Line data Source code
1 : /* openpgp-oids.c - OID helper for OpenPGP
2 : * Copyright (C) 2011 Free Software Foundation, Inc.
3 : * Copyright (C) 2013 Werner Koch
4 : *
5 : * This file is part of GnuPG.
6 : *
7 : * This file is free software; you can redistribute it and/or modify
8 : * it under the terms of either
9 : *
10 : * - the GNU Lesser General Public License as published by the Free
11 : * Software Foundation; either version 3 of the License, or (at
12 : * your option) any later version.
13 : *
14 : * or
15 : *
16 : * - the GNU General Public License as published by the Free
17 : * Software Foundation; either version 2 of the License, or (at
18 : * your option) any later version.
19 : *
20 : * or both in parallel, as here.
21 : *
22 : * This file is distributed in the hope that it will be useful,
23 : * but WITHOUT ANY WARRANTY; without even the implied warranty of
24 : * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
25 : * GNU General Public License for more details.
26 : *
27 : * You should have received a copy of the GNU General Public License
28 : * along with this program; if not, see <http://www.gnu.org/licenses/>.
29 : */
30 :
31 : #include <config.h>
32 : #include <stdlib.h>
33 : #include <errno.h>
34 : #include <ctype.h>
35 : #include <assert.h>
36 :
37 : #include "util.h"
38 :
39 :
40 : /* A table with all our supported OpenPGP curves. */
41 : static struct {
42 : const char *name; /* Standard name. */
43 : const char *oidstr; /* IETF formatted OID. */
44 : unsigned int nbits; /* Nominal bit length of the curve. */
45 : const char *alias; /* NULL or alternative name of the curve. */
46 : } oidtable[] = {
47 :
48 : { "Curve25519", "1.3.6.1.4.1.3029.1.5.1", 255, "cv25519" },
49 : { "Ed25519", "1.3.6.1.4.1.11591.15.1", 255, "ed25519" },
50 :
51 : { "NIST P-256", "1.2.840.10045.3.1.7", 256, "nistp256" },
52 : { "NIST P-384", "1.3.132.0.34", 384, "nistp384" },
53 : { "NIST P-521", "1.3.132.0.35", 521, "nistp521" },
54 :
55 : { "brainpoolP256r1", "1.3.36.3.3.2.8.1.1.7", 256 },
56 : { "brainpoolP384r1", "1.3.36.3.3.2.8.1.1.11", 384 },
57 : { "brainpoolP512r1", "1.3.36.3.3.2.8.1.1.13", 512 },
58 :
59 : { "secp256k1", "1.3.132.0.10", 256 },
60 :
61 : { NULL, NULL, 0}
62 : };
63 :
64 :
65 : /* The OID for Curve Ed25519 in OpenPGP format. */
66 : static const char oid_ed25519[] =
67 : { 0x09, 0x2b, 0x06, 0x01, 0x04, 0x01, 0xda, 0x47, 0x0f, 0x01 };
68 :
69 : /* The OID for Curve25519 in OpenPGP format. */
70 : static const char oid_crv25519[] =
71 : { 0x0a, 0x2b, 0x06, 0x01, 0x04, 0x01, 0x97, 0x55, 0x01, 0x05, 0x01 };
72 :
73 :
74 : /* Helper for openpgp_oid_from_str. */
75 : static size_t
76 90 : make_flagged_int (unsigned long value, char *buf, size_t buflen)
77 : {
78 90 : int more = 0;
79 : int shift;
80 :
81 : /* fixme: figure out the number of bits in an ulong and start with
82 : that value as shift (after making it a multiple of 7) a more
83 : straigtforward implementation is to do it in reverse order using
84 : a temporary buffer - saves a lot of compares */
85 450 : for (more=0, shift=28; shift > 0; shift -= 7)
86 : {
87 360 : if (more || value >= (1<<shift))
88 : {
89 15 : buf[buflen++] = 0x80 | (value >> shift);
90 15 : value -= (value >> shift) << shift;
91 15 : more = 1;
92 : }
93 : }
94 90 : buf[buflen++] = value;
95 90 : return buflen;
96 : }
97 :
98 :
99 : /* Convert the OID given in dotted decimal form in STRING to an DER
100 : * encoding and store it as an opaque value at R_MPI. The format of
101 : * the DER encoded is not a regular ASN.1 object but the modified
102 : * format as used by OpenPGP for the ECC curve description. On error
103 : * the function returns and error code an NULL is stored at R_BUG.
