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));
71 * Allocate a pool of secure memory. This also drops privileges where
74 gcry_control(GCRYCTL_INIT_SECMEM, 65536, 0);
76 /* Tell Libgcrypt that initialization has completed. */
77 gcry_control(GCRYCTL_INITIALIZATION_FINISHED, 0);
79 get_random_bytes_or_die((unsigned char *)&seed, sizeof(seed));
83 void crypt_shutdown(void)
86 * WK does not see a way to apply a patch for the sake of Valgrind, so
87 * as of 2018 libgrypt has no deinitialization routine to free the
92 /** S-expression for the public part of an RSA key. */
93 #define RSA_PUBKEY_SEXP "(public-key (rsa (n %m) (e %m)))"
94 /** S-expression for a private RSA key. */
95 #define RSA_PRIVKEY_SEXP "(private-key (rsa (n %m) (e %m) (d %m) (p %m) (q %m) (u %m)))"
96 /** S-expression for decryption. */
97 #define RSA_DECRYPT_SEXP "(enc-val(flags oaep)(rsa(a %m)))"
99 struct asymmetric_key {
104 static const char *gcrypt_strerror(gcry_error_t gret)
106 return gcry_strerror(gcry_err_code(gret));
109 /** Private keys start with this header. */
110 #define PRIVATE_KEY_HEADER "-----BEGIN RSA PRIVATE KEY-----"
111 /** Private keys end with this footer. */
112 #define PRIVATE_KEY_FOOTER "-----END RSA PRIVATE KEY-----"
114 static int decode_key(const char *key_file, unsigned char **result)
118 size_t map_size, key_size, blob_size;
119 unsigned char *blob = NULL;
120 char *begin, *footer, *key;
122 ret = mmap_full_file(key_file, O_RDONLY, &map, &map_size, NULL);
126 if (strncmp(map, PRIVATE_KEY_HEADER, strlen(PRIVATE_KEY_HEADER)))
128 footer = strstr(map, PRIVATE_KEY_FOOTER);
132 begin = map + strlen(PRIVATE_KEY_HEADER);
133 /* skip whitespace at the beginning */
134 for (; begin < footer; begin++) {
135 if (para_isspace(*begin))
143 key_size = footer - begin;
144 key = para_malloc(key_size + 1);
145 for (i = 0, j = 0; begin + i < footer; i++) {
146 if (para_isspace(begin[i]))
151 ret = base64_decode(key, j, (char **)&blob, &blob_size);
161 ret2 = para_munmap(map, map_size);
162 if (ret >= 0 && ret2 < 0)
173 /** ASN Types and their code. */
175 /** The next object is an integer. */
176 ASN1_TYPE_INTEGER = 0x2,
177 /** Bit string object. */
178 ASN1_TYPE_BIT_STRING = 0x03,
179 /** Keys start with one big type sequence. */
180 ASN1_TYPE_SEQUENCE = 0x30,
183 /* bit 6 has value 0 */
184 static inline bool is_primitive(unsigned char c)
186 return (c & (1<<6)) == 0;
189 static inline bool is_primitive_integer(unsigned char c)
191 if (!is_primitive(c))
193 return (c & 0x1f) == ASN1_TYPE_INTEGER;
196 /* Bit 8 is zero (and bits 7-1 give the length) */
197 static inline bool is_short_form(unsigned char c)
199 return (c & 0x80) == 0;
202 static inline int get_short_form_length(unsigned char c)
207 static inline int get_long_form_num_length_bytes(unsigned char c)
213 * Returns: Number of bytes scanned. This may differ from the value returned via
214 * bn_bytes because the latter does not include the ASN.1 prefix and a leading
215 * zero is not considered as an additional byte for bn_bytes.
