blob_get_name_by_id(): Treat id of dummy row as invalid.
[paraslash.git] / gcrypt.c
1 /*
2 * Copyright (C) 2011 Andre Noll <maan@tuebingen.mpg.de>
3 *
4 * Licensed under the GPL v2. For licencing details see COPYING.
5 */
6
7 /** \file gcrypt.c Libgrcypt-based encryption/decryption routines. */
8
9 #include <regex.h>
10 #include <gcrypt.h>
11
12 #include "para.h"
13 #include "error.h"
14 #include "string.h"
15 #include "crypt.h"
16 #include "crypt_backend.h"
17 #include "fd.h"
18
19 //#define GCRYPT_DEBUG 1
20
21 static bool libgcrypt_has_oaep;
22 static const char *rsa_decrypt_sexp;
23
24 #ifdef GCRYPT_DEBUG
25 static void dump_buffer(const char *msg, unsigned char *buf, int len)
26 {
27 int i;
28
29 fprintf(stderr, "%s (%d bytes): ", msg, len);
30 for (i = 0; i < len; i++)
31 fprintf(stderr, "%02x ", buf[i]);
32 fprintf(stderr, "\n");
33 }
34 #else
35 /** Empty. Define GCRYPT_DEBUG to dump buffers. */
36 #define dump_buffer(a, b, c)
37 #endif
38
39 void hash_function(const char *data, unsigned long len, unsigned char *hash)
40 {
41 gcry_error_t gret;
42 gcry_md_hd_t handle;
43 unsigned char *md;
44
45 gret = gcry_md_open(&handle, GCRY_MD_SHA1, 0);
46 assert(gret == 0);
47 gcry_md_write(handle, data, (size_t)len);
48 gcry_md_final(handle);
49 md = gcry_md_read(handle, GCRY_MD_SHA1);
50 assert(md);
51 memcpy(hash, md, HASH_SIZE);
52 gcry_md_close(handle);
53 }
54
55 void get_random_bytes_or_die(unsigned char *buf, int num)
56 {
57 gcry_randomize(buf, (size_t)num, GCRY_STRONG_RANDOM);
58 }
59
60 /*
61 * This is called at the beginning of every program that uses libgcrypt. We
62 * don't have to initialize any random seed here, but we must initialize the
63 * gcrypt library. This task is performed by gcry_check_version() which can
64 * also check that the gcrypt library version is at least the minimal required
65 * version. This function also tells us whether we have to use our own OAEP
66 * padding code.
67 */
68 void init_random_seed_or_die(void)
69 {
70 const char *ver, *req_ver;
71
72 ver = gcry_check_version(NULL);
73 req_ver = "1.4.0";
74 if (!gcry_check_version(req_ver)) {
75 PARA_EMERG_LOG("fatal: need at least libgcrypt-%s, have: %s\n",
76 req_ver, ver);
77 exit(EXIT_FAILURE);
78 }
79 req_ver = "1.5.0";
80 if (gcry_check_version(req_ver)) {
81 libgcrypt_has_oaep = true;
82 rsa_decrypt_sexp = "(enc-val(flags oaep)(rsa(a %m)))";
83 } else {
84 libgcrypt_has_oaep = false;
85 rsa_decrypt_sexp = "(enc-val(rsa(a %m)))";
86 }
87 }
88
89 /** S-expression for the public part of an RSA key. */
90 #define RSA_PUBKEY_SEXP "(public-key (rsa (n %m) (e %m)))"
91 /** S-expression for a private RSA key. */
92 #define RSA_PRIVKEY_SEXP "(private-key (rsa (n %m) (e %m) (d %m) (p %m) (q %m) (u %m)))"
93
94 /* rfc 3447, appendix B.2 */
95 static void mgf1(unsigned char *seed, size_t seed_len, unsigned result_len,
96 unsigned char *result)
97 {
98 gcry_error_t gret;
99 gcry_md_hd_t handle;
100 size_t n;
101 unsigned char *md;
102 unsigned char octet_string[4], *rp = result, *end = rp + result_len;
103
104 assert(result_len / HASH_SIZE < 1ULL << 31);
105 gret = gcry_md_open(&handle, GCRY_MD_SHA1, 0);
106 assert(gret == 0);
107 for (n = 0; rp < end; n++) {
108 gcry_md_write(handle, seed, seed_len);
109 octet_string[0] = (unsigned char)((n >> 24) & 255);
110 octet_string[1] = (unsigned char)((n >> 16) & 255);
111 octet_string[2] = (unsigned char)((n >> 8)) & 255;
112 octet_string[3] = (unsigned char)(n & 255);
113 gcry_md_write(handle, octet_string, 4);
