| /* |
| * 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. |
| */ |
| |
| #include "includes.h" |
| RCSID("$OpenBSD: cipher.c,v 1.51 2002/02/14 23:41:01 markus Exp $"); |
| |
| #include "xmalloc.h" |
| #include "log.h" |
| #include "cipher.h" |
| |
| #include <openssl/md5.h> |
| |
| struct Cipher { |
| char *name; |
| int number; /* for ssh1 only */ |
| u_int block_size; |
| u_int key_len; |
| void (*setkey)(CipherContext *, const u_char *, u_int); |
| void (*setiv)(CipherContext *, const u_char *, u_int); |
| void (*encrypt)(CipherContext *, u_char *, const u_char *, u_int); |
| void (*decrypt)(CipherContext *, u_char *, const u_char *, u_int); |
| }; |
| |
| /* no encryption */ |
| static void |
| none_setkey(CipherContext *cc, const u_char *key, u_int keylen) |
| { |
| } |
| static void |
| none_setiv(CipherContext *cc, const u_char *iv, u_int ivlen) |
| { |
| } |
| static void |
| none_crypt(CipherContext *cc, u_char *dest, const u_char *src, u_int len) |
| { |
| memcpy(dest, src, len); |
| } |
| |
| /* DES */ |
| static void |
| des_ssh1_setkey(CipherContext *cc, const u_char *key, u_int keylen) |
| { |
| static int dowarn = 1; |
| if (dowarn) { |
| error("Warning: use of DES is strongly discouraged " |
| "due to cryptographic weaknesses"); |
| dowarn = 0; |
| } |
| des_set_key((void *)key, cc->u.des.key); |
| } |
| static void |
| des_ssh1_setiv(CipherContext *cc, const u_char *iv, u_int ivlen) |
| { |
| memset(cc->u.des.iv, 0, sizeof(cc->u.des.iv)); |
| } |
| static void |
| des_ssh1_encrypt(CipherContext *cc, u_char *dest, const u_char *src, u_int len) |
| { |
| des_ncbc_encrypt(src, dest, len, cc->u.des.key, &cc->u.des.iv, |
| DES_ENCRYPT); |
| } |
| static void |
| des_ssh1_decrypt(CipherContext *cc, u_char *dest, const u_char *src, u_int len) |
| { |
| des_ncbc_encrypt(src, dest, len, cc->u.des.key, &cc->u.des.iv, |
| DES_DECRYPT); |
| } |
| |
| /* 3DES */ |
| static void |
| des3_setkey(CipherContext *cc, const u_char *key, u_int keylen) |
| { |
| des_set_key((void *) key, cc->u.des3.key1); |
| des_set_key((void *) (key+8), cc->u.des3.key2); |
| des_set_key((void *) (key+16), cc->u.des3.key3); |
| } |
| static void |
| des3_setiv(CipherContext *cc, const u_char *iv, u_int ivlen) |
| { |
| memset(cc->u.des3.iv1, 0, sizeof(cc->u.des3.iv1)); |
| memset(cc->u.des3.iv2, 0, sizeof(cc->u.des3.iv2)); |
| memset(cc->u.des3.iv3, 0, sizeof(cc->u.des3.iv3)); |
| if (iv == NULL) |
| return; |
| memcpy(cc->u.des3.iv3, (char *)iv, 8); |
| } |
| static void |
| des3_cbc_encrypt(CipherContext *cc, u_char *dest, const u_char *src, u_int len) |
| { |
| des_ede3_cbc_encrypt(src, dest, len, |
| cc->u.des3.key1, cc->u.des3.key2, cc->u.des3.key3, |
| &cc->u.des3.iv3, DES_ENCRYPT); |
| } |
| static void |
| des3_cbc_decrypt(CipherContext *cc, u_char *dest, const u_char *src, u_int len) |
