1 /* Copyright (C) 2011 Andre Noll <maan@tuebingen.mpg.de>, see file COPYING. */
3 /** \file gcrypt.c Libgrcypt-based encryption/decryption routines. */
12 #include "crypt_backend.h"
16 //#define GCRYPT_DEBUG 1
19 static void dump_buffer(const char *msg, unsigned char *buf, int len)
23 fprintf(stderr, "%s (%d bytes): ", msg, len);
24 for (i = 0; i < len; i++)
25 fprintf(stderr, "%02x ", buf[i]);
26 fprintf(stderr, "\n");
29 /** Empty. Define GCRYPT_DEBUG to dump buffers. */
30 #define dump_buffer(a, b, c)
33 void hash_function(const char *data, unsigned long len, unsigned char *hash)
39 gret = gcry_md_open(&handle, GCRY_MD_SHA1, 0);
41 gcry_md_write(handle, data, (size_t)len);
42 gcry_md_final(handle);
43 md = gcry_md_read(handle, GCRY_MD_SHA1);
45 memcpy(hash, md, HASH_SIZE);
46 gcry_md_close(handle);
49 void get_random_bytes_or_die(unsigned char *buf, int num)
51 gcry_randomize(buf, (size_t)num, GCRY_STRONG_RANDOM);
55 * This is called at the beginning of every program that uses libgcrypt. The
56 * call to gcry_check_version() initializes the gcrypt library and checks that
57 * we have at least the minimal required version.
61 const char *req_ver = "1.5.0";
64 if (!gcry_check_version(req_ver)) {
65 PARA_EMERG_LOG("fatal: need at least libgcrypt-%s, have: %s\n",
66 req_ver, gcry_check_version(NULL));
69 get_random_bytes_or_die((unsigned char *)&seed, sizeof(seed));
73 void crypt_shutdown(void)
76 * WK does not see a way to apply a patch for the sake of Valgrind, so
77 * as of 2018 libgrypt has no deinitialization routine to free the
82 /** S-expression for the public part of an RSA key. */
83 #define RSA_PUBKEY_SEXP "(public-key (rsa (n %m) (e %m)))"
84 /** S-expression for a private RSA key. */
85 #define RSA_PRIVKEY_SEXP "(private-key (rsa (n %m) (e %m) (d %m) (p %m) (q %m) (u %m)))"
86 /** S-expression for decryption. */
87 #define RSA_DECRYPT_SEXP "(enc-val(flags oaep)(rsa(a %m)))"
89 struct asymmetric_key {
94 static const char *gcrypt_strerror(gcry_error_t gret)
96 return gcry_strerror(gcry_err_code(gret));
99 static int decode_key(const char *key_file, const char *header_str,
100 const char *footer_str, unsigned char **result)
104 size_t map_size, key_size, blob_size;
105 unsigned char *blob = NULL;
106 char *begin, *footer, *key;
108 ret = mmap_full_file(key_file, O_RDONLY, &map, &map_size, NULL);
112 if (strncmp(map, header_str, strlen(header_str)))
114 footer = strstr(map, footer_str);
118 begin = map + strlen(header_str);
119 /* skip whitespace at the beginning */
120 for (; begin < footer; begin++) {
121 if (para_isspace(*begin))
129 key_size = footer - begin;
130 key = para_malloc(key_size + 1);
131 for (i = 0, j = 0; begin + i < footer; i++) {
132 if (para_isspace(begin[i]))
137 ret = base64_decode(key, j, (char **)&blob, &blob_size);
147 ret2 = para_munmap(map, map_size);
148 if (ret >= 0 && ret2 < 0)
159 /** ASN Types and their code. */
161 /** The next object is an integer. */
162 ASN1_TYPE_INTEGER = 0x2,
163 /** Bit string object. */
164 ASN1_TYPE_BIT_STRING = 0x03,
165 /** Keys start with one big type sequence. */
166 ASN1_TYPE_SEQUENCE = 0x30,
169 /* bit 6 has value 0 */
170 static inline bool is_primitive(unsigned char c)
172 return (c & (1<<6)) == 0;
175 static inline bool is_primitive_integer(unsigned char c)
177 if (!is_primitive(c))
179 return (c & 0x1f) == ASN1_TYPE_INTEGER;
182 /* Bit 8 is zero (and bits 7-1 give the length) */
183 static inline bool is_short_form(unsigned char c)
185 return (c & 0x80) == 0;
188 static inline int get_short_form_length(unsigned char c)
193 static inline int get_long_form_num_length_bytes(unsigned char c)
199 * Returns: Number of bytes scanned. This may differ from the value returned via
200 * bn_bytes because the latter does not include the ASN.1 prefix and a leading
201 * zero is not considered as an additional byte for bn_bytes.
