openssl: Move get_private_key() down.
[paraslash.git] / gcrypt.c
1 /* Copyright (C) 2011 Andre Noll <maan@tuebingen.mpg.de>, see file COPYING. */
2
3 /** \file gcrypt.c Libgrcypt-based encryption/decryption routines. */
4
5 #include <regex.h>
6 #include <gcrypt.h>
7
8 #include "para.h"
9 #include "error.h"
10 #include "string.h"
11 #include "crypt.h"
12 #include "crypt_backend.h"
13 #include "fd.h"
14 #include "base64.h"
15 #include "portable_io.h"
16
17 //#define GCRYPT_DEBUG 1
18
19 #ifdef GCRYPT_DEBUG
20 static void dump_buffer(const char *msg, unsigned char *buf, int len)
21 {
22 int i;
23
24 fprintf(stderr, "%s (%d bytes): ", msg, len);
25 for (i = 0; i < len; i++)
26 fprintf(stderr, "%02x ", buf[i]);
27 fprintf(stderr, "\n");
28 }
29 #else
30 /** Empty. Define GCRYPT_DEBUG to dump buffers. */
31 #define dump_buffer(a, b, c)
32 #endif
33
34 void hash_function(const char *data, unsigned long len, unsigned char *hash)
35 {
36 gcry_error_t gret;
37 gcry_md_hd_t handle;
38 unsigned char *md;
39
40 gret = gcry_md_open(&handle, GCRY_MD_SHA1, 0);
41 assert(gret == 0);
42 gcry_md_write(handle, data, (size_t)len);
43 gcry_md_final(handle);
44 md = gcry_md_read(handle, GCRY_MD_SHA1);
45 assert(md);
46 memcpy(hash, md, HASH_SIZE);
47 gcry_md_close(handle);
48 }
49
50 void get_random_bytes_or_die(unsigned char *buf, int num)
51 {
52 gcry_randomize(buf, (size_t)num, GCRY_STRONG_RANDOM);
53 }
54
55 /*
56 * This is called at the beginning of every program that uses libgcrypt. The
57 * call to gcry_check_version() initializes the gcrypt library and checks that
58 * we have at least the minimal required version.
59 */
60 void crypt_init(void)
61 {
62 const char *req_ver = "1.5.0";
63 int seed;
64
65 if (!gcry_check_version(req_ver)) {
66 PARA_EMERG_LOG("fatal: need at least libgcrypt-%s, have: %s\n",
67 req_ver, gcry_check_version(NULL));
68 exit(EXIT_FAILURE);
69 }
70
71 /*
72 * Allocate a pool of secure memory. This also drops privileges where
73 * needed.
74 */
75 gcry_control(GCRYCTL_INIT_SECMEM, 65536, 0);
76
77 /* Tell Libgcrypt that initialization has completed. */
78 gcry_control(GCRYCTL_INITIALIZATION_FINISHED, 0);
79
80 get_random_bytes_or_die((unsigned char *)&seed, sizeof(seed));
81 srandom(seed);
82 }
83
84 void crypt_shutdown(void)
85 {
86 /*
87 * WK does not see a way to apply a patch for the sake of Valgrind, so
88 * as of 2018 libgrypt has no deinitialization routine to free the
89 * resources on exit.
