2 This file is part of GNUnet.
3 (C) 2009, 2010, 2011, 2012 Christian Grothoff (and other contributing authors)
5 GNUnet is free software; you can redistribute it and/or modify
6 it under the terms of the GNU General Public License as published
7 by the Free Software Foundation; either version 3, or (at your
8 option) any later version.
10 GNUnet is distributed in the hope that it will be useful, but
11 WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 General Public License for more details.
15 You should have received a copy of the GNU General Public License
16 along with GNUnet; see the file COPYING. If not, write to the
17 Free Software Foundation, Inc., 59 Temple Place - Suite 330,
18 Boston, MA 02111-1307, USA.
22 * @file core/gnunet-service-core_kx.c
23 * @brief code for managing the key exchange (SET_KEY, PING, PONG) with other peers
24 * @author Christian Grothoff
27 #include "gnunet-service-core_kx.h"
28 #include "gnunet-service-core.h"
29 #include "gnunet-service-core_clients.h"
30 #include "gnunet-service-core_neighbours.h"
31 #include "gnunet-service-core_sessions.h"
32 #include "gnunet_statistics_service.h"
33 #include "gnunet_constants.h"
34 #include "gnunet_signatures.h"
35 #include "gnunet_protocols.h"
40 * How long do we wait for SET_KEY confirmation initially?
42 #define INITIAL_SET_KEY_RETRY_FREQUENCY GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_SECONDS, 10)
45 * What is the minimum frequency for a PING message?
47 #define MIN_PING_FREQUENCY GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_SECONDS, 5)
50 * How often do we rekey?
52 #define REKEY_FREQUENCY GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_HOURS, 12)
55 * What time difference do we tolerate?
57 #define REKEY_TOLERANCE GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_MINUTES, 5)
60 * What is the maximum age of a message for us to consider processing
61 * it? Note that this looks at the timestamp used by the other peer,
62 * so clock skew between machines does come into play here. So this
63 * should be picked high enough so that a little bit of clock skew
64 * does not prevent peers from connecting to us.
66 #define MAX_MESSAGE_AGE GNUNET_TIME_UNIT_DAYS
70 GNUNET_NETWORK_STRUCT_BEGIN
73 * Message transmitted with the signed ephemeral key of a peer. The
74 * session key is then derived from the two ephemeral keys (ECDHE).
76 struct EphemeralKeyMessage
80 * Message type is CORE_EPHEMERAL_KEY.
82 struct GNUNET_MessageHeader header;
85 * Status of the sender (should be in "enum PeerStateMachine"), nbo.
87 int32_t sender_status GNUNET_PACKED;
90 * An ECC signature of the 'origin' asserting the validity of
91 * the given ephemeral key.
93 struct GNUNET_CRYPTO_EccSignature signature;
96 * Information about what is being signed.
98 struct GNUNET_CRYPTO_EccSignaturePurpose purpose;
101 * At what time was this key created (beginning of validity).
103 struct GNUNET_TIME_AbsoluteNBO creation_time;
106 * When does the given ephemeral key expire (end of validity).
108 struct GNUNET_TIME_AbsoluteNBO expiration_time;
111 * Ephemeral public ECC key (always for NIST P-521) encoded in a format suitable
112 * for network transmission as created using 'gcry_sexp_sprint'.
114 struct GNUNET_CRYPTO_EccPublicKeyBinaryEncoded ephemeral_key;
117 * Public key of the signing peer (persistent version, not the ephemeral public key).
119 struct GNUNET_CRYPTO_EccPublicKeyBinaryEncoded origin_public_key;
125 * We're sending an (encrypted) PING to the other peer to check if he
126 * can decrypt. The other peer should respond with a PONG with the
127 * same content, except this time encrypted with the receiver's key.
132 * Message type is CORE_PING.
134 struct GNUNET_MessageHeader header;
139 uint32_t iv_seed GNUNET_PACKED;
142 * Intended target of the PING, used primarily to check
143 * that decryption actually worked.
145 struct GNUNET_PeerIdentity target;
148 * Random number chosen to make reply harder.
150 uint32_t challenge GNUNET_PACKED;
155 * Response to a PING. Includes data from the original PING.
160 * Message type is CORE_PONG.
162 struct GNUNET_MessageHeader header;
167 uint32_t iv_seed GNUNET_PACKED;
170 * Random number to make faking the reply harder. Must be
171 * first field after header (this is where we start to encrypt!).
173 uint32_t challenge GNUNET_PACKED;
176 * Reserved, always zero.
181 * Intended target of the PING, used primarily to check
182 * that decryption actually worked.
184 struct GNUNET_PeerIdentity target;
189 * Encapsulation for encrypted messages exchanged between
190 * peers. Followed by the actual encrypted data.
192 struct EncryptedMessage
195 * Message type is either CORE_ENCRYPTED_MESSAGE.
197 struct GNUNET_MessageHeader header;
200 * Random value used for IV generation.
202 uint32_t iv_seed GNUNET_PACKED;
205 * MAC of the encrypted message (starting at 'sequence_number'),
206 * used to verify message integrity. Everything after this value
207 * (excluding this value itself) will be encrypted and authenticated.
208 * ENCRYPTED_HEADER_SIZE must be set to the offset of the *next* field.
210 struct GNUNET_HashCode hmac;
213 * Sequence number, in network byte order. This field
214 * must be the first encrypted/decrypted field
216 uint32_t sequence_number GNUNET_PACKED;
219 * Reserved, always zero.
224 * Timestamp. Used to prevent reply of ancient messages
225 * (recent messages are caught with the sequence number).
227 struct GNUNET_TIME_AbsoluteNBO timestamp;
230 GNUNET_NETWORK_STRUCT_END
234 * Number of bytes (at the beginning) of "struct EncryptedMessage"
235 * that are NOT encrypted.