203 static int read_bignum(unsigned char *start, unsigned char *end, gcry_mpi_t *bn,
208 unsigned char *cp = start;
210 if (!is_primitive_integer(*cp))
211 return -E_BAD_PRIVATE_KEY;
213 if (is_short_form(*cp)) {
214 bn_size = get_short_form_length(*cp);
217 int num_bytes = get_long_form_num_length_bytes(*cp);
218 if (cp + num_bytes > end)
219 return -E_BAD_PRIVATE_KEY;
220 if (num_bytes > 4) /* nobody has such a large modulus */
221 return -E_BAD_PRIVATE_KEY;
224 for (i = 0; i < num_bytes; i++, cp++)
225 bn_size = (bn_size << 8) + *cp;
227 PARA_DEBUG_LOG("bn_size %d (0x%x)\n", bn_size, (unsigned)bn_size);
228 gret = gcry_mpi_scan(bn, GCRYMPI_FMT_STD, cp, bn_size, NULL);
230 PARA_ERROR_LOG("%s while scanning n\n",
231 gcry_strerror(gcry_err_code(gret)));
235 * Don't take the first leading zero into account for the size of the
245 // unsigned char *buf;
246 // gcry_mpi_aprint(GCRYMPI_FMT_HEX, &buf, NULL, *bn);
247 // PARA_CRIT_LOG("bn: %s\n", buf);
251 static int find_privkey_bignum_offset(const unsigned char *data, int len)
253 const unsigned char *p = data, *end = data + len;
255 /* like the public key, the whole thing is contained in a sequence */
256 if (*p != ASN1_TYPE_SEQUENCE)
257 return -E_ASN1_PARSE;
260 return -E_ASN1_PARSE;
261 if (is_short_form(*p))
264 p += 1 + get_long_form_num_length_bytes(*p);
266 return -E_ASN1_PARSE;
268 /* skip next integer */
269 if (*p != ASN1_TYPE_INTEGER)
270 return -E_ASN1_PARSE;
273 return -E_ASN1_PARSE;
274 if (is_short_form(*p))
275 p += 1 + get_short_form_length(*p);
277 p += 1 + get_long_form_num_length_bytes(*p);
279 return -E_ASN1_PARSE;
283 /** Private keys start with this header. */
284 #define PRIVATE_KEY_HEADER "-----BEGIN RSA PRIVATE KEY-----"
285 /** Private keys end with this footer. */
286 #define PRIVATE_KEY_FOOTER "-----END RSA PRIVATE KEY-----"
288 static int get_private_key(const char *key_file, struct asymmetric_key **result)
290 gcry_mpi_t n = NULL, e = NULL, d = NULL, p = NULL, q = NULL,
292 unsigned char *blob, *cp, *end;
293 int blob_size, ret, n_size;
297 struct asymmetric_key *key;
300 ret = decode_key(key_file, PRIVATE_KEY_HEADER, PRIVATE_KEY_FOOTER,
305 end = blob + blob_size;
306 ret = find_privkey_bignum_offset(blob, blob_size);
309 PARA_INFO_LOG("reading RSA params at offset %d\n", ret);
312 ret = read_bignum(cp, end, &n, &n_size);
317 ret = read_bignum(cp, end, &e, NULL);
322 ret = read_bignum(cp, end, &d, NULL);
327 ret = read_bignum(cp, end, &p, NULL);
332 ret = read_bignum(cp, end, &q, NULL);
336 ret = read_bignum(cp, end, &u, NULL);
340 * OpenSSL uses slightly different parameters than gcrypt. To use these
341 * parameters we need to swap the values of p and q and recompute u.
