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)
23 struct transform_if ops
;
24 uint32_t max_seq_skew
;
27 struct transform_inst
{
28 struct transform_inst_if ops
;
29 struct keyInstance cryptkey
;
30 struct keyInstance mackey
;
39 #include "transform-common.h"
43 static bool_t
transform_setkey(void *sst
, uint8_t *key
, int32_t keylen
)
45 struct transform_inst
*ti
=sst
;
47 if (keylen
<REQUIRED_KEYLEN
) {
48 Message(M_ERR
,"transform_create: insufficient key material supplied "
49 "(need %d bytes, got %d)\n",REQUIRED_KEYLEN
,keylen
);
55 printf("Setting key to: ");
56 hexdebug(stdout
,key
,keylen
);
61 serpentbe_makekey(&ti
->cryptkey
,256,key
);
62 serpentbe_makekey(&ti
->mackey
,256,key
+32);
63 ti
->cryptiv
=get_uint32(key
+64);
64 ti
->maciv
=get_uint32(key
+68);
65 ti
->sendseq
=get_uint32(key
+72);
66 ti
->lastrecvseq
=ti
->sendseq
;
74 static void transform_delkey(void *sst
)
76 struct transform_inst
*ti
=sst
;
78 FILLZERO(ti
->cryptkey
);
83 static uint32_t transform_forward(void *sst
, struct buffer_if
*buf
,
86 struct transform_inst
*ti
=sst
;
98 buf_prepend_uint32(buf
,ti
->sendseq
);
101 /* PKCS5, stolen from IWJ */
102 /* eg with blocksize=4 mask=3 mask+2=5 */
103 /* msgsize 20 21 22 23 24 */
104 padlen
= PKCS5_MASK
-buf
->size
; /* -17 -18 -19 -16 -17 */
105 padlen
&= PKCS5_MASK
; /* 3 2 1 0 3 */
106 padlen
++; /* 4 3 2 1 4 */
108 padp
=buf_append(buf
,padlen
);
109 memset(padp
,padlen
,padlen
);
111 /* Serpent-CBCMAC. We expand the IV from 32-bit to 128-bit using
112 one encryption. Then we do the MAC and append the result. We don't
113 bother sending the IV - it's the same each time. (If we wanted to send
114 it we've have to add 16 bytes to each message, not 4, so that the
115 message stays a multiple of 16 bytes long.) */
117 put_uint32(iv
, ti
->maciv
);
118 serpentbe_encrypt(&ti
->mackey
,iv
,macacc
);
120 /* CBCMAC: encrypt in CBC mode. The MAC is the last encrypted
121 block encrypted once again. */
122 for (n
=buf
->start
; n
<buf
->start
+buf
->size
; n
+=16)
124 for (i
= 0; i
< 16; i
++)
125 macplain
[i
] = macacc
[i
] ^ n
[i
];
126 serpentbe_encrypt(&ti
->mackey
,macplain
,macacc
);
128 serpentbe_encrypt(&ti
->mackey
,macacc
,macacc
);
129 memcpy(buf_append(buf
,16),macacc
,16);
131 /* Serpent-CBC. We expand the ID as for CBCMAC, do the encryption,
132 and prepend the IV before increasing it. */
134 put_uint32(iv
, ti
->cryptiv
);
135 serpentbe_encrypt(&ti
->cryptkey
,iv
,iv
);
137 /* CBC: each block is XORed with the previous encrypted block (or the IV)
138 before being encrypted. */
141 for (n
=buf
->start
; n
<buf
->start
+buf
->size
; n
+=16)
143 for (i
= 0; i
< 16; i
++)
145 serpentbe_encrypt(&ti
->cryptkey
,n
,n
);
149 buf_prepend_uint32(buf
,ti
->cryptiv
);
154 static uint32_t transform_reverse(void *sst
, struct buffer_if
*buf
,
157 struct transform_inst
*ti
=sst
;
164 uint8_t macplain
[16];
167 uint8_t *macexpected
;
171 if (buf
->size
< 4 + 16 + 16) {
172 *errmsg
="msg too short";
179 uint32_t ivword
= buf_unprepend_uint32(buf
);
180 put_uint32(iv
, ivword
);
182 /* Assert bufsize is multiple of blocksize */
184 *errmsg
="msg not multiple of cipher blocksize";
187 serpentbe_encrypt(&ti
->cryptkey
,iv
,iv
);
188 for (n
=buf
->start
; n
<buf
->start
+buf
->size
; n
+=16)
190 for (i
= 0; i
< 16; i
++)
192 serpentbe_decrypt(&ti
->cryptkey
,n
,n
);
193 for (i
= 0; i
< 16; i
++)
199 macexpected
=buf_unappend(buf
,16);
201 put_uint32(iv
, ti
->maciv
);
202 serpentbe_encrypt(&ti
->mackey
,iv
,macacc
);
204 /* CBCMAC: encrypt in CBC mode. The MAC is the last encrypted
205 block encrypted once again. */
206 for (n
=buf
->start
; n
<buf
->start
+buf
->size
; n
+=16)
208 for (i
= 0; i
< 16; i
++)
209 macplain
[i
] = macacc
[i
] ^ n
[i
];
210 serpentbe_encrypt(&ti