237 #define ENCRYPTED_HEADER_SIZE (offsetof(struct EncryptedMessage, sequence_number))
241 * State machine for our P2P encryption handshake. Everyone starts in
242 * "DOWN", if we receive the other peer's key (other peer initiated)
243 * we start in state RECEIVED (since we will immediately send our
244 * own); otherwise we start in SENT. If we get back a PONG from
245 * within either state, we move up to CONFIRMED (the PONG will always
246 * be sent back encrypted with the key we sent to the other peer).
256 * We've sent our session key.
261 * We've received the other peers session key.
263 KX_STATE_KEY_RECEIVED,
266 * The other peer has confirmed our session key + PING with a PONG
267 * message encrypted with his session key (which we got). Key
273 * We're rekeying (or had a timeout), so we have sent the other peer
274 * our new ephemeral key, but we did not get a matching PONG yet.
275 * This is equivalent to being 'KX_STATE_KEY_RECEIVED', except that
276 * the session is marked as 'up' with sessions (as we don't want to
277 * drop and re-establish P2P connections simply due to rekeying).
285 * Information about the status of a key exchange with another peer.
287 struct GSC_KeyExchangeInfo
293 struct GSC_KeyExchangeInfo *next;
298 struct GSC_KeyExchangeInfo *prev;
301 * Identity of the peer.
303 struct GNUNET_PeerIdentity peer;
306 * PING message we transmit to the other peer.
308 struct PingMessage ping;
311 * Key we use to encrypt our messages for the other peer
312 * (initialized by us when we do the handshake).
314 struct GNUNET_CRYPTO_AesSessionKey encrypt_key;
317 * Key we use to decrypt messages from the other peer
318 * (given to us by the other peer during the handshake).
320 struct GNUNET_CRYPTO_AesSessionKey decrypt_key;
323 * At what time did the other peer generate the decryption key?
325 struct GNUNET_TIME_Absolute foreign_key_expires;
328 * When should the session time out (if there are no PONGs)?
330 struct GNUNET_TIME_Absolute timeout;
333 * At what frequency are we currently re-trying SET_KEY messages?
335 struct GNUNET_TIME_Relative set_key_retry_frequency;
338 * ID of task used for re-trying SET_KEY and PING message.
340 GNUNET_SCHEDULER_TaskIdentifier retry_set_key_task;
343 * ID of task used for sending keep-alive pings.
345 GNUNET_SCHEDULER_TaskIdentifier keep_alive_task;
348 * Bit map indicating which of the 32 sequence numbers before the last
349 * were received (good for accepting out-of-order packets and
350 * estimating reliability of the connection)
352 unsigned int last_packets_bitmap;
355 * last sequence number received on this connection (highest)
357 uint32_t last_sequence_number_received;
360 * last sequence number transmitted
362 uint32_t last_sequence_number_sent;
365 * What was our PING challenge number (for this peer)?
367 uint32_t ping_challenge;
370 * What is our connection status?
372 enum KxStateMachine status;
380 static struct GNUNET_CRYPTO_EccPrivateKey *my_private_key;
383 * Our ephemeral private key.
385 static struct GNUNET_CRYPTO_EccPrivateKey *my_ephemeral_key;
388 * Current message we send for a key exchange.
390 static struct EphemeralKeyMessage current_ekm;
395 static struct GNUNET_CRYPTO_EccPublicKeyBinaryEncoded my_public_key;
398 * Our message stream tokenizer (for encrypted payload).
400 static struct GNUNET_SERVER_MessageStreamTokenizer *mst;
405 static struct GSC_KeyExchangeInfo *kx_head;
410 static struct GSC_KeyExchangeInfo *kx_tail;
413 * Task scheduled for periodic re-generation (and thus rekeying) of our
416 static GNUNET_SCHEDULER_TaskIdentifier rekey_task;
420 * Derive an authentication key from "set key" information
422 * @param akey authentication key to derive
423 * @param skey session key to use
424 * @param seed seed to use
427 derive_auth_key (struct GNUNET_CRYPTO_AuthKey *akey,
428 const struct GNUNET_CRYPTO_AesSessionKey *skey, uint32_t seed)
430 static const char ctx[] = "authentication key";
432 GNUNET_CRYPTO_hmac_derive_key (akey, skey, &seed, sizeof (seed), &skey->key,
433 sizeof (skey->key), ctx,
439 * Derive an IV from packet information
441 * @param iv initialization vector to initialize
442 * @param skey session key to use
443 * @param seed seed to use
444 * @param identity identity of the other peer to use
447 derive_iv (struct GNUNET_CRYPTO_AesInitializationVector *iv,
448 const struct GNUNET_CRYPTO_AesSessionKey *skey, uint32_t seed,
449 const struct GNUNET_PeerIdentity *identity)
451 static const char ctx[] = "initialization vector";
453 GNUNET_CRYPTO_aes_derive_iv (iv, skey, &seed, sizeof (seed),
454 &identity->hashPubKey.bits,
455 sizeof (identity->hashPubKey.bits), ctx,
461 * Derive an IV from pong packet information
463 * @param iv initialization vector to initialize
464 * @param skey session key to use
465 * @param seed seed to use
466 * @param challenge nonce to use
467 * @param identity identity of the other peer to use
470 derive_pong_iv (struct GNUNET_CRYPTO_AesInitializationVector *iv,
471 const struct GNUNET_CRYPTO_AesSessionKey *skey, uint32_t seed,
472 uint32_t challenge, const struct GNUNET_PeerIdentity *identity)
474 static const char ctx[] = "pong initialization vector";
476 GNUNET_CRYPTO_aes_derive_iv (iv, skey, &seed, sizeof (seed),
477 &identity->hashPubKey.bits,
478 sizeof (identity->hashPubKey.bits), &challenge,
479 sizeof (challenge), ctx, sizeof (ctx), NULL);
484 * Derive an AES key from key material
486 * @param sender peer identity of the sender
487 * @param receiver peer identity of the sender
488 * @param key_material high entropy key material to use
489 * @param skey set to derived session key
492 derive_aes_key (const struct GNUNET_PeerIdentity *sender,
493 const struct GNUNET_PeerIdentity *receiver,
494 const struct GNUNET_HashCode *key_material,
495 struct GNUNET_CRYPTO_AesSessionKey *skey)
497 static const char ctx[] = "aes key generation vector";
499 GNUNET_CRYPTO_kdf (skey, sizeof (struct GNUNET_CRYPTO_AesSessionKey),
501 skey, sizeof (struct GNUNET_CRYPTO_AesSessionKey),
502 sender, sizeof (struct GNUNET_PeerIdentity),
503 receiver, sizeof (struct GNUNET_PeerIdentity),
509 * Encrypt size bytes from in and write the result to out. Use the
510 * key for outbound traffic of the given neighbour.
