/* This file is part of GNUnet. (C) 2012, 2013 Christian Grothoff (and other contributing authors) GNUnet is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2, or (at your option) any later version. GNUnet is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with GNUnet; see the file COPYING. If not, write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ /** * @file util/crypto_ecc.c * @brief public key cryptography (ECC) with libgcrypt * @author Christian Grothoff */ #include "platform.h" #include #include "gnunet_common.h" #include "gnunet_util_lib.h" #define EXTRA_CHECKS ALLOW_EXTRA_CHECKS #define CURVE "NIST P-256" #define LOG(kind,...) GNUNET_log_from (kind, "util", __VA_ARGS__) #define LOG_STRERROR(kind,syscall) GNUNET_log_from_strerror (kind, "util", syscall) #define LOG_STRERROR_FILE(kind,syscall,filename) GNUNET_log_from_strerror_file (kind, "util", syscall, filename) /** * Log an error message at log-level 'level' that indicates * a failure of the command 'cmd' with the message given * by gcry_strerror(rc). */ #define LOG_GCRY(level, cmd, rc) do { LOG(level, _("`%s' failed at %s:%d with error: %s\n"), cmd, __FILE__, __LINE__, gcry_strerror(rc)); } while(0); /** * The private information of an ECC private key. */ struct GNUNET_CRYPTO_EccPrivateKey { /** * Libgcrypt S-expression for the ECC key. */ gcry_sexp_t sexp; }; /** * Free memory occupied by ECC key * * @param privatekey pointer to the memory to free */ void GNUNET_CRYPTO_ecc_key_free (struct GNUNET_CRYPTO_EccPrivateKey *privatekey) { gcry_sexp_release (privatekey->sexp); GNUNET_free (privatekey); } /** * Extract values from an S-expression. * * @param array where to store the result(s) * @param sexp S-expression to parse * @param topname top-level name in the S-expression that is of interest * @param elems names of the elements to extract * @return 0 on success */ static int key_from_sexp (gcry_mpi_t * array, gcry_sexp_t sexp, const char *topname, const char *elems) { gcry_sexp_t list; gcry_sexp_t l2; const char *s; unsigned int i; unsigned int idx; list = gcry_sexp_find_token (sexp, topname, 0); if (! list) return 1; l2 = gcry_sexp_cadr (list); gcry_sexp_release (list); list = l2; if (! list) return 2; idx = 0; for (s = elems; *s; s++, idx++) { l2 = gcry_sexp_find_token (list, s, 1); if (! l2) { for (i = 0; i < idx; i++) { gcry_free (array[i]); array[i] = NULL; } gcry_sexp_release (list); return 3; /* required parameter not found */ } array[idx] = gcry_sexp_nth_mpi (l2, 1, GCRYMPI_FMT_USG); gcry_sexp_release (l2); if (! array[idx]) { for (i = 0; i < idx; i++) { gcry_free (array[i]); array[i] = NULL; } gcry_sexp_release (list); return 4; /* required parameter is invalid */ } } gcry_sexp_release (list); return 0; } /** * Extract the public key for the given private key. * * @param priv the private key * @param pub where to write the public key */ void GNUNET_CRYPTO_ecc_key_get_public (const struct GNUNET_CRYPTO_EccPrivateKey *priv, struct GNUNET_CRYPTO_EccPublicKeyBinaryEncoded *pub) { gcry_mpi_t skey; size_t size; int rc; memset (pub, 0, sizeof (struct GNUNET_CRYPTO_EccPublicKeyBinaryEncoded)); rc = key_from_sexp (&skey, priv->sexp, "public-key", "q"); if (rc) rc = key_from_sexp (&skey, priv->sexp, "private-key", "q"); if (rc) rc = key_from_sexp (&skey, priv->sexp, "ecc", "q"); GNUNET_assert (0 == rc); pub->size = htons (sizeof (struct GNUNET_CRYPTO_EccPublicKeyBinaryEncoded)); size = GNUNET_CRYPTO_ECC_MAX_PUBLIC_KEY_LENGTH; GNUNET_assert (0 == gcry_mpi_print (GCRYMPI_FMT_USG, pub->key, size, &size, skey)); pub->len = htons (size); gcry_mpi_release (skey); } /** * Convert a public key to a string. * * @param