114 gcry_md_final(handle);
115 md = gcry_md_read(handle, GCRY_MD_SHA1);
116 memcpy(rp, md, PARA_MIN(HASH_SIZE, (int)(end - rp)));
117 rp += HASH_SIZE;
118 gcry_md_reset(handle);
119 }
120 gcry_md_close(handle);
121 }
122
123 /** The sha1 hash of an empty file. */
124 static const unsigned char empty_hash[HASH_SIZE] =
125 "\xda" "\x39" "\xa3" "\xee" "\x5e"
126 "\x6b" "\x4b" "\x0d" "\x32" "\x55"
127 "\xbf" "\xef" "\x95" "\x60" "\x18"
128 "\x90" "\xaf" "\xd8" "\x07" "\x09";
129
130 /* rfc3447, section 7.1.1 */
131 static void pad_oaep(unsigned char *in, size_t in_len, unsigned char *out,
132 size_t out_len)
133 {
134 size_t ps_len = out_len - in_len - 2 * HASH_SIZE - 2;
135 size_t n, mask_len = out_len - HASH_SIZE - 1;
136 unsigned char *seed = out + 1, *db = seed + HASH_SIZE,
137 *ps = db + HASH_SIZE, *one = ps + ps_len;
138 unsigned char *db_mask, seed_mask[HASH_SIZE];
139
140 assert(in_len <= out_len - 2 - 2 * HASH_SIZE);
141 assert(out_len > 2 * HASH_SIZE + 2);
142 PARA_DEBUG_LOG("padding %zu byte input -> %zu byte output\n",
143 in_len, out_len);
144 dump_buffer("unpadded buffer", in, in_len);
145
146 out[0] = '\0';
147 get_random_bytes_or_die(seed, HASH_SIZE);
148 memcpy(db, empty_hash, HASH_SIZE);
149 memset(ps, 0, ps_len);
150 *one = 0x01;
151 memcpy(one + 1, in, in_len);
152 db_mask = para_malloc(mask_len);
153 mgf1(seed, HASH_SIZE, mask_len, db_mask);
154 for (n = 0; n < mask_len; n++)
155 db[n] ^= db_mask[n];
156 mgf1(db, mask_len, HASH_SIZE, seed_mask);
157 for (n = 0; n < HASH_SIZE; n++)
158 seed[n] ^= seed_mask[n];
159 free(db_mask);
160 dump_buffer("padded buffer", out, out_len);
161 }
162
163 /* rfc 3447, section 7.1.2 */
164 static int unpad_oaep(unsigned char *in, size_t in_len, unsigned char *out,
165 size_t *out_len)
166 {
167 unsigned char *masked_seed = in + 1;
168 unsigned char *db = in + 1 + HASH_SIZE;
169 unsigned char seed[HASH_SIZE], seed_mask[HASH_SIZE];
170 unsigned char *db_mask, *p;
171 size_t n, mask_len = in_len - HASH_SIZE - 1;
172
173 mgf1(db, mask_len, HASH_SIZE, seed_mask);
174 for (n = 0; n < HASH_SIZE; n++)
175 seed[n] = masked_seed[n] ^ seed_mask[n];
176 db_mask = para_malloc(mask_len);
177 mgf1(seed, HASH_SIZE, mask_len, db_mask);
178 for (n = 0; n < mask_len; n++)
179 db[n] ^= db_mask[n];
180 free(db_mask);
181 if (memcmp(db, empty_hash, HASH_SIZE))
182 return -E_OEAP;
183 for (p = db + HASH_SIZE; p < in + in_len - 1; p++)
184 if (*p != '\0')
185 break;
186 if (p >= in + in_len - 1)
187 return -E_OEAP;
188 p++;
189 *out_len = in + in_len - p;
190 memcpy(out, p, *out_len);
191 return 1;
192 }
193
194 struct asymmetric_key {
195 gcry_sexp_t sexp;
196 int num_bytes;
197 };
198
199 static const char *gcrypt_strerror(gcry_error_t gret)
200 {
201 return gcry_strerror(gcry_err_code(gret));
202 }
203
204 static int decode_key(const char *key_file, const char *header_str,
205 const char *footer_str, unsigned char **result)
206 {
207 int ret, ret2, i, j;
208 void *map;
209 size_t map_size, key_size, blob_size;
210 unsigned char *blob = NULL;
211 char *begin, *footer, *key;
212
213 ret = mmap_full_file(key_file, O_RDONLY, &map, &map_size, NULL);
214 if (ret < 0)
215 return ret;
216 ret = -E_KEY_MARKER;
217 if (strncmp(map, header_str, strlen(header_str)))
218 goto unmap;
219 footer = strstr(map, footer_str);
220 ret = -E_KEY_MARKER;
221 if (!footer)
222 goto unmap;
223 begin = map + strlen(header_str);
224 /* skip whitespace at the beginning */
225 for (; begin < footer; begin++) {
