1 /* Transform module - bulk data transformation */
3 /* For now it's hard-coded to do sequence
4 number/pkcs5/serpent-cbcmac/serpent with a 256 bit key for each
5 instance of serpent. We also require key material for the IVs for
6 cbcmac and cbc. Hack: we're not using full 128-bit IVs, we're just
7 using 32 bits and encrypting to get the full IV to save space in
8 the packets sent over the wire. */
15 #include "unaligned.h"
18 /* Required key length in bytes */
19 #define REQUIRED_KEYLEN ((512+64+32)/8)
21 #include "transform-common.h"
23 struct transform_params
{
29 struct transform_if ops
;
30 struct transform_params p
;
33 struct transform_inst
{
34 struct transform_inst_if ops
;
35 struct transform_params p
;
36 struct keyInstance cryptkey
;
37 struct keyInstance mackey
;
45 static bool_t
transform_setkey(void *sst
, uint8_t *key
, int32_t keylen
,
48 struct transform_inst
*ti
=sst
;
50 if (keylen
<REQUIRED_KEYLEN
) {
51 Message(M_ERR
,"transform_create: insufficient key material supplied "
52 "(need %d bytes, got %d)\n",REQUIRED_KEYLEN
,keylen
);
58 printf("Setting key to: ");
59 hexdebug(stdout
,key
,keylen
);
64 serpentbe_makekey(&ti
->cryptkey
,256,key
);
65 serpentbe_makekey(&ti
->mackey
,256,key
+32);
66 ti
->cryptiv
=get_uint32(key
+64);
67 ti
->maciv
=get_uint32(key
+68);
68 uint32_t firstseq
=get_uint32(key
+72);
69 SEQNUM_KEYED_INIT(firstseq
,firstseq
);
76 static void transform_delkey(void *sst
)
78 struct transform_inst
*ti
=sst
;
80 FILLZERO(ti
->cryptkey
);
85 static uint32_t transform_forward(void *sst
, struct buffer_if
*buf
,
88 struct transform_inst
*ti
=sst
;
100 buf_prepend_uint32(buf
,ti
->sendseq
);
103 /* PKCS5, stolen from IWJ */
104 /* eg with blocksize=4 mask=3 mask+2=5 */
105 /* msgsize 20 21 22 23 24 */
106 padlen
= PKCS5_MASK
-buf
->size
; /* -17 -18 -19 -16 -17 */
107 padlen
&= PKCS5_MASK
; /* 3 2 1 0 3 */
108 padlen
++; /* 4 3 2 1 4 */
110 padp
=buf_append(buf
,padlen
);
111 memset(padp
,padlen
,padlen
);
113 /* Serpent-CBCMAC. We expand the IV from 32-bit to 128-bit using
114 one encryption. Then we do the MAC and append the result. We don't
115 bother sending the IV - it's the same each time. (If we wanted to send
116 it we've have to add 16 bytes to each message, not 4, so that the
117 message stays a multiple of 16 bytes long.) */
119 put_uint32(iv
, ti
->maciv
);
120 serpentbe_encrypt(&ti
->mackey
,iv
,macacc
);
122 /* CBCMAC: encrypt in CBC mode. The MAC is the last encrypted
123 block encrypted once again. */
124 for (n
=buf
->start
; n
<buf
->start
+buf
->size
; n
+=16)
126 for (i
= 0; i
< 16; i
++)
127 macplain
[i
] = macacc
[i
] ^ n
[i
];
128 serpentbe_encrypt(&ti
->mackey
,macplain
,macacc
);
130 serpentbe_encrypt(&ti
->mackey
,macacc
,macacc
);
131 BUF_ADD_BYTES(append
,buf
,macacc
,16);
133 /* Serpent-CBC. We expand the ID as for CBCMAC, do the encryption,
134 and prepend the IV before increasing it. */
136 put_uint32(iv
, ti
->cryptiv
);
137 serpentbe_encrypt(&ti
->cryptkey
,iv
,iv
);
139 /* CBC: each block is XORed with the previous encrypted block (or the IV)
140 before being encrypted. */
143 for (n
=buf
->start
; n
<buf
->start
+buf
->size
; n
+=16)
145 for (i
= 0; i
< 16; i
++)
147 serpentbe_encrypt(&ti
->cryptkey
,n
,n
);
151 buf_prepend_uint32(buf
,ti
->cryptiv
);
156 static uint32_t transform_reverse(void *sst
, struct buffer_if
*buf
,
159 struct transform_inst
*ti
=sst
;
166 uint8_t macplain
[16];
169 uint8_t *macexpected
;
173 if (buf
->size
< 4 + 16 + 16) {
174 *errmsg
="msg too short";
181 uint32_t ivword
= buf_unprepend_uint32(buf
);
182 put_uint32(iv
, ivword
);
184 /* Assert bufsize is multiple of blocksize */
186 *errmsg
="msg not multiple of cipher blocksize";
189 serpentbe_encrypt(&ti
->cryptkey
,iv
,iv
);
190 for (n
=buf
->start
; n
<buf
->start
+buf
->size
; n
+=16)
192 for (i
= 0; i
< 16; i
++)
194 serpentbe_decrypt(&ti
->cryptkey
,n
,n
);
195 for (i
= 0; i
< 16; i
++)
201 macexpected
=buf_unappend(buf
,16);
203 put_uint32(iv
