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1 //-----------------------------------------------------------------------------
2 // Frederik Möllers - August 2012
3 //
4 // This code is licensed to you under the terms of the GNU GPL, version 2 or,
5 // at your option, any later version. See the LICENSE.txt file for the text of
6 // the license.
7 //-----------------------------------------------------------------------------
8 // Routines to support the German eletronic "Personalausweis" (ID card)
9 // Note that the functions which do not implement USB commands do NOT initialize
10 // the card (with iso14443a_select_card etc.). If You want to use these
11 // functions, You need to do the setup before calling them!
12 //-----------------------------------------------------------------------------
13
14 #include "iso14443a.h"
15 #include "epa.h"
16 #include "cmd.h"
17
18 // Protocol and Parameter Selection Request
19 // use regular (1x) speed in both directions
20 // CRC is already included
21 static const uint8_t pps[] = {0xD0, 0x11, 0x00, 0x52, 0xA6};
22
23 // APDUs for communication with German Identification Card
24
25 // General Authenticate (request encrypted nonce) WITHOUT the Le at the end
26 static const uint8_t apdu_general_authenticate_pace_get_nonce[] = {
27 0x10, // CLA
28 0x86, // INS
29 0x00, // P1
30 0x00, // P2
31 0x02, // Lc
32 0x7C, // Type: Dynamic Authentication Data
33 0x00, // Length: 0 bytes
34 };
35
36 // MSE: Set AT (only CLA, INS, P1 and P2)
37 static const uint8_t apdu_mse_set_at_start[] = {
38 0x00, // CLA
39 0x22, // INS
40 0xC1, // P1
41 0xA4, // P2
42 };
43
44 // SELECT BINARY with the ID for EF.CardAccess
45 static const uint8_t apdu_select_binary_cardaccess[] = {
46 0x00, // CLA
47 0xA4, // INS
48 0x02, // P1
49 0x0C, // P2
50 0x02, // Lc
51 0x01, // ID
52 0x1C // ID
53 };
54
55 // READ BINARY
56 static const uint8_t apdu_read_binary[] = {
57 0x00, // CLA
58 0xB0, // INS
59 0x00, // P1
60 0x00, // P2
61 0x38 // Le
62 };
63
64
65 // the leading bytes of a PACE OID
66 static const uint8_t oid_pace_start[] = {
67 0x04, // itu-t, identified-organization
68 0x00, // etsi
69 0x7F, // reserved
70 0x00, // etsi-identified-organization
71 0x07, // bsi-de
72 0x02, // protocols
73 0x02, // smartcard
74 0x04 // id-PACE
75 };
76
77 //-----------------------------------------------------------------------------
78 // Closes the communication channel and turns off the field
79 //-----------------------------------------------------------------------------
80 void EPA_Finish()
81 {
82 FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
83 LEDsoff();
84 }
85
86 //-----------------------------------------------------------------------------
87 // Parses DER encoded data, e.g. from EF.CardAccess and fills out the given
88 // structs. If a pointer is 0, it is ignored.
89 // The function returns 0 on success and if an error occured, it returns the
90 // offset where it occured.
91 //
92 // TODO: This function can access memory outside of the given data if the DER
93 // encoding is broken
94 // TODO: Support skipping elements with a length > 0x7F
95 // TODO: Support OIDs with a length > 7F
96 // TODO: Support elements with long tags (tag is longer than 1 byte)
97 // TODO: Support proprietary PACE domain parameters
98 //-----------------------------------------------------------------------------
99 size_t EPA_Parse_CardAccess(uint8_t *data,
100 size_t length,
101 pace_version_info_t *pace_info)
102 {
103 size_t index = 0;
104
105 while (index <= length - 2) {
106 // determine type of element
107 // SET or SEQUENCE
108 if (data[index] == 0x31 || data[index] == 0x30) {
109 // enter the set (skip tag + length)
110 index += 2;
111 // check for extended length
112 if ((data[index - 1] & 0x80) != 0) {
113 index += (data[index-1] & 0x7F);
114 }
115 }
116 // OID
117 else if (data[index] == 0x06) {
118 // is this a PACE OID?
