1 /*
2 * EAP server/peer: EAP-GPSK shared routines
3 * Copyright (c) 2006-2007, Jouni Malinen <j@w1.fi>
4 *
5 * This software may be distributed under the terms of the BSD license.
6 * See README for more details.
7 */
8
9 #include "includes.h"
10
11 #include "common.h"
12 #include "crypto/aes_wrap.h"
13 #include "crypto/sha256.h"
14 #include "eap_defs.h"
15 #include "eap_gpsk_common.h"
16
17
18 /**
19 * eap_gpsk_supported_ciphersuite - Check whether ciphersuite is supported
20 * @vendor: CSuite/Vendor
21 * @specifier: CSuite/Specifier
22 * Returns: 1 if ciphersuite is support, or 0 if not
23 */
eap_gpsk_supported_ciphersuite(int vendor,int specifier)24 int eap_gpsk_supported_ciphersuite(int vendor, int specifier)
25 {
26 if (vendor == EAP_GPSK_VENDOR_IETF &&
27 specifier == EAP_GPSK_CIPHER_AES)
28 return 1;
29 #ifdef EAP_GPSK_SHA256
30 if (vendor == EAP_GPSK_VENDOR_IETF &&
31 specifier == EAP_GPSK_CIPHER_SHA256)
32 return 1;
33 #endif /* EAP_GPSK_SHA256 */
34 return 0;
35 }
36
37
eap_gpsk_gkdf_cmac(const u8 * psk,const u8 * data,size_t data_len,u8 * buf,size_t len)38 static int eap_gpsk_gkdf_cmac(const u8 *psk /* Y */,
39 const u8 *data /* Z */, size_t data_len,
40 u8 *buf, size_t len /* X */)
41 {
42 u8 *opos;
43 size_t i, n, hashlen, left, clen;
44 u8 ibuf[2], hash[16];
45 const u8 *addr[2];
46 size_t vlen[2];
47
48 hashlen = sizeof(hash);
49 /* M_i = MAC_Y (i || Z); (MAC = AES-CMAC-128) */
50 addr[0] = ibuf;
51 vlen[0] = sizeof(ibuf);
52 addr[1] = data;
53 vlen[1] = data_len;
54
55 opos = buf;
56 left = len;
57 n = (len + hashlen - 1) / hashlen;
58 for (i = 1; i <= n; i++) {
59 WPA_PUT_BE16(ibuf, i);
60 if (omac1_aes_128_vector(psk, 2, addr, vlen, hash))
61 return -1;
62 clen = left > hashlen ? hashlen : left;
63 os_memcpy(opos, hash, clen);
64 opos += clen;
65 left -= clen;
66 }
67
68 return 0;
69 }
70
71
72 #ifdef EAP_GPSK_SHA256
eap_gpsk_gkdf_sha256(const u8 * psk,const u8 * data,size_t data_len,u8 * buf,size_t len)73 static int eap_gpsk_gkdf_sha256(const u8 *psk /* Y */,
74 const u8 *data /* Z */, size_t data_len,
75 u8 *buf, size_t len /* X */)
76 {
77 u8 *opos;
78 size_t i, n, hashlen, left, clen;
79 u8 ibuf[2], hash[SHA256_MAC_LEN];
80 const u8 *addr[2];
81 size_t vlen[2];
82
83 hashlen = SHA256_MAC_LEN;
84 /* M_i = MAC_Y (i || Z); (MAC = HMAC-SHA256) */
85 addr[0] = ibuf;
86 vlen[0] = sizeof(ibuf);
87 addr[1] = data;
88 vlen[1] = data_len;
89
90 opos = buf;
91 left = len;
92 n = (len + hashlen - 1) / hashlen;
93 for (i = 1; i <= n; i++) {
94 WPA_PUT_BE16(ibuf, i);
95 hmac_sha256_vector(psk, 32, 2, addr, vlen, hash);
96 clen = left > hashlen ? hashlen : left;
97 os_memcpy(opos, hash, clen);
98 opos += clen;
99 left -= clen;
100 }
101
102 return 0;
103 }
104 #endif /* EAP_GPSK_SHA256 */
105
106