90 */
91 }
92
93 /** S-expression for the public part of an RSA key. */
94 #define RSA_PUBKEY_SEXP "(public-key (rsa (n %m) (e %m)))"
95 /** S-expression for a private RSA key. */
96 #define RSA_PRIVKEY_SEXP "(private-key (rsa (n %m) (e %m) (d %m) (p %m) (q %m) (u %m)))"
97 /** S-expression for decryption. */
98 #define RSA_DECRYPT_SEXP "(enc-val(flags oaep)(rsa(a %m)))"
99
100 struct asymmetric_key {
101 gcry_sexp_t sexp;
102 int num_bytes;
103 };
104
105 static const char *gcrypt_strerror(gcry_error_t gret)
106 {
107 return gcry_strerror(gcry_err_code(gret));
108 }
109
110 /** Private PEM keys (legacy format) start with this header. */
111 #define PRIVATE_PEM_KEY_HEADER "-----BEGIN RSA PRIVATE KEY-----"
112 /** Private OPENSSH keys (RFC4716) start with this header. */
113 #define PRIVATE_OPENSSH_KEY_HEADER "-----BEGIN OPENSSH PRIVATE KEY-----"
114 /** Private PEM keys (legacy format) end with this footer. */
115 #define PRIVATE_PEM_KEY_FOOTER "-----END RSA PRIVATE KEY-----"
116 /** Private OPENSSH keys (RFC4716) end with this footer. */
117 #define PRIVATE_OPENSSH_KEY_FOOTER "-----END OPENSSH PRIVATE KEY-----"
118 /** Legacy PEM keys (openssh-7.7 and earlier, paraslash.0.6.2 and earlier) */
119 #define PKT_PEM (0)
120 /** OPENSSH keys (since openssh-7.8, paraslash.0.6.3) */
121 #define PKT_OPENSSH (1)
122
123 static int decode_private_key(const char *key_file, unsigned char **result,
124 size_t *blob_size)
125 {
126 int ret, ret2, i, j, key_type;
127 void *map;
128 size_t map_size, key_size;
129 unsigned char *blob = NULL;
130 char *begin, *footer, *key;
131
132 ret = mmap_full_file(key_file, O_RDONLY, &map, &map_size, NULL);
133 if (ret < 0)
134 goto out;
135 ret = -E_KEY_MARKER;
136 if (strncmp(map, PRIVATE_PEM_KEY_HEADER,
137 strlen(PRIVATE_PEM_KEY_HEADER)) == 0) {
138 key_type = PKT_PEM;
139 begin = map + strlen(PRIVATE_PEM_KEY_HEADER);
140 footer = strstr(map, PRIVATE_PEM_KEY_FOOTER);
141 PARA_INFO_LOG("detected legacy PEM key %s\n", key_file);
142 } else if (strncmp(map, PRIVATE_OPENSSH_KEY_HEADER,
143 strlen(PRIVATE_OPENSSH_KEY_HEADER)) == 0) {
144 key_type = PKT_OPENSSH;
145 begin = map + strlen(PRIVATE_OPENSSH_KEY_HEADER);
146 footer = strstr(map, PRIVATE_OPENSSH_KEY_FOOTER);
147 PARA_INFO_LOG("detected openssh key %s\n", key_file);
148 } else
149 goto unmap;
150 if (!footer)
151 goto unmap;
152 /* skip whitespace at the beginning */
153 for (; begin < footer; begin++) {
154 if (para_isspace(*begin))
155 continue;
156 break;
157 }
158 ret = -E_KEY_MARKER;
159 if (begin >= footer)
160 goto unmap;
161
162 key_size = footer - begin;
163 key = para_malloc(key_size + 1);
164 for (i = 0, j = 0; begin + i < footer; i++) {
165 if (para_isspace(begin[i]))
166 continue;
167 key[j++] = begin[i];
168 }
169 key[j] = '\0';
170 ret = base64_decode(key, j, (char **)&blob, blob_size);
171 free(key);
172 if (ret < 0)
173 goto unmap;
174 ret = key_type;
175 unmap:
