Commit | Line | Data |
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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; | |
22 | uint32_t line; | |
23 | struct transform_if ops; | |
24 | uint32_t max_seq_skew; | |
25 | }; | |
26 | ||
27 | struct transform_inst { | |
28 | struct transform_inst_if ops; | |
29 | struct keyInstance cryptkey; | |
30 | struct keyInstance mackey; | |
31 | uint32_t cryptiv; | |
32 | uint32_t maciv; | |
33 | uint32_t sendseq; | |
34 | uint32_t lastrecvseq; | |
35 | uint32_t max_skew; | |
36 | bool_t keyed; | |
37 | }; | |
38 | ||
39 | #define PKCS5_MASK 15 | |
40 | ||
41 | static bool_t transform_setkey(void *sst, uint8_t *key, uint32_t keylen) | |
42 | { | |
43 | struct transform_inst *ti=sst; | |
44 | ||
45 | if (keylen<REQUIRED_KEYLEN) { | |
469fd1d9 | 46 | Message(M_ERR,"transform_create: insufficient key material supplied " |
2fe58dfd SE |
47 | "(need %d bytes, got %d)\n",REQUIRED_KEYLEN,keylen); |
48 | return False; | |
49 | } | |
50 | ||
51 | #if 0 | |
52 | { | |
53 | int i; | |
54 | printf("Setting key to: "); | |
55 | for (i=0; i<keylen; i++) | |
56 | printf("%02x",key[i]); | |
57 | printf("\n"); | |
58 | } | |
59 | #endif /* 0 */ | |
60 | ||
61 | serpent_makekey(&ti->cryptkey,256,key); | |
62 | serpent_makekey(&ti->mackey,256,key+32); | |
3b83c932 SE |
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); | |
2fe58dfd SE |
66 | ti->lastrecvseq=ti->sendseq; |
67 | ti->keyed=True; | |
68 | ||
69 | return True; | |
70 | } | |
71 | ||
72 | static void transform_delkey(void *sst) | |
73 | { | |
74 | struct transform_inst *ti=sst; | |
75 | ||
76 | memset(&ti->cryptkey,0,sizeof(ti->cryptkey)); | |
77 | memset(&ti->mackey,0,sizeof(ti->mackey)); | |
78 | ti->keyed=False; | |
79 | } | |
80 | ||
81 | static uint32_t transform_forward(void *sst, struct buffer_if *buf, | |
fe5e9cc4 | 82 | const char **errmsg) |
2fe58dfd SE |
83 | { |
84 | struct transform_inst *ti=sst; | |
85 | uint8_t *padp; | |
86 | int padlen; | |
3b83c932 SE |
87 | uint8_t iv[16]; |
88 | uint8_t macplain[16]; | |
89 | uint8_t macacc[16]; | |
90 | uint8_t *p, *n; | |
91 | int i; | |
2fe58dfd SE |
92 | |
93 | if (!ti->keyed) { | |
94 | *errmsg="transform unkeyed"; | |
95 | return 1; | |
96 | } | |
97 | ||
98 | /* Sequence number */ | |
59635212 | 99 | buf_prepend_uint32(buf,ti->sendseq); |
2fe58dfd SE |
100 | ti->sendseq++; |
101 | ||
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 */ | |
108 | ||
109 | padp=buf_append(buf,padlen); | |
110 | memset(padp,padlen,padlen); | |
111 | ||
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.) */ | |
117 | memset(iv,0,16); | |
3b83c932 | 118 | PUT_32BIT_MSB_FIRST(iv, ti->maciv); |
2fe58dfd SE |
119 | serpent_encrypt(&ti->mackey,iv,macacc); |
120 | ||
121 | /* CBCMAC: encrypt in CBC mode. The MAC is the last encrypted | |
122 | block encrypted once again. */ | |
3b83c932 | 123 | for (n=buf->start; n<buf->start+buf->size; n+=16) |
2fe58dfd | 124 | { |
3b83c932 SE |
125 | for (i = 0; i < 16; i++) |
126 | macplain[i] = macacc[i] ^ n[i]; | |
2fe58dfd SE |
127 | serpent_encrypt(&ti->mackey,macplain,macacc); |
128 | } | |
129 | serpent_encrypt(&ti->mackey,macacc,macacc); | |
130 | memcpy(buf_append(buf,16),macacc,16); | |
131 | ||
132 | /* Serpent-CBC. We expand the ID as for CBCMAC, do the encryption, | |
133 | and prepend the IV before increasing it. */ | |
134 | memset(iv,0,16); | |
3b83c932 | 135 | PUT_32BIT_MSB_FIRST(iv, ti->cryptiv); |
2fe58dfd SE |
136 | serpent_encrypt(&ti->cryptkey,iv,iv); |
137 | ||
138 | /* CBC: each block is XORed with the previous encrypted block (or the IV) | |
139 | before being encrypted. */ | |
140 | p=iv; | |
3b83c932 SE |
141 | |