eap_gpsk_derive_keys_helper(u32 csuite_specifier,u8 * kdf_out,size_t kdf_out_len,const u8 * psk,size_t psk_len,const u8 * seed,size_t seed_len,u8 * msk,u8 * emsk,u8 * sk,size_t sk_len,u8 * pk,size_t pk_len)107 static int eap_gpsk_derive_keys_helper(u32 csuite_specifier,
108 u8 *kdf_out, size_t kdf_out_len,
109 const u8 *psk, size_t psk_len,
110 const u8 *seed, size_t seed_len,
111 u8 *msk, u8 *emsk,
112 u8 *sk, size_t sk_len,
113 u8 *pk, size_t pk_len)
114 {
115 u8 mk[32], *pos, *data;
116 size_t data_len, mk_len;
117 int (*gkdf)(const u8 *_psk, const u8 *_data, size_t _data_len,
118 u8 *buf, size_t len);
119
120 gkdf = NULL;
121 switch (csuite_specifier) {
122 case EAP_GPSK_CIPHER_AES:
123 gkdf = eap_gpsk_gkdf_cmac;
124 mk_len = 16;
125 break;
126 #ifdef EAP_GPSK_SHA256
127 case EAP_GPSK_CIPHER_SHA256:
128 gkdf = eap_gpsk_gkdf_sha256;
129 mk_len = SHA256_MAC_LEN;
130 break;
131 #endif /* EAP_GPSK_SHA256 */
132 default:
133 return -1;
134 }
135
136 if (psk_len < mk_len)
137 return -1;
138
139 data_len = 2 + psk_len + 6 + seed_len;
140 data = os_malloc(data_len);
141 if (data == NULL)
142 return -1;
143 pos = data;
144 WPA_PUT_BE16(pos, psk_len);
145 pos += 2;
146 os_memcpy(pos, psk, psk_len);
147 pos += psk_len;
148 WPA_PUT_BE32(pos, EAP_GPSK_VENDOR_IETF); /* CSuite/Vendor = IETF */
149 pos += 4;
150 WPA_PUT_BE16(pos, csuite_specifier); /* CSuite/Specifier */
151 pos += 2;
152 os_memcpy(pos, seed, seed_len); /* inputString */
153 wpa_hexdump_key(MSG_DEBUG, "EAP-GPSK: Data to MK derivation",
154 data, data_len);
155
156 if (gkdf(psk, data, data_len, mk, mk_len) < 0) {
157 os_free(data);
158 return -1;
159 }
160 os_free(data);
161 wpa_hexdump_key(MSG_DEBUG, "EAP-GPSK: MK", mk, mk_len);
162
163 if (gkdf(mk, seed, seed_len, kdf_out, kdf_out_len) < 0)
164 return -1;
165
166 pos = kdf_out;
167 wpa_hexdump_key(MSG_DEBUG, "EAP-GPSK: MSK", pos, EAP_MSK_LEN);
168 os_memcpy(msk, pos, EAP_MSK_LEN);
169 pos += EAP_MSK_LEN;
170
171 wpa_hexdump_key(MSG_DEBUG, "EAP-GPSK: EMSK", pos, EAP_EMSK_LEN);
172 os_memcpy(emsk, pos, EAP_EMSK_LEN);
173 pos += EAP_EMSK_LEN;
174
175 wpa_hexdump_key(MSG_DEBUG, "EAP-GPSK: SK", pos, sk_len);
176 os_memcpy(sk, pos, sk_len);
177 pos += sk_len;
178
179 if (pk) {
180 wpa_hexdump_key(MSG_DEBUG, "EAP-GPSK: PK", pos, pk_len);
181 os_memcpy(pk, pos, pk_len);
182 }
183
184 return 0;
185 }
186
187
eap_gpsk_derive_keys_aes(const u8 * psk,size_t psk_len,const u8 * seed,size_t seed_len,u8 * msk,u8 * emsk,u8 * sk,size_t * sk_len,u8 * pk,size_t * pk_len)188 static int eap_gpsk_derive_keys_aes(const u8 *psk, size_t psk_len,
189 const u8 *seed, size_t seed_len,
190 u8 *msk, u8 *emsk, u8 *sk, size_t *sk_len,
191 u8 *pk, size_t *pk_len)
192 {
193 #define EAP_GPSK_SK_LEN_AES 16
194 #define EAP_GPSK_PK_LEN_AES 16
195 u8 kdf_out[EAP_MSK_LEN + EAP_EMSK_LEN + EAP_GPSK_SK_LEN_AES +
196 EAP_GPSK_PK_LEN_AES];
197
198 /*
199 * inputString = RAND_Peer || ID_Peer || RAND_Server || ID_Server
200 * (= seed)