512 * @param kx key information context
513 * @param iv initialization vector to use
514 * @param in ciphertext
515 * @param out plaintext
516 * @param size size of in/out
517 * @return GNUNET_OK on success
520 do_encrypt (struct GSC_KeyExchangeInfo *kx,
521 const struct GNUNET_CRYPTO_AesInitializationVector *iv,
522 const void *in, void *out, size_t size)
524 if (size != (uint16_t) size)
529 GNUNET_assert (size ==
530 GNUNET_CRYPTO_aes_encrypt (in, (uint16_t) size,
531 &kx->encrypt_key, iv, out));
532 GNUNET_STATISTICS_update (GSC_stats, gettext_noop ("# bytes encrypted"), size,
534 /* the following is too sensitive to write to log files by accident,
535 so we require manual intervention to get this one... */
537 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
538 "Encrypted %u bytes for `%4s' using key %u, IV %u\n",
539 (unsigned int) size, GNUNET_i2s (&kx->peer),
540 (unsigned int) kx->encrypt_key.crc32, GNUNET_CRYPTO_crc32_n (iv,
549 * Decrypt size bytes from in and write the result to out. Use the
550 * key for inbound traffic of the given neighbour. This function does
551 * NOT do any integrity-checks on the result.
553 * @param kx key information context
554 * @param iv initialization vector to use
555 * @param in ciphertext
556 * @param out plaintext
557 * @param size size of in/out
558 * @return GNUNET_OK on success
561 do_decrypt (struct GSC_KeyExchangeInfo *kx,
562 const struct GNUNET_CRYPTO_AesInitializationVector *iv,
563 const void *in, void *out, size_t size)
565 if (size != (uint16_t) size)
570 if ( (kx->status != KX_STATE_KEY_RECEIVED) && (kx->status != KX_STATE_UP) &&
571 (kx->status != KX_STATE_REKEY_SENT) )
574 return GNUNET_SYSERR;
577 GNUNET_CRYPTO_aes_decrypt (in, (uint16_t) size, &kx->decrypt_key, iv,
581 return GNUNET_SYSERR;
583 GNUNET_STATISTICS_update (GSC_stats, gettext_noop ("# bytes decrypted"), size,
585 /* the following is too sensitive to write to log files by accident,
586 so we require manual intervention to get this one... */
588 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
589 "Decrypted %u bytes from `%4s' using key %u, IV %u\n",
590 (unsigned int) size, GNUNET_i2s (&kx->peer),
591 (unsigned int) kx->decrypt_key.crc32, GNUNET_CRYPTO_crc32_n (iv,
600 * Send our key (and encrypted PING) to the other peer.
602 * @param kx key exchange context
605 send_key (struct GSC_KeyExchangeInfo *kx);
609 * Task that will retry "send_key" if our previous attempt failed.
611 * @param cls our 'struct GSC_KeyExchangeInfo'
612 * @param tc scheduler context
615 set_key_retry_task (void *cls, const struct GNUNET_SCHEDULER_TaskContext *tc)
617 struct GSC_KeyExchangeInfo *kx = cls;
619 kx->retry_set_key_task = GNUNET_SCHEDULER_NO_TASK;
620 kx->set_key_retry_frequency = GNUNET_TIME_STD_BACKOFF (kx->set_key_retry_frequency);
626 * Create a fresh PING message for transmission to the other peer.
628 * @param kx key exchange context to create PING for
631 setup_fresh_ping (struct GSC_KeyExchangeInfo *kx)
633 struct PingMessage pp;
634 struct PingMessage *pm;
635 struct GNUNET_CRYPTO_AesInitializationVector iv;
638 pm->header.size = htons (sizeof (struct PingMessage));
639 pm->header.type = htons (GNUNET_MESSAGE_TYPE_CORE_PING);
641 GNUNET_CRYPTO_random_u32 (GNUNET_CRYPTO_QUALITY_NONCE, UINT32_MAX);
642 derive_iv (&iv, &kx->encrypt_key, pm->iv_seed, &kx->peer);
643 pp.challenge = kx->ping_challenge;
644 pp.target = kx->peer;
645 do_encrypt (kx, &iv, &pp.target, &pm->target,
646 sizeof (struct PingMessage) - ((void *) &pm->target -
652 * Start the key exchange with the given peer.
654 * @param pid identity of the peer to do a key exchange with
655 * @return key exchange information context
657 struct GSC_KeyExchangeInfo *
658 GSC_KX_start (const struct GNUNET_PeerIdentity *pid)
660 struct GSC_KeyExchangeInfo *kx;
662 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
663 "Initiating key exchange with `%s'\n",
665 GNUNET_STATISTICS_update (GSC_stats,
666 gettext_noop ("# key exchanges initiated"), 1,
668 kx = GNUNET_malloc (sizeof (struct GSC_KeyExchangeInfo));
670 kx->set_key_retry_frequency = INITIAL_SET_KEY_RETRY_FREQUENCY;
671 GNUNET_CONTAINER_DLL_insert (kx_head,
674 kx->status = KX_STATE_KEY_SENT;
681 * Stop key exchange with the given peer. Clean up key material.
