1 /*
2 * Public Key layer for writing key files and structures
3 *
4 * Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
5 * SPDX-License-Identifier: Apache-2.0
6 *
7 * Licensed under the Apache License, Version 2.0 (the "License"); you may
8 * not use this file except in compliance with the License.
9 * You may obtain a copy of the License at
10 *
11 * http://www.apache.org/licenses/LICENSE-2.0
12 *
13 * Unless required by applicable law or agreed to in writing, software
14 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
15 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
16 * See the License for the specific language governing permissions and
17 * limitations under the License.
18 *
19 * This file is part of mbed TLS (https://tls.mbed.org)
20 */
21
22 #if !defined(MBEDTLS_CONFIG_FILE)
23 #include "mbedtls/config.h"
24 #else
25 #include MBEDTLS_CONFIG_FILE
26 #endif
27
28 #if defined(MBEDTLS_PK_WRITE_C)
29
30 #include "mbedtls/pk.h"
31 #include "mbedtls/asn1write.h"
32 #include "mbedtls/oid.h"
33
34 #include <string.h>
35
36 #if defined(MBEDTLS_RSA_C)
37 #include "mbedtls/rsa.h"
38 #endif
39 #if defined(MBEDTLS_ECP_C)
40 #include "mbedtls/ecp.h"
41 #endif
42 #if defined(MBEDTLS_ECDSA_C)
43 #include "mbedtls/ecdsa.h"
44 #endif
45 #if defined(MBEDTLS_PEM_WRITE_C)
46 #include "mbedtls/pem.h"
47 #endif
48
49 #if defined(MBEDTLS_PLATFORM_C)
50 #include "mbedtls/platform.h"
51 #else
52 #include <stdlib.h>
53 #define mbedtls_calloc calloc
54 #define mbedtls_free free
55 #endif
56
57 #if defined(MBEDTLS_RSA_C)
58 /*
59 * RSAPublicKey ::= SEQUENCE {
60 * modulus INTEGER, -- n
61 * publicExponent INTEGER -- e
62 * }
63 */
pk_write_rsa_pubkey(unsigned char ** p,unsigned char * start,mbedtls_rsa_context * rsa)64 static int pk_write_rsa_pubkey( unsigned char **p, unsigned char *start,
65 mbedtls_rsa_context *rsa )
66 {
67 int ret;
68 size_t len = 0;
69
70 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_mpi( p, start, &rsa->E ) );
71 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_mpi( p, start, &rsa->N ) );
72
73 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, len ) );
74 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start, MBEDTLS_ASN1_CONSTRUCTED |
75 MBEDTLS_ASN1_SEQUENCE ) );
76
77 return( (int) len );
78 }
79 #endif /* MBEDTLS_RSA_C */
80
81 #if defined(MBEDTLS_ECP_C)
82 /*
83 * EC public key is an EC point
84 */
pk_write_ec_pubkey(unsigned char ** p,unsigned char * start,mbedtls_ecp_keypair * ec)85 static int pk_write_ec_pubkey( unsigned char **p, unsigned char *start,
86 mbedtls_ecp_keypair *ec )
87 {
88 int ret;
89 size_t len = 0;
90 unsigned char buf[MBEDTLS_ECP_MAX_PT_LEN];
91
92 if( ( ret = mbedtls_ecp_point_write_binary( &ec->grp, &ec->Q,
93 MBEDTLS_ECP_PF_UNCOMPRESSED,
94 &len, buf, sizeof( buf ) ) ) != 0 )
95 {
96 return( ret );
97 }
98
99 if( *p < start || (size_t)( *p - start ) < len )
100 return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
101
102 *p -= len;
103 memcpy( *p, buf, len );
104
105 return( (int) len );
106 }
107
108 /*
109 * ECParameters ::= CHOICE {
110 * namedCurve OBJECT IDENTIFIER
111 * }
112 */
pk_write_ec_param(unsigned char ** p,unsigned char * start,mbedtls_ecp_keypair * ec)113 static int pk_write_ec_param( unsigned char **p, unsigned char *start,
114 mbedtls_ecp_keypair *ec )
115 {
116 int ret;