176 ret2 = para_munmap(map, map_size);
177 if (ret >= 0 && ret2 < 0)
178 ret = ret2;
179 if (ret < 0) {
180 free(blob);
181 blob = NULL;
182 }
183 out:
184 *result = blob;
185 return ret;
186 }
187
188 /** ASN Types and their code. */
189 enum asn1_types {
190 /** The next object is an integer. */
191 ASN1_TYPE_INTEGER = 0x2,
192 /** Bit string object. */
193 ASN1_TYPE_BIT_STRING = 0x03,
194 /** Keys start with one big type sequence. */
195 ASN1_TYPE_SEQUENCE = 0x30,
196 };
197
198 /* bit 6 has value 0 */
199 static inline bool is_primitive(unsigned char c)
200 {
201 return (c & (1<<6)) == 0;
202 }
203
204 static inline bool is_primitive_integer(unsigned char c)
205 {
206 if (!is_primitive(c))
207 return false;
208 return (c & 0x1f) == ASN1_TYPE_INTEGER;
209 }
210
211 /* Bit 8 is zero (and bits 7-1 give the length) */
212 static inline bool is_short_form(unsigned char c)
213 {
214 return (c & 0x80) == 0;
215 }
216
217 static inline int get_short_form_length(unsigned char c)
218 {
219 return c & 0x7f;
220 }
221
222 static inline int get_long_form_num_length_bytes(unsigned char c)
223 {
224 return c & 0x7f;
225 }
226
227 /*
228 * Returns: Number of bytes scanned. This may differ from the value returned via
229 * bitsp because the latter does not include the ASN.1 prefix and a leading
230 * zero is not considered as an additional byte for the number of bits.
231 */
232 static int read_pem_bignum(unsigned char *start, unsigned char *end, gcry_mpi_t *bn,
233 unsigned *bitsp)
234 {
235 int i, bn_size;
236 gcry_error_t gret;
237 unsigned char *cp = start;
238
239 if (!is_primitive_integer(*cp))
240 return -E_BAD_PRIVATE_KEY;
241 cp++;
242 if (is_short_form(*cp)) {
243 bn_size = get_short_form_length(*cp);
244 cp++;
245 } else {
246 int num_bytes = get_long_form_num_length_bytes(*cp);
247 if (cp + num_bytes > end)
248 return -E_BAD_PRIVATE_KEY;
249 if (num_bytes > 4) /* nobody has such a large modulus */
250 return -E_BAD_PRIVATE_KEY;
251 cp++;
252 bn_size = 0;
253 for (i = 0; i < num_bytes; i++, cp++)
254 bn_size = (bn_size << 8) + *cp;
255 }
256 PARA_DEBUG_LOG("bn_size %d (0x%x)\n", bn_size, (unsigned)bn_size);
257 gret = gcry_mpi_scan(bn, GCRYMPI_FMT_STD, cp, bn_size, NULL);
258 if (gret) {
259 PARA_ERROR_LOG("gcry_mpi_scan: %s\n",
260 gcry_strerror(gcry_err_code(gret)));
261 return-E_MPI_SCAN;
262 }
263 /*
264 * Don't take the first leading zero into account for the size of the
265 * bignum.
266 */
267 if (*cp == '\0') {
268 cp++;
269 bn_size--;
270 }
271 if (bitsp)
272 *bitsp = bn_size * 8;
273 cp += bn_size;
274 // unsigned char *buf;
275 // gcry_mpi_aprint(GCRYMPI_FMT_HEX, &buf, NULL, *bn);
276 // PARA_CRIT_LOG("bn: %s\n", buf);
277 return cp - start;
278 }
279
280 struct rsa_params {
281 gcry_mpi_t n, e, d, p, q, u;
282 };
283
284 static int read_pem_rsa_params(unsigned char *start, unsigned char *end,
285 struct rsa_params *p)
286 {