201 * KS = 16, PL = psk_len, CSuite_Sel = 0x00000000 0x0001
202 * MK = GKDF-16 (PSK[0..15], PL || PSK || CSuite_Sel || inputString)
203 * MSK = GKDF-160 (MK, inputString)[0..63]
204 * EMSK = GKDF-160 (MK, inputString)[64..127]
205 * SK = GKDF-160 (MK, inputString)[128..143]
206 * PK = GKDF-160 (MK, inputString)[144..159]
207 * zero = 0x00 || 0x00 || ... || 0x00 (16 times)
208 * Method-ID = GKDF-16 (zero, "Method ID" || EAP_Method_Type ||
209 * CSuite_Sel || inputString)
210 */
211
212 *sk_len = EAP_GPSK_SK_LEN_AES;
213 *pk_len = EAP_GPSK_PK_LEN_AES;
214
215 return eap_gpsk_derive_keys_helper(EAP_GPSK_CIPHER_AES,
216 kdf_out, sizeof(kdf_out),
217 psk, psk_len, seed, seed_len,
218 msk, emsk, sk, *sk_len,
219 pk, *pk_len);
220 }
221
222
223 #ifdef EAP_GPSK_SHA256
eap_gpsk_derive_keys_sha256(const u8 * psk,size_t psk_len,const u8 * seed,size_t seed_len,u8 * msk,u8 * emsk,u8 * sk,size_t * sk_len)224 static int eap_gpsk_derive_keys_sha256(const u8 *psk, size_t psk_len,
225 const u8 *seed, size_t seed_len,
226 u8 *msk, u8 *emsk,
227 u8 *sk, size_t *sk_len)
228 {
229 #define EAP_GPSK_SK_LEN_SHA256 SHA256_MAC_LEN
230 #define EAP_GPSK_PK_LEN_SHA256 SHA256_MAC_LEN
231 u8 kdf_out[EAP_MSK_LEN + EAP_EMSK_LEN + EAP_GPSK_SK_LEN_SHA256 +
232 EAP_GPSK_PK_LEN_SHA256];
233
234 /*
235 * inputString = RAND_Peer || ID_Peer || RAND_Server || ID_Server
236 * (= seed)
237 * KS = 32, PL = psk_len, CSuite_Sel = 0x00000000 0x0002
238 * MK = GKDF-32 (PSK[0..31], PL || PSK || CSuite_Sel || inputString)
239 * MSK = GKDF-160 (MK, inputString)[0..63]
240 * EMSK = GKDF-160 (MK, inputString)[64..127]
241 * SK = GKDF-160 (MK, inputString)[128..159]
242 * zero = 0x00 || 0x00 || ... || 0x00 (32 times)
243 * Method-ID = GKDF-16 (zero, "Method ID" || EAP_Method_Type ||
244 * CSuite_Sel || inputString)
245 */
246
247 *sk_len = EAP_GPSK_SK_LEN_SHA256;
248
249 return eap_gpsk_derive_keys_helper(EAP_GPSK_CIPHER_SHA256,
250 kdf_out, sizeof(kdf_out),
251 psk, psk_len, seed, seed_len,
252 msk, emsk, sk, *sk_len,
253 NULL, 0);
254 }
255 #endif /* EAP_GPSK_SHA256 */
256
257
258 /**
259 * eap_gpsk_derive_keys - Derive EAP-GPSK keys
260 * @psk: Pre-shared key
261 * @psk_len: Length of psk in bytes
262 * @vendor: CSuite/Vendor
263 * @specifier: CSuite/Specifier
264 * @rand_peer: 32-byte RAND_Peer
265 * @rand_server: 32-byte RAND_Server
266 * @id_peer: ID_Peer
267 * @id_peer_len: Length of ID_Peer
268 * @id_server: ID_Server
269 * @id_server_len: Length of ID_Server
270 * @msk: Buffer for 64-byte MSK
271 * @emsk: Buffer for 64-byte EMSK
272 * @sk: Buffer for SK (at least EAP_GPSK_MAX_SK_LEN bytes)
273 * @sk_len: Buffer for returning length of SK
274 * @pk: Buffer for PK (at least EAP_GPSK_MAX_PK_LEN bytes)
275 * @pk_len: Buffer for returning length of PK
276 * Returns: 0 on success, -1 on failure
277 */