119 if (data[index + 1] == 0x0A // length matches
120 && memcmp(data + index + 2,
121 oid_pace_start,
122 sizeof(oid_pace_start)) == 0 // content matches
123 && pace_info != NULL)
124 {
125 // first, clear the pace_info struct
126 memset(pace_info, 0, sizeof(pace_version_info_t));
127 memcpy(pace_info->oid, data + index + 2, sizeof(pace_info->oid));
128 // a PACE OID is followed by the version
129 index += data[index + 1] + 2;
130 if (data[index] == 02 && data[index + 1] == 01) {
131 pace_info->version = data[index + 2];
132 index += 3;
133 }
134 else {
135 return index;
136 }
137 // after that there might(!) be the parameter ID
138 if (data[index] == 02 && data[index + 1] == 01) {
139 pace_info->parameter_id = data[index + 2];
140 index += 3;
141 }
142 }
143 else {
144 // skip this OID
145 index += 2 + data[index + 1];
146 }
147 }
148 // if the length is 0, something is wrong
149 // TODO: This needs to be extended to support long tags
150 else if (data[index + 1] == 0) {
151 return index;
152 }
153 else {
154 // skip this part
155 // TODO: This needs to be extended to support long tags
156 // TODO: This needs to be extended to support unknown elements with
157 // a size > 0x7F
158 index += 2 + data[index + 1];
159 }
160 }
161
162 // TODO: We should check whether we reached the end in error, but for that
163 // we need a better parser (e.g. with states like IN_SET or IN_PACE_INFO)
164 return 0;
165 }
166
167 //-----------------------------------------------------------------------------
168 // Read the file EF.CardAccess and save it into a buffer (at most max_length bytes)
169 // Returns -1 on failure or the length of the data on success
170 // TODO: for the moment this sends only 1 APDU regardless of the requested length
171 //-----------------------------------------------------------------------------
172 int EPA_Read_CardAccess(uint8_t *buffer, size_t max_length)
173 {
174 // the response APDU of the card
175 // since the card doesn't always care for the expected length we send it,
176 // we reserve 262 bytes here just to be safe (256-byte APDU + SW + ISO frame)
177 uint8_t response_apdu[262];
178 int rapdu_length = 0;
179
180 // select the file EF.CardAccess
181 rapdu_length = iso14_apdu((uint8_t *)apdu_select_binary_cardaccess,
182 sizeof(apdu_select_binary_cardaccess),
183 response_apdu);
184 if (rapdu_length != 6
185 || response_apdu[rapdu_length - 4] != 0x90
186 || response_apdu[rapdu_length - 3] != 0x00)
187 {
188 Dbprintf("epa - no select cardaccess");
189 return -1;
190 }
191
192 // read the file
193 rapdu_length = iso14_apdu((uint8_t *)apdu_read_binary,
194 sizeof(apdu_read_binary),
195 response_apdu);
196 if (rapdu_length <= 6
197 || response_apdu[rapdu_length - 4] != 0x90
198 || response_apdu[rapdu_length - 3] != 0x00)
199 {
200 Dbprintf("epa - no read cardaccess");
201 return -1;
202 }
203
204 // copy the content into the buffer
205 // length of data available: apdu_length - 4 (ISO frame) - 2 (SW)
206 size_t to_copy = rapdu_length - 6;
207 to_copy = to_copy < max_length ? to_copy : max_length;
208 memcpy(buffer, response_apdu+2, to_copy);
209 return to_copy;
210 }
211
212 //-----------------------------------------------------------------------------