287 unsigned char *cp = start;
288 unsigned bits;
289 int ret;
290
291 ret = read_pem_bignum(cp, end, &p->n, &bits);
292 if (ret < 0)
293 return ret;
294 cp += ret;
295 ret = read_pem_bignum(cp, end, &p->e, NULL);
296 if (ret < 0)
297 goto release_n;
298 cp += ret;
299 ret = read_pem_bignum(cp, end, &p->d, NULL);
300 if (ret < 0)
301 goto release_e;
302 cp += ret;
303 ret = read_pem_bignum(cp, end, &p->p, NULL);
304 if (ret < 0)
305 goto release_d;
306 cp += ret;
307 ret = read_pem_bignum(cp, end, &p->q, NULL);
308 if (ret < 0)
309 goto release_p;
310 cp += ret;
311 ret = read_pem_bignum(cp, end, &p->u, NULL);
312 if (ret < 0)
313 goto release_q;
314 return bits;
315 release_q:
316 gcry_mpi_release(p->q);
317 release_p:
318 gcry_mpi_release(p->p);
319 release_d:
320 gcry_mpi_release(p->d);
321 release_e:
322 gcry_mpi_release(p->e);
323 release_n:
324 gcry_mpi_release(p->n);
325 return ret;
326 }
327
328 static int find_pem_bignum_offset(const unsigned char *data, int len)
329 {
330 const unsigned char *p = data, *end = data + len;
331
332 /* like the public key, the whole thing is contained in a sequence */
333 if (*p != ASN1_TYPE_SEQUENCE)
334 return -E_ASN1_PARSE;
335 p++;
336 if (p >= end)
337 return -E_ASN1_PARSE;
338 if (is_short_form(*p))
339 p++;
340 else
341 p += 1 + get_long_form_num_length_bytes(*p);
342 if (p >= end)
343 return -E_ASN1_PARSE;
344
345 /* skip next integer */
346 if (*p != ASN1_TYPE_INTEGER)
347 return -E_ASN1_PARSE;
348 p++;
349 if (p >= end)
350 return -E_ASN1_PARSE;
351 if (is_short_form(*p))
352 p += 1 + get_short_form_length(*p);
353 else
354 p += 1 + get_long_form_num_length_bytes(*p);
355 if (p >= end)
356 return -E_ASN1_PARSE;
357 return p - data;
358 }
359
360 static int read_openssh_bignum(unsigned char *start, unsigned char *end,
361 gcry_mpi_t *bn, unsigned *bitsp)
362 {
363 gcry_error_t gret;
364 size_t nscanned;
365 unsigned bits;
366
367 gret = gcry_mpi_scan(bn, GCRYMPI_FMT_SSH, start, end - start, &nscanned);
368 if (gret) {
369 PARA_ERROR_LOG("gcry_mpi_scan: %s\n",
370 gcry_strerror(gcry_err_code(gret)));
371 return -E_MPI_SCAN;
372 }
373 bits = (nscanned - 4 - (start[4] == '\0')) * 8;
374 if (bitsp)
375 *bitsp = bits;
376 PARA_DEBUG_LOG("scanned %u-bit bignum\n", bits);
377 return nscanned;
378 }
379
380 static int read_openssh_rsa_params(unsigned char *start, unsigned char *end,
381 struct rsa_params *p)
382 {
383 unsigned char *cp = start;
384 unsigned bits;
385 int ret;
386
387 ret = read_openssh_bignum(cp, end, &p->n, &bits);
388 if (ret < 0)
389 return ret;
390 cp += ret;
391 ret = read_openssh_bignum(cp, end, &p->e, NULL);
392 if (ret < 0)
393 goto release_n;
394 cp += ret;
395 ret = read_openssh_bignum(cp, end, &p->d, NULL);
396 if (ret < 0)
397 goto release_e;
398 cp += ret;
399 ret = read_openssh_bignum(cp, end, &p->u, NULL);
400 if (ret < 0)
401 goto release_d;
402 cp += ret;
403 ret = read_openssh_bignum(cp, end, &p->p, NULL);