| { |
| des_ede3_cbc_encrypt(src, dest, len, |
| cc->u.des3.key1, cc->u.des3.key2, cc->u.des3.key3, |
| &cc->u.des3.iv3, DES_DECRYPT); |
| } |
| |
| /* |
| * 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. |
| */ |
| static void |
| des3_ssh1_setkey(CipherContext *cc, const u_char *key, u_int keylen) |
| { |
| des_set_key((void *) key, cc->u.des3.key1); |
| des_set_key((void *) (key+8), cc->u.des3.key2); |
| if (keylen <= 16) |
| des_set_key((void *) key, cc->u.des3.key3); |
| else |
| des_set_key((void *) (key+16), cc->u.des3.key3); |
| } |
| static void |
| des3_ssh1_encrypt(CipherContext *cc, u_char *dest, const u_char *src, |
| u_int len) |
| { |
| des_ncbc_encrypt(src, dest, len, cc->u.des3.key1, &cc->u.des3.iv1, |
| DES_ENCRYPT); |
| des_ncbc_encrypt(dest, dest, len, cc->u.des3.key2, &cc->u.des3.iv2, |
| DES_DECRYPT); |
| des_ncbc_encrypt(dest, dest, len, cc->u.des3.key3, &cc->u.des3.iv3, |
| DES_ENCRYPT); |
| } |
| static void |
| des3_ssh1_decrypt(CipherContext *cc, u_char *dest, const u_char *src, |
| u_int len) |
| { |
| des_ncbc_encrypt(src, dest, len, cc->u.des3.key3, &cc->u.des3.iv3, |
| DES_DECRYPT); |
| des_ncbc_encrypt(dest, dest, len, cc->u.des3.key2, &cc->u.des3.iv2, |
| DES_ENCRYPT); |
| des_ncbc_encrypt(dest, dest, len, cc->u.des3.key1, &cc->u.des3.iv1, |
| DES_DECRYPT); |
| } |
| |
| /* Blowfish */ |
| static void |
| blowfish_setkey(CipherContext *cc, const u_char *key, u_int keylen) |
| { |
| BF_set_key(&cc->u.bf.key, keylen, (u_char *)key); |
| } |
| static void |
| blowfish_setiv(CipherContext *cc, const u_char *iv, u_int ivlen) |
| { |
| if (iv == NULL) |
| memset(cc->u.bf.iv, 0, 8); |
| else |
| memcpy(cc->u.bf.iv, (char *)iv, 8); |
| } |
| static void |
| blowfish_cbc_encrypt(CipherContext *cc, u_char *dest, const u_char *src, |
| u_int len) |
| { |
| BF_cbc_encrypt((void *)src, dest, len, &cc->u.bf.key, cc->u.bf.iv, |
| BF_ENCRYPT); |
| } |
| static void |
| blowfish_cbc_decrypt(CipherContext *cc, u_char *dest, const u_char *src, |
| u_int len) |
| { |
| BF_cbc_encrypt((void *)src, dest, len, &cc->u.bf.key, cc->u.bf.iv, |
| BF_DECRYPT); |
| } |
| |
| /* |
| * 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) |
| { |
| 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 void |
| blowfish_ssh1_encrypt(CipherContext *cc, u_char *dest, const u_char *src, |
| u_int len) |
| { |
| swap_bytes(src, dest, len); |
| BF_cbc_encrypt((void *)dest, dest, len, &cc->u.bf.key, cc->u.bf.iv, |
| BF_ENCRYPT); |
| swap_bytes(dest, dest, len); |
| } |
| static void |
| blowfish_ssh1_decrypt(CipherContext *cc, u_char *dest, const u_char *src, |
| u_int len) |
| { |
| swap_bytes(src, dest, len); |
| BF_cbc_encrypt((void *)dest, dest, len, &cc->u.bf.key, cc->u.bf.iv, |
| BF_DECRYPT); |
| swap_bytes(dest, dest, len); |
