Commit | Line | Data |
---|---|---|
2fe58dfd SE |
1 | /* Transform module - bulk data transformation */ |
2 | ||
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. */ | |
9 | ||
10 | #include <stdio.h> | |
469fd1d9 | 11 | #include <string.h> |
2fe58dfd SE |
12 | #include "secnet.h" |
13 | #include "util.h" | |
14 | #include "serpent.h" | |
59635212 | 15 | #include "unaligned.h" |
2fe58dfd SE |
16 | |
17 | /* Required key length in bytes */ | |
18 | #define REQUIRED_KEYLEN ((512+64+32)/8) | |
19 | ||
20 | struct transform { | |
21 | closure_t cl; | |
2fe58dfd SE |
22 | struct transform_if ops; |
23 | uint32_t max_seq_skew; | |
24 | }; | |
25 | ||
26 | struct transform_inst { | |
27 | struct transform_inst_if ops; | |
28 | struct keyInstance cryptkey; | |
29 | struct keyInstance mackey; | |
30 | uint32_t cryptiv; | |
31 | uint32_t maciv; | |
32 | uint32_t sendseq; | |
33 | uint32_t lastrecvseq; | |
34 | uint32_t max_skew; | |
35 | bool_t keyed; | |
36 | }; | |
37 | ||
38 | #define PKCS5_MASK 15 | |
39 | ||
1caa23ff | 40 | static bool_t transform_setkey(void *sst, uint8_t *key, int32_t keylen) |
2fe58dfd SE |
41 | { |
42 | struct transform_inst *ti=sst; | |
43 | ||
44 | if (keylen<REQUIRED_KEYLEN) { | |
469fd1d9 | 45 | Message(M_ERR,"transform_create: insufficient key material supplied " |
2fe58dfd SE |
46 | "(need %d bytes, got %d)\n",REQUIRED_KEYLEN,keylen); |
47 | return False; | |
48 | } | |
49 | ||
50 | #if 0 | |
51 | { | |
52 | int i; | |
53 | printf("Setting key to: "); | |
54 | for (i=0; i<keylen; i++) | |
55 | printf("%02x",key[i]); | |
56 | printf("\n"); | |
57 | } | |
58 | #endif /* 0 */ | |
59 | ||
60 | serpent_makekey(&ti->cryptkey,256,key); | |
61 | serpent_makekey(&ti->mackey,256,key+32); | |
3b83c932 SE |
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); | |
2fe58dfd SE |
65 | ti->lastrecvseq=ti->sendseq; |
66 | ti->keyed=True; | |
67 | ||
68 | return True; | |
69 | } | |
70 | ||
71 | static void transform_delkey(void *sst) | |
72 | { | |
73 | struct transform_inst *ti=sst; | |
74 | ||
076bb54e IJ |
75 | FILLZERO(ti->cryptkey); |
76 | FILLZERO(ti->mackey); | |
2fe58dfd SE |
77 | ti->keyed=False; |
78 | } | |
79 | ||
80 | static uint32_t transform_forward(void *sst, struct buffer_if *buf, | |
fe5e9cc4 | 81 | const char **errmsg) |
2fe58dfd SE |
82 | { |
83 | struct transform_inst *ti=sst; | |
84 | uint8_t *padp; | |
85 | int padlen; | |
3b83c932 SE |
86 | uint8_t iv[16]; |
87 | uint8_t macplain[16]; | |
88 | uint8_t macacc[16]; | |
89 | uint8_t *p, *n; | |
90 | int i; | |
2fe58dfd SE |
91 | |
92 | if (!ti->keyed) { | |
93 | *errmsg="transform unkeyed"; | |
94 | return 1; | |
95 | } | |
96 | ||
97 | /* Sequence number */ | |
59635212 | 98 | buf_prepend_uint32(buf,ti->sendseq); |
2fe58dfd SE |
99 | ti->sendseq++; |
100 | ||
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 */ | |
107 | ||
108 | padp=buf_append(buf,padlen); | |
109 | memset(padp,padlen,padlen); | |
110 | ||
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.) */ | |
116 | memset(iv,0,16); | |
3b83c932 | 117 | PUT_32BIT_MSB_FIRST(iv, ti->maciv); |
2fe58dfd SE |
118 | serpent_encrypt(&ti->mackey,iv,macacc); |
119 | ||
120 | /* CBCMAC: encrypt in CBC mode. The MAC is the last encrypted | |
