/* * Author: Tatu Ylonen <ylo@cs.hut.fi> * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland * All rights reserved * * As far as I am concerned, the code I have written for this software * can be used freely for any purpose. Any derived versions of this * software must be clearly marked as such, and if the derived work is * incompatible with the protocol description in the RFC file, it must be * called by a name other than "ssh" or "Secure Shell". * * * Copyright (c) 1999 Niels Provos. All rights reserved. * Copyright (c) 1999, 2000 Markus Friedl. All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */ /* * Copyright 2009 Sun Microsystems, Inc. All rights reserved. * Use is subject to license terms. */ #include "includes.h" RCSID("$OpenBSD: cipher.c,v 1.61 2002/07/12 15:50:17 markus Exp $"); #include "xmalloc.h" #include "log.h" #include "cipher.h" #include <openssl/md5.h> /* * Symmetric ciphers can be offloaded to any engine through the EVP API only. * However, OpenSSL doesn't offer AES in counter mode through EVP. So, we must * define our own EVP functions. */ extern const EVP_CIPHER *evp_aes_128_ctr(void); extern const EVP_CIPHER *evp_aes_192_ctr(void); extern const EVP_CIPHER *evp_aes_256_ctr(void); extern void ssh_aes_ctr_iv(EVP_CIPHER_CTX *, int, u_char *, u_int); static const EVP_CIPHER *evp_ssh1_3des(void); static const EVP_CIPHER *evp_ssh1_bf(void); struct Cipher { char *name; int number; /* for ssh1 only */ u_int block_size; u_int key_len; u_int discard_len; const EVP_CIPHER *(*evptype)(void); } ciphers[] = { { "none", SSH_CIPHER_NONE, 8, 0, 0, EVP_enc_null }, { "des", SSH_CIPHER_DES, 8, 8, 0, EVP_des_cbc }, { "3des", SSH_CIPHER_3DES, 8, 16, 0, evp_ssh1_3des }, { "blowfish", SSH_CIPHER_BLOWFISH, 8, 32, 0, evp_ssh1_bf }, { "3des-cbc", SSH_CIPHER_SSH2, 8, 24, 0, EVP_des_ede3_cbc }, { "blowfish-cbc", SSH_CIPHER_SSH2, 8, 16, 0, EVP_bf_cbc }, #ifdef SOLARIS_SSH_ENABLE_CAST5_128 { "cast128-cbc", SSH_CIPHER_SSH2, 8, 16, 0, EVP_cast5_cbc }, #endif /* SOLARIS_SSH_ENABLE_CAST5_128 */ { "arcfour", SSH_CIPHER_SSH2, 8, 16, 0, EVP_rc4 }, { "arcfour128", SSH_CIPHER_SSH2, 8, 16, 1536, EVP_rc4 }, { "arcfour256", SSH_CIPHER_SSH2, 8, 32, 1536, EVP_rc4 }, { "aes128-cbc", SSH_CIPHER_SSH2, 16, 16, 0, EVP_aes_128_cbc }, { "aes192-cbc", SSH_CIPHER_SSH2, 16, 24, 0, EVP_aes_192_cbc }, { "aes256-cbc", SSH_CIPHER_SSH2, 16, 32, 0, EVP_aes_256_cbc }, { "aes128-ctr", SSH_CIPHER_SSH2, 16, 16, 0, evp_aes_128_ctr }, { "aes192-ctr", SSH_CIPHER_SSH2, 16, 24, 0, evp_aes_192_ctr }, { "aes256-ctr", SSH_CIPHER_SSH2, 16, 32, 0, evp_aes_256_ctr }, { NULL, SSH_CIPHER_ILLEGAL, 0, 0, 0, NULL } }; /*--*/ u_int cipher_blocksize(Cipher *c) { return (c->block_size); } u_int cipher_keylen(Cipher *c) { return (c->key_len); } u_int cipher_get_number(Cipher *c) { return (c->number); } u_int cipher_mask_ssh1(int client) { u_int mask = 0; mask |= 1 << SSH_CIPHER_3DES; /* Mandatory */ mask |= 1 << SSH_CIPHER_BLOWFISH; if (client) { mask |= 1 << SSH_CIPHER_DES; } return mask; } Cipher * cipher_by_name(const char *name) { Cipher *c; for (c = ciphers; c->name != NULL; c++) if (strcasecmp(c->name, name) == 0) return c; return NULL; } Cipher * cipher_by_number(int id) { Cipher *c; for (c = ciphers; c->name != NULL; c++) if (c->number == id) return c; return