213 // Abort helper function for EPA_PACE_Collect_Nonce
214 // sets relevant data in ack, sends the response
215 //-----------------------------------------------------------------------------
216 static void EPA_PACE_Collect_Nonce_Abort(uint8_t step, int func_return)
217 {
218 // // step in which the failure occured
219 // ack->arg[0] = step;
220 // // last return code
221 // ack->arg[1] = func_return;
222
223 // power down the field
224 EPA_Finish();
225
226 // send the USB packet
227 cmd_send(CMD_ACK,step,func_return,0,0,0);
228 }
229
230 //-----------------------------------------------------------------------------
231 // Acquire one encrypted PACE nonce
232 //-----------------------------------------------------------------------------
233 void EPA_PACE_Collect_Nonce(UsbCommand *c)
234 {
235 /*
236 * ack layout:
237 * arg:
238 * 1. element
239 * step where the error occured or 0 if no error occured
240 * 2. element
241 * return code of the last executed function
242 * d:
243 * Encrypted nonce
244 */
245
246 // return value of a function
247 int func_return = 0;
248
249 // // initialize ack with 0s
250 // memset(ack->arg, 0, 12);
251 // memset(ack->d.asBytes, 0, 48);
252
253 // set up communication
254 func_return = EPA_Setup();
255 if (func_return != 0) {
256 EPA_PACE_Collect_Nonce_Abort(1, func_return);
257 return;
258 }
259
260 // read the CardAccess file
261 // this array will hold the CardAccess file
262 uint8_t card_access[256] = {0};
263 int card_access_length = EPA_Read_CardAccess(card_access, 256);
264 // the response has to be at least this big to hold the OID
265 if (card_access_length < 18) {
266 EPA_PACE_Collect_Nonce_Abort(2, card_access_length);
267 return;
268 }
269
270 // this will hold the PACE info of the card
271 pace_version_info_t pace_version_info;
272 // search for the PACE OID
273 func_return = EPA_Parse_CardAccess(card_access,
274 card_access_length,
275 &pace_version_info);
276 if (func_return != 0 || pace_version_info.version == 0) {
277 EPA_PACE_Collect_Nonce_Abort(3, func_return);
278 return;
279 }
280
281 // initiate the PACE protocol
282 // use the CAN for the password since that doesn't change
283 func_return = EPA_PACE_MSE_Set_AT(pace_version_info, 2);
284
285 // now get the nonce
286 uint8_t nonce[256] = {0};
287 uint8_t requested_size = (uint8_t)c->arg[0];
288 func_return = EPA_PACE_Get_Nonce(requested_size, nonce);
289 // check if the command succeeded
290 if (func_return < 0)
291 {
292 EPA_PACE_Collect_Nonce_Abort(4, func_return);
293 return;
294 }
295
296 // all done, return
297 EPA_Finish();
298
299 // save received information
300 // ack->arg[1] = func_return;
301 // memcpy(ack->d.asBytes, nonce, func_return);
302 cmd_send(CMD_ACK,0,func_return,0,nonce,func_return);
303 }
304
305 //-----------------------------------------------------------------------------
306 // Performs the "Get Nonce" step of the PACE protocol and saves the returned
307 // nonce. The caller is responsible for allocating enough memory to store the
308 // nonce. Note that the returned size might be less or than or greater than the
309 // requested size!
310 // Returns the actual size of the nonce on success or a less-than-zero error
311 // code on failure.