117 size_t len = 0;
118 const char *oid;
119 size_t oid_len;
120
121 if( ( ret = mbedtls_oid_get_oid_by_ec_grp( ec->grp.id, &oid, &oid_len ) ) != 0 )
122 return( ret );
123
124 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_oid( p, start, oid, oid_len ) );
125
126 return( (int) len );
127 }
128 #endif /* MBEDTLS_ECP_C */
129
mbedtls_pk_write_pubkey(unsigned char ** p,unsigned char * start,const mbedtls_pk_context * key)130 int mbedtls_pk_write_pubkey( unsigned char **p, unsigned char *start,
131 const mbedtls_pk_context *key )
132 {
133 int ret;
134 size_t len = 0;
135
136 #if defined(MBEDTLS_RSA_C)
137 if( mbedtls_pk_get_type( key ) == MBEDTLS_PK_RSA )
138 MBEDTLS_ASN1_CHK_ADD( len, pk_write_rsa_pubkey( p, start, mbedtls_pk_rsa( *key ) ) );
139 else
140 #endif
141 #if defined(MBEDTLS_ECP_C)
142 if( mbedtls_pk_get_type( key ) == MBEDTLS_PK_ECKEY )
143 MBEDTLS_ASN1_CHK_ADD( len, pk_write_ec_pubkey( p, start, mbedtls_pk_ec( *key ) ) );
144 else
145 #endif
146 return( MBEDTLS_ERR_PK_FEATURE_UNAVAILABLE );
147
148 return( (int) len );
149 }
150
mbedtls_pk_write_pubkey_der(mbedtls_pk_context * key,unsigned char * buf,size_t size)151 int mbedtls_pk_write_pubkey_der( mbedtls_pk_context *key, unsigned char *buf, size_t size )
152 {
153 int ret;
154 unsigned char *c;
155 size_t len = 0, par_len = 0, oid_len;
156 const char *oid;
157
158 c = buf + size;
159
160 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_pk_write_pubkey( &c, buf, key ) );
161
162 if( c - buf < 1 )
163 return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
164
165 /*
166 * SubjectPublicKeyInfo ::= SEQUENCE {
167 * algorithm AlgorithmIdentifier,
168 * subjectPublicKey BIT STRING }
169 */
170 *--c = 0;
171 len += 1;
172
173 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( &c, buf, len ) );
174 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( &c, buf, MBEDTLS_ASN1_BIT_STRING ) );
175
176 if( ( ret = mbedtls_oid_get_oid_by_pk_alg( mbedtls_pk_get_type( key ),
177 &oid, &oid_len ) ) != 0 )
178 {
179 return( ret );
180 }
181
182 #if defined(MBEDTLS_ECP_C)
183 if( mbedtls_pk_get_type( key ) == MBEDTLS_PK_ECKEY )
184 {
185 MBEDTLS_ASN1_CHK_ADD( par_len, pk_write_ec_param( &c, buf, mbedtls_pk_ec( *key ) ) );
186 }
187 #endif
188
189 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_algorithm_identifier( &c, buf, oid, oid_len,
190 par_len ) );
191
192 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( &c, buf, len ) );
193 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( &c, buf, MBEDTLS_ASN1_CONSTRUCTED |
194 MBEDTLS_ASN1_SEQUENCE ) );
195
196 return( (int) len );
197 }
198
mbedtls_pk_write_key_der(mbedtls_pk_context * key,unsigned char * buf,size_t size)199 int mbedtls_pk_write_key_der( mbedtls_pk_context *key, unsigned char *buf, size_t size )
200 {
201 int ret;
202 unsigned char *c = buf + size;
203 size_t len = 0;
204
205 #if defined(MBEDTLS_RSA_C)
206 if( mbedtls_pk_get_type( key ) == MBEDTLS_PK_RSA )
207 {
208 mbedtls_rsa_context *rsa = mbedtls_pk_rsa( *key );
209
210 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_mpi( &c, buf, &rsa->QP ) );
211 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_mpi( &c, buf, &rsa->DQ ) );
212 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_mpi( &c, buf, &rsa->DP ) );