121 | block encrypted once again. */ | |
3b83c932 | 122 | for (n=buf->start; n<buf->start+buf->size; n+=16) |
2fe58dfd | 123 | { |
3b83c932 SE |
124 | for (i = 0; i < 16; i++) |
125 | macplain[i] = macacc[i] ^ n[i]; | |
2fe58dfd SE |
126 | serpent_encrypt(&ti->mackey,macplain,macacc); |
127 | } | |
128 | serpent_encrypt(&ti->mackey,macacc,macacc); | |
129 | memcpy(buf_append(buf,16),macacc,16); | |
130 | ||
131 | /* Serpent-CBC. We expand the ID as for CBCMAC, do the encryption, | |
132 | and prepend the IV before increasing it. */ | |
133 | memset(iv,0,16); | |
3b83c932 | 134 | PUT_32BIT_MSB_FIRST(iv, ti->cryptiv); |
2fe58dfd SE |
135 | serpent_encrypt(&ti->cryptkey,iv,iv); |
136 | ||
137 | /* CBC: each block is XORed with the previous encrypted block (or the IV) | |
138 | before being encrypted. */ | |
139 | p=iv; | |
3b83c932 SE |
140 | |
141 | for (n=buf->start; n<buf->start+buf->size; n+=16) | |
2fe58dfd | 142 | { |
3b83c932 SE |
143 | for (i = 0; i < 16; i++) |
144 | n[i] ^= p[i]; | |
2fe58dfd SE |
145 | serpent_encrypt(&ti->cryptkey,n,n); |
146 | p=n; | |
147 | } | |
148 | ||
59635212 | 149 | buf_prepend_uint32(buf,ti->cryptiv); |
2fe58dfd | 150 | ti->cryptiv++; |
2fe58dfd SE |
151 | return 0; |
152 | } | |
153 | ||
154 | static uint32_t transform_reverse(void *sst, struct buffer_if *buf, | |
fe5e9cc4 | 155 | const char **errmsg) |
2fe58dfd SE |
156 | { |
157 | struct transform_inst *ti=sst; | |
158 | uint8_t *padp; | |
1caa23ff | 159 | int padlen; |
2fe58dfd SE |
160 | int i; |
161 | uint32_t seqnum, skew; | |
3b83c932 SE |
162 | uint8_t iv[16]; |
163 | uint8_t pct[16]; | |
164 | uint8_t macplain[16]; | |
165 | uint8_t macacc[16]; | |
166 | uint8_t *n; | |
167 | uint8_t *macexpected; | |
2fe58dfd SE |
168 | |
169 | if (!ti->keyed) { | |
170 | *errmsg="transform unkeyed"; | |
171 | return 1; | |
172 | } | |
173 | ||
20138876 IJ |
174 | if (buf->size < 4 + 16 + 16) { |
175 | *errmsg="msg too short"; | |
176 | return 1; | |
177 | } | |
8689b3a9 | 178 | |
2fe58dfd SE |
179 | /* CBC */ |
180 | memset(iv,0,16); | |
3b83c932 SE |
181 | { |
182 | uint32_t ivword = buf_unprepend_uint32(buf); | |
183 | PUT_32BIT_MSB_FIRST(iv, ivword); | |
184 | } | |
8689b3a9 SE |
185 | /* Assert bufsize is multiple of blocksize */ |
186 | if (buf->size&0xf) { | |
187 | *errmsg="msg not multiple of cipher blocksize"; | |
20138876 | 188 | return 1; |
8689b3a9 | 189 | } |
2fe58dfd | 190 | serpent_encrypt(&ti->cryptkey,iv,iv); |
3b83c932 | 191 | for (n=buf->start; n<buf->start+buf->size; n+=16) |
2fe58dfd | 192 | { |
3b83c932 SE |
193 | for (i = 0; i < 16; i++) |
194 | pct[i] = n[i]; | |
2fe58dfd | 195 | serpent_decrypt(&ti->cryptkey,n,n); |
3b83c932 SE |
196 | for (i = 0; i < 16; i++) |
197 | n[i] ^= iv[i]; | |
198 | memcpy(iv, pct, 16); | |
2fe58dfd SE |
199 | } |
200 | ||
201 | /* CBCMAC */ | |
202 | macexpected=buf_unappend(buf,16); | |
203 | memset(iv,0,16); | |
3b83c932 | 204 | PUT_32BIT_MSB_FIRST(iv, ti->maciv); |
2fe58dfd SE |
205 | serpent_encrypt(&ti->mackey,iv,macacc); |
206 | ||
207 | /* CBCMAC: encrypt in CBC mode. The MAC is the last encrypted | |
208 | block encrypted once again. */ | |
3b83c932 | 209 | for (n=buf->start; n<buf->start+buf->size; n+=16) |