pub key to convert * @return string representing 'pub' */ char * GNUNET_CRYPTO_ecc_public_key_to_string (const struct GNUNET_CRYPTO_EccPublicKeyBinaryEncoded *pub) { char *pubkeybuf; size_t keylen = (sizeof (struct GNUNET_CRYPTO_EccPublicKeyBinaryEncoded)) * 8; char *end; if (keylen % 5 > 0) keylen += 5 - keylen % 5; keylen /= 5; pubkeybuf = GNUNET_malloc (keylen + 1); end = GNUNET_STRINGS_data_to_string ((unsigned char *) pub, sizeof (struct GNUNET_CRYPTO_EccPublicKeyBinaryEncoded), pubkeybuf, keylen); if (NULL == end) { GNUNET_free (pubkeybuf); return NULL; } *end = '\0'; return pubkeybuf; } /** * Convert a string representing a public key to a public key. * * @param enc encoded public key * @param enclen number of bytes in enc (without 0-terminator) * @param pub where to store the public key * @return GNUNET_OK on success */ int GNUNET_CRYPTO_ecc_public_key_from_string (const char *enc, size_t enclen, struct GNUNET_CRYPTO_EccPublicKeyBinaryEncoded *pub) { size_t keylen = (sizeof (struct GNUNET_CRYPTO_EccPublicKeyBinaryEncoded)) * 8; if (keylen % 5 > 0) keylen += 5 - keylen % 5; keylen /= 5; if (enclen != keylen) return GNUNET_SYSERR; if (GNUNET_OK != GNUNET_STRINGS_string_to_data (enc, enclen, pub, sizeof (struct GNUNET_CRYPTO_EccPublicKeyBinaryEncoded))) return GNUNET_SYSERR; if ( (ntohs (pub->size) != sizeof (struct GNUNET_CRYPTO_EccPublicKeyBinaryEncoded)) || (ntohs (pub->len) > GNUNET_CRYPTO_ECC_SIGNATURE_DATA_ENCODING_LENGTH) ) return GNUNET_SYSERR; return GNUNET_OK; } /** * Convert the given public key from the network format to the * S-expression that can be used by libgcrypt. * * @param publicKey public key to decode * @return NULL on error */ static gcry_sexp_t decode_public_key (const struct GNUNET_CRYPTO_EccPublicKeyBinaryEncoded *publicKey) { gcry_sexp_t result; gcry_mpi_t q; size_t size; size_t erroff; int rc; if (ntohs (publicKey->len) > GNUNET_CRYPTO_ECC_SIGNATURE_DATA_ENCODING_LENGTH) { GNUNET_break (0); return NULL; } size = ntohs (publicKey->len); if (0 != (rc = gcry_mpi_scan (&q, GCRYMPI_FMT_USG, publicKey->key, size, &size))) { LOG_GCRY (GNUNET_ERROR_TYPE_ERROR, "gcry_mpi_scan", rc); return NULL; } rc = gcry_sexp_build (&result, &erroff, "(public-key(ecdsa(curve \"" CURVE "\")(q %m)))", q); gcry_mpi_release (q); if (0 != rc) { LOG_GCRY (GNUNET_ERROR_TYPE_ERROR, "gcry_sexp_build", rc); /* erroff gives more info */ return NULL; } #if EXTRA_CHECKS if (0 != (rc = gcry_pk_testkey (result))) { LOG_GCRY (GNUNET_ERROR_TYPE_ERROR, "gcry_pk_testkey", rc); gcry_sexp_release (result); return NULL; } #endif return result; } /** * Encode the private key in a format suitable for * storing it into a file. * * @param key key to encode * @return encoding of the private key. * The first 4 bytes give the size of the array, as usual. */ struct GNUNET_CRYPTO_EccPrivateKeyBinaryEncoded * GNUNET_CRYPTO_ecc_encode_key (const struct GNUNET_CRYPTO_EccPrivateKey *key) { struct GNUNET_CRYPTO_EccPrivateKeyBinaryEncoded *retval; char buf[65536]; uint16_t be; size_t size; #if EXTRA_CHECKS if (0 != gcry_pk_testkey (key->sexp)) { GNUNET_break (0); return NULL; } #endif size = gcry_sexp_sprint (key->sexp, GCRYSEXP_FMT_DEFAULT, &buf[2], sizeof (buf) - sizeof (uint16_t)); if (0 == size) { GNUNET_break (0); return NULL; } GNUNET_assert (size < 65536 - sizeof (uint16_t)); be = htons ((uint16_t) size + (sizeof (be))); memcpy (buf, &be, sizeof (be)); size += sizeof (be); retval = GNUNET_malloc (size); memcpy (retval, buf, size); return retval; } /** * Decode the private key from the file-format back * to the "normal", internal format. * * @param buf the buffer where the private key data is stored * @param