crypto/openssh/cipher.c

   1 /* $OpenBSD: cipher.c,v 1.101 2015/12/10 17:08:40 mmcc Exp $ */
   2 /*
   3  * Author: Tatu Ylonen <ylo@cs.hut.fi>
   4  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
   5  *                    All rights reserved
   6  *
   7  * As far as I am concerned, the code I have written for this software
   8  * can be used freely for any purpose.  Any derived versions of this
   9  * software must be clearly marked as such, and if the derived work is
  10  * incompatible with the protocol description in the RFC file, it must be
  11  * called by a name other than "ssh" or "Secure Shell".
  12  *
  13  *
  14  * Copyright (c) 1999 Niels Provos.  All rights reserved.
  15  * Copyright (c) 1999, 2000 Markus Friedl.  All rights reserved.
  16  *
  17  * Redistribution and use in source and binary forms, with or without
  18  * modification, are permitted provided that the following conditions
  19  * are met:
  20  * 1. Redistributions of source code must retain the above copyright
  21  *    notice, this list of conditions and the following disclaimer.
  22  * 2. Redistributions in binary form must reproduce the above copyright
  23  *    notice, this list of conditions and the following disclaimer in the
  24  *    documentation and/or other materials provided with the distribution.
  25  *
  26  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  27  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  28  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  29  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  30  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  31  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  32  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  33  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  34  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  35  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  36  */
  37
  38 #include "includes.h"
  39
  40 #include <sys/types.h>
  41
  42 #include <string.h>
  43 #include <stdarg.h>
  44 #include <stdio.h>
  45
  46 #include "cipher.h"
  47 #include "misc.h"
  48 #include "sshbuf.h"
  49 #include "ssherr.h"
  50 #include "digest.h"
  51
  52 #include "openbsd-compat/openssl-compat.h"
  53
  54 #ifdef WITH_SSH1
  55 extern const EVP_CIPHER *evp_ssh1_bf(void);
  56 extern const EVP_CIPHER *evp_ssh1_3des(void);
  57 extern int ssh1_3des_iv(EVP_CIPHER_CTX *, int, u_char *, int);
  58 #endif
  59
  60 struct sshcipher {
  61         char    *name;
  62         int     number;         /* for ssh1 only */
  63         u_int   block_size;
  64         u_int   key_len;
  65         u_int   iv_len;         /* defaults to block_size */
  66         u_int   auth_len;
  67         u_int   discard_len;
  68         u_int   flags;
  69 #define CFLAG_CBC               (1<<0)
  70 #define CFLAG_CHACHAPOLY        (1<<1)
  71 #define CFLAG_AESCTR            (1<<2)
  72 #define CFLAG_NONE              (1<<3)
  73 #ifdef WITH_OPENSSL
  74         const EVP_CIPHER        *(*evptype)(void);
  75 #else
  76         void    *ignored;
  77 #endif
  78 };
  79
  80 static const struct sshcipher ciphers[] = {
  81 #ifdef WITH_SSH1
  82         { "des",        SSH_CIPHER_DES, 8, 8, 0, 0, 0, 1, EVP_des_cbc },
  83         { "3des",       SSH_CIPHER_3DES, 8, 16, 0, 0, 0, 1, evp_ssh1_3des },
  84 # ifndef OPENSSL_NO_BF
  85         { "blowfish",   SSH_CIPHER_BLOWFISH, 8, 32, 0, 0, 0, 1, evp_ssh1_bf },
  86 # endif /* OPENSSL_NO_BF */
  87 #endif /* WITH_SSH1 */
  88 #ifdef WITH_OPENSSL
  89         { "none",       SSH_CIPHER_NONE, 8, 0, 0, 0, 0, 0, EVP_enc_null },
  90         { "3des-cbc",   SSH_CIPHER_SSH2, 8, 24, 0, 0, 0, 1, EVP_des_ede3_cbc },
  91 # ifndef OPENSSL_NO_BF
  92         { "blowfish-cbc",
  93                         SSH_CIPHER_SSH2, 8, 16, 0, 0, 0, 1, EVP_bf_cbc },
