5 Author: Pekka Riikonen <priikone@silcnet.org>
7 Copyright (C) 1997 - 2006 Pekka Riikonen
9 This program is free software; you can redistribute it and/or modify
10 it under the terms of the GNU General Public License as published by
11 the Free Software Foundation; version 2 of the License.
13 This program is distributed in the hope that it will be useful,
14 but WITHOUT ANY WARRANTY; without even the implied warranty of
15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 GNU General Public License for more details.
19 /* Implementation of the Message Payload used as channel messages and
24 #include "silcmessage.h"
26 /*************************** Types and definitions **************************/
28 /* Calculates padding length for message payload */
29 #define SILC_MESSAGE_PAD(__payloadlen) (16 - ((__payloadlen) % 16))
31 /* Header length plus maximum padding length */
32 #define SILC_MESSAGE_HLEN 6 + 16
34 /* Maximum message length */
35 #define SILC_MESSAGE_MAX_LEN SILC_PACKET_MAX_LEN - SILC_MESSAGE_HLEN - 16
37 /* Payload encoding context */
39 SilcMessageFlags flags;
40 SilcPublicKey public_key;
41 SilcPrivateKey private_key;
46 SilcUInt16 payload_len;
50 /************************* Static utility functions *************************/
52 /* Returns the data length that fits to the packet. If data length is too
53 big it will be truncated to fit to the payload. */
56 SilcUInt32 silc_message_payload_datalen(SilcUInt32 data_len,
57 SilcUInt32 header_len,
59 SilcPublicKey public_key,
60 SilcPrivateKey private_key)
62 SilcUInt32 pklen = (flags & SILC_MESSAGE_FLAG_SIGNED && public_key ?
63 silc_pkcs_public_key_get_len(public_key) : 0);
64 SilcUInt32 prlen = (flags & SILC_MESSAGE_FLAG_SIGNED ?
65 silc_pkcs_private_key_get_len(private_key) / 8 : 0);
66 SilcUInt32 dlen = data_len + SILC_MESSAGE_HLEN + header_len + pklen + prlen;
68 if (dlen > SILC_MESSAGE_MAX_LEN)
69 data_len -= (dlen - SILC_MESSAGE_MAX_LEN);
74 /* Free signed payload */
76 static void silc_message_signed_payload_free(SilcMessageSignedPayload sig)
79 memset(sig->sign_data, 0, sig->sign_len);
80 silc_free(sig->sign_data);
82 silc_free(sig->pk_data);
85 /* Parses the SILC_MESSAGE_FLAG_SIGNED Payload */
88 silc_message_signed_payload_parse(const unsigned char *data,
90 SilcMessageSignedPayload sig)
92 SilcBufferStruct buffer;
95 SILC_LOG_DEBUG(("Parsing SILC_MESSAGE_FLAG_SIGNED Payload"));
97 SILC_LOG_HEXDUMP(("sig payload"), (unsigned char *)data, data_len);
99 silc_buffer_set(&buffer, (unsigned char *)data, data_len);
101 /* Parse the payload */
102 ret = silc_buffer_unformat(&buffer,
103 SILC_STR_UI_SHORT(&sig->pk_len),
104 SILC_STR_UI_SHORT(&sig->pk_type),
106 if (ret == -1 || sig->pk_len > data_len - 4) {
107 SILC_LOG_DEBUG(("Malformed public key in SILC_MESSAGE_FLAG_SIGNED "
112 silc_buffer_pull(&buffer, 4);
113 ret = silc_buffer_unformat(&buffer,
114 SILC_STR_UI_XNSTRING_ALLOC(&sig->pk_data,
116 SILC_STR_UI16_NSTRING_ALLOC(&sig->sign_data,
119 if (ret == -1 || sig->sign_len > silc_buffer_len(&buffer) -
121 silc_message_signed_payload_free(sig);
122 SILC_LOG_DEBUG(("Malformed SILC_MESSAGE_FLAG_SIGNED Payload"));
125 silc_buffer_push(&buffer, 4);
127 /* Signature must be provided */
128 if (sig->sign_len < 1) {