213 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_mpi( &c, buf, &rsa->Q ) );
214 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_mpi( &c, buf, &rsa->P ) );
215 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_mpi( &c, buf, &rsa->D ) );
216 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_mpi( &c, buf, &rsa->E ) );
217 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_mpi( &c, buf, &rsa->N ) );
218 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_int( &c, buf, 0 ) );
219
220 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( &c, buf, len ) );
221 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( &c, buf, MBEDTLS_ASN1_CONSTRUCTED |
222 MBEDTLS_ASN1_SEQUENCE ) );
223 }
224 else
225 #endif /* MBEDTLS_RSA_C */
226 #if defined(MBEDTLS_ECP_C)
227 if( mbedtls_pk_get_type( key ) == MBEDTLS_PK_ECKEY )
228 {
229 mbedtls_ecp_keypair *ec = mbedtls_pk_ec( *key );
230 size_t pub_len = 0, par_len = 0;
231
232 /*
233 * RFC 5915, or SEC1 Appendix C.4
234 *
235 * ECPrivateKey ::= SEQUENCE {
236 * version INTEGER { ecPrivkeyVer1(1) } (ecPrivkeyVer1),
237 * privateKey OCTET STRING,
238 * parameters [0] ECParameters {{ NamedCurve }} OPTIONAL,
239 * publicKey [1] BIT STRING OPTIONAL
240 * }
241 */
242
243 /* publicKey */
244 MBEDTLS_ASN1_CHK_ADD( pub_len, pk_write_ec_pubkey( &c, buf, ec ) );
245
246 if( c - buf < 1 )
247 return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
248 *--c = 0;
249 pub_len += 1;
250
251 MBEDTLS_ASN1_CHK_ADD( pub_len, mbedtls_asn1_write_len( &c, buf, pub_len ) );
252 MBEDTLS_ASN1_CHK_ADD( pub_len, mbedtls_asn1_write_tag( &c, buf, MBEDTLS_ASN1_BIT_STRING ) );
253
254 MBEDTLS_ASN1_CHK_ADD( pub_len, mbedtls_asn1_write_len( &c, buf, pub_len ) );
255 MBEDTLS_ASN1_CHK_ADD( pub_len, mbedtls_asn1_write_tag( &c, buf,
256 MBEDTLS_ASN1_CONTEXT_SPECIFIC | MBEDTLS_ASN1_CONSTRUCTED | 1 ) );
257 len += pub_len;
258
259 /* parameters */
260 MBEDTLS_ASN1_CHK_ADD( par_len, pk_write_ec_param( &c, buf, ec ) );
261
262 MBEDTLS_ASN1_CHK_ADD( par_len, mbedtls_asn1_write_len( &c, buf, par_len ) );
263 MBEDTLS_ASN1_CHK_ADD( par_len, mbedtls_asn1_write_tag( &c, buf,
264 MBEDTLS_ASN1_CONTEXT_SPECIFIC | MBEDTLS_ASN1_CONSTRUCTED | 0 ) );
265 len += par_len;
266
267 /* privateKey: write as MPI then fix tag */
268 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_mpi( &c, buf, &ec->d ) );
269 *c = MBEDTLS_ASN1_OCTET_STRING;
270
271 /* version */
272 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_int( &c, buf, 1 ) );
273
274 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( &c, buf, len ) );
275 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( &c, buf, MBEDTLS_ASN1_CONSTRUCTED |
276 MBEDTLS_ASN1_SEQUENCE ) );
277 }
278 else
279 #endif /* MBEDTLS_ECP_C */
280 return( MBEDTLS_ERR_PK_FEATURE_UNAVAILABLE );
281
282 return( (int) len );
283 }
284
285 #if defined(MBEDTLS_PEM_WRITE_C)
286
287 #define PEM_BEGIN_PUBLIC_KEY "-----BEGIN PUBLIC KEY-----\n"
288 #define PEM_END_PUBLIC_KEY "-----END PUBLIC KEY-----\n"
289
290 #define PEM_BEGIN_PRIVATE_KEY_RSA "-----BEGIN RSA PRIVATE KEY-----\n"
291 #define PEM_END_PRIVATE_KEY_RSA "-----END RSA PRIVATE KEY-----\n"
292 #define PEM_BEGIN_PRIVATE_KEY_EC "-----BEGIN EC PRIVATE KEY-----\n"
293 #define PEM_END_PRIVATE_KEY_EC "-----END EC PRIVATE KEY-----\n"
294
295 /*
296 * Max sizes of key per types. Shown as tag + len (+ content).