226 if (para_isspace(*begin))
227 continue;
228 break;
229 }
230 ret = -E_KEY_MARKER;
231 if (begin >= footer)
232 goto unmap;
233
234 key_size = footer - begin;
235 key = para_malloc(key_size + 1);
236 for (i = 0, j = 0; begin + i < footer; i++) {
237 if (para_isspace(begin[i]))
238 continue;
239 key[j++] = begin[i];
240 }
241 key[j] = '\0';
242 blob_size = key_size * 2;
243 blob = para_malloc(blob_size);
244 ret = base64_decode(key, blob, blob_size);
245 free(key);
246 if (ret < 0)
247 goto free_unmap;
248 goto unmap;
249 free_unmap:
250 free(blob);
251 blob = NULL;
252 unmap:
253 ret2 = para_munmap(map, map_size);
254 if (ret >= 0 && ret2 < 0)
255 ret = ret2;
256 if (ret < 0) {
257 free(blob);
258 blob = NULL;
259 }
260 *result = blob;
261 return ret;
262 }
263
264 /** ASN Types and their code. */
265 enum asn1_types {
266 /** The next object is an integer. */
267 ASN1_TYPE_INTEGER = 0x2,
268 /** Bit string object. */
269 ASN1_TYPE_BIT_STRING = 0x03,
270 /** Keys start with one big type sequence. */
271 ASN1_TYPE_SEQUENCE = 0x30,
272 };
273
274 /* bit 6 has value 0 */
275 static inline bool is_primitive(unsigned char c)
276 {
277 return (c & (1<<6)) == 0;
278 }
279
280 static inline bool is_primitive_integer(unsigned char c)
281 {
282 if (!is_primitive(c))
283 return false;
284 return (c & 0x1f) == ASN1_TYPE_INTEGER;
285 }
286
287 /* Bit 8 is zero (and bits 7-1 give the length) */
288 static inline bool is_short_form(unsigned char c)
289 {
290 return (c & 0x80) == 0;
291 }
292
293 static inline int get_short_form_length(unsigned char c)
294 {
295 return c & 0x7f;
296 }
297
298 static inline int get_long_form_num_length_bytes(unsigned char c)
299 {
300 return c & 0x7f;
301 }
302
303 static int find_pubkey_bignum_offset(const unsigned char *data, int len)
304 {
305 const unsigned char *p = data, *end = data + len;
306
307 /* the whole thing starts with one sequence */
308 if (*p != ASN1_TYPE_SEQUENCE)
309 return -E_ASN1_PARSE;
310 p++;
311 if (p >= end)
312 return -E_ASN1_PARSE;
313 if (is_short_form(*p))
314 p++;
315 else
316 p += 1 + get_long_form_num_length_bytes(*p);
317 if (p >= end)
318 return -E_ASN1_PARSE;
319 /* another sequence containing the object id, skip it */
320 if (*p != ASN1_TYPE_SEQUENCE)
321 return -E_ASN1_PARSE;
322 p++;
323 if (p >= end)
324 return -E_ASN1_PARSE;
325 if (!is_short_form(*p))
326 return -E_ASN1_PARSE;
327 p += 1 + get_short_form_length(*p);
328 if (p >= end)
329 return -E_ASN1_PARSE;
330 /* all numbers are wrapped in a bit string object that follows */
331 if (*p != ASN1_TYPE_BIT_STRING)
332 return -E_ASN1_PARSE;
333 p++;
334 if (p >= end)
335 return -E_ASN1_PARSE;
336 if (is_short_form(*p))
337 p++;
338 else
339 p += 1 + get_long_form_num_length_bytes(*p);
340 p++; /* skip number of unused bits in the bit string */
341 if (p >= end)
342 return -E_ASN1_PARSE;
343
344 /* next, we have a sequence of two integers (n and e) */
345 if (*p != ASN1_TYPE_SEQUENCE)
346 return -E_ASN1_PARSE;
347 p++;
348 if (p >= end)
349 return -E_ASN1_PARSE;
350 if (is_short_form(*p))
351 p++;
352 else
353 p += 1 + get_long_form_num_length_bytes(*p);
354 if (p >= end)
355 return -E_ASN1_PARSE;
356 if (*p != ASN1_TYPE_INTEGER)
357 return -E_ASN1_PARSE;
358 return p - data;
359 }
360
361 /*
362 * Returns: Number of bytes scanned. This may differ from the value returned via
363 * bn_bytes because the latter does not include the ASN.1 prefix and a leading
364 * zero is not considered as an additional byte for bn_bytes.