129 SILC_LOG_DEBUG(("Malformed signature in SILC_MESSAGE_SIGNED_PAYLOAD "
131 silc_message_signed_payload_free(sig);
138 /* Encodes the data to be signed to SILC_MESSAGE_FLAG_SIGNED Payload */
141 silc_message_signed_encode_data(const unsigned char *message_payload,
142 SilcUInt32 message_payload_len,
144 SilcUInt32 pk_len, SilcUInt32 pk_type)
148 sign = silc_buffer_alloc_size(message_payload_len + 4 + pk_len);
152 silc_buffer_format(sign,
153 SILC_STR_UI_XNSTRING(message_payload,
154 message_payload_len),
155 SILC_STR_UI_SHORT(pk_len),
156 SILC_STR_UI_SHORT(pk_type),
160 silc_buffer_pull(sign, message_payload_len + 4);
161 silc_buffer_format(sign,
162 SILC_STR_UI_XNSTRING(pk, pk_len),
164 silc_buffer_push(sign, message_payload_len + 4);
170 /* Encodes the SILC_MESSAGE_FLAG_SIGNED Payload and computes the digital
174 silc_message_signed_payload_encode(const unsigned char *message_payload,
175 SilcUInt32 message_payload_len,
176 SilcPublicKey public_key,
177 SilcPrivateKey private_key,
180 SilcBuffer buffer, sign;
181 unsigned char auth_data[2048 + 1];
183 unsigned char *pk = NULL;
184 SilcUInt32 pk_len = 0;
187 if (!message_payload || !message_payload_len || !private_key || !hash)
191 pk = silc_pkcs_public_key_encode(public_key, &pk_len);
195 pk_type = silc_pkcs_get_type(public_key);
197 /* Encode the data to be signed */
198 sign = silc_message_signed_encode_data(message_payload,
200 pk, pk_len, pk_type);
206 /* Sign the buffer */
208 /* Compute the hash and the signature. */
209 if (!silc_pkcs_sign(private_key, sign->data, silc_buffer_len(sign),
210 auth_data, sizeof(auth_data) - 1, &auth_len, hash)) {
211 SILC_LOG_ERROR(("Could not compute signature"));
212 silc_buffer_clear(sign);
213 silc_buffer_free(sign);
218 /* Encode the SILC_MESSAGE_FLAG_SIGNED Payload */
220 buffer = silc_buffer_alloc_size(4 + pk_len + 2 + auth_len);
222 silc_buffer_clear(sign);
223 silc_buffer_free(sign);
224 memset(auth_data, 0, sizeof(auth_data));
229 silc_buffer_format(buffer,
230 SILC_STR_UI_SHORT(pk_len),
231 SILC_STR_UI_SHORT(pk_type),
235 silc_buffer_pull(buffer, 4);
236 silc_buffer_format(buffer,
237 SILC_STR_UI_XNSTRING(pk, pk_len),
239 silc_buffer_push(buffer, 4);
242 silc_buffer_pull(buffer, 4 + pk_len);
243 silc_buffer_format(buffer,
244 SILC_STR_UI_SHORT(auth_len),
245 SILC_STR_UI_XNSTRING(auth_data, auth_len),
247 silc_buffer_push(buffer, 4 + pk_len);
249 SILC_LOG_HEXDUMP(("sig payload"), buffer->data, silc_buffer_len(buffer));
251 memset(auth_data, 0, sizeof(auth_data));
252 silc_buffer_clear(sign);
253 silc_buffer_free(sign);
260 /***************************** Payload parsing ******************************/
262 /* Decrypts the Message Payload. The `data' is the actual Message Payload. */
264 SilcBool silc_message_payload_decrypt(unsigned char *data,
266 SilcBool private_message,
272 SilcUInt32 mac_len, iv_len = 0, block_len;
273 SilcUInt16 len, totlen;
274 unsigned char mac[32], *ivp;
276 mac_len = silc_hmac_len(hmac);
277 block_len = silc_cipher_get_block_len(cipher);
279 /* IV is present for all channel messages, and private messages when
280 static key (pre-shared key) is used. */
281 if (!private_message || (private_message && static_key))
284 if (data_len < (mac_len + iv_len + block_len))
288 /* Check the MAC of the message */
