xref: /openssh-portable/cipher-aes.c (revision f60845fd)
1 /*
2  * Copyright (c) 2003 Markus Friedl.  All rights reserved.
3  *
4  * Redistribution and use in source and binary forms, with or without
5  * modification, are permitted provided that the following conditions
6  * are met:
7  * 1. Redistributions of source code must retain the above copyright
8  *    notice, this list of conditions and the following disclaimer.
9  * 2. Redistributions in binary form must reproduce the above copyright
10  *    notice, this list of conditions and the following disclaimer in the
11  *    documentation and/or other materials provided with the distribution.
12  *
13  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
14  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
15  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
16  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
17  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
18  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
19  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
20  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
21  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
22  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
23  */
24 
25 #include "includes.h"
26 
27 /* compatibility with old or broken OpenSSL versions */
28 #include "openbsd-compat/openssl-compat.h"
29 
30 #ifdef USE_BUILTIN_RIJNDAEL
31 #include <sys/types.h>
32 
33 #include <openssl/evp.h>
34 
35 #include <stdarg.h>
36 #include <string.h>
37 
38 #include "rijndael.h"
39 #include "xmalloc.h"
40 #include "log.h"
41 
42 #define RIJNDAEL_BLOCKSIZE 16
43 struct ssh_rijndael_ctx
44 {
45 	rijndael_ctx	r_ctx;
46 	u_char		r_iv[RIJNDAEL_BLOCKSIZE];
47 };
48 
49 static int
ssh_rijndael_init(EVP_CIPHER_CTX * ctx,const u_char * key,const u_char * iv,int enc)50 ssh_rijndael_init(EVP_CIPHER_CTX *ctx, const u_char *key, const u_char *iv,
51     int enc)
52 {
53 	struct ssh_rijndael_ctx *c;
54 
55 	if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) == NULL) {
56 		c = xmalloc(sizeof(*c));
57 		EVP_CIPHER_CTX_set_app_data(ctx, c);
58 	}
59 	if (key != NULL) {
60 		if (enc == -1)
61 			enc = ctx->encrypt;
62 		rijndael_set_key(&c->r_ctx, (u_char *)key,
63 		    8*EVP_CIPHER_CTX_key_length(ctx), enc);
64 	}
65 	if (iv != NULL)
66 		memcpy(c->r_iv, iv, RIJNDAEL_BLOCKSIZE);
67 	return (1);
68 }
69 
70 static int
ssh_rijndael_cbc(EVP_CIPHER_CTX * ctx,u_char * dest,const u_char * src,LIBCRYPTO_EVP_INL_TYPE len)71 ssh_rijndael_cbc(EVP_CIPHER_CTX *ctx, u_char *dest, const u_char *src,
72     LIBCRYPTO_EVP_INL_TYPE len)
73 {
74 	struct ssh_rijndael_ctx *c;
75 	u_char buf[RIJNDAEL_BLOCKSIZE];
76 	u_char *cprev, *cnow, *plain, *ivp;
77 	int i, j, blocks = len / RIJNDAEL_BLOCKSIZE;
78 
79 	if (len == 0)
80 		return (1);
81 	if (len % RIJNDAEL_BLOCKSIZE)
82 		fatal("ssh_rijndael_cbc: bad len %d", len);
83 	if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) == NULL) {
84 		error("ssh_rijndael_cbc: no context");
85 		return (0);
86 	}
87 	if (ctx->encrypt) {
88 		cnow  = dest;
89 		plain = (u_char *)src;
90 		cprev = c->r_iv;
91 		for (i = 0; i < blocks; i++, plain+=RIJNDAEL_BLOCKSIZE,
92 		    cnow+=RIJNDAEL_BLOCKSIZE) {
93 			for (j = 0; j < RIJNDAEL_BLOCKSIZE; j++)
94 				buf[j] = plain[j] ^ cprev[j];
95 			rijndael_encrypt(&c->r_ctx, buf, cnow);
96 			cprev = cnow;
97 		}
98 		memcpy(c->r_iv, cprev, RIJNDAEL_BLOCKSIZE);
99 	} else {
100 		cnow  = (u_char *) (src+len-RIJNDAEL_BLOCKSIZE);
101 		plain = dest+len-RIJNDAEL_BLOCKSIZE;
102 
103 		memcpy(buf, cnow, RIJNDAEL_BLOCKSIZE);
104 		for (i = blocks; i > 0; i--, cnow-=RIJNDAEL_BLOCKSIZE,
105 		    plain-=RIJNDAEL_BLOCKSIZE) {
106 			rijndael_decrypt(&c->r_ctx, cnow, plain);
107 			ivp = (i == 1) ? c->r_iv : cnow-RIJNDAEL_BLOCKSIZE;
108 			for (j = 0; j < RIJNDAEL_BLOCKSIZE; j++)
109 				plain[j] ^= ivp[j];
110 		}
111 		memcpy(c->r_iv, buf, RIJNDAEL_BLOCKSIZE);
112 	}
113 	return (1);
114 }
115 
116 static int
ssh_rijndael_cleanup(EVP_CIPHER_CTX * ctx)117 ssh_rijndael_cleanup(EVP_CIPHER_CTX *ctx)
118 {
119 	struct ssh_rijndael_ctx *c;
120 
121 	if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) != NULL) {
122 		memset(c, 0, sizeof(*c));
123 		free(c);
124 		EVP_CIPHER_CTX_set_app_data(ctx, NULL);
125 	}
126 	return (1);
127 }
128 
129 void
ssh_rijndael_iv(EVP_CIPHER_CTX * evp,int doset,u_char * iv,u_int len)130 ssh_rijndael_iv(EVP_CIPHER_CTX *evp, int doset, u_char * iv, u_int len)
131 {
132 	struct ssh_rijndael_ctx *c;
133 
134 	if ((c = EVP_CIPHER_CTX_get_app_data(evp)) == NULL)
135 		fatal("ssh_rijndael_iv: no context");
136 	if (doset)
137 		memcpy(c->r_iv, iv, len);
138 	else
139 		memcpy(iv, c->r_iv, len);
140 }
141 
142 const EVP_CIPHER *
evp_rijndael(void)143 evp_rijndael(void)
144 {
145 	static EVP_CIPHER rijndal_cbc;
146 
147 	memset(&rijndal_cbc, 0, sizeof(EVP_CIPHER));
148 	rijndal_cbc.nid = NID_undef;
149 	rijndal_cbc.block_size = RIJNDAEL_BLOCKSIZE;
150 	rijndal_cbc.iv_len = RIJNDAEL_BLOCKSIZE;
151 	rijndal_cbc.key_len = 16;
152 	rijndal_cbc.init = ssh_rijndael_init;
153 	rijndal_cbc.cleanup = ssh_rijndael_cleanup;
154 	rijndal_cbc.do_cipher = ssh_rijndael_cbc;
155 #ifndef SSH_OLD_EVP
156 	rijndal_cbc.flags = EVP_CIPH_CBC_MODE | EVP_CIPH_VARIABLE_LENGTH |
157 	    EVP_CIPH_ALWAYS_CALL_INIT | EVP_CIPH_CUSTOM_IV;
158 #endif
159 	return (&rijndal_cbc);
160 }
161 #endif /* USE_BUILTIN_RIJNDAEL */
162