NULL; } #define CIPHER_SEP "," int ciphers_valid(const char *names) { Cipher *c; char *ciphers, *cp; char *p; if (names == NULL || strcmp(names, "") == 0) return 0; ciphers = cp = xstrdup(names); for ((p = strsep(&cp, CIPHER_SEP)); p && *p != '\0'; (p = strsep(&cp, CIPHER_SEP))) { c = cipher_by_name(p); if (c == NULL || c->number != SSH_CIPHER_SSH2) { debug("bad cipher %s [%s]", p, names); xfree(ciphers); return 0; } else { debug3("cipher ok: %s [%s]", p, names); } } debug3("ciphers ok: [%s]", names); xfree(ciphers); return 1; } /* * Parses the name of the cipher. Returns the number of the corresponding * cipher, or -1 on error. */ int cipher_number(const char *name) { Cipher *c; if (name == NULL) return -1; c = cipher_by_name(name); return (c==NULL) ? -1 : c->number; } char * cipher_name(int id) { Cipher *c = cipher_by_number(id); return (c==NULL) ? "<unknown>" : c->name; } void cipher_init(CipherContext *cc, Cipher *cipher, const u_char *key, u_int keylen, const u_char *iv, u_int ivlen, int encrypt) { static int dowarn = 1; const EVP_CIPHER *type; int klen; u_char *junk, *discard; if (cipher->number == SSH_CIPHER_DES) { if (dowarn) { error("Warning: use of DES is strongly discouraged " "due to cryptographic weaknesses"); dowarn = 0; } if (keylen > 8) keylen = 8; } cc->plaintext = (cipher->number == SSH_CIPHER_NONE); if (keylen < cipher->key_len) fatal("cipher_init: key length %d is insufficient for %s.", keylen, cipher->name); if (iv != NULL && ivlen < cipher->block_size) fatal("cipher_init: iv length %d is insufficient for %s.", ivlen, cipher->name); cc->cipher = cipher; type = (*cipher->evptype)(); EVP_CIPHER_CTX_init(&cc->evp); /* * cc->evp is of type EVP_CIPHER_CTX and its key_len will be set to the * default value here for the cipher type. If the requested key length * is different from the default value we will call EVP_CipherInit() * again, see below. */ if (EVP_CipherInit(&cc->evp, type, NULL, (u_char *)iv, (encrypt == CIPHER_ENCRYPT)) == 0) fatal("cipher_init: EVP_CipherInit failed for %s", cipher->name); klen = EVP_CIPHER_CTX_key_length(&cc->evp); if (klen > 0 && keylen != klen) { debug("cipher_init: set keylen (%d -> %d)", klen, keylen); if (EVP_CIPHER_CTX_set_key_length(&cc->evp, keylen) == 0) fatal("cipher_init: set keylen failed (%d -> %d)", klen, keylen); } if (EVP_CipherInit(&cc->evp, NULL, (u_char *)key, NULL, -1) == 0) fatal("cipher_init: EVP_CipherInit: set key failed for %s", cipher->name); if (cipher->discard_len > 0) { junk = xmalloc(cipher->discard_len); discard = xmalloc(cipher->discard_len); if (EVP_Cipher(&cc->evp, discard, junk, cipher->discard_len) == 0) fatal("cipher_init: EVP_Cipher failed during discard"); memset(discard, 0, cipher->discard_len); xfree(junk); xfree(discard); } } void cipher_crypt(CipherContext *cc, u_char *dest, const u_char *src, u_int len) { if (len % cc->cipher->block_size) fatal("cipher_encrypt: bad plaintext length %d", len); if (EVP_Cipher(&cc->evp, dest, (u_char *)src, len) == 0) fatal("evp_crypt: EVP_Cipher failed"); } void cipher_cleanup(CipherContext *cc) { if (EVP_CIPHER_CTX_cleanup(&cc->evp) == 0) error("cipher_cleanup: EVP_CIPHER_CTX_cleanup failed"); } /* * Selects the cipher, and keys if by computing the MD5 checksum of the * passphrase and using the resulting 