| } |
| |
| /* alleged rc4 */ |
| static void |
| arcfour_setkey(CipherContext *cc, const u_char *key, u_int keylen) |
| { |
| RC4_set_key(&cc->u.rc4, keylen, (u_char *)key); |
| } |
| static void |
| arcfour_crypt(CipherContext *cc, u_char *dest, const u_char *src, u_int len) |
| { |
| RC4(&cc->u.rc4, len, (u_char *)src, dest); |
| } |
| |
| /* CAST */ |
| static void |
| cast_setkey(CipherContext *cc, const u_char *key, u_int keylen) |
| { |
| CAST_set_key(&cc->u.cast.key, keylen, (u_char *) key); |
| } |
| static void |
| cast_setiv(CipherContext *cc, const u_char *iv, u_int ivlen) |
| { |
| if (iv == NULL) |
| fatal("no IV for %s.", cc->cipher->name); |
| memcpy(cc->u.cast.iv, (char *)iv, 8); |
| } |
| static void |
| cast_cbc_encrypt(CipherContext *cc, u_char *dest, const u_char *src, u_int len) |
| { |
| CAST_cbc_encrypt(src, dest, len, &cc->u.cast.key, cc->u.cast.iv, |
| CAST_ENCRYPT); |
| } |
| static void |
| cast_cbc_decrypt(CipherContext *cc, u_char *dest, const u_char *src, u_int len) |
| { |
| CAST_cbc_encrypt(src, dest, len, &cc->u.cast.key, cc->u.cast.iv, |
| CAST_DECRYPT); |
| } |
| |
| /* RIJNDAEL */ |
| |
| #define RIJNDAEL_BLOCKSIZE 16 |
| static void |
| rijndael_setkey(CipherContext *cc, const u_char *key, u_int keylen) |
| { |
| rijndael_set_key(&cc->u.rijndael.enc, (char *)key, 8*keylen, 1); |
| rijndael_set_key(&cc->u.rijndael.dec, (char *)key, 8*keylen, 0); |
| } |
| static void |
| rijndael_setiv(CipherContext *cc, const u_char *iv, u_int ivlen) |
| { |
| if (iv == NULL || ivlen != RIJNDAEL_BLOCKSIZE) |
| fatal("bad/no IV for %s.", cc->cipher->name); |
| memcpy(cc->u.rijndael.iv, iv, RIJNDAEL_BLOCKSIZE); |
| } |
| static void |
| rijndael_cbc_encrypt(CipherContext *cc, u_char *dest, const u_char *src, |
| u_int len) |
| { |
| rijndael_ctx *ctx = &cc->u.rijndael.enc; |
| u_char *iv = cc->u.rijndael.iv; |
| u_char in[RIJNDAEL_BLOCKSIZE]; |
| u_char *cprev, *cnow, *plain; |
| int i, j, blocks = len / RIJNDAEL_BLOCKSIZE; |
| |
| if (len == 0) |
| return; |
| if (len % RIJNDAEL_BLOCKSIZE) |
| fatal("rijndael_cbc_encrypt: bad len %d", len); |
| cnow = dest; |
| plain = (u_char *)src; |
| cprev = iv; |
| for (i = 0; i < blocks; i++, plain+=RIJNDAEL_BLOCKSIZE, |
| cnow+=RIJNDAEL_BLOCKSIZE) { |
| for (j = 0; j < RIJNDAEL_BLOCKSIZE; j++) |
| in[j] = plain[j] ^ cprev[j]; |
| rijndael_encrypt(ctx, in, cnow); |
| cprev = cnow; |
| } |
| memcpy(iv, cprev, RIJNDAEL_BLOCKSIZE); |
| } |
| static void |
| rijndael_cbc_decrypt(CipherContext *cc, u_char *dest, const u_char *src, |
| u_int len) |
| { |
| rijndael_ctx *ctx = &cc->u.rijndael.dec; |
| u_char *iv = cc->u.rijndael.iv; |
| u_char ivsaved[RIJNDAEL_BLOCKSIZE]; |
| u_char *cnow = (u_char *) (src+len-RIJNDAEL_BLOCKSIZE); |
| u_char *plain = dest+len-RIJNDAEL_BLOCKSIZE; |