2fe58dfd | 210 | { |
3b83c932 SE |
211 | for (i = 0; i < 16; i++) |
212 | macplain[i] = macacc[i] ^ n[i]; | |
2fe58dfd SE |
213 | serpent_encrypt(&ti->mackey,macplain,macacc); |
214 | } | |
215 | serpent_encrypt(&ti->mackey,macacc,macacc); | |
216 | if (memcmp(macexpected,macacc,16)!=0) { | |
217 | *errmsg="invalid MAC"; | |
218 | return 1; | |
219 | } | |
220 | ||
221 | /* PKCS5, stolen from IWJ */ | |
222 | ||
223 | padp=buf_unappend(buf,1); | |
224 | padlen=*padp; | |
225 | if (!padlen || (padlen > PKCS5_MASK+1)) { | |
226 | *errmsg="pkcs5: invalid length"; | |
227 | return 1; | |
228 | } | |
229 | ||
230 | padp=buf_unappend(buf,padlen-1); | |
231 | for (i=0; i<padlen-1; i++) { | |
232 | if (*++padp != padlen) { | |
233 | *errmsg="pkcs5: corrupted padding"; | |
234 | return 1; | |
235 | } | |
236 | } | |
237 | ||
238 | /* Sequence number must be within max_skew of lastrecvseq; lastrecvseq | |
239 | is only allowed to increase. */ | |
59635212 | 240 | seqnum=buf_unprepend_uint32(buf); |
2fe58dfd | 241 | skew=seqnum-ti->lastrecvseq; |
c6f79b17 | 242 | if (skew<0x8fffffff) { |
2fe58dfd SE |
243 | /* Ok */ |
244 | ti->lastrecvseq=seqnum; | |
c6f79b17 | 245 | } else if ((0-skew)<ti->max_skew) { |
2fe58dfd SE |
246 | /* Ok */ |
247 | } else { | |
248 | /* Too much skew */ | |
249 | *errmsg="seqnum: too much skew"; | |
250 | return 1; | |
251 | } | |
252 | ||
253 | return 0; | |
254 | } | |
255 | ||
256 | static void transform_destroy(void *sst) | |
257 | { | |
258 | struct transform_inst *st=sst; | |
259 | ||
076bb54e | 260 | FILLZERO(*st); /* Destroy key material */ |
2fe58dfd SE |
261 | free(st); |
262 | } | |
263 | ||
264 | static struct transform_inst_if *transform_create(void *sst) | |
265 | { | |
266 | struct transform_inst *ti; | |
267 | struct transform *st=sst; | |
268 | ||
269 | ti=safe_malloc(sizeof(*ti),"transform_create"); | |
270 | /* mlock XXX */ | |
271 | ||
272 | ti->ops.st=ti; | |
273 | ti->ops.setkey=transform_setkey; | |
274 | ti->ops.delkey=transform_delkey; | |
275 | ti->ops.forwards=transform_forward; | |
276 | ti->ops.reverse=transform_reverse; | |
277 | ti->ops.destroy=transform_destroy; | |
278 | ti->max_skew=st->max_seq_skew; | |
279 | ti->keyed=False; | |
280 | ||
281 | return &ti->ops; | |
282 | } | |
283 | ||
284 | static list_t *transform_apply(closure_t *self, struct cloc loc, | |
285 | dict_t *context, list_t *args) | |
286 | { | |
287 | struct transform *st; | |
288 | item_t *item; | |
289 | dict_t *dict; | |
290 | ||
291 | st=safe_malloc(sizeof(*st),"serpent"); | |
292 | st->cl.description="serpent-cbc256"; | |
293 | st->cl.type=CL_TRANSFORM; | |
294 | st->cl.apply=NULL; | |
295 | st->cl.interface=&st->ops; | |
296 | st->ops.st=st; | |
297 | st->ops.max_start_pad=28; /* 4byte seqnum, 16byte pad, 4byte MACIV, | |
298 | 4byte IV */ | |
299 | st->ops.max_end_pad=16; /* 16byte CBCMAC */ | |
300 | ||
301 | /* We need 256*2 bits for serpent keys, 32 bits for CBC-IV and 32 bits | |
302 | for CBCMAC-IV, and 32 bits for init sequence number */ | |
303 | st->ops.keylen=REQUIRED_KEYLEN; | |
304 | st->ops.create=transform_create; | |
305 | ||
306 | /* First parameter must be a dict */ | |