142 | for (n=buf->start; n<buf->start+buf->size; n+=16) | |
2fe58dfd | 143 | { |
3b83c932 SE |
144 | for (i = 0; i < 16; i++) |
145 | n[i] ^= p[i]; | |
2fe58dfd SE |
146 | serpent_encrypt(&ti->cryptkey,n,n); |
147 | p=n; | |
148 | } | |
149 | ||
59635212 | 150 | buf_prepend_uint32(buf,ti->cryptiv); |
2fe58dfd | 151 | ti->cryptiv++; |
2fe58dfd SE |
152 | return 0; |
153 | } | |
154 | ||
155 | static uint32_t transform_reverse(void *sst, struct buffer_if *buf, | |
fe5e9cc4 | 156 | const char **errmsg) |
2fe58dfd SE |
157 | { |
158 | struct transform_inst *ti=sst; | |
159 | uint8_t *padp; | |
160 | unsigned padlen; | |
161 | int i; | |
162 | uint32_t seqnum, skew; | |
3b83c932 SE |
163 | uint8_t iv[16]; |
164 | uint8_t pct[16]; | |
165 | uint8_t macplain[16]; | |
166 | uint8_t macacc[16]; | |
167 | uint8_t *n; | |
168 | uint8_t *macexpected; | |
2fe58dfd SE |
169 | |
170 | if (!ti->keyed) { | |
171 | *errmsg="transform unkeyed"; | |
172 | return 1; | |
173 | } | |
174 | ||
8689b3a9 | 175 | |
2fe58dfd SE |
176 | /* CBC */ |
177 | memset(iv,0,16); | |
3b83c932 SE |
178 | { |
179 | uint32_t ivword = buf_unprepend_uint32(buf); | |
180 | PUT_32BIT_MSB_FIRST(iv, ivword); | |
181 | } | |
8689b3a9 SE |
182 | /* Assert bufsize is multiple of blocksize */ |
183 | if (buf->size&0xf) { | |
184 | *errmsg="msg not multiple of cipher blocksize"; | |
185 | } | |
2fe58dfd | 186 | serpent_encrypt(&ti->cryptkey,iv,iv); |
3b83c932 | 187 | for (n=buf->start; n<buf->start+buf->size; n+=16) |
2fe58dfd | 188 | { |
3b83c932 SE |
189 | for (i = 0; i < 16; i++) |
190 | pct[i] = n[i]; | |
2fe58dfd | 191 | serpent_decrypt(&ti->cryptkey,n,n); |
3b83c932 SE |
192 | for (i = 0; i < 16; i++) |
193 | n[i] ^= iv[i]; | |
194 | memcpy(iv, pct, 16); | |
2fe58dfd SE |
195 | } |
196 | ||
197 | /* CBCMAC */ | |
198 | macexpected=buf_unappend(buf,16); | |
199 | memset(iv,0,16); | |
3b83c932 | 200 | PUT_32BIT_MSB_FIRST(iv, ti->maciv); |
2fe58dfd SE |
201 | serpent_encrypt(&ti->mackey,iv,macacc); |
202 | ||
203 | /* CBCMAC: encrypt in CBC mode. The MAC is the last encrypted | |
204 | block encrypted once again. */ | |
3b83c932 | 205 | for (n=buf->start; n<buf->start+buf->size; n+=16) |
2fe58dfd | 206 | { |
3b83c932 SE |
207 | for (i = 0; i < 16; i++) |
208 | macplain[i] = macacc[i] ^ n[i]; | |
2fe58dfd SE |
209 | serpent_encrypt(&ti->mackey,macplain,macacc); |
210 | } | |
211 | serpent_encrypt(&ti->mackey,macacc,macacc); | |
212 | if (memcmp(macexpected,macacc,16)!=0) { | |
213 | *errmsg="invalid MAC"; | |
214 | return 1; | |
215 | } | |
216 | ||
217 | /* PKCS5, stolen from IWJ */ | |
218 | ||
219 | padp=buf_unappend(buf,1); | |
220 | padlen=*padp; | |
221 | if (!padlen || (padlen > PKCS5_MASK+1)) { | |
222 | *errmsg="pkcs5: invalid length"; | |
223 | return 1; | |
224 | } | |
225 | ||
226 | padp=buf_unappend(buf,padlen-1); | |
227 | for (i=0; i<padlen-1; i++) { | |
228 | if (*++padp != padlen) { | |
229 | *errmsg="pkcs5: corrupted padding"; | |
230 | return 1; | |
231 | } | |
232 | } | |
233 | ||
234 | /* Sequence number must be within max_skew of lastrecvseq; lastrecvseq | |
235 | is only allowed to increase. */ | |
59635212 | 236 | seqnum=buf_unprepend_uint32(buf); |
2fe58dfd | 237 | skew=seqnum-ti->lastrecvseq; |
c6f79b17 | 238 | if (skew<0x8fffffff) { |
2fe58dfd SE |
239 | /* Ok */ |
240 | ti->lastrecvseq=seqnum; | |
c6f79b17 | 241 | } else if ((0-skew)<ti->max_skew) { |
2fe58dfd SE |
242 | /* Ok */ |
243 | } else { | |
244 | /* Too much skew */ | |
245 | *errmsg="seqnum: too much skew"; | |
246 | return 1; | |
247 | } | |
248 | ||
249 | return 0; | |
250 | } | |
251 | ||
252 | static void transform_destroy(void *sst) | |
253 | { | |
