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 /** ASN Types and their code. */
111 /** The next object is an integer. */
112 ASN1_TYPE_INTEGER = 0x2,
113 /** Bit string object. */
114 ASN1_TYPE_BIT_STRING = 0x03,
115 /** Keys start with one big type sequence. */
116 ASN1_TYPE_SEQUENCE = 0x30,
119 /* bit 6 has value 0 */
120 static inline bool is_primitive(unsigned char c)
122 return (c & (1<<6)) == 0;
125 static inline bool is_primitive_integer(unsigned char c)
127 if (!is_primitive(c))
129 return (c & 0x1f) == ASN1_TYPE_INTEGER;
132 /* Bit 8 is zero (and bits 7-1 give the length) */
133 static inline bool is_short_form(unsigned char c)
135 return (c & 0x80) == 0;
138 static inline int get_short_form_length(unsigned char c)
143 static inline int get_long_form_num_length_bytes(unsigned char c)
149 * Returns: Number of bytes scanned. This may differ from the value returned via
150 * bitsp because the latter does not include the ASN.1 prefix and a leading
151 * zero is not considered as an additional byte for the number of bits.
153 static int read_pem_bignum(unsigned char *start, unsigned char *end, gcry_mpi_t *bn,
158 unsigned char *cp = start;
160 if (!is_primitive_integer(*cp))
161 return -E_BAD_PRIVATE_KEY;
163 if (is_short_form(*cp)) {
164 bn_size = get_short_form_length(*cp);
167 int num_bytes = get_long_form_num_length_bytes(*cp);
168 if (cp + num_bytes > end)
169 return -E_BAD_PRIVATE_KEY;
170 if (num_bytes > 4) /* nobody has such a large modulus */
171 return -E_BAD_PRIVATE_KEY;
174 for (i = 0; i < num_bytes; i++, cp++)
175 bn_size = (bn_size << 8) + *cp;
177 PARA_DEBUG_LOG("bn_size %d (0x%x)\n", bn_size, (unsigned)bn_size);
178 gret = gcry_mpi_scan(bn, GCRYMPI_FMT_STD, cp, bn_size, NULL);
180 PARA_ERROR_LOG("gcry_mpi_scan: %s\n",
181 gcry_strerror(gcry_err_code(gret)));
185 * Don't take the first leading zero into account for the size of the
193 *bitsp = bn_size * 8;
195 // unsigned char *buf;
196 // gcry_mpi_aprint(GCRYMPI_FMT_HEX, &buf, NULL, *bn);
197 // PARA_CRIT_LOG("bn: %s\n", buf);
202 gcry_mpi_t n, e, d, p, q, u;
205 static int read_pem_rsa_params(unsigned char *start, unsigned char *end,
206 struct rsa_params *p)
208 unsigned char *cp = start;
212 ret = read_pem_bignum(cp, end, &p->n, &bits);
216 ret = read_pem_bignum(cp, end, &p->e, NULL);
220 ret = read_pem_bignum(cp, end, &p->d, NULL);
224 ret = read_pem_bignum(cp, end, &p->p, NULL);
228 ret = read_pem_bignum(cp, end, &p->q, NULL);
232 ret = read_pem_bignum(cp, end, &p->u, NULL);
237 gcry_mpi_release(p->q);
239 gcry_mpi_release(p->p);
241 gcry_mpi_release(p->d);
243 gcry_mpi_release(p->e);
245 gcry_mpi_release(p->n);
249 static int find_pem_bignum_offset(const unsigned char *data, int len)
251 const unsigned char *p = data, *end = data + len;
253 /* like the public key, the whole thing is contained in a sequence */
254 if (*p != ASN1_TYPE_SEQUENCE)
255 return -E_ASN1_PARSE;
258 return -E_ASN1_PARSE;
259 if (is_short_form(*p))
262 p += 1 + get_long_form_num_length_bytes(*p);
264 return -E_ASN1_PARSE;
266 /* skip next integer */
267 if (*p != ASN1_TYPE_INTEGER)
268 return -E_ASN1_PARSE;
271 return -E_ASN1_PARSE;
272 if (is_short_form(*p))
273 p += 1 + get_short_form_length(*p);
275 p += 1 + get_long_form_num_length_bytes(*p);
277 return -E_ASN1_PARSE;
281 static int read_openssh_bignum(unsigned char *start, unsigned char *end,