->mackey
,macplain
,macacc
);
212 serpentbe_encrypt(&ti
->mackey
,macacc
,macacc
);
213 if (!consttime_memeq(macexpected
,macacc
,16)!=0) {
214 *errmsg
="invalid MAC";
218 /* PKCS5, stolen from IWJ */
220 padp
=buf_unappend(buf
,1);
222 if (!padlen
|| (padlen
> PKCS5_MASK
+1)) {
223 *errmsg
="pkcs5: invalid length";
227 buf_unappend(buf
,padlen
-1);
229 /* Sequence number must be within max_skew of lastrecvseq; lastrecvseq
230 is only allowed to increase. */
231 seqnum
=buf_unprepend_uint32(buf
);
232 SEQNUM_CHECK(seqnum
, ti
->max_skew
);
239 static struct transform_inst_if
*transform_create(void *sst
)
241 struct transform
*st
=sst
;
243 TRANSFORM_CREATE_CORE
;
245 ti
->max_skew
=st
->max_seq_skew
;
250 static list_t
*transform_apply(closure_t
*self
, struct cloc loc
,
251 dict_t
*context
, list_t
*args
)
253 struct transform
*st
;
257 st
=safe_malloc(sizeof(*st
),"serpent");
258 st
->cl
.description
="serpent-cbc256";
259 st
->cl
.type
=CL_TRANSFORM
;
261 st
->cl
.interface
=&st
->ops
;
263 st
->ops
.max_start_pad
=28; /* 4byte seqnum, 16byte pad, 4byte MACIV,
265 st
->ops
.max_end_pad
=16; /* 16byte CBCMAC */
267 /* We need 256*2 bits for serpent keys, 32 bits for CBC-IV and 32 bits
268 for CBCMAC-IV, and 32 bits for init sequence number */
269 st
->ops
.keylen
=REQUIRED_KEYLEN
;
270 st
->ops
.create
=transform_create
;
272 /* First parameter must be a dict */
273 item
=list_elem(args
,0);
274 if (!item
|| item
->type
!=t_dict
)
275 cfgfatal(loc
,"userv-ipif","parameter must be a dictionary\n");
277 dict
=item
->data
.dict
;
278 st
->max_seq_skew
=dict_read_number(dict
, "max-sequence-skew",
279 False
, "serpent-cbc256", loc
, 10);
281 return new_closure(&st
->cl
);
284 void transform_cbcmac_module(dict_t
*dict
)
286 struct keyInstance k
;
288 uint8_t plaintext
[16];
289 uint8_t ciphertext
[16];
294 * This test pattern was taken directly from the Serpent test
295 * vectors, which results in a big-endian Serpent which is not
296 * compatible with other implementations.
299 /* Serpent self-test */
301 "\x00\x11\x22\x33\x44\x55\x66\x77\x88\x99\xaa\xbb\xcc\xdd\xee\xff"
302 "\xff\xee\xdd\xcc\xbb\xaa\x99\x88\x77\x66\x55\x44\x33\x22\x11\x00",
304 serpentbe_makekey(&k
,256,data
);
307 "\x01\x23\x45\x67\x89\xab\xcd\xef\xfe\xdc\xba\x98\x76\x54\x32\x10",
309 serpentbe_encrypt(&k
,plaintext
,ciphertext
);
311 if (memcmp(ciphertext
, "\xca\x7f\xa1\x93\xe3\xeb\x9e\x99"
312 "\xbd\x87\xe3\xaf\x3c\x9a\xdf\x93", 16)) {
313 fatal("transform_module: serpent failed self-test (encrypt)");
315 serpentbe_decrypt(&k
,ciphertext
,plaintext
);
316 if (memcmp(plaintext
, "\x01\x23\x45\x67\x89\xab\xcd\xef"
317 "\xfe\xdc\xba\x98\x76\x54\x32\x10", 16)) {
318 fatal("transform_module: serpent failed self-test (decrypt)");
321 add_closure(dict
,"serpent256-cbc",transform_apply
);
323 #ifdef TEST_WHOLE_TRANSFORM
325 struct transform
*tr
;
327 struct buffer_if buf
;
328 const char text
[] = "This is a piece of test text.";
329 char keymaterial
[76] =
330 "Seventy-six bytes i"
331 "n four rows of 19; "
332 "this looks almost l"
333 "ike a poem but not.";
337 tr
= malloc(sizeof(struct transform
));
338 tr
->max_seq_skew
= 20;
339 ti
= transform_create(tr
);
341 transform_setkey(ti
, keymaterial
, 76);
343 buf
.base
= malloc(4096);
344 buffer_init(&buf
, 2048);
345 memcpy(buf_append(&buf
, sizeof(text
)), text
, sizeof(text
));
346 if (transform_forward(ti
, &buf
, &errmsg
)) {
347 fatal("transform_forward test: %s", errmsg
);
349 printf("transformed text is:\n");
350 for (i
= 0; i
< buf
.size
; i
++)
351 printf("%02x%c", buf
.start
[i
],
352 (i
%16==15 || i
==buf
.size
-1 ?
'\n' : ' '));
353 if (transform_reverse(ti
, &buf
, &errmsg
)) {
354 fatal("transform_reverse test: %s", errmsg
);
356 printf("transform reversal worked OK\n");