len the length of the data in 'buffer' * @param validate GNUNET_YES to validate that the key is well-formed, * GNUNET_NO if the key comes from a totally trusted source * and validation is considered too expensive * @return NULL on error */ struct GNUNET_CRYPTO_EccPrivateKey * GNUNET_CRYPTO_ecc_decode_key (const char *buf, size_t len, int validate) { struct GNUNET_CRYPTO_EccPrivateKey *ret; uint16_t be; gcry_sexp_t sexp; int rc; size_t erroff; if (len < sizeof (uint16_t)) return NULL; memcpy (&be, buf, sizeof (be)); if (len < ntohs (be)) return NULL; len = ntohs (be); if (0 != (rc = gcry_sexp_sscan (&sexp, &erroff, &buf[2], len - sizeof (uint16_t)))) { LOG_GCRY (GNUNET_ERROR_TYPE_ERROR, "gcry_sexp_scan", rc); return NULL; } if ( (GNUNET_YES == validate) && (0 != (rc = gcry_pk_testkey (sexp))) ) { LOG_GCRY (GNUNET_ERROR_TYPE_ERROR, "gcry_pk_testkey", rc); return NULL; } ret = GNUNET_malloc (sizeof (struct GNUNET_CRYPTO_EccPrivateKey)); ret->sexp = sexp; return ret; } /** * Create a new private key. Caller must free return value. * * @return fresh private key */ struct GNUNET_CRYPTO_EccPrivateKey * GNUNET_CRYPTO_ecc_key_create () { struct GNUNET_CRYPTO_EccPrivateKey *ret; gcry_sexp_t s_key; gcry_sexp_t s_keyparam; int rc; if (0 != (rc = gcry_sexp_build (&s_keyparam, NULL, "(genkey(ecdsa(curve \"" CURVE "\")))"))) { LOG_GCRY (GNUNET_ERROR_TYPE_ERROR, "gcry_sexp_build", rc); return NULL; } if (0 != (rc = gcry_pk_genkey (&s_key, s_keyparam))) { LOG_GCRY (GNUNET_ERROR_TYPE_ERROR, "gcry_pk_genkey", rc); gcry_sexp_release (s_keyparam); return NULL; } gcry_sexp_release (s_keyparam); #if EXTRA_CHECKS if (0 != (rc = gcry_pk_testkey (s_key))) { LOG_GCRY (GNUNET_ERROR_TYPE_ERROR, "gcry_pk_testkey", rc); gcry_sexp_release (s_key); return NULL; } #endif ret = GNUNET_malloc (sizeof (struct GNUNET_CRYPTO_EccPrivateKey)); ret->sexp = s_key; return ret; } /** * Try to read the private key from the given file. * * @param filename file to read the key from * @return NULL on error */ static struct GNUNET_CRYPTO_EccPrivateKey * try_read_key (const char *filename) { struct GNUNET_CRYPTO_EccPrivateKey *ret; struct GNUNET_DISK_FileHandle *fd; OFF_T fs; if (GNUNET_YES != GNUNET_DISK_file_test (filename)) return NULL; /* key file exists already, read it! */ if (NULL == (fd = GNUNET_DISK_file_open (filename, GNUNET_DISK_OPEN_READ, GNUNET_DISK_PERM_NONE))) { LOG_STRERROR_FILE (GNUNET_ERROR_TYPE_ERROR, "open", filename); return NULL; } if (GNUNET_OK != (GNUNET_DISK_file_handle_size (fd, &fs))) { LOG_STRERROR_FILE (GNUNET_ERROR_TYPE_ERROR, "stat", filename); (void) GNUNET_DISK_file_close (fd); return NULL; } if (0 == fs) { GNUNET_break (GNUNET_OK == GNUNET_DISK_file_close (fd)); return NULL; } if (fs > UINT16_MAX) { LOG (GNUNET_ERROR_TYPE_ERROR, _("File `%s' does not contain a valid private key (too long, %llu bytes). Deleting it.\n"), filename, (unsigned long long) fs); GNUNET_break (GNUNET_OK == GNUNET_DISK_file_close (fd)); if (0 != UNLINK (filename)) LOG_STRERROR_FILE (GNUNET_ERROR_TYPE_WARNING, "unlink", filename); return NULL; } { char enc[fs]; GNUNET_break (fs == GNUNET_DISK_file_read (fd, enc, fs)); if (NULL == (ret = GNUNET_CRYPTO_ecc_decode_key ((char *) enc, fs, GNUNET_YES))) { LOG (GNUNET_ERROR_TYPE_ERROR, _("File `%s' does not contain a valid private key (failed decode, %llu bytes). Deleting it.