297 */
298
299 #if defined(MBEDTLS_RSA_C)
300 /*
301 * RSA public keys:
302 * SubjectPublicKeyInfo ::= SEQUENCE { 1 + 3
303 * algorithm AlgorithmIdentifier, 1 + 1 (sequence)
304 * + 1 + 1 + 9 (rsa oid)
305 * + 1 + 1 (params null)
306 * subjectPublicKey BIT STRING } 1 + 3 + (1 + below)
307 * RSAPublicKey ::= SEQUENCE { 1 + 3
308 * modulus INTEGER, -- n 1 + 3 + MPI_MAX + 1
309 * publicExponent INTEGER -- e 1 + 3 + MPI_MAX + 1
310 * }
311 */
312 #define RSA_PUB_DER_MAX_BYTES 38 + 2 * MBEDTLS_MPI_MAX_SIZE
313
314 /*
315 * RSA private keys:
316 * RSAPrivateKey ::= SEQUENCE { 1 + 3
317 * version Version, 1 + 1 + 1
318 * modulus INTEGER, 1 + 3 + MPI_MAX + 1
319 * publicExponent INTEGER, 1 + 3 + MPI_MAX + 1
320 * privateExponent INTEGER, 1 + 3 + MPI_MAX + 1
321 * prime1 INTEGER, 1 + 3 + MPI_MAX / 2 + 1
322 * prime2 INTEGER, 1 + 3 + MPI_MAX / 2 + 1
323 * exponent1 INTEGER, 1 + 3 + MPI_MAX / 2 + 1
324 * exponent2 INTEGER, 1 + 3 + MPI_MAX / 2 + 1
325 * coefficient INTEGER, 1 + 3 + MPI_MAX / 2 + 1
326 * otherPrimeInfos OtherPrimeInfos OPTIONAL 0 (not supported)
327 * }
328 */
329 #define MPI_MAX_SIZE_2 MBEDTLS_MPI_MAX_SIZE / 2 + \
330 MBEDTLS_MPI_MAX_SIZE % 2
331 #define RSA_PRV_DER_MAX_BYTES 47 + 3 * MBEDTLS_MPI_MAX_SIZE \
332 + 5 * MPI_MAX_SIZE_2
333
334 #else /* MBEDTLS_RSA_C */
335
336 #define RSA_PUB_DER_MAX_BYTES 0
337 #define RSA_PRV_DER_MAX_BYTES 0
338
339 #endif /* MBEDTLS_RSA_C */
340
341 #if defined(MBEDTLS_ECP_C)
342 /*
343 * EC public keys:
344 * SubjectPublicKeyInfo ::= SEQUENCE { 1 + 2
345 * algorithm AlgorithmIdentifier, 1 + 1 (sequence)
346 * + 1 + 1 + 7 (ec oid)
347 * + 1 + 1 + 9 (namedCurve oid)
348 * subjectPublicKey BIT STRING 1 + 2 + 1 [1]
349 * + 1 (point format) [1]
350 * + 2 * ECP_MAX (coords) [1]
351 * }
352 */
353 #define ECP_PUB_DER_MAX_BYTES 30 + 2 * MBEDTLS_ECP_MAX_BYTES
354
355 /*
356 * EC private keys:
357 * ECPrivateKey ::= SEQUENCE { 1 + 2
358 * version INTEGER , 1 + 1 + 1
359 * privateKey OCTET STRING, 1 + 1 + ECP_MAX
360 * parameters [0] ECParameters OPTIONAL, 1 + 1 + (1 + 1 + 9)
361 * publicKey [1] BIT STRING OPTIONAL 1 + 2 + [1] above
362 * }
363 */
364 #define ECP_PRV_DER_MAX_BYTES 29 + 3 * MBEDTLS_ECP_MAX_BYTES