289 SILC_LOG_DEBUG(("Checking message MAC"));
290 silc_hmac_init(hmac);
291 silc_hmac_update(hmac, data, data_len - mac_len);
292 silc_hmac_final(hmac, mac, &mac_len);
293 if (memcmp(data + (data_len - mac_len), mac, mac_len)) {
294 SILC_LOG_DEBUG(("Message MAC does not match"));
297 SILC_LOG_DEBUG(("MAC is Ok"));
300 /* Decrypt first only one block to get the header and then rest of
301 the data. This is done because there might be unencrypted data at
302 the end and we don't know the encrypted length yet. */
304 /* Get pointer to the IV */
305 ivp = (iv_len ? data + (data_len - iv_len - mac_len) :
306 silc_cipher_get_iv(cipher));
309 if (!silc_cipher_decrypt(cipher, data, data, block_len, ivp)) {
314 /* Get the payload length and decrypt rest */
316 SILC_GET16_MSB(len, data + totlen);
318 if (totlen + iv_len + mac_len + 2 > data_len)
321 if (totlen >= block_len)
322 if (!silc_cipher_decrypt(cipher, data + block_len, data + block_len,
323 (totlen - block_len) + SILC_MESSAGE_PAD(totlen),
332 /* Parses Message Payload returning new payload structure. This also
333 decrypts it and checks the MAC. */
336 silc_message_payload_parse(unsigned char *payload,
337 SilcUInt32 payload_len,
338 SilcBool private_message,
343 SilcBool no_allocation,
344 SilcMessagePayload message)
346 SilcBufferStruct buffer;
347 SilcMessagePayload newp = NULL;
349 SilcUInt32 mac_len = 0, iv_len = 0;
351 SILC_LOG_DEBUG(("Parsing Message Payload"));
353 silc_buffer_set(&buffer, payload, payload_len);
355 /* Decrypt the payload */
357 ret = silc_message_payload_decrypt(buffer.data, silc_buffer_len(&buffer),
358 private_message, static_key,
365 mac_len = silc_hmac_len(hmac);
367 /* IV is present for all channel messages, and private messages when
368 static key (pre-shared key) is used. */
369 if (cipher && (!private_message || (private_message && static_key)))
370 iv_len = silc_cipher_get_block_len(cipher);
373 newp = message = silc_calloc(1, sizeof(*newp));
377 memset(message, 0, sizeof(*message));
378 message->allocated = (stack || no_allocation ? FALSE : TRUE);
380 /* Parse the Message Payload. */
382 ret = silc_buffer_sunformat(stack, &buffer,
383 SILC_STR_UI_SHORT(&message->flags),
384 SILC_STR_UI16_NSTRING_ALLOC(&message->data,
386 SILC_STR_UI16_NSTRING_ALLOC(&message->pad,
390 ret = silc_buffer_unformat(&buffer,
391 SILC_STR_UI_SHORT(&message->flags),
392 SILC_STR_UI16_NSTRING(&message->data,
394 SILC_STR_UI16_NSTRING(&message->pad,
400 if ((message->data_len > silc_buffer_len(&buffer) - 6 - mac_len - iv_len) ||
401 (message->pad_len + message->data_len > silc_buffer_len(&buffer) -
402 6 - mac_len - iv_len)) {
403 SILC_LOG_ERROR(("Incorrect Message Payload in packet"));
407 /* Parse Signed Message Payload if provided */
408 if (message->flags & SILC_MESSAGE_FLAG_SIGNED &&
409 message->data_len + message->pad_len + 6 + mac_len +
410 iv_len < silc_buffer_len(&buffer)) {
411 if (!silc_message_signed_payload_parse(buffer.data + 6 +
414 silc_buffer_len(&buffer) -
415 iv_len - mac_len - 6 -
422 /* Parse MAC from the payload */
424 message->mac = buffer.data + (silc_buffer_len(&buffer) - mac_len);
430 silc_message_payload_free(newp);
435 /***************************** Payload encoding *****************************/