217 static int read_bignum(unsigned char *start, unsigned char *end, gcry_mpi_t *bn,
222 unsigned char *cp = start;
224 if (!is_primitive_integer(*cp))
225 return -E_BAD_PRIVATE_KEY;
227 if (is_short_form(*cp)) {
228 bn_size = get_short_form_length(*cp);
231 int num_bytes = get_long_form_num_length_bytes(*cp);
232 if (cp + num_bytes > end)
233 return -E_BAD_PRIVATE_KEY;
234 if (num_bytes > 4) /* nobody has such a large modulus */
235 return -E_BAD_PRIVATE_KEY;
238 for (i = 0; i < num_bytes; i++, cp++)
239 bn_size = (bn_size << 8) + *cp;
241 PARA_DEBUG_LOG("bn_size %d (0x%x)\n", bn_size, (unsigned)bn_size);
242 gret = gcry_mpi_scan(bn, GCRYMPI_FMT_STD, cp, bn_size, NULL);
244 PARA_ERROR_LOG("gcry_mpi_scan: %s\n",
245 gcry_strerror(gcry_err_code(gret)));
249 * Don't take the first leading zero into account for the size of the
259 // unsigned char *buf;
260 // gcry_mpi_aprint(GCRYMPI_FMT_HEX, &buf, NULL, *bn);
261 // PARA_CRIT_LOG("bn: %s\n", buf);
265 static int find_privkey_bignum_offset(const unsigned char *data, int len)
267 const unsigned char *p = data, *end = data + len;
269 /* like the public key, the whole thing is contained in a sequence */
270 if (*p != ASN1_TYPE_SEQUENCE)
271 return -E_ASN1_PARSE;
274 return -E_ASN1_PARSE;
275 if (is_short_form(*p))
278 p += 1 + get_long_form_num_length_bytes(*p);
280 return -E_ASN1_PARSE;
282 /* skip next integer */
283 if (*p != ASN1_TYPE_INTEGER)
284 return -E_ASN1_PARSE;
287 return -E_ASN1_PARSE;
288 if (is_short_form(*p))
289 p += 1 + get_short_form_length(*p);
291 p += 1 + get_long_form_num_length_bytes(*p);
293 return -E_ASN1_PARSE;
297 static int get_private_key(const char *key_file, struct asymmetric_key **result)
299 gcry_mpi_t n = NULL, e = NULL, d = NULL, p = NULL, q = NULL,
301 unsigned char *blob, *cp, *end;
302 int blob_size, ret, n_size;
306 struct asymmetric_key *key;
309 ret = decode_key(key_file, &blob);
313 end = blob + blob_size;
314 ret = find_privkey_bignum_offset(blob, blob_size);
317 PARA_INFO_LOG("reading RSA params at offset %d\n", ret);
320 ret = read_bignum(cp, end, &n, &n_size);
325 ret = read_bignum(cp, end, &e, NULL);
330 ret = read_bignum(cp, end, &d, NULL);
335 ret = read_bignum(cp, end, &p, NULL);
340 ret = read_bignum(cp, end, &q, NULL);
344 ret = read_bignum(cp, end, &u, NULL);
348 * OpenSSL uses slightly different parameters than gcrypt. To use these
349 * parameters we need to swap the values of p and q and recompute u.
351 if (gcry_mpi_cmp(p, q) > 0) {
353 gcry_mpi_invm(u, p, q);
355 gret = gcry_sexp_build(&sexp, &erroff, RSA_PRIVKEY_SEXP,
359 PARA_ERROR_LOG("offset %zu: %s\n", erroff,
360 gcry_strerror(gcry_err_code(gret)));
364 key = para_malloc(sizeof(*key));
368 PARA_INFO_LOG("succesfully read %d bit private key\n", ret);
386 int apc_get_pubkey(const char *key_file, struct asymmetric_key **result)
388 unsigned char *blob, *p, *end;
391 size_t nr_scanned, erroff, decoded_size;
394 struct asymmetric_key *key;
396 ret = decode_ssh_key(key_file, &blob, &decoded_size);
400 end = blob + decoded_size;
401 PARA_DEBUG_LOG("scanning modulus and public exponent\n");
402 gret = gcry_mpi_scan(&e, GCRYMPI_FMT_SSH, p, end - p, &nr_scanned);
405 PARA_CRIT_LOG("%s\n", gcry_strerror(gcry_err_code(gret)));
408 PARA_DEBUG_LOG("scanned e (%zu bytes)\n", nr_scanned);
412 gret = gcry_mpi_scan(&n, GCRYMPI_FMT_SSH, p, end - p, &nr_scanned);
415 PARA_ERROR_LOG("%s\n", gcry_strerror(gcry_err_code(gret)));
418 PARA_DEBUG_LOG("scanned n (%zu bytes)\n", nr_scanned);
419 gret = gcry_sexp_build(&sexp, &erroff, RSA_PUBKEY_SEXP, n, e);
421 PARA_ERROR_LOG("offset %zu: %s\n", erroff,
422 gcry_strerror(gcry_err_code(gret)));
426 ret = ROUND_DOWN(nr_scanned, 32);