16 bytes as the key. */ void cipher_set_key_string(CipherContext *cc, Cipher *cipher, const char *passphrase, int encrypt) { MD5_CTX md; u_char digest[16]; MD5_Init(&md); MD5_Update(&md, (const u_char *)passphrase, strlen(passphrase)); MD5_Final(digest, &md); cipher_init(cc, cipher, digest, 16, NULL, 0, encrypt); memset(digest, 0, sizeof(digest)); memset(&md, 0, sizeof(md)); } /* Implementations for other non-EVP ciphers */ /* * This is used by SSH1: * * What kind of triple DES are these 2 routines? * * Why is there a redundant initialization vector? * * If only iv3 was used, then, this would till effect have been * outer-cbc. However, there is also a private iv1 == iv2 which * perhaps makes differential analysis easier. On the other hand, the * private iv1 probably makes the CRC-32 attack ineffective. This is a * result of that there is no longer any known iv1 to use when * choosing the X block. */ struct ssh1_3des_ctx { EVP_CIPHER_CTX k1, k2, k3; }; static int ssh1_3des_init(EVP_CIPHER_CTX *ctx, const u_char *key, const u_char *iv, int enc) { struct ssh1_3des_ctx *c; u_char *k1, *k2, *k3; if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) == NULL) { c = xmalloc(sizeof(*c)); EVP_CIPHER_CTX_set_app_data(ctx, c); } if (key == NULL) return (1); if (enc == -1) enc = ctx->encrypt; k1 = k2 = k3 = (u_char *) key; k2 += 8; if (EVP_CIPHER_CTX_key_length(ctx) >= 16+8) { if (enc) k3 += 16; else k1 += 16; } EVP_CIPHER_CTX_init(&c->k1); EVP_CIPHER_CTX_init(&c->k2); EVP_CIPHER_CTX_init(&c->k3); if (EVP_CipherInit(&c->k1, EVP_des_cbc(), k1, NULL, enc) == 0 || EVP_CipherInit(&c->k2, EVP_des_cbc(), k2, NULL, !enc) == 0 || EVP_CipherInit(&c->k3, EVP_des_cbc(), k3, NULL, enc) == 0) { memset(c, 0, sizeof(*c)); xfree(c); EVP_CIPHER_CTX_set_app_data(ctx, NULL); return (0); } return (1); } static int ssh1_3des_cbc(EVP_CIPHER_CTX *ctx, u_char *dest, const u_char *src, u_int len) { struct ssh1_3des_ctx *c; if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) == NULL) { error("ssh1_3des_cbc: no context"); return (0); } if (EVP_Cipher(&c->k1, dest, (u_char *)src, len) == 0 || EVP_Cipher(&c->k2, dest, dest, len) == 0 || EVP_Cipher(&c->k3, dest, dest, len) == 0) return (0); return (1); } static int ssh1_3des_cleanup(EVP_CIPHER_CTX *ctx) { struct ssh1_3des_ctx *c; if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) != NULL) { memset(c, 0, sizeof(*c)); xfree(c); EVP_CIPHER_CTX_set_app_data(ctx, NULL); } return (1); } static const EVP_CIPHER * evp_ssh1_3des(void) { static EVP_CIPHER ssh1_3des; memset(&ssh1_3des, 0, sizeof(EVP_CIPHER)); ssh1_3des.nid = NID_undef; ssh1_3des.block_size = 8; ssh1_3des.iv_len = 0; ssh1_3des.key_len = 16; ssh1_3des.init = ssh1_3des_init; ssh1_3des.cleanup = ssh1_3des_cleanup; ssh1_3des.do_cipher = ssh1_3des_cbc; ssh1_3des.flags = EVP_CIPH_CBC_MODE | EVP_CIPH_VARIABLE_LENGTH; return (&ssh1_3des); } /* * SSH1 uses a variation on Blowfish, all bytes must be swapped before * and after encryption/decryption. Thus the swap_bytes stuff (yuk). */ static void swap_bytes(const u_char *src, u_char *dst, int n) { u_char c[4]; /* Process 4 bytes every lap. */ for (n = n / 4; n > 0; n--) { c[3] = *src++; c[2] = *src++; c[1] = *src++; c[0] = *src++; *dst++ = c[0]; *dst++ = c[1]; *dst++ = c[2]; *dst++ = c[3]; } } static int (*orig_bf)(EVP_CIPHER_CTX *, u_char *, const u_char *, u_int) = NULL; static int bf_ssh1_cipher(EVP_CIPHER_CTX *ctx, u_char *out, const u_char *in, u_int len) { int ret; swap_bytes(in, out, len); ret = (*orig_bf)(ctx, out, out, len); swap_bytes(out, out, len); return (ret); } static const EVP_CIPHER * evp_ssh1_bf(void) { static EVP_CIPHER ssh1_bf; memcpy(&ssh1_bf, EVP_bf_cbc(), sizeof(EVP_CIPHER)); orig_bf = ssh1_bf.do_cipher; ssh1_bf.nid = NID_undef; ssh1_bf.do_cipher = bf_ssh1_cipher; ssh1_bf.key_len = 32; return (&ssh1_bf); } /* * Exports an IV from the CipherContext required to export the key * state back from the unprivileged child to the privileged parent * process. */ int cipher_get_keyiv_len(CipherContext *cc) { Cipher *c = cc->cipher; int ivlen; if (c->number == SSH_CIPHER_3DES) ivlen = 24; else ivlen = EVP_CIPHER_CTX_iv_length(&cc->evp); return (ivlen); } void cipher_get_keyiv(CipherContext *cc, u_char *iv, u_int len) { Cipher *c = cc->cipher; u_char *civ = NULL; int evplen; switch (c->number) { case SSH_CIPHER_SSH2: case SSH_CIPHER_DES: case SSH_CIPHER_BLOWFISH: evplen = EVP_CIPHER_CTX_iv_length(&cc->evp); if (evplen == 0) return; if (evplen != len) fatal("%s: wrong iv length %d != %d", __func__, evplen, len); if (c->evptype == evp_aes_128_ctr) { ssh_aes_ctr_iv(&cc->evp, 0, iv, len); return; } else { civ = cc->evp.iv; } break; case SSH_CIPHER_3DES: { struct ssh1_3des_ctx *desc; if (len != 24) fatal("%s: bad 3des iv length: %d", __func__, len); desc = EVP_CIPHER_CTX_get_app_data(&cc->evp); if (desc == NULL) fatal("%s: no 3des context", __func__); debug3("%s: Copying 3DES IV", __func__); memcpy(iv, desc->k1.iv, 8); memcpy(iv + 8, desc->k2.iv, 8); memcpy(iv + 16, desc->k3.iv, 8); return; } default: fatal("%s: bad cipher %d", __func__, c->number); } memcpy(iv, civ, len); } void cipher_set_keyiv(CipherContext *cc, u_char *iv) { Cipher *c = cc->cipher; u_char *div = NULL; int evplen = 0; switch (c->number) { case SSH_CIPHER_SSH2: case SSH_CIPHER_DES: case SSH_CIPHER_BLOWFISH: evplen = EVP_CIPHER_CTX_iv_length(&cc->evp); if (evplen == 0) return; if (c->evptype == evp_aes_128_ctr) { ssh_aes_ctr_iv(&cc->evp, 1, iv, evplen); return; } else { div = cc->evp.iv; } break; case SSH_CIPHER_3DES: { struct ssh1_3des_ctx *desc; desc = EVP_CIPHER_CTX_get_app_data(&cc->evp); if (desc == NULL) fatal("%s: no 3des context", __func__); debug3("%s: Installed 3DES IV", __func__); memcpy(desc->k1.iv, iv, 8); memcpy(desc->k2.iv, iv + 8, 8); memcpy(desc->k3.iv, iv + 16, 8); return; } default: fatal("%s: bad cipher %d", __func__, c->number); } memcpy(div, iv, evplen); } #if OPENSSL_VERSION_NUMBER < 0x00907000L #define EVP_X_STATE(evp) &(evp).c #define EVP_X_STATE_LEN(evp) sizeof((evp).c) #else #define EVP_X_STATE(evp) (evp).cipher_data #define EVP_X_STATE_LEN(evp) (evp).cipher->ctx_size #endif int cipher_get_keycontext(CipherContext *cc, u_char *dat) { int plen = 0; Cipher *c = cc->cipher; if (c->evptype == EVP_rc4) { plen = EVP_X_STATE_LEN(cc->evp); if (dat == NULL) return (plen); memcpy(dat, EVP_X_STATE(cc->evp), plen); } return (plen); } void cipher_set_keycontext(CipherContext *cc, u_char *dat) { Cipher *c = cc->cipher; int plen; if (c->evptype == EVP_rc4) { plen = EVP_X_STATE_LEN(cc->evp); memcpy(EVP_X_STATE(cc->evp), dat, plen); } }