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 static int decode_key(const char *key_file, const char *header_str,
110 const char *footer_str, unsigned char **result)
114 size_t map_size, key_size, blob_size;
115 unsigned char *blob = NULL;
116 char *begin, *footer, *key;
118 ret = mmap_full_file(key_file, O_RDONLY, &map, &map_size, NULL);
122 if (strncmp(map, header_str, strlen(header_str)))
124 footer = strstr(map, footer_str);
128 begin = map + strlen(header_str);
129 /* skip whitespace at the beginning */
130 for (; begin < footer; begin++) {
131 if (para_isspace(*begin))
139 key_size = footer - begin;
140 key = para_malloc(key_size + 1);
141 for (i = 0, j = 0; begin + i < footer; i++) {
142 if (para_isspace(begin[i]))
147 ret = base64_decode(key, j, (char **)&blob, &blob_size);
157 ret2 = para_munmap(map, map_size);
158 if (ret >= 0 && ret2 < 0)
169 /** ASN Types and their code. */
171 /** The next object is an integer. */
172 ASN1_TYPE_INTEGER = 0x2,
173 /** Bit string object. */
174 ASN1_TYPE_BIT_STRING = 0x03,
175 /** Keys start with one big type sequence. */
176 ASN1_TYPE_SEQUENCE = 0x30,
179 /* bit 6 has value 0 */
180 static inline bool is_primitive(unsigned char c)
182 return (c & (1<<6)) == 0;
185 static inline bool is_primitive_integer(unsigned char c)
187 if (!is_primitive(c))
189 return (c & 0x1f) == ASN1_TYPE_INTEGER;
192 /* Bit 8 is zero (and bits 7-1 give the length) */
193 static inline bool is_short_form(unsigned char c)
195 return (c & 0x80) == 0;
198 static inline int get_short_form_length(unsigned char c)
203 static inline int get_long_form_num_length_bytes(unsigned char c)
209 * Returns: Number of bytes scanned. This may differ from the value returned via
210 * bn_bytes because the latter does not include the ASN.1 prefix and a leading
211 * zero is not considered as an additional byte for bn_bytes.
213 static int read_bignum(unsigned char *start, unsigned char *end, gcry_mpi_t *bn,
218 unsigned char *cp = start;
220 if (!is_primitive_integer(*cp))
221 return -E_BAD_PRIVATE_KEY;
223 if (is_short_form(*cp)) {
224 bn_size = get_short_form_length(*cp);
227 int num_bytes = get_long_form_num_length_bytes(*cp);
228 if (cp + num_bytes > end)
229 return -E_BAD_PRIVATE_KEY;
230 if (num_bytes > 4) /* nobody has such a large modulus */
231 return -E_BAD_PRIVATE_KEY;
234 for (i = 0; i < num_bytes; i++, cp++)
235 bn_size = (bn_size << 8) + *cp;
237 PARA_DEBUG_LOG("bn_size %d (0x%x)\n", bn_size, (unsigned)bn_size);
238 gret = gcry_mpi_scan(bn, GCRYMPI_FMT_STD, cp, bn_size, NULL);
240 PARA_ERROR_LOG("gcry_mpi_scan: %s\n",
241 gcry_strerror(gcry_err_code(gret)));
245 * Don't take the first leading zero into account for the size of the
255 // unsigned char *buf;
256 // gcry_mpi_aprint(GCRYMPI_FMT_HEX, &buf, NULL, *bn);
257 // PARA_CRIT_LOG("bn: %s\n", buf);
261 static int find_privkey_bignum_offset(const unsigned char *data, int len)
263 const unsigned char *p = data, *end = data + len;
265 /* like the public key, the whole thing is contained in a sequence */
266 if (*p != ASN1_TYPE_SEQUENCE)
267 return -E_ASN1_PARSE;
270 return -E_ASN1_PARSE;
271 if (is_short_form(*p))
274 p += 1 + get_long_form_num_length_bytes(*p);