104 : * Note that scanning STRING stops at the first white space
105 : * character. */
106 : gpg_error_t
107 21 : openpgp_oid_from_str (const char *string, gcry_mpi_t *r_mpi)
108 : {
109 : unsigned char *buf;
110 : size_t buflen;
111 : unsigned long val1, val;
112 : const char *endp;
113 : int arcno;
114 :
115 21 : *r_mpi = NULL;
116 :
117 21 : if (!string || !*string)
118 1 : return gpg_error (GPG_ERR_INV_VALUE);
119 :
120 : /* We can safely assume that the encoded OID is shorter than the string. */
121 20 : buf = xtrymalloc (1 + strlen (string) + 2);
122 20 : if (!buf)
123 0 : return gpg_error_from_syserror ();
124 : /* Save the first byte for the length. */
125 20 : buflen = 1;
126 :
127 20 : val1 = 0; /* Avoid compiler warning. */
128 20 : arcno = 0;
129 : do {
130 128 : arcno++;
131 128 : val = strtoul (string, (char**)&endp, 10);
132 128 : if (!digitp (string) || !(*endp == '.' || !*endp))
133 : {
134 1 : xfree (buf);
135 1 : return gpg_error (GPG_ERR_INV_OID_STRING);
136 : }
137 127 : if (*endp == '.')
138 108 : string = endp+1;
139 :
140 127 : if (arcno == 1)
141 : {
142 19 : if (val > 2)
143 0 : break; /* Not allowed, error catched below. */
144 19 : val1 = val;
145 : }
146 108 : else if (arcno == 2)
147 : { /* Need to combine the first two arcs in one octet. */
148 18 : if (val1 < 2)
149 : {
150 18 : if (val > 39)
151 : {
152 0 : xfree (buf);
153 0 : return gpg_error (GPG_ERR_INV_OID_STRING);
154 : }
155 18 : buf[buflen++] = val1*40 + val;
156 : }
157 : else
158 : {
159 0 : val += 80;
160 0 : buflen = make_flagged_int (val, buf, buflen);
161 : }
162 : }
163 : else
164 : {
165 90 : buflen = make_flagged_int (val, buf, buflen);
166 : }
167 127 : } while (*endp == '.');
168 :
169 19 : if (arcno == 1 || buflen < 2 || buflen > 254 )
170 : { /* It is not possible to encode only the first arc. */
171 1 : xfree (buf);
172 1 : return gpg_error (GPG_ERR_INV_OID_STRING);
173 : }
174 :
175 18 : *buf = buflen - 1;
176 18 : *r_mpi = gcry_mpi_set_opaque (NULL, buf, buflen * 8);
177 18 : if (!*r_mpi)
178 : {
179 0 : xfree (buf);
180 0 : return gpg_error_from_syserror ();
181 : }
182 18 : return 0;
183 : }
184 :
185 :
186 : /* Return a malloced string represenation of the OID in the opaque MPI
187 : A. In case of an error NULL is returned and ERRNO is set. */
188 : char *
189 465 : openpgp_oid_to_str (gcry_mpi_t a)
190 : {
191 : const unsigned char *buf;
192 : size_t length;
193 : unsigned int lengthi;
194 : char *string, *p;
195 465 : int n = 0;
196 : unsigned long val, valmask;
197 :
198 465 : valmask = (unsigned long)0xfe << (8 * (sizeof (valmask) - 1));
199 :
200 465 : if (!a
201 465 : || !gcry_mpi_get_flag (a, GCRYMPI_FLAG_OPAQUE)
202 465 : || !(buf = gcry_mpi_get_opaque (a, &lengthi)))
203 : {
204 0 : gpg_err_set_errno (EINVAL);
205 0 : return NULL;
206 : }
207 :
208 465 : buf = gcry_mpi_get_opaque (a, &lengthi);