eap_gpsk_derive_keys(const u8 * psk,size_t psk_len,int vendor,int specifier,const u8 * rand_peer,const u8 * rand_server,const u8 * id_peer,size_t id_peer_len,const u8 * id_server,size_t id_server_len,u8 * msk,u8 * emsk,u8 * sk,size_t * sk_len,u8 * pk,size_t * pk_len)278 int eap_gpsk_derive_keys(const u8 *psk, size_t psk_len, int vendor,
279 int specifier,
280 const u8 *rand_peer, const u8 *rand_server,
281 const u8 *id_peer, size_t id_peer_len,
282 const u8 *id_server, size_t id_server_len,
283 u8 *msk, u8 *emsk, u8 *sk, size_t *sk_len,
284 u8 *pk, size_t *pk_len)
285 {
286 u8 *seed, *pos;
287 int ret;
288
289 wpa_printf(MSG_DEBUG, "EAP-GPSK: Deriving keys (%d:%d)",
290 vendor, specifier);
291
292 if (vendor != EAP_GPSK_VENDOR_IETF)
293 return -1;
294
295 wpa_hexdump_key(MSG_DEBUG, "EAP-GPSK: PSK", psk, psk_len);
296
297 /* Seed = RAND_Peer || ID_Peer || RAND_Server || ID_Server */
298 seed = os_malloc(2 * EAP_GPSK_RAND_LEN + id_server_len + id_peer_len);
299 if (seed == NULL) {
300 wpa_printf(MSG_DEBUG, "EAP-GPSK: Failed to allocate memory "
301 "for key derivation");
302 return -1;
303 }
304
305 pos = seed;
306 os_memcpy(pos, rand_peer, EAP_GPSK_RAND_LEN);
307 pos += EAP_GPSK_RAND_LEN;
308 os_memcpy(pos, id_peer, id_peer_len);
309 pos += id_peer_len;
310 os_memcpy(pos, rand_server, EAP_GPSK_RAND_LEN);
311 pos += EAP_GPSK_RAND_LEN;
312 os_memcpy(pos, id_server, id_server_len);
313 pos += id_server_len;
314 wpa_hexdump(MSG_DEBUG, "EAP-GPSK: Seed", seed, pos - seed);
315
316 switch (specifier) {
317 case EAP_GPSK_CIPHER_AES:
318 ret = eap_gpsk_derive_keys_aes(psk, psk_len, seed, pos - seed,
319 msk, emsk, sk, sk_len,
320 pk, pk_len);
321 break;
322 #ifdef EAP_GPSK_SHA256
323 case EAP_GPSK_CIPHER_SHA256:
324 ret = eap_gpsk_derive_keys_sha256(psk, psk_len, seed,
325 pos - seed,
326 msk, emsk, sk, sk_len);
327 break;
328 #endif /* EAP_GPSK_SHA256 */
329 default:
330 wpa_printf(MSG_DEBUG, "EAP-GPSK: Unknown cipher %d:%d used in "
331 "key derivation", vendor, specifier);
332 ret = -1;
333 break;
334 }
335
336 os_free(seed);
337
338 return ret;
339 }
340
341
eap_gpsk_derive_mid_helper(u32 csuite_specifier,u8 * kdf_out,size_t kdf_out_len,const u8 * psk,const u8 * seed,size_t seed_len,u8 method_type)342 static int eap_gpsk_derive_mid_helper(u32 csuite_specifier,
343 u8 *kdf_out, size_t kdf_out_len,
344 const u8 *psk, const u8 *seed,
345 size_t seed_len, u8 method_type)
346 {
347 u8 *pos, *data;
348 size_t data_len;
349 int (*gkdf)(const u8 *_psk, const u8 *_data, size_t _data_len,
350 u8 *buf, size_t len);
351
352 gkdf = NULL;
353 switch (csuite_specifier) {
354 case EAP_GPSK_CIPHER_AES:
355 gkdf = eap_gpsk_gkdf_cmac;
356 break;
357 #ifdef EAP_GPSK_SHA256
358 case EAP_GPSK_CIPHER_SHA256:
359 gkdf = eap_gpsk_gkdf_sha256;
360 break;
361 #endif /* EAP_GPSK_SHA256 */
362 default:
363 wpa_printf(MSG_DEBUG, "EAP-GPSK: Unknown cipher %d used in "
364 "Session-Id derivation", csuite_specifier);
365 return -1;