683 * @param kx key exchange to stop
686 GSC_KX_stop (struct GSC_KeyExchangeInfo *kx)
688 GNUNET_STATISTICS_update (GSC_stats, gettext_noop ("# key exchanges stopped"),
690 if (kx->retry_set_key_task != GNUNET_SCHEDULER_NO_TASK)
692 GNUNET_SCHEDULER_cancel (kx->retry_set_key_task);
693 kx->retry_set_key_task = GNUNET_SCHEDULER_NO_TASK;
695 if (kx->keep_alive_task != GNUNET_SCHEDULER_NO_TASK)
697 GNUNET_SCHEDULER_cancel (kx->keep_alive_task);
698 kx->keep_alive_task = GNUNET_SCHEDULER_NO_TASK;
700 GNUNET_CONTAINER_DLL_remove (kx_head,
708 * Send our PING to the other peer.
710 * @param kx key exchange context
713 send_ping (struct GSC_KeyExchangeInfo *kx)
715 GSC_NEIGHBOURS_transmit (&kx->peer, &kx->ping.header,
720 * We received a SET_KEY message. Validate and update
721 * our key material and status.
723 * @param kx key exchange status for the corresponding peer
724 * @param msg the set key message we received
727 GSC_KX_handle_ephemeral_key (struct GSC_KeyExchangeInfo *kx,
728 const struct GNUNET_MessageHeader *msg)
730 const struct EphemeralKeyMessage *m;
731 struct GNUNET_TIME_Absolute start_t;
732 struct GNUNET_TIME_Absolute end_t;
733 struct GNUNET_TIME_Absolute now;
734 struct GNUNET_PeerIdentity signer_id;
735 enum KxStateMachine sender_status;
737 struct GNUNET_HashCode key_material;
739 size = ntohs (msg->size);
740 if (sizeof (struct EphemeralKeyMessage) != size)
745 m = (const struct EphemeralKeyMessage *) msg;
746 GNUNET_STATISTICS_update (GSC_stats, gettext_noop ("# ephemeral keys received"),
749 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
750 "Core service receives `%s' request from `%4s'.\n", "EPHEMERAL_KEY",
751 GNUNET_i2s (&kx->peer));
752 GNUNET_CRYPTO_hash (&m->origin_public_key,
753 sizeof (struct GNUNET_CRYPTO_EccPublicKeyBinaryEncoded),
754 &signer_id.hashPubKey);
756 memcmp (&signer_id, &kx->peer,
757 sizeof (struct GNUNET_PeerIdentity)))
762 if ((ntohl (m->purpose.size) !=
763 sizeof (struct GNUNET_CRYPTO_EccSignaturePurpose) +
764 sizeof (struct GNUNET_TIME_AbsoluteNBO) +
765 sizeof (struct GNUNET_TIME_AbsoluteNBO) +
766 sizeof (struct GNUNET_CRYPTO_EccPublicKeyBinaryEncoded) +
767 sizeof (struct GNUNET_CRYPTO_EccPublicKeyBinaryEncoded)) ||
769 GNUNET_CRYPTO_ecc_verify (GNUNET_SIGNATURE_PURPOSE_SET_ECC_KEY,
771 &m->signature, &m->origin_public_key)))
773 /* invalid signature */
777 start_t = GNUNET_TIME_absolute_ntoh (m->creation_time);
778 end_t = GNUNET_TIME_absolute_ntoh (m->expiration_time);
779 now = GNUNET_TIME_absolute_get ();
780 if ( (end_t.abs_value < GNUNET_TIME_absolute_subtract (now, REKEY_TOLERANCE).abs_value) ||
781 (start_t.abs_value > GNUNET_TIME_absolute_add (now, REKEY_TOLERANCE).abs_value) )
783 GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
784 _("Ephemeral key message rejected as its validity range does not match our system time (%llu not in [%llu,%llu]).\n"),
791 GNUNET_CRYPTO_ecc_ecdh (my_ephemeral_key,
798 GNUNET_STATISTICS_update (GSC_stats,
799 gettext_noop ("# EPHEMERAL_KEY messages decrypted"), 1,
801 derive_aes_key (&GSC_my_identity,
805 derive_aes_key (&kx->peer,
809 /* fresh key, reset sequence numbers */
810 kx->last_sequence_number_received = 0;
811 kx->last_packets_bitmap = 0;
812 kx->foreign_key_expires = end_t;
813 setup_fresh_ping (kx);
815 /* check if we still need to send the sender our key */
816 sender_status = (enum KxStateMachine) ntohl (m->sender_status);
817 switch (sender_status)
820 /* makes no sense, should be at least KX_STATE_KEY_SENT */
823 case KX_STATE_KEY_SENT:
826 case KX_STATE_KEY_RECEIVED:
828 case KX_STATE_REKEY_SENT:
829 /* other peer already got our key */
835 /* check if we need to confirm everything is fine via PING + PONG */
839 kx->status = KX_STATE_KEY_RECEIVED;
842 case KX_STATE_KEY_SENT:
843 kx->status = KX_STATE_KEY_RECEIVED;
846 case KX_STATE_KEY_RECEIVED:
850 kx->status = KX_STATE_REKEY_SENT;
851 /* we got a new key, need to reconfirm! */
854 case KX_STATE_REKEY_SENT:
855 kx->status = KX_STATE_REKEY_SENT;
856 /* we got a new key, need to reconfirm! */
867 * We received a PING message. Validate and transmit