365 */
366 static int read_bignum(unsigned char *start, unsigned char *end, gcry_mpi_t *bn,
367 int *bn_bytes)
368 {
369 int i, bn_size;
370 gcry_error_t gret;
371 unsigned char *cp = start;
372
373 if (!is_primitive_integer(*cp))
374 return -E_BAD_PRIVATE_KEY;
375 cp++;
376 if (is_short_form(*cp)) {
377 bn_size = get_short_form_length(*cp);
378 cp++;
379 } else {
380 int num_bytes = get_long_form_num_length_bytes(*cp);
381 if (cp + num_bytes > end)
382 return -E_BAD_PRIVATE_KEY;
383 if (num_bytes > 4) /* nobody has such a large modulus */
384 return -E_BAD_PRIVATE_KEY;
385 cp++;
386 bn_size = 0;
387 for (i = 0; i < num_bytes; i++, cp++)
388 bn_size = (bn_size << 8) + *cp;
389 }
390 PARA_DEBUG_LOG("bn_size %d (0x%x)\n", bn_size, bn_size);
391 gret = gcry_mpi_scan(bn, GCRYMPI_FMT_STD, cp, bn_size, NULL);
392 if (gret) {
393 PARA_ERROR_LOG("%s while scanning n\n",
394 gcry_strerror(gcry_err_code(gret)));
395 return-E_MPI_SCAN;
396 }
397 /*
398 * Don't take the first leading zero into account for the size of the
399 * bignum.
400 */
401 if (*cp == '\0') {
402 cp++;
403 bn_size--;
404 }
405 if (bn_bytes)
406 *bn_bytes = bn_size;
407 cp += bn_size;
408 // unsigned char *buf;
409 // gcry_mpi_aprint(GCRYMPI_FMT_HEX, &buf, NULL, *bn);
410 // PARA_CRIT_LOG("bn: %s\n", buf);
411 return cp - start;
412 }
413
414 static int find_privkey_bignum_offset(const unsigned char *data, int len)
415 {
416 const unsigned char *p = data, *end = data + len;
417
418 /* like the public key, the whole thing is contained in a sequence */
419 if (*p != ASN1_TYPE_SEQUENCE)
420 return -E_ASN1_PARSE;
421 p++;
422 if (p >= end)
423 return -E_ASN1_PARSE;
424 if (is_short_form(*p))
425 p++;
426 else
427 p += 1 + get_long_form_num_length_bytes(*p);
428 if (p >= end)
429 return -E_ASN1_PARSE;
430
431 /* skip next integer */
432 if (*p != ASN1_TYPE_INTEGER)
433 return -E_ASN1_PARSE;
434 p++;
435 if (p >= end)
436 return -E_ASN1_PARSE;
437 if (is_short_form(*p))
438 p += 1 + get_short_form_length(*p);
439 else
440 p += 1 + get_long_form_num_length_bytes(*p);
441 if (p >= end)
442 return -E_ASN1_PARSE;
443 return p - data;
444 }
445
446 /** Private keys start with this header. */
447 #define PRIVATE_KEY_HEADER "-----BEGIN RSA PRIVATE KEY-----"
448 /** Private keys end with this footer. */
449 #define PRIVATE_KEY_FOOTER "-----END RSA PRIVATE KEY-----"
450
451 static int get_private_key(const char *key_file, struct asymmetric_key **result)
452 {
453 gcry_mpi_t n = NULL, e = NULL, d = NULL, p = NULL, q = NULL,
454 u = NULL;
455 unsigned char *blob, *cp, *end;
456 int blob_size, ret, n_size;
457 gcry_error_t gret;
458 size_t erroff;
459 gcry_sexp_t sexp;
460 struct asymmetric_key *key;
461
462 ret = decode_key(key_file, PRIVATE_KEY_HEADER, PRIVATE_KEY_FOOTER,
463 &blob);
464 if (ret < 0)
465 return ret;
466 blob_size = ret;
467 end = blob + blob_size;
468 ret = find_privkey_bignum_offset(blob, blob_size);
469 if (ret < 0)
470 goto free_blob;
471 PARA_INFO_LOG("reading RSA params at offset %d\n", ret);
472 cp = blob + ret;
473
474 ret = read_bignum(cp, end, &n, &n_size);
475 if (ret < 0)
476 goto free_blob;
477 cp += ret;
478
479 ret = read_bignum(cp, end, &e, NULL);
480 if (ret < 0)
481 goto release_n;
482 cp += ret;
483
484 ret = read_bignum(cp, end, &d, NULL);
485 if (ret < 0)
486 goto release_e;
487 cp += ret;
488
489 ret = read_bignum(cp, end, &p, NULL);
490 if (ret < 0)
491 goto release_d;
492 cp += ret;
493
494 ret = read_bignum(cp, end, &q, NULL);
495 if (ret < 0)
496 goto release_p;
497 cp += ret;
498 ret = read_bignum(cp, end, &u, NULL);
499 if (ret < 0)
500 goto release_q;
501 /*
502 * OpenSSL uses slightly different parameters than gcrypt. To use these
503 * parameters we need to swap the values of p and q and recompute u.