404 if (ret < 0)
405 goto release_u;
406 cp += ret;
407 ret = read_openssh_bignum(cp, end, &p->q, NULL);
408 if (ret < 0)
409 goto release_p;
410 return bits;
411 release_p:
412 gcry_mpi_release(p->p);
413 release_u:
414 gcry_mpi_release(p->u);
415 release_d:
416 gcry_mpi_release(p->d);
417 release_e:
418 gcry_mpi_release(p->e);
419 release_n:
420 gcry_mpi_release(p->n);
421 return ret;
422 }
423
424 static int get_private_key(const char *key_file, struct asymmetric_key **result)
425 {
426 struct rsa_params params;
427 unsigned char *blob, *end;
428 unsigned bits;
429 int ret, key_type;
430 gcry_error_t gret;
431 size_t erroff, blob_size;
432 gcry_sexp_t sexp;
433 struct asymmetric_key *key;
434
435 *result = NULL;
436 ret = decode_private_key(key_file, &blob, &blob_size);
437 if (ret < 0)
438 return ret;
439 key_type = ret;
440 end = blob + blob_size;
441 if (key_type == PKT_PEM)
442 ret = find_pem_bignum_offset(blob, blob_size);
443 else
444 ret = find_openssh_bignum_offset(blob, blob_size);
445 if (ret < 0)
446 goto free_blob;
447 PARA_INFO_LOG("reading RSA params at offset %d\n", ret);
448 if (key_type == PKT_PEM)
449 ret = read_pem_rsa_params(blob + ret, end, &params);
450 else
451 ret = read_openssh_rsa_params(blob + ret, end, &params);
452 if (ret < 0)
453 goto free_blob;
454 bits = ret;
455 /*
456 * OpenSSL uses slightly different parameters than gcrypt. To use these
457 * parameters we need to swap the values of p and q and recompute u.
458 */
459 if (gcry_mpi_cmp(params.p, params.q) > 0) {
460 gcry_mpi_swap(params.p, params.q);
461 gcry_mpi_invm(params.u, params.p, params.q);
462 }
463 gret = gcry_sexp_build(&sexp, &erroff, RSA_PRIVKEY_SEXP, params.n,
464 params.e, params.d, params.p, params.q, params.u);
465
466 if (gret) {
467 PARA_ERROR_LOG("offset %zu: %s\n", erroff,
468 gcry_strerror(gcry_err_code(gret)));
469 ret = -E_SEXP_BUILD;
470 goto free_params;
471 }
472 key = para_malloc(sizeof(*key));
473 key->sexp = sexp;
474 *result = key;
475 ret = bits;
476 PARA_INFO_LOG("succesfully read %d bit private key\n", ret);
477 free_params:
478 gcry_mpi_release(params.n);
479 gcry_mpi_release(params.e);
480 gcry_mpi_release(params.d);
481 gcry_mpi_release(params.u);
482 gcry_mpi_release(params.p);
483 gcry_mpi_release(params.q);
484
485 free_blob:
486 free(blob);
487 return ret;
488 }
489
490 int apc_get_pubkey(const char *key_file, struct asymmetric_key **result)
491 {
492 unsigned char *blob, *p, *end;
493 int ret;
494 gcry_error_t gret;
495 size_t erroff, decoded_size;
496 gcry_mpi_t e, n;
497 gcry_sexp_t sexp;
498 struct asymmetric_key *key;
499 unsigned bits;
500
501 ret = decode_public_key(key_file, &blob, &decoded_size);
502 if (ret < 0)
503 return ret;
504 p = blob + ret;
505 end = blob + decoded_size;
506 PARA_DEBUG_LOG("scanning modulus and public exponent\n");
507 ret = read_openssh_bignum(p, end, &e, NULL);
508 if (ret < 0)