276 return -E_ASN1_PARSE;
278 /* skip next integer */
279 if (*p != ASN1_TYPE_INTEGER)
280 return -E_ASN1_PARSE;
283 return -E_ASN1_PARSE;
284 if (is_short_form(*p))
285 p += 1 + get_short_form_length(*p);
287 p += 1 + get_long_form_num_length_bytes(*p);
289 return -E_ASN1_PARSE;
293 /** Private keys start with this header. */
294 #define PRIVATE_KEY_HEADER "-----BEGIN RSA PRIVATE KEY-----"
295 /** Private keys end with this footer. */
296 #define PRIVATE_KEY_FOOTER "-----END RSA PRIVATE KEY-----"
298 static int get_private_key(const char *key_file, struct asymmetric_key **result)
300 gcry_mpi_t n = NULL, e = NULL, d = NULL, p = NULL, q = NULL,
302 unsigned char *blob, *cp, *end;
303 int blob_size, ret, n_size;
307 struct asymmetric_key *key;
310 ret = decode_key(key_file, PRIVATE_KEY_HEADER, PRIVATE_KEY_FOOTER,
315 end = blob + blob_size;
316 ret = find_privkey_bignum_offset(blob, blob_size);
319 PARA_INFO_LOG("reading RSA params at offset %d\n", ret);
322 ret = read_bignum(cp, end, &n, &n_size);
327 ret = read_bignum(cp, end, &e, NULL);
332 ret = read_bignum(cp, end, &d, NULL);
337 ret = read_bignum(cp, end, &p, NULL);
342 ret = read_bignum(cp, end, &q, NULL);
346 ret = read_bignum(cp, end, &u, NULL);
350 * OpenSSL uses slightly different parameters than gcrypt. To use these
351 * parameters we need to swap the values of p and q and recompute u.
353 if (gcry_mpi_cmp(p, q) > 0) {
355 gcry_mpi_invm(u, p, q);
357 gret = gcry_sexp_build(&sexp, &erroff, RSA_PRIVKEY_SEXP,
361 PARA_ERROR_LOG("offset %zu: %s\n", erroff,
362 gcry_strerror(gcry_err_code(gret)));
366 key = para_malloc(sizeof(*key));
370 PARA_INFO_LOG("succesfully read %d bit private key\n", ret);
388 int apc_get_pubkey(const char *key_file, struct asymmetric_key **result)
390 unsigned char *blob, *p, *end;
393 size_t nr_scanned, erroff, decoded_size;
396 struct asymmetric_key *key;
398 ret = decode_ssh_key(key_file, &blob, &decoded_size);
402 end = blob + decoded_size;
403 PARA_DEBUG_LOG("scanning modulus and public exponent\n");
404 gret = gcry_mpi_scan(&e, GCRYMPI_FMT_SSH, p, end - p, &nr_scanned);
407 PARA_CRIT_LOG("%s\n", gcry_strerror(gcry_err_code(gret)));
410 PARA_DEBUG_LOG("scanned e (%zu bytes)\n", nr_scanned);
414 gret = gcry_mpi_scan(&n, GCRYMPI_FMT_SSH, p, end - p, &nr_scanned);
417 PARA_ERROR_LOG("%s\n", gcry_strerror(gcry_err_code(gret)));
420 PARA_DEBUG_LOG("scanned n (%zu bytes)\n", nr_scanned);
421 gret = gcry_sexp_build(&sexp, &erroff, RSA_PUBKEY_SEXP, n, e);
423 PARA_ERROR_LOG("offset %zu: %s\n", erroff,
424 gcry_strerror(gcry_err_code(gret)));
428 ret = ROUND_DOWN(nr_scanned, 32);
429 PARA_INFO_LOG("successfully read %d bit ssh public key\n", ret * 8);
430 key = para_malloc(sizeof(*key));
431 key->num_bytes = ret;
443 void apc_free_pubkey(struct asymmetric_key *key)
447 gcry_sexp_release(key->sexp);
451 static int decode_rsa(gcry_sexp_t sexp, unsigned char *outbuf, size_t *nbytes)
453 const char *p = gcry_sexp_nth_data(sexp, 1, nbytes);
456 return -E_RSA_DECODE;
457 memcpy(outbuf, p, *nbytes);
461 int apc_priv_decrypt(const char *key_file, unsigned char *outbuf,
462 unsigned char *inbuf, int inlen)
466 struct asymmetric_key *priv;