870 * @param kx key exchange status for the corresponding peer
871 * @param msg the encrypted PING message itself
874 GSC_KX_handle_ping (struct GSC_KeyExchangeInfo *kx,
875 const struct GNUNET_MessageHeader *msg)
877 const struct PingMessage *m;
878 struct PingMessage t;
879 struct PongMessage tx;
880 struct PongMessage tp;
881 struct GNUNET_CRYPTO_AesInitializationVector iv;
884 msize = ntohs (msg->size);
885 if (msize != sizeof (struct PingMessage))
890 GNUNET_STATISTICS_update (GSC_stats,
891 gettext_noop ("# PING messages received"), 1,
893 if ( (kx->status != KX_STATE_KEY_RECEIVED) &&
894 (kx->status != KX_STATE_UP) &&
895 (kx->status != KX_STATE_REKEY_SENT))
898 GNUNET_STATISTICS_update (GSC_stats,
899 gettext_noop ("# PING messages dropped (out of order)"), 1,
903 m = (const struct PingMessage *) msg;
904 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
905 "Core service receives `%s' request from `%4s'.\n", "PING",
906 GNUNET_i2s (&kx->peer));
907 derive_iv (&iv, &kx->decrypt_key, m->iv_seed, &GSC_my_identity);
909 do_decrypt (kx, &iv, &m->target, &t.target,
910 sizeof (struct PingMessage) - ((void *) &m->target -
917 memcmp (&t.target, &GSC_my_identity, sizeof (struct GNUNET_PeerIdentity)))
922 GNUNET_snprintf (sender, sizeof (sender), "%8s", GNUNET_i2s (&kx->peer));
923 GNUNET_snprintf (peer, sizeof (peer), "%8s", GNUNET_i2s (&t.target));
924 GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
926 ("Received PING from `%s' for different identity: I am `%s', PONG identity: `%s'\n"),
927 sender, GNUNET_i2s (&GSC_my_identity), peer);
933 tx.challenge = t.challenge;
934 tx.target = t.target;
935 tp.header.type = htons (GNUNET_MESSAGE_TYPE_CORE_PONG);
936 tp.header.size = htons (sizeof (struct PongMessage));
938 GNUNET_CRYPTO_random_u32 (GNUNET_CRYPTO_QUALITY_NONCE, UINT32_MAX);
939 derive_pong_iv (&iv, &kx->encrypt_key, tp.iv_seed, t.challenge, &kx->peer);
940 do_encrypt (kx, &iv, &tx.challenge, &tp.challenge,
941 sizeof (struct PongMessage) - ((void *) &tp.challenge -
943 GNUNET_STATISTICS_update (GSC_stats, gettext_noop ("# PONG messages created"),
945 GSC_NEIGHBOURS_transmit (&kx->peer, &tp.header,
946 GNUNET_TIME_UNIT_FOREVER_REL /* FIXME: timeout */ );
951 * Task triggered when a neighbour entry is about to time out
952 * (and we should prevent this by sending a PING).
954 * @param cls the 'struct GSC_KeyExchangeInfo'
955 * @param tc scheduler context (not used)
958 send_keep_alive (void *cls, const struct GNUNET_SCHEDULER_TaskContext *tc)
960 struct GSC_KeyExchangeInfo *kx = cls;
961 struct GNUNET_TIME_Relative retry;
962 struct GNUNET_TIME_Relative left;
964 kx->keep_alive_task = GNUNET_SCHEDULER_NO_TASK;
965 left = GNUNET_TIME_absolute_get_remaining (kx->timeout);
966 if (0 == left.rel_value)
968 GNUNET_STATISTICS_update (GSC_stats,
969 gettext_noop ("# sessions terminated by timeout"),
971 GSC_SESSIONS_end (&kx->peer);
972 kx->status = KX_STATE_KEY_SENT;
976 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "Sending KEEPALIVE to `%s'\n",
977 GNUNET_i2s (&kx->peer));
978 GNUNET_STATISTICS_update (GSC_stats,
979 gettext_noop ("# keepalive messages sent"), 1,
981 setup_fresh_ping (kx);
982 GSC_NEIGHBOURS_transmit (&kx->peer, &kx->ping.header,
983 kx->set_key_retry_frequency);
985 GNUNET_TIME_relative_max (GNUNET_TIME_relative_divide (left, 2),
987 kx->keep_alive_task =
988 GNUNET_SCHEDULER_add_delayed (retry, &send_keep_alive, kx);
993 * We've seen a valid message from the other peer.
994 * Update the time when the session would time out
995 * and delay sending our keep alive message further.
997 * @param kx key exchange where we saw activity
1000 update_timeout (struct GSC_KeyExchangeInfo *kx)
1003 GNUNET_TIME_relative_to_absolute
1004 (GNUNET_CONSTANTS_IDLE_CONNECTION_TIMEOUT);
1005 if (kx->keep_alive_task != GNUNET_SCHEDULER_NO_TASK)
1006 GNUNET_SCHEDULER_cancel (kx->keep_alive_task);
1007 kx->keep_alive_task =
1008 GNUNET_SCHEDULER_add_delayed (GNUNET_TIME_relative_divide
1009 (GNUNET_CONSTANTS_IDLE_CONNECTION_TIMEOUT,
1010 2), &send_keep_alive, kx);
1015 * We received a PONG message. Validate and update our status.