366 }
367
368 #define SID_LABEL "Method ID"
369 /* "Method ID" || EAP_Method_Type || CSuite_Sel || inputString */
370 data_len = strlen(SID_LABEL) + 1 + 6 + seed_len;
371 data = os_malloc(data_len);
372 if (data == NULL)
373 return -1;
374 pos = data;
375 os_memcpy(pos, SID_LABEL, strlen(SID_LABEL));
376 pos += strlen(SID_LABEL);
377 #undef SID_LABEL
378 os_memcpy(pos, &method_type, 1);
379 pos += 1;
380 WPA_PUT_BE32(pos, EAP_GPSK_VENDOR_IETF); /* CSuite/Vendor = IETF */
381 pos += 4;
382 WPA_PUT_BE16(pos, csuite_specifier); /* CSuite/Specifier */
383 pos += 2;
384 os_memcpy(pos, seed, seed_len); /* inputString */
385 wpa_hexdump(MSG_DEBUG, "EAP-GPSK: Data to Method ID derivation",
386 data, data_len);
387
388 if (gkdf(psk, data, data_len, kdf_out, kdf_out_len) < 0) {
389 os_free(data);
390 return -1;
391 }
392 os_free(data);
393 wpa_hexdump(MSG_DEBUG, "EAP-GPSK: Method ID", kdf_out, kdf_out_len);
394
395 return 0;
396 }
397
398
399 /**
400 * eap_gpsk_session_id - Derive EAP-GPSK Session ID
401 * @psk: Pre-shared key
402 * @psk_len: Length of psk in bytes
403 * @vendor: CSuite/Vendor
404 * @specifier: CSuite/Specifier
405 * @rand_peer: 32-byte RAND_Peer
406 * @rand_server: 32-byte RAND_Server
407 * @id_peer: ID_Peer
408 * @id_peer_len: Length of ID_Peer
409 * @id_server: ID_Server
410 * @id_server_len: Length of ID_Server
411 * @method_type: EAP Authentication Method Type
412 * @sid: Buffer for 17-byte Session ID
413 * @sid_len: Buffer for returning length of Session ID
414 * Returns: 0 on success, -1 on failure
415 */
eap_gpsk_derive_session_id(const u8 * psk,size_t psk_len,int vendor,int specifier,const u8 * rand_peer,const u8 * rand_server,const u8 * id_peer,size_t id_peer_len,const u8 * id_server,size_t id_server_len,u8 method_type,u8 * sid,size_t * sid_len)416 int eap_gpsk_derive_session_id(const u8 *psk, size_t psk_len, int vendor,
417 int specifier,
418 const u8 *rand_peer, const u8 *rand_server,
419 const u8 *id_peer, size_t id_peer_len,
420 const u8 *id_server, size_t id_server_len,
421 u8 method_type, u8 *sid, size_t *sid_len)
422 {
423 u8 *seed, *pos;
424 u8 kdf_out[16];
425 int ret;
426
427 wpa_printf(MSG_DEBUG, "EAP-GPSK: Deriving Session ID(%d:%d)",
428 vendor, specifier);
429
430 if (vendor != EAP_GPSK_VENDOR_IETF)
431 return -1;
432
433 wpa_hexdump_key(MSG_DEBUG, "EAP-GPSK: PSK", psk, psk_len);
434
435 /*
436 * inputString = RAND_Peer || ID_Peer || RAND_Server || ID_Server
437 * (= seed)
438 * KS = 16, CSuite_Sel = 0x00000000 0x0001
439 * Method-ID = GKDF-16 (zero, "Method ID" || EAP_Method_Type ||
440 * CSuite_Sel || inputString)
441 */
442 seed = os_malloc(2 * EAP_GPSK_RAND_LEN + id_server_len + id_peer_len);
443 if (seed == NULL) {
444 wpa_printf(MSG_DEBUG, "EAP-GPSK: Failed to allocate memory "
445 "for Session-Id derivation");
446 return -1;
447 }
448
449 pos = seed;