467 gcry_mpi_t in_mpi = NULL;
468 gcry_sexp_t in, out, priv_key;
471 ret = check_private_key_file(key_file);
474 PARA_INFO_LOG("decrypting %d byte input\n", inlen);
475 /* key_file -> asymmetric key priv */
476 ret = get_private_key(key_file, &priv);
480 /* asymmetric key priv -> sexp priv_key */
482 priv_key = gcry_sexp_find_token(priv->sexp, "private-key", 0);
486 /* inbuf -> in_mpi */
487 gret = gcry_mpi_scan(&in_mpi, GCRYMPI_FMT_USG, inbuf,
490 PARA_ERROR_LOG("%s\n", gcrypt_strerror(gret));
494 /* in_mpi -> in sexp */
495 gret = gcry_sexp_build(&in, NULL, RSA_DECRYPT_SEXP, in_mpi);
497 PARA_ERROR_LOG("%s\n", gcrypt_strerror(gret));
502 /* rsa decryption: in sexp -> out sexp */
503 gret = gcry_pk_decrypt(&out, in, priv_key);
505 PARA_ERROR_LOG("decrypt: %s\n", gcrypt_strerror(gret));
506 ret = -E_SEXP_DECRYPT;
509 ret = decode_rsa(out, outbuf, &nbytes);
512 PARA_INFO_LOG("successfully decrypted %zu byte message\n", nbytes);
515 gcry_sexp_release(out);
517 gcry_sexp_release(in);
519 gcry_mpi_release(in_mpi);
521 gcry_sexp_release(priv_key);
523 gcry_sexp_release(priv->sexp);
528 int apc_pub_encrypt(struct asymmetric_key *pub, unsigned char *inbuf,
529 unsigned len, unsigned char *outbuf)
532 gcry_sexp_t pub_key, in, out, out_a;
533 gcry_mpi_t out_mpi = NULL;
537 PARA_INFO_LOG("encrypting %u byte input with %d-byte key\n", len, pub->num_bytes);
540 pub_key = gcry_sexp_find_token(pub->sexp, "public-key", 0);
543 gret = gcry_sexp_build(&in, NULL, "(data(flags oaep)(value %b))", len, inbuf);
545 PARA_ERROR_LOG("%s\n", gcrypt_strerror(gret));
549 /* rsa sexp encryption: in -> out */
550 gret = gcry_pk_encrypt(&out, in, pub_key);
552 PARA_ERROR_LOG("%s\n", gcrypt_strerror(gret));
553 ret = -E_SEXP_ENCRYPT;
556 /* extract a, an MPI with the result of the RSA operation */
558 out_a = gcry_sexp_find_token(out, "a", 0);
561 /* convert sexp out_a -> out_mpi */
562 out_mpi = gcry_sexp_nth_mpi(out_a, 1, GCRYMPI_FMT_USG);
567 gret = gcry_mpi_print(GCRYMPI_FMT_USG, outbuf, 512 /* FIXME */, &nbytes, out_mpi);
569 PARA_ERROR_LOG("%s\n", gcrypt_strerror(gret));
570 ret = -E_SEXP_ENCRYPT;
571 goto out_mpi_release;
573 PARA_INFO_LOG("encrypted buffer is %zu bytes\n", nbytes);
574 dump_buffer("enc buf", outbuf, nbytes);
578 gcry_mpi_release(out_mpi);
580 gcry_sexp_release(out_a);
582 gcry_sexp_release(out);
584 gcry_sexp_release(in);
586 gcry_sexp_release(pub_key);
590 struct stream_cipher {
591 gcry_cipher_hd_t handle;
594 struct stream_cipher *sc_new(const unsigned char *data, int len)
597 struct stream_cipher *sc = para_malloc(sizeof(*sc));
599 assert(len >= 2 * AES_CRT128_BLOCK_SIZE);
600 gret = gcry_cipher_open(&sc->handle, GCRY_CIPHER_AES128,
601 GCRY_CIPHER_MODE_CTR, 0);
603 gret = gcry_cipher_setkey(sc->handle, data,
604 AES_CRT128_BLOCK_SIZE);
606 gret = gcry_cipher_setctr(sc->handle,
607 data + AES_CRT128_BLOCK_SIZE, AES_CRT128_BLOCK_SIZE);
612 void sc_free(struct stream_cipher *sc)
616 gcry_cipher_close(sc->handle);
620 void sc_crypt(struct stream_cipher *sc, struct iovec *src, struct iovec *dst)
622 gcry_cipher_hd_t handle = sc->handle;
625 /* perform in-place encryption */
627 gret = gcry_cipher_encrypt(handle, src->iov_base, src->iov_len,