504 */
505 if (gcry_mpi_cmp(p, q) > 0) {
506 gcry_mpi_swap(p, q);
507 gcry_mpi_invm(u, p, q);
508 }
509 gret = gcry_sexp_build(&sexp, &erroff, RSA_PRIVKEY_SEXP,
510 n, e, d, p, q, u);
511
512 if (gret) {
513 PARA_ERROR_LOG("offset %zu: %s\n", erroff,
514 gcry_strerror(gcry_err_code(gret)));
515 ret = -E_SEXP_BUILD;
516 goto release_u;
517 }
518 key = para_malloc(sizeof(*key));
519 key->sexp = sexp;
520 *result = key;
521 ret = n_size * 8;
522 PARA_INFO_LOG("succesfully read %d bit private key\n", ret);
523 release_u:
524 gcry_mpi_release(u);
525 release_q:
526 gcry_mpi_release(q);
527 release_p:
528 gcry_mpi_release(p);
529 release_d:
530 gcry_mpi_release(d);
531 release_e:
532 gcry_mpi_release(e);
533 release_n:
534 gcry_mpi_release(n);
535 free_blob:
536 free(blob);
537 return ret;
538 }
539
540 /** Public keys start with this header. */
541 #define PUBLIC_KEY_HEADER "-----BEGIN PUBLIC KEY-----"
542 /** Public keys end with this footer. */
543 #define PUBLIC_KEY_FOOTER "-----END PUBLIC KEY-----"
544
545 static int get_asn_public_key(const char *key_file, struct asymmetric_key **result)
546 {
547 gcry_mpi_t n = NULL, e = NULL;
548 unsigned char *blob, *cp, *end;
549 int blob_size, ret, n_size;
550 gcry_error_t gret;
551 size_t erroff;
552 gcry_sexp_t sexp;
553 struct asymmetric_key *key;
554
555 ret = decode_key(key_file, PUBLIC_KEY_HEADER, PUBLIC_KEY_FOOTER,
556 &blob);
557 if (ret < 0)
558 return ret;
559 blob_size = ret;
560 end = blob + blob_size;
561 ret = find_pubkey_bignum_offset(blob, blob_size);
562 if (ret < 0)
563 goto free_blob;
564 PARA_DEBUG_LOG("decoding public RSA params at offset %d\n", ret);
565 cp = blob + ret;
566
567 ret = read_bignum(cp, end, &n, &n_size);
568 if (ret < 0)
569 goto free_blob;
570 cp += ret;
571
572 ret = read_bignum(cp, end, &e, NULL);
573 if (ret < 0)
574 goto release_n;
575
576 gret = gcry_sexp_build(&sexp, &erroff, RSA_PUBKEY_SEXP, n, e);
577 if (gret) {
578 PARA_ERROR_LOG("offset %zu: %s\n", erroff,
579 gcry_strerror(gcry_err_code(gret)));
580 ret = -E_SEXP_BUILD;
581 goto release_e;
582 }
583 key = para_malloc(sizeof(*key));
584 key->sexp = sexp;
585 key->num_bytes = n_size;
586 *result = key;
587 ret = n_size;
588 PARA_INFO_LOG("successfully read %u bit asn public key\n", n_size * 8);
589
590 release_e:
591 gcry_mpi_release(e);
592 release_n:
593 gcry_mpi_release(n);
594 free_blob:
595 free(blob);
596 return ret;
597 }
598
599 static int get_ssh_public_key(unsigned char *data, int size, gcry_sexp_t *result)
600 {
601 int ret;
602 gcry_error_t gret;
603 unsigned char *blob = NULL, *p, *end;
604 size_t nr_scanned, erroff, decoded_size;
605 gcry_mpi_t e = NULL, n = NULL;
606
607 PARA_DEBUG_LOG("decoding %d byte public rsa-ssh key\n", size);
608 if (size > INT_MAX / 4)
609 return -ERRNO_TO_PARA_ERROR(EOVERFLOW);
610 blob = para_malloc(2 * size);
611 ret = uudecode((char *)data, blob, 2 * size);
612 if (ret < 0)
613 goto free_blob;
614 decoded_size = ret;
615 end = blob + decoded_size;
616 dump_buffer("decoded key", blob, decoded_size);
617 ret = check_ssh_key_header(blob, decoded_size);
618 if (ret < 0)
619 goto free_blob;
620 p = blob + ret;
621 ret = -E_SSH_PARSE;
622 if (p >= end)
623 goto free_blob;
624 PARA_DEBUG_LOG("scanning modulus and public exponent\n");
