kex.h revision 1.22
1/* $NetBSD: kex.h,v 1.22 2023/07/26 17:58:15 christos Exp $ */ 2/* $OpenBSD: kex.h,v 1.118 2023/03/06 12:14:48 dtucker 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 109struct sshenc { 110 char *name; 111 const struct sshcipher *cipher; 112 int enabled; 113 u_int key_len; 114 u_int iv_len; 115 u_int block_size; 116 u_char *key; 117 u_char *iv; 118}; 119struct sshcomp { 120 u_int type; 121 int enabled; 122 char *name; 123}; 124struct newkeys { 125 struct sshenc enc; 126 struct sshmac mac; 127 struct sshcomp comp; 128}; 129 130struct ssh; 131struct sshbuf; 132 133struct kex { 134 struct newkeys *newkeys[MODE_MAX]; 135 u_int we_need; 136 u_int dh_need; 137 int server; 138 char *name; 139 char *hostkey_alg; 140 int hostkey_type; 141 int hostkey_nid; 142 u_int kex_type; 143 char *server_sig_algs; 144 int ext_info_c; 145 struct sshbuf *my; 146 struct sshbuf *peer; 147 struct sshbuf *client_version; 148 struct sshbuf *server_version; 149 struct sshbuf *session_id; 150 struct sshbuf *initial_sig; 151 struct sshkey *initial_hostkey; 152 sig_atomic_t done; 153 u_int flags; 154 int hash_alg; 155 int ec_nid; 156 char *failed_choice; 157 int (*verify_host_key)(struct sshkey *, struct ssh *); 158 struct sshkey *(*load_host_public_key)(int, int, struct ssh *); 159 struct sshkey *(*load_host_private_key)(int, int, struct ssh *); 160 int (*host_key_index)(struct sshkey *, int, struct ssh *); 161 int (*sign)(struct ssh *, struct sshkey *, struct sshkey *, 162 u_char **, size_t *, const u_char *, size_t, const char *); 163 int (*kex[KEX_MAX])(struct ssh *); 164 /* kex specific state */ 165 DH *dh; /* DH */ 166 u_int min, max, nbits; /* GEX */ 167 EC_KEY *ec_client_key; /* ECDH */ 168 const EC_GROUP *ec_group; /* ECDH */ 169 u_char c25519_client_key[CURVE25519_SIZE]; /* 25519 + KEM */ 170 u_char c25519_client_pubkey[CURVE25519_SIZE]; /* 25519 */ 171 u_char sntrup761_client_key[crypto_kem_sntrup761_SECRETKEYBYTES]; /* KEM */ 172 struct sshbuf *client_pub; 173}; 174 175int kex_names_valid(const char *); 176char *kex_alg_list(char); 177char *kex_names_cat(const char *, const char *); 178int kex_assemble_names(char **, const char *, const char *); 179void kex_proposal_populate_entries(struct ssh *, char *prop[PROPOSAL_MAX], 180 const char *, const char *, const char *, const char *, const char *); 181void kex_proposal_free_entries(char *prop[PROPOSAL_MAX]); 182 183int kex_exchange_identification(struct ssh *, int, const char *); 184 185struct kex *kex_new(void); 186int kex_ready(struct ssh *, char *[PROPOSAL_MAX]); 187int kex_setup(struct ssh *, char *[PROPOSAL_MAX]); 188void kex_free_newkeys(struct newkeys *); 189void kex_free(struct kex *); 190 191int kex_buf2prop(struct sshbuf *, int *, char ***); 192int kex_prop2buf(struct sshbuf *, char *proposal[PROPOSAL_MAX]); 193void kex_prop_free(char **); 194int kex_load_hostkey(struct ssh *, struct sshkey **, struct sshkey **); 195int kex_verify_host_key(struct ssh *, struct sshkey *); 196 197int kex_send_kexinit(struct ssh *); 198int kex_input_kexinit(int, u_int32_t, struct ssh *); 199int kex_input_ext_info(int, u_int32_t, struct ssh *); 200int kex_protocol_error(int, u_int32_t, struct ssh *); 201int kex_derive_keys(struct ssh *, u_char *, u_int, const struct sshbuf *); 202int kex_send_newkeys(struct ssh *); 203int kex_start_rekex(struct ssh *); 204 205int kexgex_client(struct ssh *); 206int kexgex_server(struct ssh *); 207int kex_gen_client(struct ssh *); 208int kex_gen_server(struct ssh *); 209 210int kex_dh_keypair(struct kex *); 211int kex_dh_enc(struct kex *, const struct sshbuf *, struct sshbuf **, 212 struct sshbuf **); 213int kex_dh_dec(struct kex *, const struct sshbuf *, struct sshbuf **); 214 215int kex_ecdh_keypair(struct kex *); 216int kex_ecdh_enc(struct kex *, const struct sshbuf *, struct sshbuf **, 217 struct sshbuf **); 218int kex_ecdh_dec(struct kex *, const struct sshbuf *, struct sshbuf **); 219 220int kex_c25519_keypair(struct kex *); 221int kex_c25519_enc(struct kex *, const struct sshbuf *, struct sshbuf **, 222 struct sshbuf **); 223int kex_c25519_dec(struct kex *, const struct sshbuf *, struct sshbuf **); 224 225int kex_kem_sntrup761x25519_keypair(struct kex *); 226int kex_kem_sntrup761x25519_enc(struct kex *, const struct sshbuf *, 227 struct sshbuf **, struct sshbuf **); 228int kex_kem_sntrup761x25519_dec(struct kex *, const struct sshbuf *, 229 struct sshbuf **); 230 231int kex_dh_keygen(struct kex *); 232int kex_dh_compute_key(struct kex *, BIGNUM *, struct sshbuf *); 233 234int kexgex_hash(int, const struct sshbuf *, const struct sshbuf *, 235 const struct sshbuf *, const struct sshbuf *, const struct sshbuf *, 236 int, int, int, 237 const BIGNUM *, const BIGNUM *, const BIGNUM *, 238 const BIGNUM *, const u_char *, size_t, 239 u_char *, size_t *); 240 241void kexc25519_keygen(u_char key[CURVE25519_SIZE], u_char pub[CURVE25519_SIZE]) 242 __attribute__((__bounded__(__minbytes__, 1, CURVE25519_SIZE))) 243 __attribute__((__bounded__(__minbytes__, 2, CURVE25519_SIZE))); 244int kexc25519_shared_key(const u_char key[CURVE25519_SIZE], 245 const u_char pub[CURVE25519_SIZE], struct sshbuf *out) 246 __attribute__((__bounded__(__minbytes__, 1, CURVE25519_SIZE))) 247 __attribute__((__bounded__(__minbytes__, 2, CURVE25519_SIZE))); 248int kexc25519_shared_key_ext(const u_char key[CURVE25519_SIZE], 249 const u_char pub[CURVE25519_SIZE], struct sshbuf *out, int) 250 __attribute__((__bounded__(__minbytes__, 1, CURVE25519_SIZE))) 251 __attribute__((__bounded__(__minbytes__, 2, CURVE25519_SIZE))); 252 253#if defined(DEBUG_KEX) || defined(DEBUG_KEXDH) || defined(DEBUG_KEXECDH) 254void dump_digest(const char *, const u_char *, int); 255#endif 256 257#endif 258