) 261void dump_digest(const char *, const u_char *, int); 262#endif 263 264#endif 265