209 465 : length = (lengthi+7)/8;
210 :
211 : /* The first bytes gives the length; check consistency. */
212 465 : if (!length || buf[0] != length -1)
213 : {
214 0 : gpg_err_set_errno (EINVAL);
215 0 : return NULL;
216 : }
217 : /* Skip length byte. */
218 465 : length--;
219 465 : buf++;
220 :
221 : /* To calculate the length of the string we can safely assume an
222 : upper limit of 3 decimal characters per byte. Two extra bytes
223 : account for the special first octect */
224 465 : string = p = xtrymalloc (length*(1+3)+2+1);
225 465 : if (!string)
226 0 : return NULL;
227 465 : if (!length)
228 : {
229 0 : *p = 0;
230 0 : return string;
231 : }
232 :
233 465 : if (buf[0] < 40)
234 1 : p += sprintf (p, "0.%d", buf[n]);
235 464 : else if (buf[0] < 80)
236 462 : p += sprintf (p, "1.%d", buf[n]-40);
237 : else {
238 2 : val = buf[n] & 0x7f;
239 5 : while ( (buf[n]&0x80) && ++n < length )
240 : {
241 1 : if ( (val & valmask) )
242 0 : goto badoid; /* Overflow. */
243 1 : val <<= 7;
244 1 : val |= buf[n] & 0x7f;
245 : }
246 2 : if (val < 80)
247 2 : goto badoid;
248 0 : val -= 80;
249 0 : sprintf (p, "2.%lu", val);
250 0 : p += strlen (p);
251 : }
252 2156 : for (n++; n < length; n++)
253 : {
254 1693 : val = buf[n] & 0x7f;
255 4002 : while ( (buf[n]&0x80) && ++n < length )
256 : {
257 616 : if ( (val & valmask) )
258 0 : goto badoid; /* Overflow. */
259 616 : val <<= 7;
260 616 : val |= buf[n] & 0x7f;
261 : }
262 1693 : sprintf (p, ".%lu", val);
263 1693 : p += strlen (p);
264 : }
265 :
266 463 : *p = 0;
267 463 : return string;
268 :
269 : badoid:
270 : /* Return a special OID (gnu.gnupg.badoid) to indicate the error
271 : case. The OID is broken and thus we return one which can't do
272 : any harm. Formally this does not need to be a bad OID but an OID
273 : with an arc that can't be represented in a 32 bit word is more
274 : than likely corrupt. */
275 2 : xfree (string);
276 2 : return xtrystrdup ("1.3.6.1.4.1.11591.2.12242973");
277 : }
278 :
279 :
280 :
281 : /* Return true if A represents the OID for Ed25519. */
282 : int
283 124 : openpgp_oid_is_ed25519 (gcry_mpi_t a)
284 : {
285 : const unsigned char *buf;
286 : unsigned int nbits;
287 : size_t n;
288 :
289 124 : if (!a || !gcry_mpi_get_flag (a, GCRYMPI_FLAG_OPAQUE))
290 91 : return 0;
291 :
292 33 : buf = gcry_mpi_get_opaque (a, &nbits);
293 33 : n = (nbits+7)/8;
294 33 : return (n == DIM (oid_ed25519)
295 33 : && !memcmp (buf, oid_ed25519, DIM (oid_ed25519)));
296 : }
297 :
298 :
299 : int
300 138 : openpgp_oid_is_crv25519 (gcry_mpi_t a)
301 : {
302 : const unsigned char *buf;
303 : unsigned int nbits;
304 : size_t n;
305 :
306 138 : if (!a || !gcry_mpi_get_flag (a, GCRYMPI_FLAG_OPAQUE))
307 0 : return 0;
308 :
309 138 : buf = gcry_mpi_get_opaque (a, &nbits);
310 138 : n = (nbits+7)/8;
311 138 : return (n == DIM (oid_crv25519)