| u_char *ivp; |
| int i, j, blocks = len / RIJNDAEL_BLOCKSIZE; |
| |
| if (len == 0) |
| return; |
| if (len % RIJNDAEL_BLOCKSIZE) |
| fatal("rijndael_cbc_decrypt: bad len %d", len); |
| memcpy(ivsaved, cnow, RIJNDAEL_BLOCKSIZE); |
| for (i = blocks; i > 0; i--, cnow-=RIJNDAEL_BLOCKSIZE, |
| plain-=RIJNDAEL_BLOCKSIZE) { |
| rijndael_decrypt(ctx, cnow, plain); |
| ivp = (i == 1) ? iv : cnow-RIJNDAEL_BLOCKSIZE; |
| for (j = 0; j < RIJNDAEL_BLOCKSIZE; j++) |
| plain[j] ^= ivp[j]; |
| } |
| memcpy(iv, ivsaved, RIJNDAEL_BLOCKSIZE); |
| } |
| |
| Cipher ciphers[] = { |
| { "none", |
| SSH_CIPHER_NONE, 8, 0, |
| none_setkey, none_setiv, |
| none_crypt, none_crypt }, |
| { "des", |
| SSH_CIPHER_DES, 8, 8, |
| des_ssh1_setkey, des_ssh1_setiv, |
| des_ssh1_encrypt, des_ssh1_decrypt }, |
| { "3des", |
| SSH_CIPHER_3DES, 8, 16, |
| des3_ssh1_setkey, des3_setiv, |
| des3_ssh1_encrypt, des3_ssh1_decrypt }, |
| { "blowfish", |
| SSH_CIPHER_BLOWFISH, 8, 16, |
| blowfish_setkey, blowfish_setiv, |
| blowfish_ssh1_encrypt, blowfish_ssh1_decrypt }, |
| |
| { "3des-cbc", |
| SSH_CIPHER_SSH2, 8, 24, |
| des3_setkey, des3_setiv, |
| des3_cbc_encrypt, des3_cbc_decrypt }, |
| { "blowfish-cbc", |
| SSH_CIPHER_SSH2, 8, 16, |
| blowfish_setkey, blowfish_setiv, |
| blowfish_cbc_encrypt, blowfish_cbc_decrypt }, |
| { "cast128-cbc", |
| SSH_CIPHER_SSH2, 8, 16, |
| cast_setkey, cast_setiv, |
| cast_cbc_encrypt, cast_cbc_decrypt }, |
| { "arcfour", |
| SSH_CIPHER_SSH2, 8, 16, |
| arcfour_setkey, none_setiv, |
| arcfour_crypt, arcfour_crypt }, |
| { "aes128-cbc", |
| SSH_CIPHER_SSH2, 16, 16, |
| rijndael_setkey, rijndael_setiv, |
| rijndael_cbc_encrypt, rijndael_cbc_decrypt }, |
| { "aes192-cbc", |
| SSH_CIPHER_SSH2, 16, 24, |
| rijndael_setkey, rijndael_setiv, |
| rijndael_cbc_encrypt, rijndael_cbc_decrypt }, |
| { "aes256-cbc", |
| SSH_CIPHER_SSH2, 16, 32, |
| rijndael_setkey, rijndael_setiv, |
| rijndael_cbc_encrypt, rijndael_cbc_decrypt }, |
| { NULL, SSH_CIPHER_ILLEGAL, 0, 0, NULL, NULL, NULL, NULL } |
| }; |
| |
| /*--*/ |
| |
| u_int |
| cipher_blocksize(Cipher *c) |
| { |
| return (c->block_size); |
| } |
| |
| u_int |
| cipher_keylen(Cipher *c) |
| { |
| return (c->key_len); |
| } |
| |
| 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) |
| { |
| 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; |
| cc->encrypt = (encrypt == CIPHER_ENCRYPT); |
| cipher->setkey(cc, key, keylen); |
| cipher->setiv(cc, iv, ivlen); |
| } |
| |
| 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 (cc->encrypt) |
| cc->cipher->encrypt(cc, dest, src, len); |
| else |
| cc->cipher->decrypt(cc, dest, src, len); |
| } |
| |
| void |
| cipher_cleanup(CipherContext *cc) |
| { |
| memset(cc, 0, sizeof(*cc)); |
| } |
| |
| /* |
| * 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)); |
| } |