, ti
->maciv
);
204 serpentbe_encrypt(&ti
->mackey
,iv
,macacc
);
206 /* CBCMAC: encrypt in CBC mode. The MAC is the last encrypted
207 block encrypted once again. */
208 for (n
=buf
->start
; n
<buf
->start
+buf
->size
; n
+=16)
210 for (i
= 0; i
< 16; i
++)
211 macplain
[i
] = macacc
[i
] ^ n
[i
];
212 serpentbe_encrypt(&ti
->mackey
,macplain
,macacc
);
214 serpentbe_encrypt(&ti
->mackey
,macacc
,macacc
);
215 if (!consttime_memeq(macexpected
,macacc
,16)!=0) {
216 *errmsg
="invalid MAC";
220 /* PKCS5, stolen from IWJ */
222 padp
=buf_unappend(buf
,1);
224 if (!padlen
|| (padlen
> PKCS5_MASK
+1)) {
225 *errmsg
="pkcs5: invalid length";
229 buf_unappend(buf
,padlen
-1);
231 /* Sequence number must be within max_skew of lastrecvseq; lastrecvseq
232 is only allowed to increase. */
233 seqnum
=buf_unprepend_uint32(buf
);
234 SEQNUM_CHECK(seqnum
, &ti
->p
);
241 static struct transform_inst_if
*transform_create(void *sst
)
243 struct transform
*st
=sst
;
245 TRANSFORM_CREATE_CORE
;
252 static list_t
*transform_apply(closure_t
*self
, struct cloc loc
,
253 dict_t
*context
, list_t
*args
)
255 struct transform
*st
;
260 st
->cl
.description
="serpent-cbc256";
261 st
->cl
.type
=CL_TRANSFORM
;
263 st
->cl
.interface
=&st
->ops
;
265 update_max_start_pad(&transform_max_start_pad
, 28);
266 /* 4byte seqnum, 16byte pad, 4byte MACIV, 4byte IV */
268 /* We need 256*2 bits for serpent keys, 32 bits for CBC-IV and 32 bits
269 for CBCMAC-IV, and 32 bits for init sequence number */
270 st
->ops
.keylen
=REQUIRED_KEYLEN
;
271 st
->ops
.create
=transform_create
;
273 /* First parameter must be a dict */
274 item
=list_elem(args
,0);
275 if (!item
|| item
->type
!=t_dict
)
276 cfgfatal(loc
,"userv-ipif","parameter must be a dictionary\n");
278 dict
=item
->data
.dict
;
280 SEQNUM_PARAMS_INIT(dict
,&st
->p
,"serpent-cbc256",loc
);
282 SET_CAPAB_TRANSFORMNUM(CAPAB_TRANSFORMNUM_SERPENT256CBC
);
284 return new_closure(&st
->cl
);
287 void transform_cbcmac_module(dict_t
*dict
)
289 struct keyInstance k
;
291 uint8_t plaintext
[16];
292 uint8_t ciphertext
[16];
297 * This test pattern was taken directly from the Serpent test
298 * vectors, which results in a big-endian Serpent which is not
299 * compatible with other implementations.
302 /* Serpent self-test */
304 "\x00\x11\x22\x33\x44\x55\x66\x77\x88\x99\xaa\xbb\xcc\xdd\xee\xff"
305 "\xff\xee\xdd\xcc\xbb\xaa\x99\x88\x77\x66\x55\x44\x33\x22\x11\x00",
307 serpentbe_makekey(&k
,256,data
);
310 "\x01\x23\x45\x67\x89\xab\xcd\xef\xfe\xdc\xba\x98\x76\x54\x32\x10",
312 serpentbe_encrypt(&k
,plaintext
,ciphertext
);
314 if (memcmp(ciphertext
, "\xca\x7f\xa1\x93\xe3\xeb\x9e\x99"
315 "\xbd\x87\xe3\xaf\x3c\x9a\xdf\x93", 16)) {
316 fatal("transform_module: serpent failed self-test (encrypt)");
318 serpentbe_decrypt(&k
,ciphertext
,plaintext
);
319 if (memcmp(plaintext
, "\x01\x23\x45\x67\x89\xab\xcd\xef"
320 "\xfe\xdc\xba\x98\x76\x54\x32\x10", 16)) {
321 fatal("transform_module: serpent failed self-test (decrypt)");
324 add_closure(dict
,"serpent256-cbc",transform_apply
);
326 #ifdef TEST_WHOLE_TRANSFORM
328 struct transform
*tr
;
330 struct buffer_if buf
;
331 const char text
[] = "This is a piece of test text.";
332 char keymaterial
[76] =
333 "Seventy-six bytes i"
334 "n four rows of 19; "
335 "this looks almost l"
336 "ike a poem but not.";
341 tr
->max_seq_skew
= 20;
342 ti
= transform_create(tr
);
344 transform_setkey(ti
, keymaterial
, 76);
346 buf
.base
= malloc(4096);
347 buffer_init(&buf
, 2048);
348 BUF_ADD_OBJ(append
, buf
, text
, sizeof(text
));
349 if (transform_forward(ti
, &buf
, &errmsg
)) {
350 fatal("transform_forward test: %s", errmsg
);
352 printf("transformed text is:\n");
353 for (i
= 0; i
< buf
.size
; i
++)
354 printf("%02x%c", buf
.start
[i
],
355 (i
%16==15 || i
==buf
.size
-1 ?
'\n' : ' '));
356 if (transform_reverse(ti
, &buf
, &errmsg
)) {
357 fatal("transform_reverse test: %s", errmsg
);
359 printf("transform reversal worked OK\n");