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"
17 /* Required key length in bytes */
18 #define REQUIRED_KEYLEN ((512+64+32)/8)
22 struct transform_if ops;
23 uint32_t max_seq_skew;
26 struct transform_inst {
27 struct transform_inst_if ops;
28 struct keyInstance cryptkey;
29 struct keyInstance mackey;
40 static bool_t transform_setkey(void *sst, uint8_t *key, int32_t keylen)
42 struct transform_inst *ti=sst;
44 if (keylen<REQUIRED_KEYLEN) {
45 Message(M_ERR,"transform_create: insufficient key material supplied "
46 "(need %d bytes, got %d)\n",REQUIRED_KEYLEN,keylen);
53 printf("Setting key to: ");
54 for (i=0; i<keylen; i++)
55 printf("%02x",key[i]);
60 serpent_makekey(&ti->cryptkey,256,key);
61 serpent_makekey(&ti->mackey,256,key+32);
62 ti->cryptiv=GET_32BIT_MSB_FIRST(key+64);
63 ti->maciv=GET_32BIT_MSB_FIRST(key+68);
64 ti->sendseq=GET_32BIT_MSB_FIRST(key+72);
65 ti->lastrecvseq=ti->sendseq;
71 static bool_t transform_valid(void *sst)
73 struct transform_inst *ti=sst;
78 static void transform_delkey(void *sst)
80 struct transform_inst *ti=sst;
82 FILLZERO(ti->cryptkey);
87 static uint32_t transform_forward(void *sst, struct buffer_if *buf,
90 struct transform_inst *ti=sst;
100 *errmsg="transform unkeyed";
104 /* Sequence number */
105 buf_prepend_uint32(buf,ti->sendseq);
108 /* PKCS5, stolen from IWJ */
109 /* eg with blocksize=4 mask=3 mask+2=5 */
110 /* msgsize 20 21 22 23 24 */
111 padlen= PKCS5_MASK-buf->size; /* -17 -18 -19 -16 -17 */
112 padlen &= PKCS5_MASK; /* 3 2 1 0 3 */
113 padlen++; /* 4 3 2 1 4 */
115 padp=buf_append(buf,padlen);
116 memset(padp,padlen,padlen);
118 /* Serpent-CBCMAC. We expand the IV from 32-bit to 128-bit using
119 one encryption. Then we do the MAC and append the result. We don't
120 bother sending the IV - it's the same each time. (If we wanted to send
121 it we've have to add 16 bytes to each message, not 4, so that the
122 message stays a multiple of 16 bytes long.) */
124 PUT_32BIT_MSB_FIRST(iv, ti->maciv);
125 serpent_encrypt(&ti->mackey,iv,macacc);
127 /* CBCMAC: encrypt in CBC mode. The MAC is the last encrypted
128 block encrypted once again. */
129 for (n=buf->start; n<buf->start+buf->size; n+=16)
131 for (i = 0; i < 16; i++)
132 macplain[i] = macacc[i] ^ n[i];
133 serpent_encrypt(&ti->mackey,macplain,macacc);
135 serpent_encrypt(&ti->mackey,macacc,macacc);
136 memcpy(buf_append(buf,16),macacc,16);
138 /* Serpent-CBC. We expand the ID as for CBCMAC, do the encryption,
139 and prepend the IV before increasing it. */
141 PUT_32BIT_MSB_FIRST(iv, ti->cryptiv);
142 serpent_encrypt(&ti->cryptkey,iv,iv);
144 /* CBC: each block is XORed with the previous encrypted block (or the IV)
145 before being encrypted. */
148 for (n=buf->start; n<buf->start+buf->size; n+=16)
150 for (i = 0; i < 16; i++)
152 serpent_encrypt(&ti->cryptkey,n,n);
156 buf_prepend_uint32(buf,ti->cryptiv);
161 static uint32_t transform_reverse(void *sst, struct buffer_if *buf,
164 struct transform_inst *ti=sst;
168 uint32_t seqnum, skew;
171 uint8_t macplain[16];
174 uint8_t *macexpected;
177 *errmsg="transform unkeyed";
181 if (buf->size < 4 + 16 + 16) {
182 *errmsg="msg too short";
189 uint32_t ivword = buf_unprepend_uint32(buf);
190 PUT_32BIT_MSB_FIRST(iv, ivword);
192 /* Assert bufsize is multiple of blocksize */
194 *errmsg="msg not multiple of cipher blocksize";
197 serpent_encrypt(&ti->cryptkey,iv,iv);
198 for (n=buf->start; n<buf->start+buf->size; n+=16)
200 for (i = 0; i < 16; i++)
202 serpent_decrypt(&ti->cryptkey,n,n);
203 for (i = 0; i < 16; i++)
209 macexpected=buf_unappend(buf,16);
211 PUT_32BIT_MSB_FIRST(iv, ti->maciv);
212 serpent_encrypt(&ti->mackey,iv,macacc);
214 /* CBCMAC: encrypt in CBC mode. The MAC is the last encrypted
215 block encrypted once again. */
216 for (n=buf->start; n<buf->start+buf->size; n+=16)
218 for (i = 0; i < 16; i++)
219 macplain[i] = macacc[i] ^ n[i];
220 serpent_encrypt(&ti->mackey,macplain,macacc);
222 serpent_encrypt(&ti->mackey,macacc,macacc);
223 if (!consttime_memeq(macexpected,macacc,16)!=0) {