  94 # endif /* OPENSSL_NO_BF */
  95 # ifndef OPENSSL_NO_CAST
  96         { "cast128-cbc",
  97                         SSH_CIPHER_SSH2, 8, 16, 0, 0, 0, 1, EVP_cast5_cbc },
  98 # endif /* OPENSSL_NO_CAST */
  99 # ifndef OPENSSL_NO_RC4
 100         { "arcfour",    SSH_CIPHER_SSH2, 8, 16, 0, 0, 0, 0, EVP_rc4 },
 101         { "arcfour128", SSH_CIPHER_SSH2, 8, 16, 0, 0, 1536, 0, EVP_rc4 },
 102         { "arcfour256", SSH_CIPHER_SSH2, 8, 32, 0, 0, 1536, 0, EVP_rc4 },
 103 # endif /* OPENSSL_NO_RC4 */
 104         { "aes128-cbc", SSH_CIPHER_SSH2, 16, 16, 0, 0, 0, 1, EVP_aes_128_cbc },
 105         { "aes192-cbc", SSH_CIPHER_SSH2, 16, 24, 0, 0, 0, 1, EVP_aes_192_cbc },
 106         { "aes256-cbc", SSH_CIPHER_SSH2, 16, 32, 0, 0, 0, 1, EVP_aes_256_cbc },
 107         { "rijndael-cbc@lysator.liu.se",
 108                         SSH_CIPHER_SSH2, 16, 32, 0, 0, 0, 1, EVP_aes_256_cbc },
 109         { "aes128-ctr", SSH_CIPHER_SSH2, 16, 16, 0, 0, 0, 0, EVP_aes_128_ctr },
 110         { "aes192-ctr", SSH_CIPHER_SSH2, 16, 24, 0, 0, 0, 0, EVP_aes_192_ctr },
 111         { "aes256-ctr", SSH_CIPHER_SSH2, 16, 32, 0, 0, 0, 0, EVP_aes_256_ctr },
 112 # ifdef OPENSSL_HAVE_EVPGCM
 113         { "aes128-gcm@openssh.com",
 114                         SSH_CIPHER_SSH2, 16, 16, 12, 16, 0, 0, EVP_aes_128_gcm },
 115         { "aes256-gcm@openssh.com",
 116                         SSH_CIPHER_SSH2, 16, 32, 12, 16, 0, 0, EVP_aes_256_gcm },
 117 # endif /* OPENSSL_HAVE_EVPGCM */
 118 #else /* WITH_OPENSSL */
 119         { "aes128-ctr", SSH_CIPHER_SSH2, 16, 16, 0, 0, 0, CFLAG_AESCTR, NULL },
 120         { "aes192-ctr", SSH_CIPHER_SSH2, 16, 24, 0, 0, 0, CFLAG_AESCTR, NULL },
 121         { "aes256-ctr", SSH_CIPHER_SSH2, 16, 32, 0, 0, 0, CFLAG_AESCTR, NULL },
 122         { "none",       SSH_CIPHER_NONE, 8, 0, 0, 0, 0, CFLAG_NONE, NULL },
 123 #endif /* WITH_OPENSSL */
 124         { "chacha20-poly1305@openssh.com",
 125                         SSH_CIPHER_SSH2, 8, 64, 0, 16, 0, CFLAG_CHACHAPOLY, NULL },
 126
 127         { NULL,         SSH_CIPHER_INVALID, 0, 0, 0, 0, 0, 0, NULL }
 128 };
 129
 130 /*--*/
 131
 132 /* Returns a comma-separated list of supported ciphers. */
 133 char *
 134 cipher_alg_list(char sep, int auth_only)
 135 {
 136         char *tmp, *ret = NULL;
 137         size_t nlen, rlen = 0;
 138         const struct sshcipher *c;
 139
 140         for (c = ciphers; c->name != NULL; c++) {
 141                 if (c->number != SSH_CIPHER_SSH2)
 142                         continue;
 143                 if (auth_only && c->auth_len == 0)
 144                         continue;
 145                 if (ret != NULL)
 146                         ret[rlen++] = sep;
 147                 nlen = strlen(c->name);
 148                 if ((tmp = realloc(ret, rlen + nlen + 2)) == NULL) {
 149                         free(ret);
 150                         return NULL;
 151                 }
 152                 ret = tmp;
 153                 memcpy(ret + rlen, c->name, nlen + 1);
 154                 rlen += nlen;
 155         }
 156         return ret;
 157 }
 158
 159 u_int
 160 cipher_blocksize(const struct sshcipher *c)
 161 {
 162         return (c->block_size);
 163 }
 164
 165 u_int
 166 cipher_keylen(const struct sshcipher *c)
 167 {
 168         return (c->key_len);
 169 }
 170
 171 u_int
 172 cipher_seclen(const struct sshcipher *c)
 173 {
 174         if (strcmp("3des-cbc", c->name) == 0)
 175                 return 14;
 176         return cipher_keylen(c);
 177 }
 178
 179 u_int
 180 cipher_authlen(const struct sshcipher *c)
 181 {
 182         return (c->auth_len);
 183 }
 184
 185 u_int
 186 cipher_ivlen(const struct sshcipher *c)
 187 {
 188         /*
 189          * Default is cipher block size, except for chacha20+poly1305 that
 190          * needs no IV. XXX make iv_len == -1 default?
