1 /* $NetBSD: kex.h,v 1.27 2024/09/24 21:32:18 christos Exp $ */ 2 /* $OpenBSD: kex.h,v 1.126 2024/09/02 12:13:56 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" 60 #define KEX_SNTRUP761X25519_SHA512_OLD "sntrup761x25519-sha512@openssh.com" 61 #define KEX_MLKEM768X25519_SHA256 "mlkem768x25519-sha256" 62 63 #define COMP_NONE 0 64 #define COMP_DELAYED 2 65 66 #define CURVE25519_SIZE 32 67 68 enum 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 82 enum kex_modes { 83 MODE_IN, 84 MODE_OUT, 85 MODE_MAX 86 }; 87 88 enum kex_exchange { 89 KEX_DH_GRP1_SHA1 = 1, 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_KEM_MLKEM768X25519_SHA256, 100 KEX_MAX 101 }; 102 103 /* kex->flags */ 104 #define KEX_INIT_SENT 0x0001 105 #define KEX_INITIAL 0x0002 106 #define KEX_HAS_PUBKEY_HOSTBOUND 0x0004 107 #define KEX_RSA_SHA2_256_SUPPORTED 0x0008 /* only set in server for now */ 108 #define KEX_RSA_SHA2_512_SUPPORTED 0x0010 /* only set in server for now */ 109 #define KEX_HAS_PING 0x0020 110 #define KEX_HAS_EXT_INFO_IN_AUTH 0x0040 111 112 struct sshenc { 113 char *name; 114 const struct sshcipher *cipher; 115 int enabled; 116 u_int key_len; 117 u_int iv_len; 118 u_int block_size; 119 u_char *key; 120 u_char *iv; 121 }; 122 struct sshcomp { 123 u_int type; 124 int enabled; 125 char *name; 126 }; 127 struct newkeys { 128 struct sshenc enc; 129 struct sshmac mac; 130 struct sshcomp comp; 131 }; 132 133 struct ssh; 134 struct sshbuf; 135 136 struct kex { 137 struct newkeys *newkeys[MODE_MAX]; 138 u_int we_need; 139 u_int dh_need; 140 int server; 141 char *name; 142 char *hostkey_alg; 143 int hostkey_type; 144 int hostkey_nid; 145 u_int kex_type; 146 char *server_sig_algs; 147 int ext_info_c; 148 int ext_info_s; 149 int kex_strict; 150 int ext_info_received; 151 struct sshbuf *my; 152 struct sshbuf *peer; 153 struct sshbuf *client_version; 154 struct sshbuf *server_version; 155 struct sshbuf *session_id; 156 struct sshbuf *initial_sig; 157 struct sshkey *initial_hostkey; 158 sig_atomic_t done; 159 u_int flags; 160 int hash_alg; 161 int ec_nid; 162 char *failed_choice; 163 int (*verify_host_key)(struct sshkey *, struct ssh *); 164 struct sshkey *(*load_host_public_key)(int, int, struct ssh *); 165 struct sshkey *(*load_host_private_key)(int, int, struct ssh *); 166 int (*host_key_index)(struct sshkey *, int, struct ssh *); 167 int (*sign)(struct ssh *, struct sshkey *, struct sshkey *, 168 u_char **, size_t *, const u_char *, size_t, const char *); 169 int (*kex[KEX_MAX])(struct ssh *); 170 /* kex specific state */ 171 DH *dh; /* DH */ 172 u_int min, max, nbits; /* GEX */ 173 EC_KEY *ec_client_key; /* ECDH */ 174 const EC_GROUP *ec_group; /* ECDH */ 175 u_char c25519_client_key[CURVE25519_SIZE]; /* 25519 + KEM */ 176 u_char c25519_client_pubkey[CURVE25519_SIZE]; /* 25519 */ 177 u_char sntrup761_client_key[crypto_kem_sntrup761_SECRETKEYBYTES]; /* KEM */ 178 u_char mlkem768_client_key[crypto_kem_mlkem768_SECRETKEYBYTES]; /* KEM */ 179 struct sshbuf *client_pub; 180 }; 181 182 int kex_name_valid(const char *); 183 u_int kex_type_from_name(const char *); 184 int kex_hash_from_name(const char *); 185 int kex_nid_from_name(const char *); 186 int kex_names_valid(const char *); 187 char *kex_alg_list(char); 188 char *kex_names_cat(const char *, const char *); 189 int kex_has_any_alg(const char *, const char *); 190 int kex_assemble_names(char **, const char *, const char *); 191 void kex_proposal_populate_entries(struct ssh *, char *prop[PROPOSAL_MAX], 192 const char *, const char *, const char *, const char *, const char *); 193 void kex_proposal_free_entries(char *prop[PROPOSAL_MAX]); 194 195 int kex_exchange_identification(struct ssh *, int, const char *); 196 197 struct kex *kex_new(void); 198 int kex_ready(struct ssh *, char *[PROPOSAL_MAX]); 199 int kex_setup(struct ssh *, char *[PROPOSAL_MAX]); 200 void kex_free_newkeys(struct newkeys *); 201 void kex_free(struct kex *); 202 203 int kex_buf2prop(struct sshbuf *, int *, char ***); 204 int kex_prop2buf(struct sshbuf *, char *proposal[PROPOSAL_MAX]); 205 void kex_prop_free(char **); 206 int kex_load_hostkey(struct ssh *, struct sshkey **, struct sshkey **); 207 int kex_verify_host_key(struct ssh *, struct sshkey *); 208 209 int kex_send_kexinit(struct ssh *); 210 int kex_input_kexinit(int, u_int32_t, struct ssh *); 211 int kex_input_ext_info(int, u_int32_t, struct ssh *); 212 int kex_protocol_error(int, u_int32_t, struct ssh *); 213 int kex_derive_keys(struct ssh *, u_char *, u_int, const struct sshbuf *); 214 int kex_send_newkeys(struct ssh *); 215 int kex_start_rekex(struct ssh *); 216 int kex_server_update_ext_info(struct ssh *); 217 void kex_set_server_sig_algs(struct ssh *, const char *); 218 219 int kexgex_client(struct ssh *); 220 int kexgex_server(struct ssh *); 221 int kex_gen_client(struct ssh *); 222 int kex_gen_server(struct ssh *); 223 224 int kex_dh_keypair(struct kex *); 225 int kex_dh_enc(struct kex *, const struct sshbuf *, struct sshbuf **, 226 struct sshbuf **); 227 int kex_dh_dec(struct kex *, const struct sshbuf *, struct sshbuf **); 228 229 int kex_ecdh_keypair(struct kex *); 230 int kex_ecdh_enc(struct kex *, const struct sshbuf *, struct sshbuf **, 231 struct sshbuf **); 232 int kex_ecdh_dec(struct kex *, const struct sshbuf *, struct sshbuf **); 233 234 int kex_c25519_keypair(struct kex *); 235 int kex_c25519_enc(struct kex *, const struct sshbuf *, struct sshbuf **, 236 struct sshbuf **); 237 int kex_c25519_dec(struct kex *, const struct sshbuf *, struct sshbuf **); 238 239 int kex_kem_sntrup761x25519_keypair(struct kex *); 240 int kex_kem_sntrup761x25519_enc(struct kex *, const struct sshbuf *, 241 struct sshbuf **, struct sshbuf **); 242 int kex_kem_sntrup761x25519_dec(struct kex *, const struct sshbuf *, 243 struct sshbuf **); 244 245 int kex_kem_mlkem768x25519_keypair(struct kex *); 246 int kex_kem_mlkem768x25519_enc(struct kex *, const struct sshbuf *, 247 struct sshbuf **, struct sshbuf **); 248 int kex_kem_mlkem768x25519_dec(struct kex *, const struct sshbuf *, 249 struct sshbuf **); 250 251 int kex_dh_keygen(struct kex *); 252 int kex_dh_compute_key(struct kex *, BIGNUM *, struct sshbuf *); 253 254 int kexgex_hash(int, const struct sshbuf *, const struct sshbuf *, 255 const struct sshbuf *, const struct sshbuf *, const struct sshbuf *, 256 int, int, int, 257 const BIGNUM *, const BIGNUM *, const BIGNUM *, 258 const BIGNUM *, const u_char *, size_t, 259 u_char *, size_t *); 260 261 void kexc25519_keygen(u_char key[CURVE25519_SIZE], u_char pub[CURVE25519_SIZE]) 262 __attribute__((__bounded__(__minbytes__, 1, CURVE25519_SIZE))) 263 __attribute__((__bounded__(__minbytes__, 2, CURVE25519_SIZE))); 264 int kexc25519_shared_key(const u_char key[CURVE25519_SIZE], 265 const u_char pub[CURVE25519_SIZE], struct sshbuf *out) 266 __attribute__((__bounded__(__minbytes__, 1, CURVE25519_SIZE))) 267 __attribute__((__bounded__(__minbytes__, 2, CURVE25519_SIZE))); 268 int kexc25519_shared_key_ext(const u_char key[CURVE25519_SIZE], 269 const u_char pub[CURVE25519_SIZE], struct sshbuf *out, int) 270 __attribute__((__bounded__(__minbytes__, 1, CURVE25519_SIZE))) 271 __attribute__((__bounded__(__minbytes__, 2, CURVE25519_SIZE))); 272 273 #if defined(DEBUG_KEX) || defined(DEBUG_KEXDH) || defined(DEBUG_KEXECDH) 274 void dump_digest(const char *, const u_char *, int); 275 #endif 276 277 #endif 278