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("%s while scanning n\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
,