 191          */
 192         return (c->iv_len != 0 || (c->flags & CFLAG_CHACHAPOLY) != 0) ?
 193             c->iv_len : c->block_size;
 194 }
 195
 196 u_int
 197 cipher_get_number(const struct sshcipher *c)
 198 {
 199         return (c->number);
 200 }
 201
 202 u_int
 203 cipher_is_cbc(const struct sshcipher *c)
 204 {
 205         return (c->flags & CFLAG_CBC) != 0;
 206 }
 207
 208 u_int
 209 cipher_mask_ssh1(int client)
 210 {
 211         u_int mask = 0;
 212         mask |= 1 << SSH_CIPHER_3DES;           /* Mandatory */
 213         mask |= 1 << SSH_CIPHER_BLOWFISH;
 214         if (client) {
 215                 mask |= 1 << SSH_CIPHER_DES;
 216         }
 217         return mask;
 218 }
 219
 220 const struct sshcipher *
 221 cipher_by_name(const char *name)
 222 {
 223         const struct sshcipher *c;
 224         for (c = ciphers; c->name != NULL; c++)
 225                 if (strcmp(c->name, name) == 0)
 226                         return c;
 227         return NULL;
 228 }
 229
 230 const struct sshcipher *
 231 cipher_by_number(int id)
 232 {
 233         const struct sshcipher *c;
 234         for (c = ciphers; c->name != NULL; c++)
 235                 if (c->number == id)
 236                         return c;
 237         return NULL;
 238 }
 239
 240 #define CIPHER_SEP      ","
 241 int
 242 ciphers_valid(const char *names)
 243 {
 244         const struct sshcipher *c;
 245         char *cipher_list, *cp;
 246         char *p;
 247
 248         if (names == NULL || strcmp(names, "") == 0)
 249                 return 0;
 250         if ((cipher_list = cp = strdup(names)) == NULL)
 251                 return 0;
 252         for ((p = strsep(&cp, CIPHER_SEP)); p && *p != '\0';
 253             (p = strsep(&cp, CIPHER_SEP))) {
 254                 c = cipher_by_name(p);
 255                 if (c == NULL || c->number != SSH_CIPHER_SSH2) {
 256                         free(cipher_list);
 257                         return 0;
 258                 }
 259         }
 260         free(cipher_list);
 261         return 1;
 262 }
 263
 264 /*
 265  * Parses the name of the cipher.  Returns the number of the corresponding
 266  * cipher, or -1 on error.