343 if (gcry_mpi_cmp(p, q) > 0) {
345 gcry_mpi_invm(u, p, q);
347 gret = gcry_sexp_build(&sexp, &erroff, RSA_PRIVKEY_SEXP,
351 PARA_ERROR_LOG("offset %zu: %s\n", erroff,
352 gcry_strerror(gcry_err_code(gret)));
356 key = para_malloc(sizeof(*key));
360 PARA_INFO_LOG("succesfully read %d bit private key\n", ret);
378 int apc_get_pubkey(const char *key_file, struct asymmetric_key **result)
380 unsigned char *blob, *p, *end;
383 size_t nr_scanned, erroff, decoded_size;
386 struct asymmetric_key *key;
388 ret = decode_ssh_key(key_file, &blob, &decoded_size);
392 end = blob + decoded_size;
393 PARA_DEBUG_LOG("scanning modulus and public exponent\n");
394 gret = gcry_mpi_scan(&e, GCRYMPI_FMT_SSH, p, end - p, &nr_scanned);
397 PARA_CRIT_LOG("%s\n", gcry_strerror(gcry_err_code(gret)));
400 PARA_DEBUG_LOG("scanned e (%zu bytes)\n", nr_scanned);
404 gret = gcry_mpi_scan(&n, GCRYMPI_FMT_SSH, p, end - p, &nr_scanned);
407 PARA_ERROR_LOG("%s\n", gcry_strerror(gcry_err_code(gret)));
410 PARA_DEBUG_LOG("scanned n (%zu bytes)\n", nr_scanned);
411 gret = gcry_sexp_build(&sexp, &erroff, RSA_PUBKEY_SEXP, n, e);
413 PARA_ERROR_LOG("offset %zu: %s\n", erroff,
414 gcry_strerror(gcry_err_code(gret)));
418 ret = ROUND_DOWN(nr_scanned, 32);
419 PARA_INFO_LOG("successfully read %d bit ssh public key\n", ret * 8);
420 key = para_malloc(sizeof(*key));
421 key->num_bytes = ret;
433 void apc_free_pubkey(struct asymmetric_key *key)
437 gcry_sexp_release(key->sexp);
441 static int decode_rsa(gcry_sexp_t sexp, unsigned char *outbuf, size_t *nbytes)
443 const char *p = gcry_sexp_nth_data(sexp, 1, nbytes);
446 return -E_RSA_DECODE;
447 memcpy(outbuf, p, *nbytes);
451 int apc_priv_decrypt(const char *key_file, unsigned char *outbuf,
452 unsigned char *inbuf, int inlen)
456 struct asymmetric_key *priv;
457 gcry_mpi_t in_mpi = NULL;
458 gcry_sexp_t in, out, priv_key;
461 ret = check_private_key_file(key_file);
464 PARA_INFO_LOG("decrypting %d byte input\n", inlen);
465 /* key_file -> asymmetric key priv */
466 ret = get_private_key(key_file, &priv);
470 /* asymmetric key priv -> sexp priv_key */
472 priv_key = gcry_sexp_find_token(priv->sexp, "private-key", 0);
476 /* inbuf -> in_mpi */
477 gret = gcry_mpi_scan(&in_mpi, GCRYMPI_FMT_USG, inbuf,
480 PARA_ERROR_LOG("%s\n", gcrypt_strerror(gret));
484 /* in_mpi -> in sexp */
485 gret = gcry_sexp_build(&in, NULL, RSA_DECRYPT_SEXP, in_mpi);
487 PARA_ERROR_LOG("%s\n", gcrypt_strerror(gret));
492 /* rsa decryption: in sexp -> out sexp */