\n"), filename, (unsigned long long) fs); GNUNET_break (GNUNET_OK == GNUNET_DISK_file_close (fd)); if (0 != UNLINK (filename)) LOG_STRERROR_FILE (GNUNET_ERROR_TYPE_WARNING, "unlink", filename); return NULL; } } GNUNET_break (GNUNET_OK == GNUNET_DISK_file_close (fd)); return ret; } /** * Wait for a short time (we're trying to lock a file or want * to give another process a shot at finishing a disk write, etc.). * Sleeps for 100ms (as that should be long enough for virtually all * modern systems to context switch and allow another process to do * some 'real' work). */ static void short_wait () { struct GNUNET_TIME_Relative timeout; timeout = GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_MILLISECONDS, 100); (void) GNUNET_NETWORK_socket_select (NULL, NULL, NULL, timeout); } /** * Create a new private key by reading it from a file. If the * files does not exist, create a new key and write it to the * file. Caller must free return value. Note that this function * can not guarantee that another process might not be trying * the same operation on the same file at the same time. * If the contents of the file * are invalid the old file is deleted and a fresh key is * created. * * @return new private key, NULL on error (for example, * permission denied) */ struct GNUNET_CRYPTO_EccPrivateKey * GNUNET_CRYPTO_ecc_key_create_from_file (const char *filename) { struct GNUNET_CRYPTO_EccPrivateKey *ret; struct GNUNET_CRYPTO_EccPrivateKeyBinaryEncoded *enc; uint16_t len; struct GNUNET_DISK_FileHandle *fd; unsigned int cnt; int ec; uint64_t fs; struct GNUNET_CRYPTO_EccPublicKeyBinaryEncoded pub; struct GNUNET_PeerIdentity pid; if (GNUNET_SYSERR == GNUNET_DISK_directory_create_for_file (filename)) return NULL; while (GNUNET_YES != GNUNET_DISK_file_test (filename)) { fd = GNUNET_DISK_file_open (filename, GNUNET_DISK_OPEN_WRITE | GNUNET_DISK_OPEN_CREATE | GNUNET_DISK_OPEN_FAILIFEXISTS, GNUNET_DISK_PERM_USER_READ | GNUNET_DISK_PERM_USER_WRITE); if (NULL == fd) { if (errno == EEXIST) { if (GNUNET_YES != GNUNET_DISK_file_test (filename)) { /* must exist but not be accessible, fail for good! */ if (0 != ACCESS (filename, R_OK)) LOG_STRERROR_FILE (GNUNET_ERROR_TYPE_ERROR, "access", filename); else GNUNET_break (0); /* what is going on!? */ return NULL; } continue; } LOG_STRERROR_FILE (GNUNET_ERROR_TYPE_ERROR, "open", filename); return NULL; } cnt = 0; while (GNUNET_YES != GNUNET_DISK_file_lock (fd, 0, sizeof (struct GNUNET_CRYPTO_EccPrivateKeyBinaryEncoded), GNUNET_YES)) { short_wait (); if (0 == ++cnt % 10) { ec = errno; LOG (GNUNET_ERROR_TYPE_ERROR, _("Could not acquire lock on file `%s': %s...\n"), filename, STRERROR (ec)); } } LOG (GNUNET_ERROR_TYPE_INFO, _("Creating a new private key. This may take a while.\n")); ret = GNUNET_CRYPTO_ecc_key_create (); GNUNET_assert (ret != NULL); enc = GNUNET_CRYPTO_ecc_encode_key (ret); GNUNET_assert (enc != NULL); GNUNET_assert (ntohs (enc->size) == GNUNET_DISK_file_write (fd, enc, ntohs (enc->size))); GNUNET_free (enc); GNUNET_DISK_file_sync (fd); if (GNUNET_YES != GNUNET_DISK_file_unlock (fd, 0, sizeof (struct GNUNET_CRYPTO_EccPrivateKeyBinaryEncoded))) LOG_STRERROR_FILE (GNUNET_ERROR_TYPE_WARNING, "fcntl", filename); GNUNET_assert (GNUNET_YES == GNUNET_DISK_file_close (fd)); GNUNET_CRYPTO_ecc_key_get_public (ret, &pub); GNUNET_CRYPTO_hash (&pub, sizeof (pub), &pid.hashPubKey); return ret; } /* key file exists already, read it! */ fd = GNUNET_DISK_file_open (filename, GNUNET_DISK_OPEN_READ, GNUNET_DISK_PERM_NONE); if (NULL == fd) { LOG_STRERROR_FILE (GNUNET_ERROR_TYPE_ERROR, "open", filename); return NULL; } cnt = 0; while (1) { if (GNUNET_YES != GNUNET_DISK_file_lock (fd, 0, sizeof (struct GNUNET_CRYPTO_EccPrivateKeyBinaryEncoded), GNUNET_NO)) { if (0 == ++cnt % 60) { ec = errno; LOG (GNUNET_ERROR_TYPE_ERROR, _("Could not acquire lock on file `%s': %s...\n"), filename, STRERROR (ec)); LOG (GNUNET_ERROR_TYPE_ERROR, _ ("This may be ok if someone is currently generating a private key.