312 //-----------------------------------------------------------------------------
313 int EPA_PACE_Get_Nonce(uint8_t requested_length, uint8_t *nonce)
314 {
315 // build the APDU
316 uint8_t apdu[sizeof(apdu_general_authenticate_pace_get_nonce) + 1];
317 // copy the constant part
318 memcpy(apdu,
319 apdu_general_authenticate_pace_get_nonce,
320 sizeof(apdu_general_authenticate_pace_get_nonce));
321 // append Le (requested length + 2 due to tag/length taking 2 bytes) in RAPDU
322 apdu[sizeof(apdu_general_authenticate_pace_get_nonce)] = requested_length + 4;
323
324 // send it
325 uint8_t response_apdu[262];
326 int send_return = iso14_apdu(apdu,
327 sizeof(apdu),
328 response_apdu);
329 // check if the command succeeded
330 if (send_return < 6
331 || response_apdu[send_return - 4] != 0x90
332 || response_apdu[send_return - 3] != 0x00)
333 {
334 return -1;
335 }
336
337 // if there is no nonce in the RAPDU, return here
338 if (send_return < 10)
339 {
340 // no error
341 return 0;
342 }
343 // get the actual length of the nonce
344 uint8_t nonce_length = response_apdu[5];
345 if (nonce_length > send_return - 10)
346 {
347 nonce_length = send_return - 10;
348 }
349 // copy the nonce
350 memcpy(nonce, response_apdu + 6, nonce_length);
351
352 return nonce_length;
353 }
354
355 //-----------------------------------------------------------------------------
356 // Initializes the PACE protocol by performing the "MSE: Set AT" step
357 // Returns 0 on success or a non-zero error code on failure
358 //-----------------------------------------------------------------------------
359 int EPA_PACE_MSE_Set_AT(pace_version_info_t pace_version_info, uint8_t password)
360 {
361 // create the MSE: Set AT APDU
362 uint8_t apdu[23];
363 // the minimum length (will be increased as more data is added)
364 size_t apdu_length = 20;
365 // copy the constant part
366 memcpy(apdu,
367 apdu_mse_set_at_start,
368 sizeof(apdu_mse_set_at_start));
369 // type: OID
370 apdu[5] = 0x80;
371 // length of the OID
372 apdu[6] = sizeof(pace_version_info.oid);
373 // copy the OID
374 memcpy(apdu + 7,
375 pace_version_info.oid,
376 sizeof(pace_version_info.oid));
377 // type: password
378 apdu[17] = 0x83;
379 // length: 1
380 apdu[18] = 1;
381 // password
382 apdu[19] = password;
383 // if standardized domain parameters are used, copy the ID
384 if (pace_version_info.parameter_id != 0) {
385 apdu_length += 3;
386 // type: domain parameter
387 apdu[20] = 0x84;
388 // length: 1
389 apdu[21] = 1;
390 // copy the parameter ID
391 apdu[22] = pace_version_info.parameter_id;
392 }
393 // now set Lc to the actual length
394 apdu[4] = apdu_length - 5;
395 // send it
396 uint8_t response_apdu[6];
397 int send_return = iso14_apdu(apdu,
398 apdu_length,
399 response_apdu);
400 // check if the command succeeded
401 if (send_return != 6
402 || response_apdu[send_return - 4] != 0x90
403 || response_apdu[send_return - 3] != 0x00)
404 {
405 return 1;
406 }
407 return 0;
408 }
409
410 //-----------------------------------------------------------------------------
411 // Set up a communication channel (Card Select, PPS)
412 // Returns 0 on success or a non-zero error code on failure
413 //-----------------------------------------------------------------------------
414 int EPA_Setup()
415 {
416
417 int return_code = 0;
418 uint8_t uid[10];
419 uint8_t pps_response[3];
420 uint8_t pps_response_par[1];
421 iso14a_card_select_t card_select_info;
422
423 // power up the field
424 iso14443a_setup(FPGA_HF_ISO14443A_READER_MOD);
425
426 // select the card
427 return_code = iso14443a_select_card(uid, &card_select_info, NULL);
428 if (return_code != 1) {
429 Dbprintf("Epa: Can't select card");
430 return 1;
431 }
432
433 // send the PPS request
434 ReaderTransmit((uint8_t *)pps, sizeof(pps), NULL);
435 return_code = ReaderReceive(pps_response, pps_response_par);
436 if (return_code != 3 || pps_response[0] != 0xD0) {
437 return return_code == 0 ? 2 : return_code;
438 }
439
440 return 0;
441 }
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