1017 * @param kx key exchange context for the the PONG
1018 * @param msg the encrypted PONG message itself
1021 GSC_KX_handle_pong (struct GSC_KeyExchangeInfo *kx,
1022 const struct GNUNET_MessageHeader *msg)
1024 const struct PongMessage *m;
1025 struct PongMessage t;
1026 struct GNUNET_CRYPTO_AesInitializationVector iv;
1029 msize = ntohs (msg->size);
1030 if (sizeof (struct PongMessage) != msize)
1032 GNUNET_break_op (0);
1035 GNUNET_STATISTICS_update (GSC_stats,
1036 gettext_noop ("# PONG messages received"), 1,
1041 GNUNET_STATISTICS_update (GSC_stats,
1042 gettext_noop ("# PONG messages dropped (connection down)"), 1,
1045 case KX_STATE_KEY_SENT:
1046 GNUNET_STATISTICS_update (GSC_stats,
1047 gettext_noop ("# PONG messages dropped (out of order)"), 1,
1050 case KX_STATE_KEY_RECEIVED:
1054 case KX_STATE_REKEY_SENT:
1060 m = (const struct PongMessage *) msg;
1061 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
1062 "Core service receives `%s' response from `%4s'.\n", "PONG",
1063 GNUNET_i2s (&kx->peer));
1064 /* mark as garbage, just to be sure */
1065 memset (&t, 255, sizeof (t));
1066 derive_pong_iv (&iv, &kx->decrypt_key, m->iv_seed, kx->ping_challenge,
1069 do_decrypt (kx, &iv, &m->challenge, &t.challenge,
1070 sizeof (struct PongMessage) - ((void *) &m->challenge -
1073 GNUNET_break_op (0);
1076 GNUNET_STATISTICS_update (GSC_stats,
1077 gettext_noop ("# PONG messages decrypted"), 1,
1079 if ((0 != memcmp (&t.target, &kx->peer, sizeof (struct GNUNET_PeerIdentity)))
1080 || (kx->ping_challenge != t.challenge))
1082 /* PONG malformed */
1083 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
1084 "Received malformed `%s' wanted sender `%4s' with challenge %u\n",
1085 "PONG", GNUNET_i2s (&kx->peer),
1086 (unsigned int) kx->ping_challenge);
1087 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
1088 "Received malformed `%s' received from `%4s' with challenge %u\n",
1089 "PONG", GNUNET_i2s (&t.target), (unsigned int) t.challenge);
1092 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "Received PONG from `%s'\n",
1093 GNUNET_i2s (&kx->peer));
1094 /* no need to resend key any longer */
1095 if (GNUNET_SCHEDULER_NO_TASK != kx->retry_set_key_task)
1097 GNUNET_SCHEDULER_cancel (kx->retry_set_key_task);
1098 kx->retry_set_key_task = GNUNET_SCHEDULER_NO_TASK;
1103 GNUNET_assert (0); /* should be impossible */
1105 case KX_STATE_KEY_SENT:
1106 GNUNET_assert (0); /* should be impossible */
1108 case KX_STATE_KEY_RECEIVED:
1109 GNUNET_STATISTICS_update (GSC_stats,
1111 ("# session keys confirmed via PONG"), 1,
1113 kx->status = KX_STATE_UP;
1114 GSC_SESSIONS_create (&kx->peer, kx);
1115 GNUNET_assert (GNUNET_SCHEDULER_NO_TASK == kx->keep_alive_task);
1116 update_timeout (kx);
1119 GNUNET_STATISTICS_update (GSC_stats,
1121 ("# timeouts prevented via PONG"), 1,
1123 update_timeout (kx);
1125 case KX_STATE_REKEY_SENT:
1126 GNUNET_STATISTICS_update (GSC_stats,
1128 ("# rekey operations confirmed via PONG"), 1,
1130 kx->status = KX_STATE_UP;
1131 update_timeout (kx);
1141 * Send our key to the other peer.
1143 * @param kx key exchange context
1146 send_key (struct GSC_KeyExchangeInfo *kx)
1148 if (GNUNET_SCHEDULER_NO_TASK != kx->retry_set_key_task)
1150 GNUNET_SCHEDULER_cancel (kx->retry_set_key_task);
1151 kx->retry_set_key_task = GNUNET_SCHEDULER_NO_TASK;
1153 /* always update sender status in SET KEY message */
1154 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
1155 "Sending key to `%s' (my status: %d)\n",
1156 GNUNET_i2s (&kx->peer),
1158 current_ekm.sender_status = htonl ((int32_t) (kx->status));
1159 GSC_NEIGHBOURS_transmit (&kx->peer, ¤t_ekm.header,
1160 kx->set_key_retry_frequency);
1161 kx->retry_set_key_task =
1162 GNUNET_SCHEDULER_add_delayed (kx->set_key_retry_frequency,
1163 &set_key_retry_task, kx);
1168 * Encrypt and transmit a message with the given payload.
1170 * @param kx key exchange context
1171 * @param payload payload of the message
1172 * @param payload_size number of bytes in 'payload'
1175 GSC_KX_encrypt_and_transmit (struct GSC_KeyExchangeInfo *kx,
1176 const void *payload, size_t payload_size)
1178 size_t used = payload_size + sizeof (struct EncryptedMessage);
1179 char pbuf[used]; /* plaintext */
1180 char cbuf[used]; /* ciphertext */
1181 struct EncryptedMessage *em; /* encrypted message */
1182 struct EncryptedMessage *ph; /* plaintext header */
1183 struct GNUNET_CRYPTO_AesInitializationVector iv;
1184 struct GNUNET_CRYPTO_AuthKey auth_key;
1186 ph = (struct EncryptedMessage *) pbuf;
1188 htonl (GNUNET_CRYPTO_random_u32
1189 (GNUNET_CRYPTO_QUALITY_NONCE, UINT32_MAX));
1190 ph->sequence_number = htonl (++kx->last_sequence_number_sent);
1192 ph->timestamp = GNUNET_TIME_absolute_hton (GNUNET_TIME_absolute_get ());
1193 memcpy (&ph[1], payload, payload_size);
1195 em = (struct EncryptedMessage *) cbuf;
1196 em->header.size = htons (used);
1197 em->header.type = htons (GNUNET_MESSAGE_TYPE_CORE_ENCRYPTED_MESSAGE);
1198 em->iv_seed = ph->iv_seed;
1199 derive_iv (&iv, &kx->encrypt_key, ph->iv_seed, &kx->peer);
1200 GNUNET_assert (GNUNET_OK ==
1201 do_encrypt (kx, &iv, &ph->sequence_number,
1202 &em->sequence_number,
1203 used - ENCRYPTED_HEADER_SIZE));
1204 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "Encrypted %u bytes for %s\n",
1205 used - ENCRYPTED_HEADER_SIZE, GNUNET_i2s (&kx->peer));
1206 derive_auth_key (&auth_key,
1209 GNUNET_CRYPTO_hmac (&auth_key, &em->sequence_number,
1210 used - ENCRYPTED_HEADER_SIZE, &em->hmac);
1211 GSC_NEIGHBOURS_transmit (&kx->peer, &em->header,
1212 GNUNET_TIME_UNIT_FOREVER_REL);
1217 * Closure for 'deliver_message'
1219 struct DeliverMessageContext
1223 * Performance information for the connection.
1225 const struct GNUNET_ATS_Information *atsi;
1228 * Key exchange context.
1230 struct GSC_KeyExchangeInfo *kx;
1233 * Sender of the message.