509 goto free_blob;
510 p += ret;
511 ret = read_openssh_bignum(p, end, &n, &bits);
512 if (ret < 0)
513 goto release_e;
514 gret = gcry_sexp_build(&sexp, &erroff, RSA_PUBKEY_SEXP, n, e);
515 if (gret) {
516 PARA_ERROR_LOG("offset %zu: %s\n", erroff,
517 gcry_strerror(gcry_err_code(gret)));
518 ret = -E_SEXP_BUILD;
519 goto release_n;
520 }
521 PARA_INFO_LOG("successfully read %u bit ssh public key\n", bits);
522 key = para_malloc(sizeof(*key));
523 key->num_bytes = ret;
524 key->sexp = sexp;
525 *result = key;
526 ret = bits;
527 release_n:
528 gcry_mpi_release(n);
529 release_e:
530 gcry_mpi_release(e);
531 free_blob:
532 free(blob);
533 return ret;
534 }
535
536 void apc_free_pubkey(struct asymmetric_key *key)
537 {
538 if (!key)
539 return;
540 gcry_sexp_release(key->sexp);
541 free(key);
542 }
543
544 static int decode_rsa(gcry_sexp_t sexp, unsigned char *outbuf, size_t *nbytes)
545 {
546 const char *p = gcry_sexp_nth_data(sexp, 1, nbytes);
547
548 if (!p)
549 return -E_RSA_DECODE;
550 memcpy(outbuf, p, *nbytes);
551 return 1;
552 }
553
554 int apc_priv_decrypt(const char *key_file, unsigned char *outbuf,
555 unsigned char *inbuf, int inlen)
556 {
557 gcry_error_t gret;
558 int ret;
559 struct asymmetric_key *priv;
560 gcry_mpi_t in_mpi = NULL;
561 gcry_sexp_t in, out, priv_key;
562 size_t nbytes;
563
564 ret = check_private_key_file(key_file);
565 if (ret < 0)
566 return ret;
567 PARA_INFO_LOG("decrypting %d byte input\n", inlen);
568 /* key_file -> asymmetric key priv */
569 ret = get_private_key(key_file, &priv);
570 if (ret < 0)
571 return ret;
572
573 /* asymmetric key priv -> sexp priv_key */
574 ret = -E_SEXP_FIND;
575 priv_key = gcry_sexp_find_token(priv->sexp, "private-key", 0);
576 if (!priv_key)
577 goto free_key;
578
579 /* inbuf -> in_mpi */
580 gret = gcry_mpi_scan(&in_mpi, GCRYMPI_FMT_USG, inbuf,
581 inlen, NULL);
582 if (gret) {
583 PARA_ERROR_LOG("%s\n", gcrypt_strerror(gret));
584 ret = -E_MPI_SCAN;
585 goto key_release;
586 }
587 /* in_mpi -> in sexp */
588 gret = gcry_sexp_build(&in, NULL, RSA_DECRYPT_SEXP, in_mpi);
589 if (gret) {
590 PARA_ERROR_LOG("%s\n", gcrypt_strerror(gret));
591 ret = -E_SEXP_BUILD;
592 goto in_mpi_release;
593 }
594
595 /* rsa decryption: in sexp -> out sexp */
596 gret = gcry_pk_decrypt(&out, in, priv_key);
597 if (gret) {
598 PARA_ERROR_LOG("decrypt: %s\n", gcrypt_strerror(gret));
599 ret = -E_SEXP_DECRYPT;
600 goto in_release;
601 }
602 ret = decode_rsa(out, outbuf, &nbytes);
603 if (ret < 0)
604 goto out_release;
605 PARA_INFO_LOG("successfully decrypted %zu byte message\n", nbytes);
606 ret = nbytes;
607 out_release:
608 gcry_sexp_release(out);
609 in_release:
610 gcry_sexp_release(in);
611 in_mpi_release:
612 gcry_mpi_release(in_mpi);
613 key_release:
614 gcry_sexp_release(priv_key);
615 free_key:
616 gcry_sexp_release(priv->sexp);
617 free(priv);
618 return ret;
619 }
620
