xref: /freebsd/contrib/wpa/src/eap_common/eap_gpsk_common.c (revision 59e2ff550c448126b988150ce800cdf73bb5103e)
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  */
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 
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
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 
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 
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
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  */
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 
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  */
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  */
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 
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  */
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