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)
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;
41 static bool_t transform_setkey(void *sst, uint8_t *key, uint32_t keylen)
43 struct transform_inst *ti=sst;
45 if (keylen<REQUIRED_KEYLEN) {
46 Message(M_ERR,"transform_create: insufficient key material supplied "
47 "(need %d bytes, got %d)\n",REQUIRED_KEYLEN,keylen);
54 printf("Setting key to: ");
55 for (i=0; i<keylen; i++)
56 printf("%02x",key[i]);
61 serpent_makekey(&ti->cryptkey,256,key);
62 serpent_makekey(&ti->mackey,256,key+32);
63 ti->cryptiv=GET_32BIT_MSB_FIRST(key+64);
64 ti->maciv=GET_32BIT_MSB_FIRST(key+68);
65 ti->sendseq=GET_32BIT_MSB_FIRST(key+72);
66 ti->lastrecvseq=ti->sendseq;
72 static void transform_delkey(void *sst)
74 struct transform_inst *ti=sst;
76 memset(&ti->cryptkey,0,sizeof(ti->cryptkey));
77 memset(&ti->mackey,0,sizeof(ti->mackey));
81 static uint32_t transform_forward(void *sst, struct buffer_if *buf,
84 struct transform_inst *ti=sst;
94 *errmsg="transform unkeyed";
99 buf_prepend_uint32(buf,ti->sendseq);
102 /* PKCS5, stolen from IWJ */
103 /* eg with blocksize=4 mask=3 mask+2=5 */
104 /* msgsize 20 21 22 23 24 */
105 padlen= PKCS5_MASK-buf->size; /* -17 -18 -19 -16 -17 */
106 padlen &= PKCS5_MASK; /* 3 2 1 0 3 */
107 padlen++; /* 4 3 2 1 4 */
109 padp=buf_append(buf,padlen);
110 memset(padp,padlen,padlen);
112 /* Serpent-CBCMAC. We expand the IV from 32-bit to 128-bit using
113 one encryption. Then we do the MAC and append the result. We don't
114 bother sending the IV - it's the same each time. (If we wanted to send
115 it we've have to add 16 bytes to each message, not 4, so that the
116 message stays a multiple of 16 bytes long.) */
118 PUT_32BIT_MSB_FIRST(iv, ti->maciv);
119 serpent_encrypt(&ti->mackey,iv,macacc);
121 /* CBCMAC: encrypt in CBC mode. The MAC is the last encrypted
122 block encrypted once again. */
123 for (n=buf->start; n<buf->start+buf->size; n+=16)
125 for (i = 0; i < 16; i++)
126 macplain[i] = macacc[i] ^ n[i];
127 serpent_encrypt(&ti->mackey,macplain,macacc);
129 serpent_encrypt(&ti->mackey,macacc,macacc);
130 memcpy(buf_append(buf,16),macacc,16);
132 /* Serpent-CBC. We expand the ID as for CBCMAC, do the encryption,
133 and prepend the IV before increasing it. */
135 PUT_32BIT_MSB_FIRST(iv, ti->cryptiv);
136 serpent_encrypt(&ti->cryptkey,iv,iv);
138 /* CBC: each block is XORed with the previous encrypted block (or the IV)
139 before being encrypted. */
142 for (n=buf->start; n<buf->start+buf->size; n+=16)
144 for (i = 0; i < 16; i++)
146 serpent_encrypt(&ti->cryptkey,n,n);
150 buf_prepend_uint32(buf,ti->cryptiv);
155 static uint32_t transform_reverse(void *sst, struct buffer_if *buf,
158 struct transform_inst *ti=sst;
162 uint32_t seqnum, skew;
165 uint8_t macplain[16];
168 uint8_t *macexpected;
171 *errmsg="transform unkeyed";
179 uint32_t ivword = buf_unprepend_uint32(buf);
180 PUT_32BIT_MSB_FIRST(iv, ivword);
182 /* Assert bufsize is multiple of blocksize */
184 *errmsg="msg not multiple of cipher blocksize";
186 serpent_encrypt(&ti->cryptkey,iv,iv);
187 for (n=buf->start; n<buf->start+buf->size; n+=16)
189 for (i = 0; i < 16; i++)
191 serpent_decrypt(&ti->cryptkey,n,n);
192 for (i = 0; i < 16; i++)
198 macexpected=buf_unappend(buf,16);
200 PUT_32BIT_MSB_FIRST(iv, ti->maciv);
201 serpent_encrypt(&ti->mackey,iv,macacc);
203 /* CBCMAC: encrypt in CBC mode. The MAC is the last encrypted
204 block encrypted once again. */
205 for (n=buf->start; n<buf->start+buf->size; n+=16)
207 for (i = 0; i < 16; i++)
208 macplain[i] = macacc[i] ^ n[i];
209 serpent_encrypt(&ti->mackey,macplain,macacc);
211 serpent_encrypt(&ti->mackey,macacc,macacc);
212 if (memcmp(macexpected,macacc,16)!=0) {
213 *errmsg="invalid MAC";
217 /* PKCS5, stolen from IWJ */
219 padp=buf_unappend(buf,1);
221 if (!padlen || (padlen > PKCS5_MASK+1)) {
222 *errmsg="pkcs5: invalid length";
226 padp=buf_unappend(buf,padlen-1);