1235 const struct GNUNET_PeerIdentity *peer;
1238 * Number of entries in 'atsi' array.
1240 uint32_t atsi_count;
1245 * We received an encrypted message. Decrypt, validate and
1246 * pass on to the appropriate clients.
1248 * @param kx key exchange context for encrypting the message
1249 * @param msg encrypted message
1250 * @param atsi performance data
1251 * @param atsi_count number of entries in ats (excluding 0-termination)
1254 GSC_KX_handle_encrypted_message (struct GSC_KeyExchangeInfo *kx,
1255 const struct GNUNET_MessageHeader *msg,
1256 const struct GNUNET_ATS_Information *atsi,
1257 uint32_t atsi_count)
1259 const struct EncryptedMessage *m;
1260 struct EncryptedMessage *pt; /* plaintext */
1261 struct GNUNET_HashCode ph;
1263 struct GNUNET_TIME_Absolute t;
1264 struct GNUNET_CRYPTO_AesInitializationVector iv;
1265 struct GNUNET_CRYPTO_AuthKey auth_key;
1266 struct DeliverMessageContext dmc;
1267 uint16_t size = ntohs (msg->size);
1268 char buf[size] GNUNET_ALIGN;
1271 sizeof (struct EncryptedMessage) + sizeof (struct GNUNET_MessageHeader))
1273 GNUNET_break_op (0);
1276 m = (const struct EncryptedMessage *) msg;
1277 if (kx->status != KX_STATE_UP)
1279 GNUNET_STATISTICS_update (GSC_stats,
1281 ("# DATA message dropped (out of order)"),
1285 if (0 == GNUNET_TIME_absolute_get_remaining (kx->foreign_key_expires).rel_value)
1287 GNUNET_STATISTICS_update (GSC_stats,
1288 gettext_noop ("# sessions terminated by key expiration"),
1290 GSC_SESSIONS_end (&kx->peer);
1291 kx->status = KX_STATE_KEY_SENT;
1297 derive_auth_key (&auth_key, &kx->decrypt_key, m->iv_seed);
1298 GNUNET_CRYPTO_hmac (&auth_key, &m->sequence_number,
1299 size - ENCRYPTED_HEADER_SIZE, &ph);
1300 if (0 != memcmp (&ph, &m->hmac, sizeof (struct GNUNET_HashCode)))
1302 /* checksum failed */
1303 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
1304 "Failed checksum validation for a message from `%s'\n",
1305 GNUNET_i2s (&kx->peer));
1308 derive_iv (&iv, &kx->decrypt_key, m->iv_seed, &GSC_my_identity);
1311 do_decrypt (kx, &iv, &m->sequence_number, &buf[ENCRYPTED_HEADER_SIZE],
1312 size - ENCRYPTED_HEADER_SIZE))
1314 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "Decrypted %u bytes from %s\n",
1315 size - ENCRYPTED_HEADER_SIZE, GNUNET_i2s (&kx->peer));
1316 pt = (struct EncryptedMessage *) buf;
1318 /* validate sequence number */
1319 snum = ntohl (pt->sequence_number);
1320 if (kx->last_sequence_number_received == snum)
1322 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
1323 "Received duplicate message, ignoring.\n");
1324 /* duplicate, ignore */
1325 GNUNET_STATISTICS_update (GSC_stats,
1326 gettext_noop ("# bytes dropped (duplicates)"),
1330 if ((kx->last_sequence_number_received > snum) &&
1331 (kx->last_sequence_number_received - snum > 32))
1333 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
1334 "Received ancient out of sequence message, ignoring.\n");
1335 /* ancient out of sequence, ignore */
1336 GNUNET_STATISTICS_update (GSC_stats,
1338 ("# bytes dropped (out of sequence)"), size,
1342 if (kx->last_sequence_number_received > snum)
1344 unsigned int rotbit = 1 << (kx->last_sequence_number_received - snum - 1);
1346 if ((kx->last_packets_bitmap & rotbit) != 0)
1348 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
1349 "Received duplicate message, ignoring.\n");
1350 GNUNET_STATISTICS_update (GSC_stats,
1351 gettext_noop ("# bytes dropped (duplicates)"),
1353 /* duplicate, ignore */
1356 kx->last_packets_bitmap |= rotbit;
1358 if (kx->last_sequence_number_received < snum)
1360 unsigned int shift = (snum - kx->last_sequence_number_received);
1362 if (shift >= 8 * sizeof (kx->last_packets_bitmap))
1363 kx->last_packets_bitmap = 0;
1365 kx->last_packets_bitmap <<= shift;
1366 kx->last_sequence_number_received = snum;
1369 /* check timestamp */
1370 t = GNUNET_TIME_absolute_ntoh (pt->timestamp);
1371 if (GNUNET_TIME_absolute_get_duration (t).rel_value >
1372 MAX_MESSAGE_AGE.rel_value)
1374 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
1375 "Message received far too old (%s). Content ignored.\n",
1376 GNUNET_STRINGS_relative_time_to_string (GNUNET_TIME_absolute_get_duration (t), GNUNET_YES));
1377 GNUNET_STATISTICS_update (GSC_stats,
1379 ("# bytes dropped (ancient message)"), size,
1384 /* process decrypted message(s) */
1385 update_timeout (kx);
1386 GNUNET_STATISTICS_update (GSC_stats,
1387 gettext_noop ("# bytes of payload decrypted"),
1388 size - sizeof (struct EncryptedMessage), GNUNET_NO);
1391 dmc.atsi_count = atsi_count;
1392 dmc.peer = &kx->peer;
1394 GNUNET_SERVER_mst_receive (mst, &dmc,
1395 &buf[sizeof (struct EncryptedMessage)],
1396 size - sizeof (struct EncryptedMessage),
1397 GNUNET_YES, GNUNET_NO))
1398 GNUNET_break_op (0);
1403 * Deliver P2P message to interested clients.
