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70791e56 | 1 | /* |
2 | * Copyright (c) 2003 Markus Friedl <markus@openbsd.org> | |
3 | * | |
4 | * Permission to use, copy, modify, and distribute this software for any | |
5 | * purpose with or without fee is hereby granted, provided that the above | |
6 | * copyright notice and this permission notice appear in all copies. | |
7 | * | |
8 | * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES | |
9 | * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF | |
10 | * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR | |
11 | * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES | |
12 | * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN | |
13 | * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF | |
14 | * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. | |
15 | */ | |
16 | #include "includes.h" | |
416fd2a8 | 17 | RCSID("$OpenBSD: cipher-ctr.c,v 1.4 2004/02/06 23:41:13 dtucker Exp $"); |
70791e56 | 18 | |
19 | #include <openssl/evp.h> | |
20 | ||
21 | #include "log.h" | |
22 | #include "xmalloc.h" | |
23 | ||
24 | #if OPENSSL_VERSION_NUMBER < 0x00906000L | |
25 | #define SSH_OLD_EVP | |
26 | #endif | |
27 | ||
28 | #if OPENSSL_VERSION_NUMBER < 0x00907000L | |
29 | #include "rijndael.h" | |
30 | #define AES_KEY rijndael_ctx | |
31 | #define AES_BLOCK_SIZE 16 | |
32 | #define AES_encrypt(a, b, c) rijndael_encrypt(c, a, b) | |
33 | #define AES_set_encrypt_key(a, b, c) rijndael_set_key(c, (char *)a, b, 1) | |
34 | #else | |
35 | #include <openssl/aes.h> | |
36 | #endif | |
37 | ||
38 | const EVP_CIPHER *evp_aes_128_ctr(void); | |
39 | void ssh_aes_ctr_iv(EVP_CIPHER_CTX *, int, u_char *, u_int); | |
40 | ||
41 | struct ssh_aes_ctr_ctx | |
42 | { | |
43 | AES_KEY aes_ctx; | |
44 | u_char aes_counter[AES_BLOCK_SIZE]; | |
45 | }; | |
46 | ||
47 | /* | |
48 | * increment counter 'ctr', | |
49 | * the counter is of size 'len' bytes and stored in network-byte-order. | |
50 | * (LSB at ctr[len-1], MSB at ctr[0]) | |
51 | */ | |
52 | static void | |
53 | ssh_ctr_inc(u_char *ctr, u_int len) | |
54 | { | |
55 | int i; | |
56 | ||
57 | for (i = len - 1; i >= 0; i--) | |
58 | if (++ctr[i]) /* continue on overflow */ | |
59 | return; | |
60 | } | |
61 | ||
62 | static int | |
63 | ssh_aes_ctr(EVP_CIPHER_CTX *ctx, u_char *dest, const u_char *src, | |
64 | u_int len) | |
65 | { | |
66 | struct ssh_aes_ctr_ctx *c; | |
67 | u_int n = 0; | |
68 | u_char buf[AES_BLOCK_SIZE]; | |
69 | ||
70 | if (len == 0) | |
71 | return (1); | |
72 | if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) == NULL) | |
73 | return (0); | |
74 | ||
75 | while ((len--) > 0) { | |
76 | if (n == 0) { | |
77 | AES_encrypt(c->aes_counter, buf, &c->aes_ctx); | |
78 | ssh_ctr_inc(c->aes_counter, AES_BLOCK_SIZE); | |
79 | } | |
80 | *(dest++) = *(src++) ^ buf[n]; | |
81 | n = (n + 1) % AES_BLOCK_SIZE; | |
82 | } | |
83 | return (1); | |
84 | } | |
85 | ||
86 | static int | |
87 | ssh_aes_ctr_init(EVP_CIPHER_CTX *ctx, const u_char *key, const u_char *iv, | |
88 | int enc) | |
89 | { | |
90 | struct ssh_aes_ctr_ctx *c; | |
91 | ||
92 | if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) == NULL) { | |
93 | c = xmalloc(sizeof(*c)); | |
94 | EVP_CIPHER_CTX_set_app_data(ctx, c); | |
95 | } | |
96 | if (key != NULL) | |
416fd2a8 | 97 | AES_set_encrypt_key(key, EVP_CIPHER_CTX_key_length(ctx) * 8, |
98 | &c->aes_ctx); | |
70791e56 | 99 | if (iv != NULL) |
100 | memcpy(c->aes_counter, iv, AES_BLOCK_SIZE); | |
101 | return (1); | |
102 | } | |
103 | ||
104 | static int | |
105 | ssh_aes_ctr_cleanup(EVP_CIPHER_CTX *ctx) | |
106 | { | |
107 | struct ssh_aes_ctr_ctx *c; | |
108 | ||
109 | if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) != NULL) { | |
110 | memset(c, 0, sizeof(*c)); | |
111 | xfree(c); | |
112 | EVP_CIPHER_CTX_set_app_data(ctx, NULL); | |
113 | } | |
114 | return (1); | |
115 | } | |
116 | ||
117 | void | |
118 | ssh_aes_ctr_iv(EVP_CIPHER_CTX *evp, int doset, u_char * iv, u_int len) | |
119 | { | |
120 | struct ssh_aes_ctr_ctx *c; | |
121 | ||
122 | if ((c = EVP_CIPHER_CTX_get_app_data(evp)) == NULL) | |
123 | fatal("ssh_aes_ctr_iv: no context"); | |
124 | if (doset) | |
125 | memcpy(c->aes_counter, iv, len); | |
126 | else | |
127 | memcpy(iv, c->aes_counter, len); | |
128 | } | |
129 | ||
130 | const EVP_CIPHER * | |
131 | evp_aes_128_ctr(void) | |
132 | { | |
133 | static EVP_CIPHER aes_ctr; | |
134 | ||
135 | memset(&aes_ctr, 0, sizeof(EVP_CIPHER)); | |
136 | aes_ctr.nid = NID_undef; | |
137 | aes_ctr.block_size = AES_BLOCK_SIZE; | |
138 | aes_ctr.iv_len = AES_BLOCK_SIZE; | |
139 | aes_ctr.key_len = 16; | |
140 | aes_ctr.init = ssh_aes_ctr_init; | |
141 | aes_ctr.cleanup = ssh_aes_ctr_cleanup; | |
142 | aes_ctr.do_cipher = ssh_aes_ctr; | |
143 | #ifndef SSH_OLD_EVP | |
144 | aes_ctr.flags = EVP_CIPH_CBC_MODE | EVP_CIPH_VARIABLE_LENGTH | | |
145 | EVP_CIPH_ALWAYS_CALL_INIT | EVP_CIPH_CUSTOM_IV; | |
146 | #endif | |
147 | return (&aes_ctr); | |
148 | } |