227 for (i=0; i<padlen-1; i++) {
228 if (*++padp != padlen) {
229 *errmsg="pkcs5: corrupted padding";
234 /* Sequence number must be within max_skew of lastrecvseq; lastrecvseq
235 is only allowed to increase. */
236 seqnum=buf_unprepend_uint32(buf);
237 skew=seqnum-ti->lastrecvseq;
238 if (skew<0x8fffffff) {
240 ti->lastrecvseq=seqnum;
241 } else if ((0-skew)<ti->max_skew) {
245 *errmsg="seqnum: too much skew";
252 static void transform_destroy(void *sst)
254 struct transform_inst *st=sst;
256 memset(st,0,sizeof(*st)); /* Destroy key material */
260 static struct transform_inst_if *transform_create(void *sst)
262 struct transform_inst *ti;
263 struct transform *st=sst;
265 ti=safe_malloc(sizeof(*ti),"transform_create");
269 ti->ops.setkey=transform_setkey;
270 ti->ops.delkey=transform_delkey;
271 ti->ops.forwards=transform_forward;
272 ti->ops.reverse=transform_reverse;
273 ti->ops.destroy=transform_destroy;
274 ti->max_skew=st->max_seq_skew;
280 static list_t *transform_apply(closure_t *self, struct cloc loc,
281 dict_t *context, list_t *args)
283 struct transform *st;
287 st=safe_malloc(sizeof(*st),"serpent");
288 st->cl.description="serpent-cbc256";
289 st->cl.type=CL_TRANSFORM;
291 st->cl.interface=&st->ops;
293 st->ops.max_start_pad=28; /* 4byte seqnum, 16byte pad, 4byte MACIV,
295 st->ops.max_end_pad=16; /* 16byte CBCMAC */
297 /* We need 256*2 bits for serpent keys, 32 bits for CBC-IV and 32 bits
298 for CBCMAC-IV, and 32 bits for init sequence number */
299 st->ops.keylen=REQUIRED_KEYLEN;
300 st->ops.create=transform_create;
302 /* First parameter must be a dict */
303 item=list_elem(args,0);
304 if (!item || item->type!=t_dict)
305 cfgfatal(loc,"userv-ipif","parameter must be a dictionary\n");
307 dict=item->data.dict;
308 st->max_seq_skew=dict_read_number(dict, "max-sequence-skew",
309 False, "serpent-cbc256", loc, 10);
311 return new_closure(&st->cl);
314 init_module transform_module;
315 void transform_module(dict_t *dict)
317 struct keyInstance k;
319 uint8_t plaintext[16];
320 uint8_t ciphertext[16];
325 * This test pattern is taken directly from the Serpent test
326 * vectors, to ensure we have all endianness issues correct. -sgt
329 /* Serpent self-test */
331 "\x00\x11\x22\x33\x44\x55\x66\x77\x88\x99\xaa\xbb\xcc\xdd\xee\xff"
332 "\xff\xee\xdd\xcc\xbb\xaa\x99\x88\x77\x66\x55\x44\x33\x22\x11\x00",
334 serpent_makekey(&k,256,data);
337 "\x01\x23\x45\x67\x89\xab\xcd\xef\xfe\xdc\xba\x98\x76\x54\x32\x10",
339 serpent_encrypt(&k,plaintext,ciphertext);
341 if (memcmp(ciphertext, "\xca\x7f\xa1\x93\xe3\xeb\x9e\x99"
342 "\xbd\x87\xe3\xaf\x3c\x9a\xdf\x93", 16)) {
343 fatal("transform_module: serpent failed self-test (encrypt)");
345 serpent_decrypt(&k,ciphertext,plaintext);
346 if (memcmp(plaintext, "\x01\x23\x45\x67\x89\xab\xcd\xef"
347 "\xfe\xdc\xba\x98\x76\x54\x32\x10", 16)) {
348 fatal("transform_module: serpent failed self-test (decrypt)");
351 add_closure(dict,"serpent256-cbc",transform_apply);
353 #ifdef TEST_WHOLE_TRANSFORM
355 struct transform *tr;
357 struct buffer_if buf;
358 const char text[] = "This is a piece of test text.";
359 char keymaterial[76] =
360 "Seventy-six bytes i"
361 "n four rows of 19; "
362 "this looks almost l"
363 "ike a poem but not.";
367 tr = malloc(sizeof(struct transform));
368 tr->max_seq_skew = 20;
369 ti = transform_create(tr);
371 transform_setkey(ti, keymaterial, 76);
373 buf.base = malloc(4096);
374 buffer_init(&buf, 2048);
375 memcpy(buf_append(&buf, sizeof(text)), text, sizeof(text));
376 if (transform_forward(ti, &buf, &errmsg)) {
377 fatal("transform_forward test: %s", errmsg);
379 printf("transformed text is:\n");
380 for (i = 0; i < buf.size; i++)
381 printf("%02x%c", buf.start[i],
382 (i%16==15 || i==buf.size-1 ? '\n' : ' '));
383 if (transform_reverse(ti, &buf, &errmsg)) {
384 fatal("transform_reverse test: %s", errmsg);
386 printf("transform reversal worked OK\n");