625 gret = gcry_mpi_scan(&e, GCRYMPI_FMT_SSH, p, end - p, &nr_scanned);
626 if (gret) {
627 ret = -E_MPI_SCAN;
628 PARA_CRIT_LOG("%s\n", gcry_strerror(gcry_err_code(gret)));
629 goto free_blob;
630 }
631 PARA_DEBUG_LOG("scanned e (%zu bytes)\n", nr_scanned);
632 // gcry_mpi_aprint(GCRYMPI_FMT_HEX, &buf, NULL, rsa_e);
633 // PARA_CRIT_LOG("e: %s\n", buf);
634 p += nr_scanned;
635 if (p >= end)
636 goto release_e;
637 gret = gcry_mpi_scan(&n, GCRYMPI_FMT_SSH, p, end - p, &nr_scanned);
638 if (gret) {
639 ret = -E_MPI_SCAN;
640 PARA_ERROR_LOG("%s\n", gcry_strerror(gcry_err_code(gret)));
641 goto release_e;
642 }
643 PARA_DEBUG_LOG("scanned n (%zu bytes)\n", nr_scanned);
644 // gcry_mpi_aprint(GCRYMPI_FMT_HEX, &buf, NULL, rsa_n);
645 // PARA_CRIT_LOG("n: %s\n", buf);
646 gret = gcry_sexp_build(result, &erroff, RSA_PUBKEY_SEXP, n, e);
647 if (gret) {
648 PARA_ERROR_LOG("offset %zu: %s\n", erroff,
649 gcry_strerror(gcry_err_code(gret)));
650 ret = -E_SEXP_BUILD;
651 goto release_n;
652 }
653 ret = nr_scanned / 32 * 32;
654 PARA_INFO_LOG("successfully read %u bit ssh public key\n", ret * 8);
655 release_n:
656 gcry_mpi_release(n);
657 release_e:
658 gcry_mpi_release(e);
659 free_blob:
660 free(blob);
661 return ret;
662 }
663
664 int get_asymmetric_key(const char *key_file, int private,
665 struct asymmetric_key **result)
666 {
667 int ret, ret2;
668 void *map;
669 size_t map_size;
670 unsigned char *start, *end;
671 gcry_sexp_t sexp;
672 struct asymmetric_key *key;
673
674 if (private)
675 return get_private_key(key_file, result);
676 ret = mmap_full_file(key_file, O_RDONLY, &map, &map_size, NULL);
677 if (ret < 0)
678 return ret;
679 ret = is_ssh_rsa_key(map, map_size);
680 if (!ret) {
681 ret = para_munmap(map, map_size);
682 if (ret < 0)
683 return ret;
684 return get_asn_public_key(key_file, result);
685 }
686 start = map + ret;
687 end = map + map_size;
688 ret = -E_SSH_PARSE;
689 if (start >= end)
690 goto unmap;
691 ret = get_ssh_public_key(start, end - start, &sexp);
692 if (ret < 0)
693 goto unmap;
694 key = para_malloc(sizeof(*key));
695 key->num_bytes = ret;
696 key->sexp = sexp;
697 *result = key;
698 unmap:
699 ret2 = para_munmap(map, map_size);
700 if (ret >= 0 && ret2 < 0)
701 ret = ret2;
702 return ret;
703 }
704
705 void free_asymmetric_key(struct asymmetric_key *key)
706 {
707 if (!key)
708 return;
709 gcry_sexp_release(key->sexp);
710 free(key);
711 }
712
713 static int decode_rsa(gcry_sexp_t sexp, int key_size, unsigned char *outbuf,
714 size_t *nbytes)
715 {
716 int ret;
717 gcry_error_t gret;
718 unsigned char oaep_buf[512];
719 gcry_mpi_t out_mpi;
720
721 if (libgcrypt_has_oaep) {
722 const char *p = gcry_sexp_nth_data(sexp, 1, nbytes);
723
724 if (!p) {
725 PARA_ERROR_LOG("could not get data from list\n");
726 return -E_OEAP;
727 }
728 memcpy(outbuf, p, *nbytes);
729 return 1;
730 }
731 out_mpi = gcry_sexp_nth_mpi(sexp, 0, GCRYMPI_FMT_USG);
732 if (!out_mpi)
733 return -E_SEXP_FIND;
734 gret = gcry_mpi_print(GCRYMPI_FMT_USG, oaep_buf, sizeof(oaep_buf),
735 nbytes, out_mpi);
736 if (gret) {
737 PARA_ERROR_LOG("mpi_print: %s\n", gcrypt_strerror(gret));
738 ret = -E_MPI_PRINT;
739 goto out_mpi_release;
740 }
741 /*
742 * An oaep-encoded buffer always starts with at least one zero byte.