224 *errmsg="invalid MAC";
228 /* PKCS5, stolen from IWJ */
230 padp=buf_unappend(buf,1);
232 if (!padlen || (padlen > PKCS5_MASK+1)) {
233 *errmsg="pkcs5: invalid length";
237 buf_unappend(buf,padlen-1);
239 /* Sequence number must be within max_skew of lastrecvseq; lastrecvseq
240 is only allowed to increase. */
241 seqnum=buf_unprepend_uint32(buf);
242 skew=seqnum-ti->lastrecvseq;
243 if (skew<0x8fffffff) {
245 ti->lastrecvseq=seqnum;
246 } else if ((0-skew)<ti->max_skew) {
250 *errmsg="seqnum: too much skew";
257 static void transform_destroy(void *sst)
259 struct transform_inst *st=sst;
261 FILLZERO(*st); /* Destroy key material */
265 static struct transform_inst_if *transform_create(void *sst)
267 struct transform_inst *ti;
268 struct transform *st=sst;
270 ti=safe_malloc(sizeof(*ti),"transform_create");
274 ti->ops.setkey=transform_setkey;
275 ti->ops.valid=transform_valid;
276 ti->ops.delkey=transform_delkey;
277 ti->ops.forwards=transform_forward;
278 ti->ops.reverse=transform_reverse;
279 ti->ops.destroy=transform_destroy;
280 ti->max_skew=st->max_seq_skew;
286 static list_t *transform_apply(closure_t *self, struct cloc loc,
287 dict_t *context, list_t *args)
289 struct transform *st;
293 st=safe_malloc(sizeof(*st),"serpent");
294 st->cl.description="serpent-cbc256";
295 st->cl.type=CL_TRANSFORM;
297 st->cl.interface=&st->ops;
299 st->ops.max_start_pad=28; /* 4byte seqnum, 16byte pad, 4byte MACIV,
301 st->ops.max_end_pad=16; /* 16byte CBCMAC */
303 /* We need 256*2 bits for serpent keys, 32 bits for CBC-IV and 32 bits
304 for CBCMAC-IV, and 32 bits for init sequence number */
305 st->ops.keylen=REQUIRED_KEYLEN;
306 st->ops.create=transform_create;
308 /* First parameter must be a dict */
309 item=list_elem(args,0);
310 if (!item || item->type!=t_dict)
311 cfgfatal(loc,"userv-ipif","parameter must be a dictionary\n");
313 dict=item->data.dict;
314 st->max_seq_skew=dict_read_number(dict, "max-sequence-skew",
315 False, "serpent-cbc256", loc, 10);
317 return new_closure(&st->cl);
320 void transform_module(dict_t *dict)
322 struct keyInstance k;
324 uint8_t plaintext[16];
325 uint8_t ciphertext[16];
330 * This test pattern is taken directly from the Serpent test
331 * vectors, to ensure we have all endianness issues correct. -sgt
334 /* Serpent self-test */
336 "\x00\x11\x22\x33\x44\x55\x66\x77\x88\x99\xaa\xbb\xcc\xdd\xee\xff"
337 "\xff\xee\xdd\xcc\xbb\xaa\x99\x88\x77\x66\x55\x44\x33\x22\x11\x00",
339 serpent_makekey(&k,256,data);
342 "\x01\x23\x45\x67\x89\xab\xcd\xef\xfe\xdc\xba\x98\x76\x54\x32\x10",
344 serpent_encrypt(&k,plaintext,ciphertext);
346 if (memcmp(ciphertext, "\xca\x7f\xa1\x93\xe3\xeb\x9e\x99"
347 "\xbd\x87\xe3\xaf\x3c\x9a\xdf\x93", 16)) {
348 fatal("transform_module: serpent failed self-test (encrypt)");
350 serpent_decrypt(&k,ciphertext,plaintext);
351 if (memcmp(plaintext, "\x01\x23\x45\x67\x89\xab\xcd\xef"
352 "\xfe\xdc\xba\x98\x76\x54\x32\x10", 16)) {
353 fatal("transform_module: serpent failed self-test (decrypt)");
356 add_closure(dict,"serpent256-cbc",transform_apply);
358 #ifdef TEST_WHOLE_TRANSFORM
360 struct transform *tr;
362 struct buffer_if buf;
363 const char text[] = "This is a piece of test text.";
364 char keymaterial[76] =
365 "Seventy-six bytes i"
366 "n four rows of 19; "
367 "this looks almost l"
368 "ike a poem but not.";
372 tr = malloc(sizeof(struct transform));
373 tr->max_seq_skew = 20;
374 ti = transform_create(tr);
376 transform_setkey(ti, keymaterial, 76);
378 buf.base = malloc(4096);
379 buffer_init(&buf, 2048);
380 memcpy(buf_append(&buf, sizeof(text)), text, sizeof(text));
381 if (transform_forward(ti, &buf, &errmsg)) {
382 fatal("transform_forward test: %s", errmsg);
384 printf("transformed text is:\n");
385 for (i = 0; i < buf.size; i++)
386 printf("%02x%c", buf.start[i],
387 (i%16==15 || i==buf.size-1 ? '\n' : ' '));
388 if (transform_reverse(ti, &buf, &errmsg)) {
389 fatal("transform_reverse test: %s", errmsg);
391 printf("transform reversal worked OK\n");