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 struct transform_params {
22 uint32_t max_seq_skew;
27 struct transform_if ops;
28 struct transform_params p;
31 struct transform_inst {
32 struct transform_inst_if ops;
33 struct transform_params p;
34 struct keyInstance cryptkey;
35 struct keyInstance mackey;
43 #include "transform-common.h"
47 static bool_t transform_setkey(void *sst, uint8_t *key, int32_t keylen,
50 struct transform_inst *ti=sst;
52 if (keylen<REQUIRED_KEYLEN) {
53 Message(M_ERR,"transform_create: insufficient key material supplied "
54 "(need %d bytes, got %d)\n",REQUIRED_KEYLEN,keylen);
60 printf("Setting key to: ");
61 hexdebug(stdout,key,keylen);
66 serpentbe_makekey(&ti->cryptkey,256,key);
67 serpentbe_makekey(&ti->mackey,256,key+32);
68 ti->cryptiv=get_uint32(key+64);
69 ti->maciv=get_uint32(key+68);
70 ti->sendseq=get_uint32(key+72);
71 ti->lastrecvseq=ti->sendseq;
79 static void transform_delkey(void *sst)
81 struct transform_inst *ti=sst;
83 FILLZERO(ti->cryptkey);
88 static uint32_t transform_forward(void *sst, struct buffer_if *buf,
91 struct transform_inst *ti=sst;
102 /* Sequence number */
103 buf_prepend_uint32(buf,ti->sendseq);
106 /* PKCS5, stolen from IWJ */
107 /* eg with blocksize=4 mask=3 mask+2=5 */
108 /* msgsize 20 21 22 23 24 */
109 padlen= PKCS5_MASK-buf->size; /* -17 -18 -19 -16 -17 */
110 padlen &= PKCS5_MASK; /* 3 2 1 0 3 */
111 padlen++; /* 4 3 2 1 4 */
113 padp=buf_append(buf,padlen);
114 memset(padp,padlen,padlen);
116 /* Serpent-CBCMAC. We expand the IV from 32-bit to 128-bit using
117 one encryption. Then we do the MAC and append the result. We don't
118 bother sending the IV - it's the same each time. (If we wanted to send
119 it we've have to add 16 bytes to each message, not 4, so that the
120 message stays a multiple of 16 bytes long.) */
122 put_uint32(iv, ti->maciv);
123 serpentbe_encrypt(&ti->mackey,iv,macacc);
125 /* CBCMAC: encrypt in CBC mode. The MAC is the last encrypted
126 block encrypted once again. */
127 for (n=buf->start; n<buf->start+buf->size; n+=16)
129 for (i = 0; i < 16; i++)
130 macplain[i] = macacc[i] ^ n[i];
131 serpentbe_encrypt(&ti->mackey,macplain,macacc);
133 serpentbe_encrypt(&ti->mackey,macacc,macacc);
134 BUF_ADD_BYTES(append,buf,macacc,16);
136 /* Serpent-CBC. We expand the ID as for CBCMAC, do the encryption,
137 and prepend the IV before increasing it. */
139 put_uint32(iv, ti->cryptiv);
140 serpentbe_encrypt(&ti->cryptkey,iv,iv);
142 /* CBC: each block is XORed with the previous encrypted block (or the IV)
143 before being encrypted. */
146 for (n=buf->start; n<buf->start+buf->size; n+=16)
148 for (i = 0; i < 16; i++)
150 serpentbe_encrypt(&ti->cryptkey,n,n);
154 buf_prepend_uint32(buf,ti->cryptiv);
159 static uint32_t transform_reverse(void *sst, struct buffer_if *buf,
162 struct transform_inst *ti=sst;
169 uint8_t macplain[16];
172 uint8_t *macexpected;
176 if (buf->size < 4 + 16 + 16) {
177 *errmsg="msg too short";
184 uint32_t ivword = buf_unprepend_uint32(buf);
185 put_uint32(iv, ivword);
187 /* Assert bufsize is multiple of blocksize */
189 *errmsg="msg not multiple of cipher blocksize";
192 serpentbe_encrypt(&ti->cryptkey,iv,iv);
193 for (n=buf->start; n<buf->start+buf->size; n+=16)
195 for (i = 0; i < 16; i++)
197 serpentbe_decrypt(&ti->cryptkey,n,n);
198 for (i = 0; i < 16; i++)
204 macexpected=buf_unappend(buf,16);
206 put_uint32(iv, ti->maciv);
207 serpentbe_encrypt(&ti->mackey,iv,macacc);
209 /* CBCMAC: encrypt in CBC mode. The MAC is the last encrypted
210 block encrypted once again. */
211 for (n=buf->start; n<buf->start+buf->size; n+=16)
213 for (i = 0; i < 16; i++)
214 macplain[i] = macacc[i] ^ n[i];