 267  */
 268
 269 int
 270 cipher_number(const char *name)
 271 {
 272         const struct sshcipher *c;
 273         if (name == NULL)
 274                 return -1;
 275         for (c = ciphers; c->name != NULL; c++)
 276                 if (strcasecmp(c->name, name) == 0)
 277                         return c->number;
 278         return -1;
 279 }
 280
 281 char *
 282 cipher_name(int id)
 283 {
 284         const struct sshcipher *c = cipher_by_number(id);
 285         return (c==NULL) ? "<unknown>" : c->name;
 286 }
 287
 288 const char *
 289 cipher_warning_message(const struct sshcipher_ctx *cc)
 290 {
 291         if (cc == NULL || cc->cipher == NULL)
 292                 return NULL;
 293         if (cc->cipher->number == SSH_CIPHER_DES)
 294                 return "use of DES is strongly discouraged due to "
 295                     "cryptographic weaknesses";
 296         return NULL;
 297 }
 298
 299 int
 300 cipher_init(struct sshcipher_ctx *cc, const struct sshcipher *cipher,
 301     const u_char *key, u_int keylen, const u_char *iv, u_int ivlen,
 302     int do_encrypt)
 303 {
 304 #ifdef WITH_OPENSSL
 305         int ret = SSH_ERR_INTERNAL_ERROR;
 306         const EVP_CIPHER *type;
 307         int klen;
 308         u_char *junk, *discard;
 309
 310         if (cipher->number == SSH_CIPHER_DES) {
 311                 if (keylen > 8)
 312                         keylen = 8;
 313         }
 314 #endif
 315         cc->plaintext = (cipher->number == SSH_CIPHER_NONE);
 316         cc->encrypt = do_encrypt;
 317
 318         if (keylen < cipher->key_len ||
 319             (iv != NULL && ivlen < cipher_ivlen(cipher)))
 320                 return SSH_ERR_INVALID_ARGUMENT;
 321
 322         cc->cipher = cipher;
 323         if ((cc->cipher->flags & CFLAG_CHACHAPOLY) != 0) {
 324                 return chachapoly_init(&cc->cp_ctx, key, keylen);
 325         }
 326 #ifndef WITH_OPENSSL
 327         if ((cc->cipher->flags & CFLAG_AESCTR) != 0) {
 328                 aesctr_keysetup(&cc->ac_ctx, key, 8 * keylen, 8 * ivlen);
 329                 aesctr_ivsetup(&cc->ac_ctx, iv);
 330                 return 0;
 331         }
 332         if ((cc->cipher->flags & CFLAG_NONE) != 0)
 333                 return 0;
 334         return SSH_ERR_INVALID_ARGUMENT;
 335 #else
 336         type = (*cipher->evptype)();
 337         EVP_CIPHER_CTX_init(&cc->evp);
 338         if (EVP_CipherInit(&cc->evp, type, NULL, (u_char *)iv,
 339             (do_encrypt == CIPHER_ENCRYPT)) == 0) {
 340                 ret = SSH_ERR_LIBCRYPTO_ERROR;
 341                 goto bad;
 342         }
 343         if (cipher_authlen(cipher) &&
 344             !EVP_CIPHER_CTX_ctrl(&cc->evp, EVP_CTRL_GCM_SET_IV_FIXED,
 345             -1, (u_char *)iv)) {
 346                 ret = SSH_ERR_LIBCRYPTO_ERROR;
 347                 goto bad;
 348         }
 349         klen = EVP_CIPHER_CTX_key_length(&cc->evp);
 350         if (klen > 0 && keylen != (u_int)klen) {
 351                 if (EVP_CIPHER_CTX_set_key_length(&cc->evp, keylen) == 0) {
 352                         ret = SSH_ERR_LIBCRYPTO_ERROR;
 353                         goto bad;
 354                 }
 355         }
 356         if (EVP_CipherInit(&cc->evp, NULL, (u_char *)key, NULL, -1) == 0) {
 357                 ret = SSH_ERR_LIBCRYPTO_ERROR;
 358                 goto bad;
 359         }
 360
 361         if (cipher->discard_len > 0) {
 362                 if ((junk = malloc(cipher->discard_len)) == NULL ||
 363                     (discard = malloc(cipher->discard_len)) == NULL) {
 364                         free(junk);
 365                         ret = SSH_ERR_ALLOC_FAIL;
 366                         goto bad;
 367                 }
 368                 ret = EVP_Cipher(&cc->evp, discard, junk, cipher->discard_len);
 369                 explicit_bzero(discard, cipher->discard_len);
 370                 free(junk);
 371                 free(discard);
 372                 if (ret != 1) {
 373                         ret = SSH_ERR_LIBCRYPTO_ERROR;
 374  bad:
 375                         EVP_CIPHER_CTX_cleanup(&cc->evp);
 376                         return ret;
 377                 }
 378         }
 379 #endif
 380         return 0;
 381 }
 382
 383 /*
 384  * cipher_crypt() operates as following:
 385  * Copy 'aadlen' bytes (without en/decryption) from 'src' to 'dest'.