312 138 : && !memcmp (buf, oid_crv25519, DIM (oid_crv25519)));
313 : }
314 :
315 :
316 : /* Map the Libgcrypt ECC curve NAME to an OID. If R_NBITS is not NULL
317 : store the bit size of the curve there. Returns NULL for unknown
318 : curve names. */
319 : const char *
320 0 : openpgp_curve_to_oid (const char *name, unsigned int *r_nbits)
321 : {
322 : int i;
323 0 : unsigned int nbits = 0;
324 0 : const char *oidstr = NULL;
325 :
326 0 : if (name)
327 : {
328 0 : for (i=0; oidtable[i].name; i++)
329 0 : if (!strcmp (oidtable[i].name, name)
330 0 : || (oidtable[i].alias && !strcmp (oidtable[i].alias, name)))
331 : {
332 0 : oidstr = oidtable[i].oidstr;
333 0 : nbits = oidtable[i].nbits;
334 0 : break;
335 : }
336 0 : if (!oidtable[i].name)
337 : {
338 : /* If not found assume the input is already an OID and check
339 : whether we support it. */
340 0 : for (i=0; oidtable[i].name; i++)
341 0 : if (!strcmp (name, oidtable[i].oidstr))
342 : {
343 0 : oidstr = oidtable[i].oidstr;
344 0 : nbits = oidtable[i].nbits;
345 0 : break;
346 : }
347 : }
348 : }
349 :
350 0 : if (r_nbits)
351 0 : *r_nbits = nbits;
352 0 : return oidstr;
353 : }
354 :
355 :
356 : /* Map an OpenPGP OID to the Libgcrypt curve NAME. Returns NULL for
357 : unknown curve names. Unless CANON is set we prefer an alias name
358 : here which is more suitable for printing. */
359 : const char *
360 39 : openpgp_oid_to_curve (const char *oidstr, int canon)
361 : {
362 : int i;
363 :
364 39 : if (!oidstr)
365 0 : return NULL;
366 :
367 156 : for (i=0; oidtable[i].name; i++)
368 156 : if (!strcmp (oidtable[i].oidstr, oidstr))
369 39 : return !canon && oidtable[i].alias? oidtable[i].alias : oidtable[i].name;
370 :
371 0 : return NULL;
372 : }
373 :
374 :
375 : /* Return true if the curve with NAME is supported. */
376 : static int
377 9 : curve_supported_p (const char *name)
378 : {
379 9 : int result = 0;
380 : gcry_sexp_t keyparms;
381 :
382 9 : if (!gcry_sexp_build (&keyparms, NULL, "(public-key(ecc(curve %s)))", name))
383 : {
384 9 : result = !!gcry_pk_get_curve (keyparms, 0, NULL);
385 9 : gcry_sexp_release (keyparms);
386 : }
387 9 : return result;
388 : }
389 :
390 :
391 : /* Enumerate available and supported OpenPGP curves. The caller needs
392 : to set the integer variable at ITERP to zero and keep on calling
393 : this fucntion until NULL is returned. */
394 : const char *
395 10 : openpgp_enum_curves (int *iterp)
396 : {
397 10 : int idx = *iterp;
398 :
399 20 : while (idx >= 0 && idx < DIM (oidtable) && oidtable[idx].name)
400 : {
401 9 : if (curve_supported_p (oidtable[idx].name))
402 : {
403 9 : *iterp = idx + 1;
404 9 : return oidtable[idx].alias? oidtable[idx].alias : oidtable[idx].name;
405 : }
406 0 : idx++;
407 : }
408 1 : *iterp = idx;
409 1 : return NULL;
410 : }
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