254 | struct transform_inst *st=sst; | |
255 | ||
256 | memset(st,0,sizeof(*st)); /* Destroy key material */ | |
257 | free(st); | |
258 | } | |
259 | ||
260 | static struct transform_inst_if *transform_create(void *sst) | |
261 | { | |
262 | struct transform_inst *ti; | |
263 | struct transform *st=sst; | |
264 | ||
265 | ti=safe_malloc(sizeof(*ti),"transform_create"); | |
266 | /* mlock XXX */ | |
267 | ||
268 | ti->ops.st=ti; | |
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; | |
275 | ti->keyed=False; | |
276 | ||
277 | return &ti->ops; | |
278 | } | |
279 | ||
280 | static list_t *transform_apply(closure_t *self, struct cloc loc, | |
281 | dict_t *context, list_t *args) | |
282 | { | |
283 | struct transform *st; | |
284 | item_t *item; | |
285 | dict_t *dict; | |
286 | ||
287 | st=safe_malloc(sizeof(*st),"serpent"); | |
288 | st->cl.description="serpent-cbc256"; | |
289 | st->cl.type=CL_TRANSFORM; | |
290 | st->cl.apply=NULL; | |
291 | st->cl.interface=&st->ops; | |
292 | st->ops.st=st; | |
293 | st->ops.max_start_pad=28; /* 4byte seqnum, 16byte pad, 4byte MACIV, | |
294 | 4byte IV */ | |
295 | st->ops.max_end_pad=16; /* 16byte CBCMAC */ | |
296 | ||
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; | |
301 | ||
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"); | |
306 | ||
307 | dict=item->data.dict; | |
308 | st->max_seq_skew=dict_read_number(dict, "max-sequence-skew", | |
309 | False, "serpent-cbc256", loc, 10); | |
310 | ||
311 | return new_closure(&st->cl); | |
312 | } | |
313 | ||
314 | init_module transform_module; | |
315 | void transform_module(dict_t *dict) | |
316 | { | |
317 | struct keyInstance k; | |
318 | uint8_t data[32]; | |
3b83c932 SE |
319 | uint8_t plaintext[16]; |
320 | uint8_t ciphertext[16]; | |
321 | ||
322 | /* | |
323 | * Serpent self-test. | |
324 | * | |
325 | * This test pattern is taken directly from the Serpent test | |
326 | * vectors, to ensure we have all endianness issues correct. -sgt | |
327 | */ | |
2fe58dfd SE |
328 | |
329 | /* Serpent self-test */ | |
3b83c932 SE |
330 | memcpy(data, |
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", | |
333 | 32); | |
2fe58dfd | 334 | serpent_makekey(&k,256,data); |
3b83c932 SE |
335 | |
336 | memcpy(plaintext, | |
337 | "\x01\x23\x45\x67\x89\xab\xcd\xef\xfe\xdc\xba\x98\x76\x54\x32\x10", | |
338 | 16); | |
2fe58dfd | 339 | serpent_encrypt(&k,plaintext,ciphertext); |
3b83c932 SE |
340 | |
341 | if (memcmp(ciphertext, "\xca\x7f\xa1\x93\xe3\xeb\x9e\x99" | |
342 | "\xbd\x87\xe3\xaf\x3c\x9a\xdf\x93", 16)) { | |
4f5e39ec | 343 | fatal("transform_module: serpent failed self-test (encrypt)"); |
2fe58dfd SE |
344 | } |
345 | serpent_decrypt(&k,ciphertext,plaintext); | |
3b83c932 SE |
346 | if (memcmp(plaintext, "\x01\x23\x45\x67\x89\xab\xcd\xef" |
347 | "\xfe\xdc\xba\x98\x76\x54\x32\x10", 16)) { | |
4f5e39ec | 348 | fatal("transform_module: serpent failed self-test (decrypt)"); |
2fe58dfd SE |
349 | } |
350 | ||
351 | add_closure(dict,"serpent256-cbc",transform_apply); | |
3b83c932 SE |
352 | |
353 | #ifdef TEST_WHOLE_TRANSFORM | |
354 | { | |
355 | struct transform *tr; | |
356 | void *ti; | |
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."; | |
364 | const char *errmsg; | |
365 | int i; | |
366 | ||
367 | tr = malloc(sizeof(struct transform)); | |
368 | tr->max_seq_skew = 20; | |
369 | ti = transform_create(tr); | |
370 | ||
371 | transform_setkey(ti, keymaterial, 76); | |
372 | ||
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); | |
378 | } | |
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); | |
385 | } | |
386 | printf("transform reversal worked OK\n"); | |
387 | } | |
388 | #endif | |
2fe58dfd | 389 | } |