 386  * Theses bytes are treated as additional authenticated data for
 387  * authenticated encryption modes.
 388  * En/Decrypt 'len' bytes at offset 'aadlen' from 'src' to 'dest'.
 389  * Use 'authlen' bytes at offset 'len'+'aadlen' as the authentication tag.
 390  * This tag is written on encryption and verified on decryption.
 391  * Both 'aadlen' and 'authlen' can be set to 0.
 392  */
 393 int
 394 cipher_crypt(struct sshcipher_ctx *cc, u_int seqnr, u_char *dest,
 395    const u_char *src, u_int len, u_int aadlen, u_int authlen)
 396 {
 397         if ((cc->cipher->flags & CFLAG_CHACHAPOLY) != 0) {
 398                 return chachapoly_crypt(&cc->cp_ctx, seqnr, dest, src,
 399                     len, aadlen, authlen, cc->encrypt);
 400         }
 401 #ifndef WITH_OPENSSL
 402         if ((cc->cipher->flags & CFLAG_AESCTR) != 0) {
 403                 if (aadlen)
 404                         memcpy(dest, src, aadlen);
 405                 aesctr_encrypt_bytes(&cc->ac_ctx, src + aadlen,
 406                     dest + aadlen, len);
 407                 return 0;
 408         }
 409         if ((cc->cipher->flags & CFLAG_NONE) != 0) {
 410                 memcpy(dest, src, aadlen + len);
 411                 return 0;
 412         }
 413         return SSH_ERR_INVALID_ARGUMENT;
 414 #else
 415         if (authlen) {
 416                 u_char lastiv[1];
 417
 418                 if (authlen != cipher_authlen(cc->cipher))
 419                         return SSH_ERR_INVALID_ARGUMENT;
 420                 /* increment IV */
 421                 if (!EVP_CIPHER_CTX_ctrl(&cc->evp, EVP_CTRL_GCM_IV_GEN,
 422                     1, lastiv))
 423                         return SSH_ERR_LIBCRYPTO_ERROR;
 424                 /* set tag on decyption */
 425                 if (!cc->encrypt &&
 426                     !EVP_CIPHER_CTX_ctrl(&cc->evp, EVP_CTRL_GCM_SET_TAG,
 427                     authlen, (u_char *)src + aadlen + len))
 428                         return SSH_ERR_LIBCRYPTO_ERROR;
 429         }
 430         if (aadlen) {
 431                 if (authlen &&
 432                     EVP_Cipher(&cc->evp, NULL, (u_char *)src, aadlen) < 0)
 433                         return SSH_ERR_LIBCRYPTO_ERROR;
 434                 memcpy(dest, src, aadlen);
 435         }
 436         if (len % cc->cipher->block_size)
 437                 return SSH_ERR_INVALID_ARGUMENT;
 438         if (EVP_Cipher(&cc->evp, dest + aadlen, (u_char *)src + aadlen,
 439             len) < 0)
 440                 return SSH_ERR_LIBCRYPTO_ERROR;
 441         if (authlen) {
 442                 /* compute tag (on encrypt) or verify tag (on decrypt) */
 443                 if (EVP_Cipher(&cc->evp, NULL, NULL, 0) < 0)
 444                         return cc->encrypt ?
 445                             SSH_ERR_LIBCRYPTO_ERROR : SSH_ERR_MAC_INVALID;
 446                 if (cc->encrypt &&
 447                     !EVP_CIPHER_CTX_ctrl(&cc->evp, EVP_CTRL_GCM_GET_TAG,
 448                     authlen, dest + aadlen + len))
 449                         return SSH_ERR_LIBCRYPTO_ERROR;
 450         }
 451         return 0;
 452 #endif
 453 }
 454
 455 /* Extract the packet length, including any decryption necessary beforehand */
 456 int
 457 cipher_get_length(struct sshcipher_ctx *cc, u_int *plenp, u_int seqnr,
 458     const u_char *cp, u_int len)
 459 {
 460         if ((cc->cipher->flags & CFLAG_CHACHAPOLY) != 0)
 461                 return chachapoly_get_length(&cc->cp_ctx, plenp, seqnr,
 462                     cp, len);
 463         if (len < 4)
 464                 return SSH_ERR_MESSAGE_INCOMPLETE;
 465         *plenp = get_u32(cp);
 466         return 0;
 467 }
 468
 469 int
 470 cipher_cleanup(struct sshcipher_ctx *cc)
 471 {
 472         if (cc == NULL || cc->cipher == NULL)
 473                 return 0;
 474         if ((cc->cipher->flags & CFLAG_CHACHAPOLY) != 0)
 475                 explicit_bzero(&cc->cp_ctx, sizeof(cc->cp_ctx));
 476         else if ((cc->cipher->flags & CFLAG_AESCTR) != 0)
 477                 explicit_bzero(&cc->ac_ctx, sizeof(cc->ac_ctx));
 478 #ifdef WITH_OPENSSL
 479         else if (EVP_CIPHER_CTX_cleanup(&cc->evp) == 0)
 480                 return SSH_ERR_LIBCRYPTO_ERROR;
 481 #endif
 482         return 0;
 483 }
 484
 485 /*
 486  * Selects the cipher, and keys if by computing the MD5 checksum of the
 487  * passphrase and using the resulting 16 bytes as the key.