\n")); } short_wait (); continue; } if (GNUNET_YES != GNUNET_DISK_file_test (filename)) { /* eh, what!? File we opened is now gone!? */ LOG_STRERROR_FILE (GNUNET_ERROR_TYPE_WARNING, "stat", filename); if (GNUNET_YES != GNUNET_DISK_file_unlock (fd, 0, sizeof (struct GNUNET_CRYPTO_EccPrivateKeyBinaryEncoded))) LOG_STRERROR_FILE (GNUNET_ERROR_TYPE_WARNING, "fcntl", filename); GNUNET_assert (GNUNET_OK == GNUNET_DISK_file_close (fd)); return NULL; } if (GNUNET_OK != GNUNET_DISK_file_size (filename, &fs, GNUNET_YES, GNUNET_YES)) fs = 0; if (fs < sizeof (struct GNUNET_CRYPTO_EccPrivateKeyBinaryEncoded)) { /* maybe we got the read lock before the key generating * process had a chance to get the write lock; give it up! */ if (GNUNET_YES != GNUNET_DISK_file_unlock (fd, 0, sizeof (struct GNUNET_CRYPTO_EccPrivateKeyBinaryEncoded))) LOG_STRERROR_FILE (GNUNET_ERROR_TYPE_WARNING, "fcntl", filename); if (0 == ++cnt % 10) { LOG (GNUNET_ERROR_TYPE_ERROR, _ ("When trying to read key file `%s' I found %u bytes but I need at least %u.\n"), filename, (unsigned int) fs, (unsigned int) sizeof (struct GNUNET_CRYPTO_EccPrivateKeyBinaryEncoded)); LOG (GNUNET_ERROR_TYPE_ERROR, _ ("This may be ok if someone is currently generating a key.\n")); } short_wait (); /* wait a bit longer! */ continue; } break; } enc = GNUNET_malloc (fs); GNUNET_assert (fs == GNUNET_DISK_file_read (fd, enc, fs)); len = ntohs (enc->size); ret = NULL; if ((len > fs) || (NULL == (ret = GNUNET_CRYPTO_ecc_decode_key ((char *) enc, len, GNUNET_YES)))) { LOG (GNUNET_ERROR_TYPE_ERROR, _("File `%s' does not contain a valid private key. Deleting it.\n"), filename); if (0 != UNLINK (filename)) { LOG_STRERROR_FILE (GNUNET_ERROR_TYPE_WARNING, "unlink", filename); } } GNUNET_free (enc); if (GNUNET_YES != GNUNET_DISK_file_unlock (fd, 0, sizeof (struct GNUNET_CRYPTO_EccPrivateKeyBinaryEncoded))) LOG_STRERROR_FILE (GNUNET_ERROR_TYPE_WARNING, "fcntl", filename); GNUNET_assert (GNUNET_YES == GNUNET_DISK_file_close (fd)); if (ret != NULL) { GNUNET_CRYPTO_ecc_key_get_public (ret, &pub); GNUNET_CRYPTO_hash (&pub, sizeof (pub), &pid.hashPubKey); } return ret; } /** * Handle to cancel private key generation and state for the * key generation operation. */ struct GNUNET_CRYPTO_EccKeyGenerationContext { /** * Continuation to call upon completion. */ GNUNET_CRYPTO_EccKeyCallback cont; /** * Closure for 'cont'. */ void *cont_cls; /** * Name of the file. */ char *filename; /** * Handle to the helper process which does the key generation. */ struct GNUNET_OS_Process *gnunet_ecc; /** * Handle to 'stdout' of gnunet-ecc. We 'read' on stdout to detect * process termination (instead of messing with SIGCHLD). */ struct GNUNET_DISK_PipeHandle *gnunet_ecc_out; /** * Location where we store the private key if it already existed. * (if this is used, 'filename', 'gnunet_ecc' and 'gnunet_ecc_out' will * not be used). */ struct GNUNET_CRYPTO_EccPrivateKey *pk; /** * Task reading from 'gnunet_ecc_out' to wait for process termination. */ GNUNET_SCHEDULER_TaskIdentifier read_task; }; /** * Abort ECC key generation. * * @param gc key generation context to abort */ void GNUNET_CRYPTO_ecc_key_create_stop (struct GNUNET_CRYPTO_EccKeyGenerationContext *gc) { if (GNUNET_SCHEDULER_NO_TASK != gc->read_task) { GNUNET_SCHEDULER_cancel (gc->read_task); gc->read_task = GNUNET_SCHEDULER_NO_TASK; } if (NULL != gc->gnunet_ecc) { (void) GNUNET_OS_process_kill (gc->gnunet_ecc, SIGKILL); GNUNET_break (GNUNET_OK == GNUNET_OS_process_wait (gc->gnunet_ecc)); GNUNET_OS_process_destroy (gc->gnunet_ecc); GNUNET_DISK_pipe_close (gc->gnunet_ecc_out); } if (NULL != gc->filename) { if (0 != UNLINK (gc->filename)) GNUNET_log_strerror_file (GNUNET_ERROR_TYPE_WARNING, "unlink", gc->filename); GNUNET_free (gc->filename); } if (NULL != gc->pk) GNUNET_CRYPTO_ecc_key_free (gc->pk); GNUNET_free (gc); } /** * Task called upon shutdown or process termination of 'gnunet-ecc' during * ECC key generation. Check where we are and perform the appropriate * action. * * @param cls the 'struct GNUNET_CRYPTO_EccKeyGenerationContext' * @param tc scheduler context */ static void check_key_generation_completion (void *cls, const struct GNUNET_SCHEDULER_TaskContext *tc) { struct GNUNET_CRYPTO_EccKeyGenerationContext *gc = cls; struct GNUNET_CRYPTO_EccPrivateKey *pk; gc->read_task = GNUNET_SCHEDULER_NO_TASK; if (0 != (tc->reason & GNUNET_SCHEDULER_REASON_SHUTDOWN)) { gc->cont (gc->cont_cls, NULL, _("interrupted by shutdown")); GNUNET_CRYPTO_ecc_key_create_stop (gc); return; } GNUNET_assert (GNUNET_OK == GNUNET_OS_process_wait (gc->gnunet_ecc)); GNUNET_OS_process_destroy (gc->gnunet_ecc); gc->gnunet_ecc = NULL; if (NULL == (pk = try_read_key (gc->filename))) { GNUNET_break (0); gc->cont (gc->cont_cls, NULL, _("gnunet-ecc failed")); GNUNET_CRYPTO_ecc_key_create_stop (gc); return; } gc->cont (gc->cont_cls, pk, NULL); GNUNET_DISK_pipe_close (gc->gnunet_ecc_out); GNUNET_free (gc->filename); GNUNET_free (gc); } /** * Return the private ECC key which already existed on disk * (asynchronously) to the caller. * * @param cls the 'struct GNUNET_CRYPTO_EccKeyGenerationContext' * @param tc scheduler context (unused) */ static void async_return_key (void *cls, const struct GNUNET_SCHEDULER_TaskContext *tc) { struct GNUNET_CRYPTO_EccKeyGenerationContext *gc = cls; gc->cont (gc->cont_cls, gc->pk, NULL); GNUNET_free (gc); } /** * Create a new private key by reading it from a file. If the files * does not exist, create a new key and write it to the file. If the * contents of the file are invalid the old file is deleted and a * fresh key is created. * * @param filename name of file to use for storage * @param cont function to call when done (or on errors) * @param cont_cls closure for 'cont' * @return handle to abort operation, NULL on fatal errors (cont will not be called if NULL is returned) */ struct GNUNET_CRYPTO_EccKeyGenerationContext * GNUNET_CRYPTO_ecc_key_create_start (const char *filename, GNUNET_CRYPTO_EccKeyCallback cont, void *cont_cls) { struct GNUNET_CRYPTO_EccKeyGenerationContext *gc; struct GNUNET_CRYPTO_EccPrivateKey *pk; if (NULL != (pk = try_read_key (filename))) { /* quick happy ending: key already exists! */ gc = GNUNET_malloc (sizeof (struct GNUNET_CRYPTO_EccKeyGenerationContext)); gc->pk = pk; gc->cont = cont; gc->cont_cls = cont_cls; gc->read_task = GNUNET_SCHEDULER_add_now (&async_return_key, gc); return gc; } gc = GNUNET_malloc (sizeof (struct GNUNET_CRYPTO_EccKeyGenerationContext)); gc->filename = GNUNET_strdup (filename); gc->cont = cont; gc->cont_cls = cont_cls; gc->gnunet_ecc_out = GNUNET_DISK_pipe (GNUNET_NO, GNUNET_NO, GNUNET_NO, GNUNET_YES); if (NULL == gc->gnunet_ecc_out) { GNUNET_log_strerror (GNUNET_ERROR_TYPE_WARNING, "pipe"); GNUNET_free (gc->filename); GNUNET_free (gc); return NULL; } gc->gnunet_ecc = GNUNET_OS_start_process (GNUNET_NO, GNUNET_OS_INHERIT_STD_ERR, NULL, gc->gnunet_ecc_out, "gnunet-ecc", "gnunet-ecc", gc->filename, NULL); if (NULL == gc->gnunet_ecc) { GNUNET_log_strerror (GNUNET_ERROR_TYPE_WARNING, "fork"); GNUNET_DISK_pipe_close (gc->gnunet_ecc_out); GNUNET_free (gc->filename); GNUNET_free (gc); return NULL; } GNUNET_assert (GNUNET_OK == GNUNET_DISK_pipe_close_end (gc->gnunet_ecc_out, GNUNET_DISK_PIPE_END_WRITE)); gc->read_task = GNUNET_SCHEDULER_add_read_file (GNUNET_TIME_UNIT_FOREVER_REL, GNUNET_DISK_pipe_handle (gc->gnunet_ecc_out, GNUNET_DISK_PIPE_END_READ), &check_key_generation_completion, gc); return gc; } /** * Setup a key file for a peer given the name of the * configuration file (!). This function is used so that * at a later point code can be certain that reading a * key is fast (for example in time-dependent testcases). * * @param cfg_name name of the configuration file to use */ void GNUNET_CRYPTO_ecc_setup_key (const char *cfg_name) { struct GNUNET_CONFIGURATION_Handle *cfg; struct GNUNET_CRYPTO_EccPrivateKey *pk; char *fn; cfg = GNUNET_CONFIGURATION_create (); (void) GNUNET_CONFIGURATION_load (cfg, cfg_name); if (GNUNET_OK == GNUNET_CONFIGURATION_get_value_filename (cfg, "PEER", "PRIVATE_KEY", &fn)) { pk = GNUNET_CRYPTO_ecc_key_create_from_file (fn); if (NULL != pk) GNUNET_CRYPTO_ecc_key_free (pk); GNUNET_free (fn); } GNUNET_CONFIGURATION_destroy (cfg); } /** * Convert the data specified in the given purpose argument to an * S-expression suitable for signature operations. * * @param purpose data to convert * @return converted s-expression */ static gcry_sexp_t data_to_pkcs1 (const struct GNUNET_CRYPTO_EccSignaturePurpose *purpose) { struct GNUNET_CRYPTO_ShortHashCode hc; size_t bufSize; gcry_sexp_t data; GNUNET_CRYPTO_short_hash (purpose, ntohl (purpose->size), &hc); #define FORMATSTRING "(4:data(5:flags3:raw)(5:value32:01234567890123456789012345678901))" bufSize = strlen (FORMATSTRING) + 1; { char buff[bufSize]; memcpy (buff, FORMATSTRING, bufSize); memcpy (&buff [bufSize - strlen ("01234567890123456789012345678901))") - 1], &hc, sizeof (struct GNUNET_CRYPTO_ShortHashCode)); GNUNET_assert (0 == gcry_sexp_new (&data, buff, bufSize, 0)); } #undef FORMATSTRING return data; } /** * Sign a given block. * * @param key private key to use for the signing * @param purpose what to sign (size, purpose) * @param sig where to write the signature * @return GNUNET_SYSERR on error, GNUNET_OK on success */ int GNUNET_CRYPTO_ecc_sign (const struct GNUNET_CRYPTO_EccPrivateKey *key, const struct GNUNET_CRYPTO_EccSignaturePurpose *purpose, struct GNUNET_CRYPTO_EccSignature *sig) { gcry_sexp_t result; gcry_sexp_t data; size_t ssize; int rc; data = data_to_pkcs1 (purpose); if (0 != (rc = gcry_pk_sign (&result, data, key->sexp))) { LOG (GNUNET_ERROR_TYPE_WARNING, _("ECC signing failed at %s:%d: %s\n"), __FILE__, __LINE__, gcry_strerror (rc)); gcry_sexp_release (data); return GNUNET_SYSERR; } gcry_sexp_release (data); ssize = gcry_sexp_sprint (result, GCRYSEXP_FMT_DEFAULT, sig->sexpr, GNUNET_CRYPTO_ECC_SIGNATURE_DATA_ENCODING_LENGTH); if (0 == ssize) { GNUNET_break (0); return GNUNET_SYSERR; } sig->size = htons ((uint16_t) (ssize + sizeof (uint16_t))); /* padd with zeros */ memset (&sig->sexpr[ssize], 0, GNUNET_CRYPTO_ECC_SIGNATURE_DATA_ENCODING_LENGTH - ssize); gcry_sexp_release (result); return GNUNET_OK; } /** * Verify signature. * * @param purpose what is the purpose that the signature should have? * @param validate block to validate (size, purpose, data) * @param sig signature that is being validated * @param publicKey public key of the signer * @returns GNUNET_OK if ok, GNUNET_SYSERR if invalid */ int GNUNET_CRYPTO_ecc_verify (uint32_t purpose, const struct GNUNET_CRYPTO_EccSignaturePurpose *validate, const struct GNUNET_CRYPTO_EccSignature *sig, const struct GNUNET_CRYPTO_EccPublicKeyBinaryEncoded *publicKey) { gcry_sexp_t data; gcry_sexp_t sigdata; size_t size; gcry_sexp_t psexp; size_t erroff; int rc; if (purpose != ntohl (validate->purpose)) return GNUNET_SYSERR; /* purpose mismatch */ size = ntohs (sig->size); if ( (size < sizeof (uint16_t)) || (size > GNUNET_CRYPTO_ECC_SIGNATURE_DATA_ENCODING_LENGTH - sizeof (uint16_t)) ) return GNUNET_SYSERR; /* size out of range */ data = data_to_pkcs1 (validate); GNUNET_assert (0 == gcry_sexp_sscan (&sigdata, &erroff, sig->sexpr, size - sizeof (uint16_t))); if (! (psexp = decode_public_key (publicKey))) { gcry_sexp_release (data); gcry_sexp_release (sigdata); return GNUNET_SYSERR; } rc = gcry_pk_verify (sigdata, data, psexp); gcry_sexp_release (psexp); gcry_sexp_release (data); gcry_sexp_release (sigdata); if (0 != rc) { LOG (GNUNET_ERROR_TYPE_WARNING, _("ECC signature verification failed at %s:%d: %s\n"), __FILE__, __LINE__, gcry_strerror (rc)); return GNUNET_SYSERR; } return GNUNET_OK; } /** * Derive key material from a public and a private ECC key. * * @param key private key to use for the ECDH (x) * @param pub public key to use for the ECDY (yG) * @param key_material where to write the key material (xyG) * @return GNUNET_SYSERR on error, GNUNET_OK on success */ int GNUNET_CRYPTO_ecc_ecdh (const struct GNUNET_CRYPTO_EccPrivateKey *key, const struct GNUNET_CRYPTO_EccPublicKeyBinaryEncoded *pub, struct GNUNET_HashCode *key_material) { size_t slen; size_t erroff; int rc; unsigned char sdata_buf[2048]; /* big enough to print dh-shared-secret as S-expression */ gcry_mpi_point_t result; gcry_mpi_point_t q; gcry_mpi_t d; gcry_ctx_t ctx; gcry_sexp_t psexp; gcry_mpi_t result_x; gcry_mpi_t result_y; /* first, extract the q = dP value from the public key */ if (! (psexp = decode_public_key (pub))) return GNUNET_SYSERR; if (0 != (rc = gcry_mpi_ec_new (&ctx, psexp, NULL))) { LOG_GCRY (GNUNET_ERROR_TYPE_ERROR, "gcry_mpi_ec_new", rc); /* erroff gives more info */ return GNUNET_SYSERR; } gcry_sexp_release (psexp); q = gcry_mpi_ec_get_point ("q", ctx, 0); gcry_ctx_release (ctx); /* second, extract the d value from our private key */ rc = key_from_sexp (&d, key->sexp, "private-key", "d"); if (rc) rc = key_from_sexp (&d, key->sexp, "ecc", "d"); if (0 != rc) { GNUNET_break (0); gcry_mpi_point_release (q); return GNUNET_SYSERR; } /* create a new context for definitively the correct curve; theoretically the 'public_key' might not use the right curve */ if (0 != (rc = gcry_mpi_ec_new (&ctx, NULL, "NIST P-256"))) { LOG_GCRY (GNUNET_ERROR_TYPE_ERROR, "gcry_mpi_ec_new", rc); /* erroff gives more info */ gcry_mpi_release (d); gcry_mpi_point_release (q); return GNUNET_SYSERR; } /* then call the 'multiply' function, to compute the product */ GNUNET_assert (NULL != ctx); result = gcry_mpi_point_new (0); gcry_mpi_ec_mul (result, d, q, ctx); gcry_mpi_point_release (q); gcry_mpi_release (d); /* finally, convert point to string for hashing */ result_x = gcry_mpi_new (256); result_y = gcry_mpi_new (256); if (gcry_mpi_ec_get_affine (result_x, result_y, result, ctx)) { LOG_GCRY (GNUNET_ERROR_TYPE_ERROR, "get_affine failed", 0); gcry_mpi_point_release (result); gcry_ctx_release (ctx); return GNUNET_SYSERR; } gcry_mpi_point_release (result); gcry_ctx_release (ctx); if (0 != (rc = gcry_sexp_build (&psexp, &erroff, "(dh-shared-secret (x %m)(y %m))", result_x, result_y))) { LOG_GCRY (GNUNET_ERROR_TYPE_ERROR, "gcry_sexp_build", rc); /* erroff gives more info */ gcry_mpi_release (result_x); gcry_mpi_release (result_y); return GNUNET_SYSERR; } gcry_mpi_release (result_x); gcry_mpi_release (result_y); slen = gcry_sexp_sprint (psexp, GCRYSEXP_FMT_DEFAULT, sdata_buf, sizeof (sdata_buf)); GNUNET_assert (0 != slen); gcry_sexp_release (psexp); /* finally, get a string of the resulting S-expression and hash it to generate the key material */ GNUNET_CRYPTO_hash (sdata_buf, slen, key_material); return GNUNET_OK; } /* end of crypto_ecc.c */