493 gret = gcry_pk_decrypt(&out, in, priv_key);
495 PARA_ERROR_LOG("decrypt: %s\n", gcrypt_strerror(gret));
496 ret = -E_SEXP_DECRYPT;
499 ret = decode_rsa(out, outbuf, &nbytes);
502 PARA_INFO_LOG("successfully decrypted %zu byte message\n", nbytes);
505 gcry_sexp_release(out);
507 gcry_sexp_release(in);
509 gcry_mpi_release(in_mpi);
511 gcry_sexp_release(priv_key);
513 gcry_sexp_release(priv->sexp);
518 int apc_pub_encrypt(struct asymmetric_key *pub, unsigned char *inbuf,
519 unsigned len, unsigned char *outbuf)
522 gcry_sexp_t pub_key, in, out, out_a;
523 gcry_mpi_t out_mpi = NULL;
527 PARA_INFO_LOG("encrypting %u byte input with %d-byte key\n", len, pub->num_bytes);
530 pub_key = gcry_sexp_find_token(pub->sexp, "public-key", 0);
533 gret = gcry_sexp_build(&in, NULL, "(data(flags oaep)(value %b))", len, inbuf);
535 PARA_ERROR_LOG("%s\n", gcrypt_strerror(gret));
539 /* rsa sexp encryption: in -> out */
540 gret = gcry_pk_encrypt(&out, in, pub_key);
542 PARA_ERROR_LOG("%s\n", gcrypt_strerror(gret));
543 ret = -E_SEXP_ENCRYPT;
546 /* extract a, an MPI with the result of the RSA operation */
548 out_a = gcry_sexp_find_token(out, "a", 0);
551 /* convert sexp out_a -> out_mpi */
552 out_mpi = gcry_sexp_nth_mpi(out_a, 1, GCRYMPI_FMT_USG);
557 gret = gcry_mpi_print(GCRYMPI_FMT_USG, outbuf, 512 /* FIXME */, &nbytes, out_mpi);
559 PARA_ERROR_LOG("%s\n", gcrypt_strerror(gret));
560 ret = -E_SEXP_ENCRYPT;
561 goto out_mpi_release;
563 PARA_INFO_LOG("encrypted buffer is %zu bytes\n", nbytes);
564 dump_buffer("enc buf", outbuf, nbytes);
568 gcry_mpi_release(out_mpi);
570 gcry_sexp_release(out_a);
572 gcry_sexp_release(out);
574 gcry_sexp_release(in);
576 gcry_sexp_release(pub_key);
580 struct stream_cipher {
581 gcry_cipher_hd_t handle;
584 struct stream_cipher *sc_new(const unsigned char *data, int len)
587 struct stream_cipher *sc = para_malloc(sizeof(*sc));
589 assert(len >= 2 * AES_CRT128_BLOCK_SIZE);
590 gret = gcry_cipher_open(&sc->handle, GCRY_CIPHER_AES128,
591 GCRY_CIPHER_MODE_CTR, 0);
593 gret = gcry_cipher_setkey(sc->handle, data,
594 AES_CRT128_BLOCK_SIZE);
596 gret = gcry_cipher_setctr(sc->handle,
597 data + AES_CRT128_BLOCK_SIZE, AES_CRT128_BLOCK_SIZE);
602 void sc_free(struct stream_cipher *sc)
606 gcry_cipher_close(sc->handle);
610 void sc_crypt(struct stream_cipher *sc, struct iovec *src, struct iovec *dst)
612 gcry_cipher_hd_t handle = sc->handle;
615 /* perform in-place encryption */
617 gret = gcry_cipher_encrypt(handle, src->iov_base, src->iov_len,