282 gcry_mpi_t *bn, unsigned *bitsp)
288 gret = gcry_mpi_scan(bn, GCRYMPI_FMT_SSH, start, end - start, &nscanned);
290 PARA_ERROR_LOG("gcry_mpi_scan: %s\n",
291 gcry_strerror(gcry_err_code(gret)));
294 bits = (nscanned - 4 - (start[4] == '\0')) * 8;
297 PARA_DEBUG_LOG("scanned %u-bit bignum\n", bits);
301 static int read_openssh_rsa_params(unsigned char *start, unsigned char *end,
302 struct rsa_params *p)
304 unsigned char *cp = start;
308 ret = read_openssh_bignum(cp, end, &p->n, &bits);
312 ret = read_openssh_bignum(cp, end, &p->e, NULL);
316 ret = read_openssh_bignum(cp, end, &p->d, NULL);
320 ret = read_openssh_bignum(cp, end, &p->u, NULL);
324 ret = read_openssh_bignum(cp, end, &p->p, NULL);
328 ret = read_openssh_bignum(cp, end, &p->q, NULL);
333 gcry_mpi_release(p->p);
335 gcry_mpi_release(p->u);
337 gcry_mpi_release(p->d);
339 gcry_mpi_release(p->e);
341 gcry_mpi_release(p->n);
345 static int get_private_key(const char *key_file, struct asymmetric_key **result)
347 struct rsa_params params;
348 unsigned char *blob, *end;
352 size_t erroff, blob_size;
354 struct asymmetric_key *key;
357 ret = decode_private_key(key_file, &blob, &blob_size);
361 end = blob + blob_size;
362 if (key_type == PKT_PEM)
363 ret = find_pem_bignum_offset(blob, blob_size);
365 ret = find_openssh_bignum_offset(blob, blob_size);
368 PARA_INFO_LOG("reading RSA params at offset %d\n", ret);
369 if (key_type == PKT_PEM)
370 ret = read_pem_rsa_params(blob + ret, end, ¶ms);
372 ret = read_openssh_rsa_params(blob + ret, end, ¶ms);
377 * OpenSSL uses slightly different parameters than gcrypt. To use these
378 * parameters we need to swap the values of p and q and recompute u.
380 if (gcry_mpi_cmp(params.p, params.q) > 0) {
381 gcry_mpi_swap(params.p, params.q);
382 gcry_mpi_invm(params.u, params.p, params.q);
384 gret = gcry_sexp_build(&sexp, &erroff, RSA_PRIVKEY_SEXP, params.n,
385 params.e, params.d, params.p, params.q, params.u);
388 PARA_ERROR_LOG("offset %zu: %s\n", erroff,
389 gcry_strerror(gcry_err_code(gret)));
393 key = para_malloc(sizeof(*key));
397 PARA_INFO_LOG("succesfully read %d bit private key\n", ret);
399 gcry_mpi_release(params.n);
400 gcry_mpi_release(params.e);
401 gcry_mpi_release(params.d);
402 gcry_mpi_release(params.u);
403 gcry_mpi_release(params.p);
404 gcry_mpi_release(params.q);
411 int apc_get_pubkey(const char *key_file, struct asymmetric_key **result)
413 unsigned char *blob, *p, *end;
416 size_t erroff, decoded_size;
419 struct asymmetric_key *key;
422 ret = decode_public_key(key_file, &blob, &decoded_size);
426 end = blob + decoded_size;
427 PARA_DEBUG_LOG("scanning modulus and public exponent\n");
428 ret = read_openssh_bignum(p, end, &e, NULL);
432 ret = read_openssh_bignum(p, end, &n, &bits);
435 gret = gcry_sexp_build(&sexp, &erroff, RSA_PUBKEY_SEXP, n, e);
437 PARA_ERROR_LOG("offset %zu: %s\n", erroff,
438 gcry_strerror(gcry_err_code(gret)));
442 PARA_INFO_LOG("successfully read %u bit ssh public key\n", bits);
443 key = para_malloc(sizeof(*key));
444 key->num_bytes = ret;
457 void apc_free_pubkey(struct asymmetric_key *key)
461 gcry_sexp_release(key->sexp);
465 static int decode_rsa(gcry_sexp_t sexp, unsigned char *outbuf, size_t *nbytes)
467 const char *p = gcry_sexp_nth_data(sexp, 1, nbytes);
470 return -E_RSA_DECODE;
471 memcpy(outbuf, p, *nbytes);