365
366 #else /* MBEDTLS_ECP_C */
367
368 #define ECP_PUB_DER_MAX_BYTES 0
369 #define ECP_PRV_DER_MAX_BYTES 0
370
371 #endif /* MBEDTLS_ECP_C */
372
373 #define PUB_DER_MAX_BYTES RSA_PUB_DER_MAX_BYTES > ECP_PUB_DER_MAX_BYTES ? \
374 RSA_PUB_DER_MAX_BYTES : ECP_PUB_DER_MAX_BYTES
375 #define PRV_DER_MAX_BYTES RSA_PRV_DER_MAX_BYTES > ECP_PRV_DER_MAX_BYTES ? \
376 RSA_PRV_DER_MAX_BYTES : ECP_PRV_DER_MAX_BYTES
377
mbedtls_pk_write_pubkey_pem(mbedtls_pk_context * key,unsigned char * buf,size_t size)378 int mbedtls_pk_write_pubkey_pem( mbedtls_pk_context *key, unsigned char *buf, size_t size )
379 {
380 int ret;
381 unsigned char output_buf[PUB_DER_MAX_BYTES];
382 size_t olen = 0;
383
384 if( ( ret = mbedtls_pk_write_pubkey_der( key, output_buf,
385 sizeof(output_buf) ) ) < 0 )
386 {
387 return( ret );
388 }
389
390 if( ( ret = mbedtls_pem_write_buffer( PEM_BEGIN_PUBLIC_KEY, PEM_END_PUBLIC_KEY,
391 output_buf + sizeof(output_buf) - ret,
392 ret, buf, size, &olen ) ) != 0 )
393 {
394 return( ret );
395 }
396
397 return( 0 );
398 }
399
mbedtls_pk_write_key_pem(mbedtls_pk_context * key,unsigned char * buf,size_t size)400 int mbedtls_pk_write_key_pem( mbedtls_pk_context *key, unsigned char *buf, size_t size )
401 {
402 int ret;
403 unsigned char output_buf[PRV_DER_MAX_BYTES];
404 const char *begin, *end;
405 size_t olen = 0;
406
407 if( ( ret = mbedtls_pk_write_key_der( key, output_buf, sizeof(output_buf) ) ) < 0 )
408 return( ret );
409
410 #if defined(MBEDTLS_RSA_C)
411 if( mbedtls_pk_get_type( key ) == MBEDTLS_PK_RSA )
412 {
413 begin = PEM_BEGIN_PRIVATE_KEY_RSA;
414 end = PEM_END_PRIVATE_KEY_RSA;
415 }
416 else
417 #endif
418 #if defined(MBEDTLS_ECP_C)
419 if( mbedtls_pk_get_type( key ) == MBEDTLS_PK_ECKEY )
420 {
421 begin = PEM_BEGIN_PRIVATE_KEY_EC;
422 end = PEM_END_PRIVATE_KEY_EC;
423 }
424 else
425 #endif
426 return( MBEDTLS_ERR_PK_FEATURE_UNAVAILABLE );
427
428 if( ( ret = mbedtls_pem_write_buffer( begin, end,
429 output_buf + sizeof(output_buf) - ret,
430 ret, buf, size, &olen ) ) != 0 )
431 {
432 return( ret );
433 }
434
435 return( 0 );
436 }
437 #endif /* MBEDTLS_PEM_WRITE_C */
438
439 #endif /* MBEDTLS_PK_WRITE_C */
440