743 * However, leading zeroes in an mpi are omitted in the output of
744 * gcry_mpi_print() when using the GCRYMPI_FMT_USG format. The
745 * alternative, GCRYMPI_FMT_STD, does not work either because here the
746 * leading zero(es) might also be omitted, depending on the value of
747 * the second byte.
748 *
749 * To circumvent this, we shift the oaep buffer to the right. But first
750 * we check that the buffer actually started with a zero byte, i.e. that
751 * nbytes < key_size. Otherwise a decoding error occurred.
752 */
753 ret = -E_SEXP_DECRYPT;
754 if (*nbytes >= key_size)
755 goto out_mpi_release;
756 memmove(oaep_buf + key_size - *nbytes, oaep_buf, *nbytes);
757 memset(oaep_buf, 0, key_size - *nbytes);
758
759 PARA_DEBUG_LOG("decrypted buffer before unpad (%d bytes):\n",
760 key_size);
761 dump_buffer("non-unpadded decrypted buffer", oaep_buf, key_size);
762 ret = unpad_oaep(oaep_buf, key_size, outbuf, nbytes);
763 if (ret < 0)
764 goto out_mpi_release;
765 PARA_DEBUG_LOG("decrypted buffer after unpad (%zu bytes):\n",
766 *nbytes);
767 dump_buffer("unpadded decrypted buffer", outbuf, *nbytes);
768 ret = 1;
769 out_mpi_release:
770 gcry_mpi_release(out_mpi);
771 return ret;
772 }
773
774 int priv_decrypt(const char *key_file, unsigned char *outbuf,
775 unsigned char *inbuf, int inlen)
776 {
777 gcry_error_t gret;
778 int ret, key_size;
779 struct asymmetric_key *priv;
780 gcry_mpi_t in_mpi = NULL;
781 gcry_sexp_t in, out, priv_key;
782 size_t nbytes;
783
784 PARA_INFO_LOG("decrypting %d byte input\n", inlen);
785 /* key_file -> asymmetric key priv */
786 ret = get_private_key(key_file, &priv);
787 if (ret < 0)
788 return ret;
789 key_size = ret / 8;
790
791 /* asymmetric key priv -> sexp priv_key */
792 ret = -E_SEXP_FIND;
793 priv_key = gcry_sexp_find_token(priv->sexp, "private-key", 0);
794 if (!priv_key)
795 goto free_key;
796
797 /* inbuf -> in_mpi */
798 gret = gcry_mpi_scan(&in_mpi, GCRYMPI_FMT_USG, inbuf,
799 inlen, NULL);
800 if (gret) {
801 PARA_ERROR_LOG("%s\n", gcrypt_strerror(gret));
802 ret = -E_MPI_SCAN;
803 goto key_release;
804 }
805 /* in_mpi -> in sexp */
806 gret = gcry_sexp_build(&in, NULL, rsa_decrypt_sexp, in_mpi);
807 if (gret) {
808 PARA_ERROR_LOG("%s\n", gcrypt_strerror(gret));
809 ret = -E_SEXP_BUILD;
810 goto in_mpi_release;
811 }
812
813 /* rsa decryption: in sexp -> out sexp */
814 gret = gcry_pk_decrypt(&out, in, priv_key);
815 if (gret) {
816 PARA_ERROR_LOG("decrypt: %s\n", gcrypt_strerror(gret));
817 ret = -E_SEXP_DECRYPT;
818 goto in_release;
819 }
820 ret = decode_rsa(out, key_size, outbuf, &nbytes);
821 if (ret < 0)
822 goto out_release;
823 PARA_INFO_LOG("successfully decrypted %zu byte message\n", nbytes);
824 ret = nbytes;
825 out_release:
826 gcry_sexp_release(out);
827 in_release:
828 gcry_sexp_release(in);
829 in_mpi_release:
830 gcry_mpi_release(in_mpi);
831 key_release:
832 gcry_sexp_release(priv_key);
833 free_key:
834 free_asymmetric_key(priv);
835 return ret;
836 }
837
838 int pub_encrypt(struct asymmetric_key *pub, unsigned char *inbuf,
839 unsigned len, unsigned char *outbuf)
840 {
841 gcry_error_t gret;
842 gcry_sexp_t pub_key, in, out, out_a;
843 gcry_mpi_t out_mpi = NULL;
844 size_t nbytes;
845 int ret;
846
847 PARA_INFO_LOG("encrypting %u byte input with %d-byte key\n", len, pub->num_bytes);
