1 /* $OpenBSD: kex.h,v 1.126 2024/09/02 12:13:56 djm Exp $ */ 2 3 /* 4 * Copyright (c) 2000, 2001 Markus Friedl. All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 25 */ 26 #ifndef KEX_H 27 #define KEX_H 28 29 #include "mac.h" 30 #include "crypto_api.h" 31 32 #ifdef WITH_OPENSSL 33 #include <openssl/bn.h> 34 #include <openssl/dh.h> 35 #include <openssl/ec.h> 36 #include <openssl/ecdsa.h> 37 #else /* OPENSSL */ 38 #define BIGNUM void 39 #define DH void 40 #define EC_KEY void 41 #define EC_GROUP void 42 #endif /* WITH_OPENSSL */ 43 44 #define KEX_COOKIE_LEN 16 45 46 #define KEX_DH1 "diffie-hellman-group1-sha1" 47 #define KEX_DH14_SHA1 "diffie-hellman-group14-sha1" 48 #define KEX_DH14_SHA256 "diffie-hellman-group14-sha256" 49 #define KEX_DH16_SHA512 "diffie-hellman-group16-sha512" 50 #define KEX_DH18_SHA512 "diffie-hellman-group18-sha512" 51 #define KEX_DHGEX_SHA1 "diffie-hellman-group-exchange-sha1" 52 #define KEX_DHGEX_SHA256 "diffie-hellman-group-exchange-sha256" 53 #define KEX_ECDH_SHA2_NISTP256 "ecdh-sha2-nistp256" 54 #define KEX_ECDH_SHA2_NISTP384 "ecdh-sha2-nistp384" 55 #define KEX_ECDH_SHA2_NISTP521 "ecdh-sha2-nistp521" 56 #define KEX_CURVE25519_SHA256 "curve25519-sha256" 57 #define KEX_CURVE25519_SHA256_OLD "curve25519-sha256@libssh.org" 58 #define KEX_SNTRUP761X25519_SHA512 "sntrup761x25519-sha512" 59 #define KEX_SNTRUP761X25519_SHA512_OLD "sntrup761x25519-sha512@openssh.com" 60 #define KEX_MLKEM768X25519_SHA256 "mlkem768x25519-sha256" 61 62 #define COMP_NONE 0 63 #define COMP_DELAYED 2 64 65 #define CURVE25519_SIZE 32 66 67 enum kex_init_proposals { 68 PROPOSAL_KEX_ALGS, 69 PROPOSAL_SERVER_HOST_KEY_ALGS, 70 PROPOSAL_ENC_ALGS_CTOS, 71 PROPOSAL_ENC_ALGS_STOC, 72 PROPOSAL_MAC_ALGS_CTOS, 73 PROPOSAL_MAC_ALGS_STOC, 74 PROPOSAL_COMP_ALGS_CTOS, 75 PROPOSAL_COMP_ALGS_STOC, 76 PROPOSAL_LANG_CTOS, 77 PROPOSAL_LANG_STOC, 78 PROPOSAL_MAX 79 }; 80 81 enum kex_modes { 82 MODE_IN, 83 MODE_OUT, 84 MODE_MAX 85 }; 86 87 enum kex_exchange { 88 KEX_DH_GRP1_SHA1 = 1, 89 KEX_DH_GRP14_SHA1, 90 KEX_DH_GRP14_SHA256, 91 KEX_DH_GRP16_SHA512, 92 KEX_DH_GRP18_SHA512, 93 KEX_DH_GEX_SHA1, 94 KEX_DH_GEX_SHA256, 95 KEX_ECDH_SHA2, 96 KEX_C25519_SHA256, 97 KEX_KEM_SNTRUP761X25519_SHA512, 98 KEX_KEM_MLKEM768X25519_SHA256, 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 110 111 struct 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 }; 121 struct sshcomp { 122 u_int type; 123 int enabled; 124 char *name; 125 }; 126 struct newkeys { 127 struct sshenc enc; 128 struct sshmac mac; 129 struct sshcomp comp; 130 }; 131 132 struct ssh; 133 struct sshbuf; 134 135 struct 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 u_char mlkem768_client_key[crypto_kem_mlkem768_SECRETKEYBYTES]; /* KEM */ 178 struct sshbuf *client_pub; 179 }; 180 181 int kex_name_valid(const char *); 182 u_int kex_type_from_name(const char *); 183 int kex_hash_from_name(const char *); 184 int kex_nid_from_name(const char *); 185 int kex_names_valid(const char *); 186 char *kex_alg_list(char); 187 char *kex_names_cat(const char *, const char *); 188 int kex_has_any_alg(const char *, const char *); 189 int kex_assemble_names(char **, const char *, const char *); 190 void kex_proposal_populate_entries(struct ssh *, char *prop[PROPOSAL_MAX], 191 const char *, const char *, const char *, const char *, const char *); 192 void kex_proposal_free_entries(char *prop[PROPOSAL_MAX]); 193 194 int kex_exchange_identification(struct ssh *, int, const char *); 195 196 struct kex *kex_new(void); 197 int kex_ready(struct ssh *, char *[PROPOSAL_MAX]); 198 int