307 | item=list_elem(args,0); | |
308 | if (!item || item->type!=t_dict) | |
309 | cfgfatal(loc,"userv-ipif","parameter must be a dictionary\n"); | |
310 | ||
311 | dict=item->data.dict; | |
312 | st->max_seq_skew=dict_read_number(dict, "max-sequence-skew", | |
313 | False, "serpent-cbc256", loc, 10); | |
314 | ||
315 | return new_closure(&st->cl); | |
316 | } | |
317 | ||
2fe58dfd SE |
318 | void transform_module(dict_t *dict) |
319 | { | |
320 | struct keyInstance k; | |
321 | uint8_t data[32]; | |
3b83c932 SE |
322 | uint8_t plaintext[16]; |
323 | uint8_t ciphertext[16]; | |
324 | ||
325 | /* | |
326 | * Serpent self-test. | |
327 | * | |
328 | * This test pattern is taken directly from the Serpent test | |
329 | * vectors, to ensure we have all endianness issues correct. -sgt | |
330 | */ | |
2fe58dfd SE |
331 | |
332 | /* Serpent self-test */ | |
3b83c932 SE |
333 | memcpy(data, |
334 | "\x00\x11\x22\x33\x44\x55\x66\x77\x88\x99\xaa\xbb\xcc\xdd\xee\xff" | |
335 | "\xff\xee\xdd\xcc\xbb\xaa\x99\x88\x77\x66\x55\x44\x33\x22\x11\x00", | |
336 | 32); | |
2fe58dfd | 337 | serpent_makekey(&k,256,data); |
3b83c932 SE |
338 | |
339 | memcpy(plaintext, | |
340 | "\x01\x23\x45\x67\x89\xab\xcd\xef\xfe\xdc\xba\x98\x76\x54\x32\x10", | |
341 | 16); | |
2fe58dfd | 342 | serpent_encrypt(&k,plaintext,ciphertext); |
3b83c932 SE |
343 | |
344 | if (memcmp(ciphertext, "\xca\x7f\xa1\x93\xe3\xeb\x9e\x99" | |
345 | "\xbd\x87\xe3\xaf\x3c\x9a\xdf\x93", 16)) { | |
4f5e39ec | 346 | fatal("transform_module: serpent failed self-test (encrypt)"); |
2fe58dfd SE |
347 | } |
348 | serpent_decrypt(&k,ciphertext,plaintext); | |
3b83c932 SE |
349 | if (memcmp(plaintext, "\x01\x23\x45\x67\x89\xab\xcd\xef" |
350 | "\xfe\xdc\xba\x98\x76\x54\x32\x10", 16)) { | |
4f5e39ec | 351 | fatal("transform_module: serpent failed self-test (decrypt)"); |
2fe58dfd SE |
352 | } |
353 | ||
354 | add_closure(dict,"serpent256-cbc",transform_apply); | |
3b83c932 SE |
355 | |
356 | #ifdef TEST_WHOLE_TRANSFORM | |
357 | { | |
358 | struct transform *tr; | |
359 | void *ti; | |
360 | struct buffer_if buf; | |
361 | const char text[] = "This is a piece of test text."; | |
362 | char keymaterial[76] = | |
363 | "Seventy-six bytes i" | |
364 | "n four rows of 19; " | |
365 | "this looks almost l" | |
366 | "ike a poem but not."; | |
367 | const char *errmsg; | |
368 | int i; | |
369 | ||
370 | tr = malloc(sizeof(struct transform)); | |
371 | tr->max_seq_skew = 20; | |
372 | ti = transform_create(tr); | |
373 | ||
374 | transform_setkey(ti, keymaterial, 76); | |
375 | ||
376 | buf.base = malloc(4096); | |
377 | buffer_init(&buf, 2048); | |
378 | memcpy(buf_append(&buf, sizeof(text)), text, sizeof(text)); | |
379 | if (transform_forward(ti, &buf, &errmsg)) { | |
380 | fatal("transform_forward test: %s", errmsg); | |
381 | } | |
382 | printf("transformed text is:\n"); | |
383 | for (i = 0; i < buf.size; i++) | |
384 | printf("%02x%c", buf.start[i], | |
385 | (i%16==15 || i==buf.size-1 ? '\n' : ' ')); | |
386 | if (transform_reverse(ti, &buf, &errmsg)) { | |
387 | fatal("transform_reverse test: %s", errmsg); | |
388 | } | |
389 | printf("transform reversal worked OK\n"); | |
390 | } | |
391 | #endif | |
2fe58dfd | 392 | } |