215 serpentbe_encrypt(&ti->mackey,macplain,macacc);
217 serpentbe_encrypt(&ti->mackey,macacc,macacc);
218 if (!consttime_memeq(macexpected,macacc,16)!=0) {
219 *errmsg="invalid MAC";
223 /* PKCS5, stolen from IWJ */
225 padp=buf_unappend(buf,1);
227 if (!padlen || (padlen > PKCS5_MASK+1)) {
228 *errmsg="pkcs5: invalid length";
232 buf_unappend(buf,padlen-1);
234 /* Sequence number must be within max_skew of lastrecvseq; lastrecvseq
235 is only allowed to increase. */
236 seqnum=buf_unprepend_uint32(buf);
237 SEQNUM_CHECK(seqnum, ti->p.max_seq_skew);
244 static struct transform_inst_if *transform_create(void *sst)
246 struct transform *st=sst;
248 TRANSFORM_CREATE_CORE;
255 static list_t *transform_apply(closure_t *self, struct cloc loc,
256 dict_t *context, list_t *args)
258 struct transform *st;
262 st=safe_malloc(sizeof(*st),"serpent");
263 st->cl.description="serpent-cbc256";
264 st->cl.type=CL_TRANSFORM;
266 st->cl.interface=&st->ops;
268 update_max_start_pad(&transform_max_start_pad, 28);
269 /* 4byte seqnum, 16byte pad, 4byte MACIV, 4byte IV */
271 /* We need 256*2 bits for serpent keys, 32 bits for CBC-IV and 32 bits
272 for CBCMAC-IV, and 32 bits for init sequence number */
273 st->ops.keylen=REQUIRED_KEYLEN;
274 st->ops.create=transform_create;
276 /* First parameter must be a dict */
277 item=list_elem(args,0);
278 if (!item || item->type!=t_dict)
279 cfgfatal(loc,"userv-ipif","parameter must be a dictionary\n");
281 dict=item->data.dict;
282 st->p.max_seq_skew=dict_read_number(dict, "max-sequence-skew",
283 False, "serpent-cbc256", loc, 10);
285 SET_CAPAB_TRANSFORMNUM(CAPAB_TRANSFORMNUM_SERPENT256CBC);
287 return new_closure(&st->cl);
290 void transform_cbcmac_module(dict_t *dict)
292 struct keyInstance k;
294 uint8_t plaintext[16];
295 uint8_t ciphertext[16];
300 * This test pattern was taken directly from the Serpent test
301 * vectors, which results in a big-endian Serpent which is not
302 * compatible with other implementations.
305 /* Serpent self-test */
307 "\x00\x11\x22\x33\x44\x55\x66\x77\x88\x99\xaa\xbb\xcc\xdd\xee\xff"
308 "\xff\xee\xdd\xcc\xbb\xaa\x99\x88\x77\x66\x55\x44\x33\x22\x11\x00",
310 serpentbe_makekey(&k,256,data);
313 "\x01\x23\x45\x67\x89\xab\xcd\xef\xfe\xdc\xba\x98\x76\x54\x32\x10",
315 serpentbe_encrypt(&k,plaintext,ciphertext);
317 if (memcmp(ciphertext, "\xca\x7f\xa1\x93\xe3\xeb\x9e\x99"
318 "\xbd\x87\xe3\xaf\x3c\x9a\xdf\x93", 16)) {
319 fatal("transform_module: serpent failed self-test (encrypt)");
321 serpentbe_decrypt(&k,ciphertext,plaintext);
322 if (memcmp(plaintext, "\x01\x23\x45\x67\x89\xab\xcd\xef"
323 "\xfe\xdc\xba\x98\x76\x54\x32\x10", 16)) {
324 fatal("transform_module: serpent failed self-test (decrypt)");
327 add_closure(dict,"serpent256-cbc",transform_apply);
329 #ifdef TEST_WHOLE_TRANSFORM
331 struct transform *tr;
333 struct buffer_if buf;
334 const char text[] = "This is a piece of test text.";
335 char keymaterial[76] =
336 "Seventy-six bytes i"
337 "n four rows of 19; "
338 "this looks almost l"
339 "ike a poem but not.";
343 tr = safe_malloc(sizeof(struct transform),"test transform");
344 tr->max_seq_skew = 20;
345 ti = transform_create(tr);
347 transform_setkey(ti, keymaterial, 76);
349 buf.base = malloc(4096);
350 buffer_init(&buf, 2048);
351 BUF_ADD_OBJ(append, buf, text, sizeof(text));
352 if (transform_forward(ti, &buf, &errmsg)) {
353 fatal("transform_forward test: %s", errmsg);
355 printf("transformed text is:\n");
356 for (i = 0; i < buf.size; i++)
357 printf("%02x%c", buf.start[i],
358 (i%16==15 || i==buf.size-1 ? '\n' : ' '));
359 if (transform_reverse(ti, &buf, &errmsg)) {
360 fatal("transform_reverse test: %s", errmsg);
362 printf("transform reversal worked OK\n");