 488  */
 489 int
 490 cipher_set_key_string(struct sshcipher_ctx *cc, const struct sshcipher *cipher,
 491     const char *passphrase, int do_encrypt)
 492 {
 493         u_char digest[16];
 494         int r = SSH_ERR_INTERNAL_ERROR;
 495
 496         if ((r = ssh_digest_memory(SSH_DIGEST_MD5,
 497             passphrase, strlen(passphrase),
 498             digest, sizeof(digest))) != 0)
 499                 goto out;
 500
 501         r = cipher_init(cc, cipher, digest, 16, NULL, 0, do_encrypt);
 502  out:
 503         explicit_bzero(digest, sizeof(digest));
 504         return r;
 505 }
 506
 507 /*
 508  * Exports an IV from the sshcipher_ctx required to export the key
 509  * state back from the unprivileged child to the privileged parent
 510  * process.
 511  */
 512 int
 513 cipher_get_keyiv_len(const struct sshcipher_ctx *cc)
 514 {
 515         const struct sshcipher *c = cc->cipher;
 516         int ivlen = 0;
 517
 518         if (c->number == SSH_CIPHER_3DES)
 519                 ivlen = 24;
 520         else if ((cc->cipher->flags & CFLAG_CHACHAPOLY) != 0)
 521                 ivlen = 0;
 522         else if ((cc->cipher->flags & CFLAG_AESCTR) != 0)
 523                 ivlen = sizeof(cc->ac_ctx.ctr);
 524 #ifdef WITH_OPENSSL
 525         else
 526                 ivlen = EVP_CIPHER_CTX_iv_length(&cc->evp);
 527 #endif /* WITH_OPENSSL */
 528         return (ivlen);
 529 }
 530
 531 int
 532 cipher_get_keyiv(struct sshcipher_ctx *cc, u_char *iv, u_int len)
 533 {
 534         const struct sshcipher *c = cc->cipher;
 535 #ifdef WITH_OPENSSL
 536         int evplen;
 537 #endif
 538
 539         if ((cc->cipher->flags & CFLAG_CHACHAPOLY) != 0) {
 540                 if (len != 0)
 541                         return SSH_ERR_INVALID_ARGUMENT;
 542                 return 0;
 543         }
 544         if ((cc->cipher->flags & CFLAG_AESCTR) != 0) {
 545                 if (len != sizeof(cc->ac_ctx.ctr))
 546                         return SSH_ERR_INVALID_ARGUMENT;
 547                 memcpy(iv, cc->ac_ctx.ctr, len);
 548                 return 0;
 549         }
 550         if ((cc->cipher->flags & CFLAG_NONE) != 0)
 551                 return 0;
 552
 553         switch (c->number) {
 554 #ifdef WITH_OPENSSL
 555         case SSH_CIPHER_SSH2:
 556         case SSH_CIPHER_DES:
 557         case SSH_CIPHER_BLOWFISH:
 558                 evplen = EVP_CIPHER_CTX_iv_length(&cc->evp);
 559                 if (evplen == 0)
 560                         return 0;
 561                 else if (evplen < 0)
 562                         return SSH_ERR_LIBCRYPTO_ERROR;
 563                 if ((u_int)evplen != len)
 564                         return SSH_ERR_INVALID_ARGUMENT;
 565 #ifndef OPENSSL_HAVE_EVPCTR
 566                 if (c->evptype == evp_aes_128_ctr)
 567                         ssh_aes_ctr_iv(&cc->evp, 0, iv, len);
 568                 else
 569 #endif
 570                 if (cipher_authlen(c)) {
 571                         if (!EVP_CIPHER_CTX_ctrl(&cc->evp, EVP_CTRL_GCM_IV_GEN,
 572                            len, iv))