475 int apc_priv_decrypt(const char *key_file, unsigned char *outbuf,
476 unsigned char *inbuf, int inlen)
480 struct asymmetric_key *priv;
481 gcry_mpi_t in_mpi = NULL;
482 gcry_sexp_t in, out, priv_key;
485 ret = check_private_key_file(key_file);
488 PARA_INFO_LOG("decrypting %d byte input\n", inlen);
489 /* key_file -> asymmetric key priv */
490 ret = get_private_key(key_file, &priv);
494 /* asymmetric key priv -> sexp priv_key */
496 priv_key = gcry_sexp_find_token(priv->sexp, "private-key", 0);
500 /* inbuf -> in_mpi */
501 gret = gcry_mpi_scan(&in_mpi, GCRYMPI_FMT_USG, inbuf,
504 PARA_ERROR_LOG("%s\n", gcrypt_strerror(gret));
508 /* in_mpi -> in sexp */
509 gret = gcry_sexp_build(&in, NULL, RSA_DECRYPT_SEXP, in_mpi);
511 PARA_ERROR_LOG("%s\n", gcrypt_strerror(gret));
516 /* rsa decryption: in sexp -> out sexp */
517 gret = gcry_pk_decrypt(&out, in, priv_key);
519 PARA_ERROR_LOG("decrypt: %s\n", gcrypt_strerror(gret));
520 ret = -E_SEXP_DECRYPT;
523 ret = decode_rsa(out, outbuf, &nbytes);
526 PARA_INFO_LOG("successfully decrypted %zu byte message\n", nbytes);
529 gcry_sexp_release(out);
531 gcry_sexp_release(in);
533 gcry_mpi_release(in_mpi);
535 gcry_sexp_release(priv_key);
537 gcry_sexp_release(priv->sexp);
542 int apc_pub_encrypt(struct asymmetric_key *pub, unsigned char *inbuf,
543 unsigned len, unsigned char *outbuf)
546 gcry_sexp_t pub_key, in, out, out_a;
547 gcry_mpi_t out_mpi = NULL;
551 PARA_INFO_LOG("encrypting %u byte input with %d-byte key\n", len, pub->num_bytes);
554 pub_key = gcry_sexp_find_token(pub->sexp, "public-key", 0);
557 gret = gcry_sexp_build(&in, NULL, "(data(flags oaep)(value %b))", len, inbuf);
559 PARA_ERROR_LOG("%s\n", gcrypt_strerror(gret));
563 /* rsa sexp encryption: in -> out */
564 gret = gcry_pk_encrypt(&out, in, pub_key);
566 PARA_ERROR_LOG("%s\n", gcrypt_strerror(gret));
567 ret = -E_SEXP_ENCRYPT;
570 /* extract a, an MPI with the result of the RSA operation */
572 out_a = gcry_sexp_find_token(out, "a", 0);
575 /* convert sexp out_a -> out_mpi */
576 out_mpi = gcry_sexp_nth_mpi(out_a, 1, GCRYMPI_FMT_USG);
581 gret = gcry_mpi_print(GCRYMPI_FMT_USG, outbuf, 512 /* FIXME */, &nbytes, out_mpi);
583 PARA_ERROR_LOG("%s\n", gcrypt_strerror(gret));
584 ret = -E_SEXP_ENCRYPT;
585 goto out_mpi_release;
587 PARA_INFO_LOG("encrypted buffer is %zu bytes\n", nbytes);
588 dump_buffer("enc buf", outbuf, nbytes);
592 gcry_mpi_release(out_mpi);
594 gcry_sexp_release(out_a);
596 gcry_sexp_release(out);
598 gcry_sexp_release(in);
600 gcry_sexp_release(pub_key);
604 struct stream_cipher {
605 gcry_cipher_hd_t handle;
608 struct stream_cipher *sc_new(const unsigned char *data, int len)
611 struct stream_cipher *sc = para_malloc(sizeof(*sc));
613 assert(len >= 2 * AES_CRT128_BLOCK_SIZE);
614 gret = gcry_cipher_open(&sc->handle, GCRY_CIPHER_AES128,
615 GCRY_CIPHER_MODE_CTR, 0);
617 gret = gcry_cipher_setkey(sc->handle, data,
618 AES_CRT128_BLOCK_SIZE);
620 gret = gcry_cipher_setctr(sc->handle,
621 data + AES_CRT128_BLOCK_SIZE, AES_CRT128_BLOCK_SIZE);
626 void sc_free(struct stream_cipher *sc)
630 gcry_cipher_close(sc->handle);
634 void sc_crypt(struct stream_cipher *sc, struct iovec *src, struct iovec *dst)
636 gcry_cipher_hd_t handle = sc->handle;
639 /* perform in-place encryption */
641 gret = gcry_cipher_encrypt(handle, src->iov_base, src->iov_len,