1404 * Invokes send twice, once for clients that want the full message, and once
1405 * for clients that only want the header
1407 * @param cls always NULL
1408 * @param client who sent us the message (struct GSC_KeyExchangeInfo)
1409 * @param m the message
1412 deliver_message (void *cls, void *client, const struct GNUNET_MessageHeader *m)
1414 struct DeliverMessageContext *dmc = client;
1416 if (KX_STATE_UP != dmc->kx->status)
1418 GNUNET_STATISTICS_update (GSC_stats,
1420 ("# PAYLOAD dropped (out of order)"),
1424 switch (ntohs (m->type))
1426 case GNUNET_MESSAGE_TYPE_CORE_BINARY_TYPE_MAP:
1427 case GNUNET_MESSAGE_TYPE_CORE_COMPRESSED_TYPE_MAP:
1428 GSC_SESSIONS_set_typemap (dmc->peer, m);
1431 GSC_CLIENTS_deliver_message (dmc->peer, dmc->atsi, dmc->atsi_count, m,
1433 GNUNET_CORE_OPTION_SEND_FULL_INBOUND);
1434 GSC_CLIENTS_deliver_message (dmc->peer, dmc->atsi, dmc->atsi_count, m,
1435 sizeof (struct GNUNET_MessageHeader),
1436 GNUNET_CORE_OPTION_SEND_HDR_INBOUND);
1443 * Setup the message that links the ephemeral key to our persistent
1444 * public key and generate the appropriate signature.
1447 sign_ephemeral_key ()
1449 current_ekm.header.size = htons (sizeof (struct EphemeralKeyMessage));
1450 current_ekm.header.type = htons (GNUNET_MESSAGE_TYPE_CORE_EPHEMERAL_KEY);
1451 current_ekm.sender_status = 0; /* to be set later */
1452 current_ekm.purpose.purpose = htonl (GNUNET_SIGNATURE_PURPOSE_SET_ECC_KEY);
1453 current_ekm.purpose.size = htonl (sizeof (struct GNUNET_CRYPTO_EccSignaturePurpose) +
1454 sizeof (struct GNUNET_TIME_AbsoluteNBO) +
1455 sizeof (struct GNUNET_TIME_AbsoluteNBO) +
1456 sizeof (struct GNUNET_CRYPTO_EccPublicKeyBinaryEncoded) +
1457 sizeof (struct GNUNET_CRYPTO_EccPublicKeyBinaryEncoded));
1458 current_ekm.creation_time = GNUNET_TIME_absolute_hton (GNUNET_TIME_absolute_get ());
1459 current_ekm.expiration_time = GNUNET_TIME_absolute_hton (GNUNET_TIME_relative_to_absolute (GNUNET_TIME_relative_add (REKEY_FREQUENCY,
1461 GNUNET_CRYPTO_ecc_key_get_public (my_ephemeral_key,
1462 ¤t_ekm.ephemeral_key);
1463 current_ekm.origin_public_key = my_public_key;
1464 GNUNET_assert (GNUNET_OK ==
1465 GNUNET_CRYPTO_ecc_sign (my_private_key,
1466 ¤t_ekm.purpose,
1467 ¤t_ekm.signature));
1472 * Task run to trigger rekeying.
1474 * @param cls closure, NULL
1475 * @param tc scheduler context
1478 do_rekey (void *cls,
1479 const struct GNUNET_SCHEDULER_TaskContext *tc)
1481 struct GSC_KeyExchangeInfo *pos;
1483 rekey_task = GNUNET_SCHEDULER_add_delayed (REKEY_FREQUENCY,
1486 if (NULL != my_ephemeral_key)
1487 GNUNET_CRYPTO_ecc_key_free (my_ephemeral_key);
1488 my_ephemeral_key = GNUNET_CRYPTO_ecc_key_create ();
1489 GNUNET_assert (NULL != my_ephemeral_key);
1490 sign_ephemeral_key ();
1491 for (pos = kx_head; NULL != pos; pos = pos->next)
1493 pos->status = KX_STATE_REKEY_SENT;
1500 * Initialize KX subsystem.
1502 * @param pk private key to use for the peer
1503 * @return GNUNET_OK on success, GNUNET_SYSERR on failure
1506 GSC_KX_init (struct GNUNET_CRYPTO_EccPrivateKey *pk)
1508 GNUNET_assert (NULL != pk);
1509 my_private_key = pk;
1510 GNUNET_CRYPTO_ecc_key_get_public (my_private_key, &my_public_key);
1511 GNUNET_CRYPTO_hash (&my_public_key, sizeof (my_public_key),
1512 &GSC_my_identity.hashPubKey);
1514 GNUNET_CONFIGURATION_get_value_yesno (GSC_cfg,
1516 "USE_EPHEMERAL_KEYS"))
1518 my_ephemeral_key = GNUNET_CRYPTO_ecc_key_create ();
1519 if (NULL == my_ephemeral_key)
1522 GNUNET_CRYPTO_ecc_key_free (my_private_key);
1523 my_private_key = NULL;
1524 return GNUNET_SYSERR;
1526 sign_ephemeral_key ();
1527 rekey_task = GNUNET_SCHEDULER_add_delayed (REKEY_FREQUENCY,
1533 my_ephemeral_key = my_private_key;
1534 sign_ephemeral_key ();
1536 mst = GNUNET_SERVER_mst_create (&deliver_message, NULL);
1542 * Shutdown KX subsystem.
1547 if (GNUNET_SCHEDULER_NO_TASK != rekey_task)
1549 GNUNET_SCHEDULER_cancel (rekey_task);
1550 rekey_task = GNUNET_SCHEDULER_NO_TASK;
1552 if ( (NULL != my_ephemeral_key) &&
1553 (my_ephemeral_key != my_private_key) )
1555 GNUNET_CRYPTO_ecc_key_free (my_ephemeral_key);
1556 my_ephemeral_key = NULL;
1558 if (NULL != my_private_key)
1560 GNUNET_CRYPTO_ecc_key_free (my_private_key);
1561 my_private_key = NULL;
1565 GNUNET_SERVER_mst_destroy (mst);
1570 /* end of gnunet-service-core_kx.c */