 573                                return SSH_ERR_LIBCRYPTO_ERROR;
 574                 } else
 575                         memcpy(iv, cc->evp.iv, len);
 576                 break;
 577 #endif
 578 #ifdef WITH_SSH1
 579         case SSH_CIPHER_3DES:
 580                 return ssh1_3des_iv(&cc->evp, 0, iv, 24);
 581 #endif
 582         default:
 583                 return SSH_ERR_INVALID_ARGUMENT;
 584         }
 585         return 0;
 586 }
 587
 588 int
 589 cipher_set_keyiv(struct sshcipher_ctx *cc, const u_char *iv)
 590 {
 591         const struct sshcipher *c = cc->cipher;
 592 #ifdef WITH_OPENSSL
 593         int evplen = 0;
 594 #endif
 595
 596         if ((cc->cipher->flags & CFLAG_CHACHAPOLY) != 0)
 597                 return 0;
 598         if ((cc->cipher->flags & CFLAG_NONE) != 0)
 599                 return 0;
 600
 601         switch (c->number) {
 602 #ifdef WITH_OPENSSL
 603         case SSH_CIPHER_SSH2:
 604         case SSH_CIPHER_DES:
 605         case SSH_CIPHER_BLOWFISH:
 606                 evplen = EVP_CIPHER_CTX_iv_length(&cc->evp);
 607                 if (evplen <= 0)
 608                         return SSH_ERR_LIBCRYPTO_ERROR;
 609                 if (cipher_authlen(c)) {
 610                         /* XXX iv arg is const, but EVP_CIPHER_CTX_ctrl isn't */
 611                         if (!EVP_CIPHER_CTX_ctrl(&cc->evp,
 612                             EVP_CTRL_GCM_SET_IV_FIXED, -1, (void *)iv))
 613                                 return SSH_ERR_LIBCRYPTO_ERROR;
 614                 } else
 615                         memcpy(cc->evp.iv, iv, evplen);
 616                 break;
 617 #endif
 618 #ifdef WITH_SSH1
 619         case SSH_CIPHER_3DES:
 620                 return ssh1_3des_iv(&cc->evp, 1, (u_char *)iv, 24);
 621 #endif
 622         default:
 623                 return SSH_ERR_INVALID_ARGUMENT;
 624         }
 625         return 0;
 626 }
 627
 628 #ifdef WITH_OPENSSL
 629 #define EVP_X_STATE(evp)        (evp).cipher_data
 630 #define EVP_X_STATE_LEN(evp)    (evp).cipher->ctx_size
 631 #endif
 632
 633 int
 634 cipher_get_keycontext(const struct sshcipher_ctx *cc, u_char *dat)
 635 {
 636 #if defined(WITH_OPENSSL) && !defined(OPENSSL_NO_RC4)
 637         const struct sshcipher *c = cc->cipher;
 638         int plen = 0;
 639
 640         if (c->evptype == EVP_rc4) {
 641                 plen = EVP_X_STATE_LEN(cc->evp);
 642                 if (dat == NULL)
 643                         return (plen);
 644                 memcpy(dat, EVP_X_STATE(cc->evp), plen);
 645         }
 646         return (plen);
 647 #else
 648         return 0;
 649 #endif
 650 }
 651
 652 void
 653 cipher_set_keycontext(struct sshcipher_ctx *cc, const u_char *dat)
 654 {
 655 #if defined(WITH_OPENSSL) && !defined(OPENSSL_NO_RC4)
 656         const struct sshcipher *c = cc->cipher;
 657         int plen;
 658
 659         if (c->evptype == EVP_rc4) {
 660                 plen = EVP_X_STATE_LEN(cc->evp);
 661                 memcpy(EVP_X_STATE(cc->evp), dat, plen);
 662         }
 663 #endif
 664 }