427 PARA_INFO_LOG("successfully read %d bit ssh public key\n", ret * 8);
428 key = para_malloc(sizeof(*key));
429 key->num_bytes = ret;
441 void apc_free_pubkey(struct asymmetric_key *key)
445 gcry_sexp_release(key->sexp);
449 static int decode_rsa(gcry_sexp_t sexp, unsigned char *outbuf, size_t *nbytes)
451 const char *p = gcry_sexp_nth_data(sexp, 1, nbytes);
454 return -E_RSA_DECODE;
455 memcpy(outbuf, p, *nbytes);
459 int apc_priv_decrypt(const char *key_file, unsigned char *outbuf,
460 unsigned char *inbuf, int inlen)
464 struct asymmetric_key *priv;
465 gcry_mpi_t in_mpi = NULL;
466 gcry_sexp_t in, out, priv_key;
469 ret = check_private_key_file(key_file);
472 PARA_INFO_LOG("decrypting %d byte input\n", inlen);
473 /* key_file -> asymmetric key priv */
474 ret = get_private_key(key_file, &priv);
478 /* asymmetric key priv -> sexp priv_key */
480 priv_key = gcry_sexp_find_token(priv->sexp, "private-key", 0);
484 /* inbuf -> in_mpi */
485 gret = gcry_mpi_scan(&in_mpi, GCRYMPI_FMT_USG, inbuf,
488 PARA_ERROR_LOG("%s\n", gcrypt_strerror(gret));
492 /* in_mpi -> in sexp */
493 gret = gcry_sexp_build(&in, NULL, RSA_DECRYPT_SEXP, in_mpi);
495 PARA_ERROR_LOG("%s\n", gcrypt_strerror(gret));
500 /* rsa decryption: in sexp -> out sexp */
501 gret = gcry_pk_decrypt(&out, in, priv_key);
503 PARA_ERROR_LOG("decrypt: %s\n", gcrypt_strerror(gret));
504 ret = -E_SEXP_DECRYPT;
507 ret = decode_rsa(out, outbuf, &nbytes);
510 PARA_INFO_LOG("successfully decrypted %zu byte message\n", nbytes);
513 gcry_sexp_release(out);
515 gcry_sexp_release(in);
517 gcry_mpi_release(in_mpi);
519 gcry_sexp_release(priv_key);
521 gcry_sexp_release(priv->sexp);
526 int apc_pub_encrypt(struct asymmetric_key *pub, unsigned char *inbuf,
527 unsigned len, unsigned char *outbuf)
530 gcry_sexp_t pub_key, in, out, out_a;
531 gcry_mpi_t out_mpi = NULL;
535 PARA_INFO_LOG("encrypting %u byte input with %d-byte key\n", len, pub->num_bytes);
538 pub_key = gcry_sexp_find_token(pub->sexp, "public-key", 0);
541 gret = gcry_sexp_build(&in, NULL, "(data(flags oaep)(value %b))", len, inbuf);
543 PARA_ERROR_LOG("%s\n", gcrypt_strerror(gret));
547 /* rsa sexp encryption: in -> out */
548 gret = gcry_pk_encrypt(&out, in, pub_key);
550 PARA_ERROR_LOG("%s\n", gcrypt_strerror(gret));
551 ret = -E_SEXP_ENCRYPT;
554 /* extract a, an MPI with the result of the RSA operation */
556 out_a = gcry_sexp_find_token(out, "a", 0);
559 /* convert sexp out_a -> out_mpi */
560 out_mpi = gcry_sexp_nth_mpi(out_a, 1, GCRYMPI_FMT_USG);
565 gret = gcry_mpi_print(GCRYMPI_FMT_USG, outbuf, 512 /* FIXME */, &nbytes, out_mpi);
567 PARA_ERROR_LOG("%s\n", gcrypt_strerror(gret));
568 ret = -E_SEXP_ENCRYPT;
569 goto out_mpi_release;
571 PARA_INFO_LOG("encrypted buffer is %zu bytes\n", nbytes);
572 dump_buffer("enc buf", outbuf, nbytes);
576 gcry_mpi_release(out_mpi);
578 gcry_sexp_release(out_a);
580 gcry_sexp_release(out);
582 gcry_sexp_release(in);
584 gcry_sexp_release(pub_key);
588 struct stream_cipher {
589 gcry_cipher_hd_t handle;
592 struct stream_cipher *sc_new(const unsigned char *data, int len)
595 struct stream_cipher *sc = para_malloc(sizeof(*sc));
597 assert(len >= 2 * AES_CRT128_BLOCK_SIZE);
598 gret = gcry_cipher_open(&sc->handle, GCRY_CIPHER_AES128,
599 GCRY_CIPHER_MODE_CTR, 0);
601 gret = gcry_cipher_setkey(sc->handle, data,
602 AES_CRT128_BLOCK_SIZE);
604 gret = gcry_cipher_setctr(sc->handle,
605 data + AES_CRT128_BLOCK_SIZE, AES_CRT128_BLOCK_SIZE);
610 void sc_free(struct stream_cipher *sc)
614 gcry_cipher_close(sc->handle);
618 void sc_crypt(struct stream_cipher *sc, struct iovec *src, struct iovec *dst)
620 gcry_cipher_hd_t handle = sc->handle;
623 /* perform in-place encryption */
625 gret = gcry_cipher_encrypt(handle, src->iov_base, src->iov_len,