848
849 /* get pub key */
850 pub_key = gcry_sexp_find_token(pub->sexp, "public-key", 0);
851 if (!pub_key)
852 return -E_SEXP_FIND;
853 if (libgcrypt_has_oaep) {
854 gret = gcry_sexp_build(&in, NULL,
855 "(data(flags oaep)(value %b))", len, inbuf);
856 } else {
857 unsigned char padded_input[256];
858 const size_t pad_size = 256;
859 /* inbuf -> padded inbuf */
860 pad_oaep(inbuf, len, padded_input, pad_size);
861 /* padded inbuf -> in sexp */
862 gret = gcry_sexp_build(&in, NULL,
863 "(data(flags raw)(value %b))", pad_size, padded_input);
864 }
865 if (gret) {
866 PARA_ERROR_LOG("%s\n", gcrypt_strerror(gret));
867 ret = -E_SEXP_BUILD;
868 goto key_release;
869 }
870 /* rsa sexp encryption: in -> out */
871 gret = gcry_pk_encrypt(&out, in, pub_key);
872 if (gret) {
873 PARA_ERROR_LOG("%s\n", gcrypt_strerror(gret));
874 ret = -E_SEXP_ENCRYPT;
875 goto in_release;
876 }
877 /* extract a, an MPI with the result of the RSA operation */
878 ret = -E_SEXP_FIND;
879 out_a = gcry_sexp_find_token(out, "a", 0);
880 if (!out_a)
881 goto out_release;
882 /* convert sexp out_a -> out_mpi */
883 out_mpi = gcry_sexp_nth_mpi(out_a, 1, GCRYMPI_FMT_USG);
884 if (!out_mpi) {
885 ret = -E_SEXP_FIND;
886 goto out_a_release;
887 }
888 gret = gcry_mpi_print(GCRYMPI_FMT_USG, outbuf, 512 /* FIXME */, &nbytes, out_mpi);
889 if (gret) {
890 PARA_ERROR_LOG("%s\n", gcrypt_strerror(gret));
891 ret = -E_SEXP_ENCRYPT;
892 goto out_mpi_release;
893 }
894 PARA_INFO_LOG("encrypted buffer is %zu bytes\n", nbytes);
895 dump_buffer("enc buf", outbuf, nbytes);
896 ret = nbytes;
897
898 out_mpi_release:
899 gcry_mpi_release(out_mpi);
900 out_a_release:
901 gcry_sexp_release(out_a);
902 out_release:
903 gcry_sexp_release(out);
904 in_release:
905 gcry_sexp_release(in);
906 key_release:
907 gcry_sexp_release(pub_key);
908 return ret;
909 }
910
911 struct stream_cipher {
912 gcry_cipher_hd_t handle;
913 };
914
915 struct stream_cipher *sc_new(const unsigned char *data, int len,
916 bool use_aes)
917 {
918 gcry_error_t gret;
919 struct stream_cipher *sc = para_malloc(sizeof(*sc));
920
921 if (use_aes) {
922 assert(len >= 2 * AES_CRT128_BLOCK_SIZE);
923 gret = gcry_cipher_open(&sc->handle, GCRY_CIPHER_AES128,
924 GCRY_CIPHER_MODE_CTR, 0);
925 assert(gret == 0);
926 gret = gcry_cipher_setkey(sc->handle, data,
927 AES_CRT128_BLOCK_SIZE);
928 assert(gret == 0);
929 gret = gcry_cipher_setctr(sc->handle,
930 data + AES_CRT128_BLOCK_SIZE, AES_CRT128_BLOCK_SIZE);
931 assert(gret == 0);
932 return sc;
933 }
934 gret = gcry_cipher_open(&sc->handle, GCRY_CIPHER_ARCFOUR,
935 GCRY_CIPHER_MODE_STREAM, 0);
936 if (gret) {
937 PARA_ERROR_LOG("%s\n", gcrypt_strerror(gret));
938 free(sc);
939 return NULL;
940 }
941 gret = gcry_cipher_setkey(sc->handle, data, (size_t)len);
942 assert(gret == 0);
943 return sc;
944 }
945
946 void sc_free(struct stream_cipher *sc)
947 {
948 if (!sc)
949 return;
950 gcry_cipher_close(sc->handle);
951 free(sc);
952 }
953
954 void sc_crypt(struct stream_cipher *sc, struct iovec *src, struct iovec *dst)
955 {
956 gcry_cipher_hd_t handle = sc->handle;
957 gcry_error_t gret;
958
959 /* perform in-place encryption */
960 *dst = *src;
961 gret = gcry_cipher_encrypt(handle, src->iov_base, src->iov_len,
962 NULL, 0);
963 assert(gret == 0);
964 }