kex_setup(struct ssh *, char *[PROPOSAL_MAX]); 199 void kex_free_newkeys(struct newkeys *); 200 void kex_free(struct kex *); 201 202 int kex_buf2prop(struct sshbuf *, int *, char ***); 203 int kex_prop2buf(struct sshbuf *, char *proposal[PROPOSAL_MAX]); 204 void kex_prop_free(char **); 205 int kex_load_hostkey(struct ssh *, struct sshkey **, struct sshkey **); 206 int kex_verify_host_key(struct ssh *, struct sshkey *); 207 208 int kex_send_kexinit(struct ssh *); 209 int kex_input_kexinit(int, u_int32_t, struct ssh *); 210 int kex_input_ext_info(int, u_int32_t, struct ssh *); 211 int kex_protocol_error(int, u_int32_t, struct ssh *); 212 int kex_derive_keys(struct ssh *, u_char *, u_int, const struct sshbuf *); 213 int kex_send_newkeys(struct ssh *); 214 int kex_start_rekex(struct ssh *); 215 int kex_server_update_ext_info(struct ssh *); 216 void kex_set_server_sig_algs(struct ssh *, const char *); 217 218 int kexgex_client(struct ssh *); 219 int kexgex_server(struct ssh *); 220 int kex_gen_client(struct ssh *); 221 int kex_gen_server(struct ssh *); 222 223 int kex_dh_keypair(struct kex *); 224 int kex_dh_enc(struct kex *, const struct sshbuf *, struct sshbuf **, 225 struct sshbuf **); 226 int kex_dh_dec(struct kex *, const struct sshbuf *, struct sshbuf **); 227 228 int kex_ecdh_keypair(struct kex *); 229 int kex_ecdh_enc(struct kex *, const struct sshbuf *, struct sshbuf **, 230 struct sshbuf **); 231 int kex_ecdh_dec(struct kex *, const struct sshbuf *, struct sshbuf **); 232 233 int kex_c25519_keypair(struct kex *); 234 int kex_c25519_enc(struct kex *, const struct sshbuf *, struct sshbuf **, 235 struct sshbuf **); 236 int kex_c25519_dec(struct kex *, const struct sshbuf *, struct sshbuf **); 237 238 int kex_kem_sntrup761x25519_keypair(struct kex *); 239 int kex_kem_sntrup761x25519_enc(struct kex *, const struct sshbuf *, 240 struct sshbuf **, struct sshbuf **); 241 int kex_kem_sntrup761x25519_dec(struct kex *, const struct sshbuf *, 242 struct sshbuf **); 243 244 int kex_kem_mlkem768x25519_keypair(struct kex *); 245 int kex_kem_mlkem768x25519_enc(struct kex *, const struct sshbuf *, 246 struct sshbuf **, struct sshbuf **); 247 int kex_kem_mlkem768x25519_dec(struct kex *, const struct sshbuf *, 248 struct sshbuf **); 249 250 int kex_dh_keygen(struct kex *); 251 int kex_dh_compute_key(struct kex *, BIGNUM *, struct sshbuf *); 252 253 int kexgex_hash(int, const struct sshbuf *, const struct sshbuf *, 254 const struct sshbuf *, const struct sshbuf *, const struct sshbuf *, 255 int, int, int, 256 const BIGNUM *, const BIGNUM *, const BIGNUM *, 257 const BIGNUM *, const u_char *, size_t, 258 u_char *, size_t *); 259 260 void kexc25519_keygen(u_char key[CURVE25519_SIZE], u_char pub[CURVE25519_SIZE]) 261 __attribute__((__bounded__(__minbytes__, 1, CURVE25519_SIZE))) 262 __attribute__((__bounded__(__minbytes__, 2, CURVE25519_SIZE))); 263 int kexc25519_shared_key(const u_char key[CURVE25519_SIZE], 264 const u_char pub[CURVE25519_SIZE], struct sshbuf *out) 265 __attribute__((__bounded__(__minbytes__, 1, CURVE25519_SIZE))) 266 __attribute__((__bounded__(__minbytes__, 2, CURVE25519_SIZE))); 267 int kexc25519_shared_key_ext(const u_char key[CURVE25519_SIZE], 268 const u_char pub[CURVE25519_SIZE], struct sshbuf *out, int) 269 __attribute__((__bounded__(__minbytes__, 1, CURVE25519_SIZE))) 270 __attribute__((__bounded__(__minbytes__, 2, CURVE25519_SIZE))); 271 272 #if defined(DEBUG_KEX) || defined(DEBUG_KEXDH) || defined(DEBUG_KEXECDH) 273 void dump_digest(const char *, const u_char *, int); 274 #endif 275 276 #endif 277