621 int apc_pub_encrypt(struct asymmetric_key *pub, unsigned char *inbuf,
622 unsigned len, unsigned char *outbuf)
623 {
624 gcry_error_t gret;
625 gcry_sexp_t pub_key, in, out, out_a;
626 gcry_mpi_t out_mpi = NULL;
627 size_t nbytes;
628 int ret;
629
630 PARA_INFO_LOG("encrypting %u byte input with %d-byte key\n", len, pub->num_bytes);
631
632 /* get pub key */
633 pub_key = gcry_sexp_find_token(pub->sexp, "public-key", 0);
634 if (!pub_key)
635 return -E_SEXP_FIND;
636 gret = gcry_sexp_build(&in, NULL, "(data(flags oaep)(value %b))", len, inbuf);
637 if (gret) {
638 PARA_ERROR_LOG("%s\n", gcrypt_strerror(gret));
639 ret = -E_SEXP_BUILD;
640 goto key_release;
641 }
642 /* rsa sexp encryption: in -> out */
643 gret = gcry_pk_encrypt(&out, in, pub_key);
644 if (gret) {
645 PARA_ERROR_LOG("%s\n", gcrypt_strerror(gret));
646 ret = -E_SEXP_ENCRYPT;
647 goto in_release;
648 }
649 /* extract a, an MPI with the result of the RSA operation */
650 ret = -E_SEXP_FIND;
651 out_a = gcry_sexp_find_token(out, "a", 0);
652 if (!out_a)
653 goto out_release;
654 /* convert sexp out_a -> out_mpi */
655 out_mpi = gcry_sexp_nth_mpi(out_a, 1, GCRYMPI_FMT_USG);
656 if (!out_mpi) {
657 ret = -E_SEXP_FIND;
658 goto out_a_release;
659 }
660 gret = gcry_mpi_print(GCRYMPI_FMT_USG, outbuf, 512 /* FIXME */, &nbytes, out_mpi);
661 if (gret) {
662 PARA_ERROR_LOG("%s\n", gcrypt_strerror(gret));
663 ret = -E_SEXP_ENCRYPT;
664 goto out_mpi_release;
665 }
666 PARA_INFO_LOG("encrypted buffer is %zu bytes\n", nbytes);
667 dump_buffer("enc buf", outbuf, nbytes);
668 ret = nbytes;
669
670 out_mpi_release:
671 gcry_mpi_release(out_mpi);
672 out_a_release:
673 gcry_sexp_release(out_a);
674 out_release:
675 gcry_sexp_release(out);
676 in_release:
677 gcry_sexp_release(in);
678 key_release:
679 gcry_sexp_release(pub_key);
680 return ret;
681 }
682
683 struct stream_cipher {
684 gcry_cipher_hd_t handle;
685 };
686
687 struct stream_cipher *sc_new(const unsigned char *data, int len)
688 {
689 gcry_error_t gret;
690 struct stream_cipher *sc = para_malloc(sizeof(*sc));
691
692 assert(len >= 2 * AES_CRT128_BLOCK_SIZE);
693 gret = gcry_cipher_open(&sc->handle, GCRY_CIPHER_AES128,
694 GCRY_CIPHER_MODE_CTR, 0);
695 assert(gret == 0);
696 gret = gcry_cipher_setkey(sc->handle, data,
697 AES_CRT128_BLOCK_SIZE);
698 assert(gret == 0);
699 gret = gcry_cipher_setctr(sc->handle,
700 data + AES_CRT128_BLOCK_SIZE, AES_CRT128_BLOCK_SIZE);
701 assert(gret == 0);
702 return sc;
703 }
704
705 void sc_free(struct stream_cipher *sc)
706 {
707 if (!sc)
708 return;
709 gcry_cipher_close(sc->handle);
710 free(sc);
711 }
712
713 void sc_crypt(struct stream_cipher *sc, struct iovec *src, struct iovec *dst)
714 {
715 gcry_cipher_hd_t handle = sc->handle;
716 gcry_error_t gret;
717
718 /* perform in-place encryption */
719 *dst = *src;
720 gret = gcry_cipher_encrypt(handle, src->iov_base, src->iov_len,
721 NULL, 0);
722 assert(gret == 0);
723 }