450 os_memcpy(pos, rand_peer, EAP_GPSK_RAND_LEN);
451 pos += EAP_GPSK_RAND_LEN;
452 os_memcpy(pos, id_peer, id_peer_len);
453 pos += id_peer_len;
454 os_memcpy(pos, rand_server, EAP_GPSK_RAND_LEN);
455 pos += EAP_GPSK_RAND_LEN;
456 os_memcpy(pos, id_server, id_server_len);
457 pos += id_server_len;
458 wpa_hexdump(MSG_DEBUG, "EAP-GPSK: Seed", seed, pos - seed);
459
460 ret = eap_gpsk_derive_mid_helper(specifier,
461 kdf_out, sizeof(kdf_out),
462 psk, seed, pos - seed,
463 method_type);
464
465 sid[0] = method_type;
466 os_memcpy(sid + 1, kdf_out, sizeof(kdf_out));
467 *sid_len = 1 + sizeof(kdf_out);
468
469 os_free(seed);
470
471 return ret;
472 }
473
474
475 /**
476 * eap_gpsk_mic_len - Get the length of the MIC
477 * @vendor: CSuite/Vendor
478 * @specifier: CSuite/Specifier
479 * Returns: MIC length in bytes
480 */
eap_gpsk_mic_len(int vendor,int specifier)481 size_t eap_gpsk_mic_len(int vendor, int specifier)
482 {
483 if (vendor != EAP_GPSK_VENDOR_IETF)
484 return 0;
485
486 switch (specifier) {
487 case EAP_GPSK_CIPHER_AES:
488 return 16;
489 #ifdef EAP_GPSK_SHA256
490 case EAP_GPSK_CIPHER_SHA256:
491 return 32;
492 #endif /* EAP_GPSK_SHA256 */
493 default:
494 return 0;
495 }
496 }
497
498
eap_gpsk_compute_mic_aes(const u8 * sk,size_t sk_len,const u8 * data,size_t len,u8 * mic)499 static int eap_gpsk_compute_mic_aes(const u8 *sk, size_t sk_len,
500 const u8 *data, size_t len, u8 *mic)
501 {
502 if (sk_len != 16) {
503 wpa_printf(MSG_DEBUG, "EAP-GPSK: Invalid SK length %lu for "
504 "AES-CMAC MIC", (unsigned long) sk_len);
505 return -1;
506 }
507
508 return omac1_aes_128(sk, data, len, mic);
509 }
510
511
512 /**
513 * eap_gpsk_compute_mic - Compute EAP-GPSK MIC for an EAP packet
514 * @sk: Session key SK from eap_gpsk_derive_keys()
515 * @sk_len: SK length in bytes from eap_gpsk_derive_keys()
516 * @vendor: CSuite/Vendor
517 * @specifier: CSuite/Specifier
518 * @data: Input data to MIC
519 * @len: Input data length in bytes
520 * @mic: Buffer for the computed MIC, eap_gpsk_mic_len(cipher) bytes
521 * Returns: 0 on success, -1 on failure
522 */
eap_gpsk_compute_mic(const u8 * sk,size_t sk_len,int vendor,int specifier,const u8 * data,size_t len,u8 * mic)523 int eap_gpsk_compute_mic(const u8 *sk, size_t sk_len, int vendor,
524 int specifier, const u8 *data, size_t len, u8 *mic)
525 {
526 int ret;
527
528 if (vendor != EAP_GPSK_VENDOR_IETF)
529 return -1;
530
531 switch (specifier) {
532 case EAP_GPSK_CIPHER_AES:
533 ret = eap_gpsk_compute_mic_aes(sk, sk_len, data, len, mic);
534 break;
535 #ifdef EAP_GPSK_SHA256
536 case EAP_GPSK_CIPHER_SHA256:
537 hmac_sha256(sk, sk_len, data, len, mic);
538 ret = 0;
539 break;
540 #endif /* EAP_GPSK_SHA256 */
541 default:
542 wpa_printf(MSG_DEBUG, "EAP-GPSK: Unknown cipher %d:%d used in "
543 "MIC computation", vendor, specifier);
544 ret = -1;
545 break;
546 }
547
548 return ret;
549 }
550