437 /* This function is used to encrypt the Messsage Payload which is
438 the `data' and `data_len'. This is used internally by the Message
439 Payload encoding routines but application may call this too if needed.
440 The `true_len' is the data length which is used to create MAC out of. */
442 SilcBool silc_message_payload_encrypt(unsigned char *data,
449 /* Encrypt payload of the packet */
450 if (!silc_cipher_encrypt(cipher, data, data, data_len, iv))
453 /* Compute the MAC of the encrypted message data */
454 silc_hmac_init(hmac);
455 silc_hmac_update(hmac, data, true_len);
456 silc_hmac_final(hmac, data + true_len, NULL);
461 /* Encrypt message payload */
463 static int silc_message_payload_encode_encrypt(SilcBuffer buffer,
464 void *value, void *context)
466 SilcMessageEncode *e = context;
469 if (!e->cipher || !e->hmac)
472 mac_len = silc_hmac_len(e->hmac);
473 if (!silc_buffer_enlarge(buffer, mac_len))
476 if (!silc_message_payload_encrypt(buffer->head,
478 silc_buffer_headlen(buffer),
479 e->iv, e->cipher, e->hmac))
485 /* Compute message signature */
487 static int silc_message_payload_encode_sig(SilcBuffer buffer,
488 void *value, void *context)
490 SilcMessageEncode *e = context;
494 if (!(e->flags & SILC_MESSAGE_FLAG_SIGNED))
497 sig = silc_message_signed_payload_encode(buffer->head,
498 silc_buffer_headlen(buffer),
499 e->public_key, e->private_key,
504 len = silc_buffer_format(buffer,
505 SILC_STR_DATA(silc_buffer_data(sig),
506 silc_buffer_len(sig)),
509 silc_buffer_free(sig);
513 silc_buffer_free(sig);
517 /* Encodes Message Payload into a buffer and returns it. */
519 SilcBuffer silc_message_payload_encode(SilcMessageFlags flags,
520 const unsigned char *data,
522 SilcBool generate_iv,
523 SilcBool private_message,
527 SilcPublicKey public_key,
528 SilcPrivateKey private_key,
532 SilcUInt32 pad_len = 0, mac_len = 0, iv_len = 0;
533 unsigned char pad[16], iv[SILC_CIPHER_MAX_IV_SIZE];
534 SilcBuffer buf = NULL;
538 SILC_LOG_DEBUG(("Encoding Message Payload"));
542 if (!private_message && (!cipher || !hmac))
546 buf = buffer = silc_buffer_alloc(0);
550 silc_buffer_reset(buffer);
552 /* For channel messages IV is always generated */
553 if (!private_message && !generate_iv)
557 if (cipher && generate_iv) {
558 iv_len = silc_cipher_get_block_len(cipher);
560 for (i = 0; i < iv_len; i++) iv[i] = silc_rng_get_byte_fast(rng);
562 for (i = 0; i < iv_len; i++) iv[i] = silc_rng_global_get_byte_fast();
567 mac_len = silc_hmac_len(hmac);
568 data_len = silc_message_payload_datalen(data_len, mac_len + iv_len, flags,
569 public_key, private_key);
571 /* Calculate length of padding. IV is not included into the calculation
572 since it is not encrypted. */
573 pad_len = SILC_MESSAGE_PAD(6 + data_len);
575 /* Generate padding */
578 for (i = 0; i < pad_len; i++) pad[i] = silc_rng_get_byte_fast(rng);
580 for (i = 0; i < pad_len; i++) pad[i] = silc_rng_global_get_byte_fast();
585 e.public_key = public_key;
586 e.private_key = private_key;
590 e.iv = iv_len ? iv : NULL;
591 e.payload_len = 6 + data_len + pad_len;
593 /* Encode the Message Payload */
594 if (silc_buffer_format(buffer,
595 SILC_STR_UI_SHORT(flags),
596 SILC_STR_UI_SHORT(data_len),
597 SILC_STR_DATA(data, data_len),
598 SILC_STR_UI_SHORT(pad_len),
599 SILC_STR_DATA(pad, pad_len),
600 SILC_STR_FUNC(silc_message_payload_encode_sig,
602 SILC_STR_DATA(iv, iv_len),
603 SILC_STR_FUNC(silc_message_payload_encode_encrypt,
606 silc_buffer_free(buf);
613 /* Free's Message Payload */
615 void silc_message_payload_free(SilcMessagePayload payload)
618 memset(payload->data, 0, payload->data_len);
619 if (payload->allocated)
620 silc_free(payload->data);
622 if (payload->allocated) {
623 silc_free(payload->pad);
626 silc_message_signed_payload_free(&payload->sig);
631 SilcMessageFlags silc_message_get_flags(SilcMessagePayload payload)
633 return payload->flags;
638 unsigned char *silc_message_get_data(SilcMessagePayload payload,
639 SilcUInt32 *data_len)
642 *data_len = payload->data_len;
643 return payload->data;
646 /* Return MAC. The caller knows the length of the MAC */
648 unsigned char *silc_message_get_mac(SilcMessagePayload payload)
653 /* Verify the signature in SILC_MESSAGE_FLAG_SIGNED Payload */
655 SilcAuthResult silc_message_signed_verify(SilcMessagePayload message,
656 SilcPublicKey remote_public_key,
659 int ret = SILC_AUTH_FAILED;
660 SilcBuffer sign, tmp;
661 SilcMessageSignedPayload sig = &message->sig;
663 if (!(message->flags & SILC_MESSAGE_FLAG_SIGNED) ||
664 !sig->sign_len || !remote_public_key || !hash)
667 /* Generate the signature verification data, the Message Payload */
668 tmp = silc_buffer_alloc_size(6 + message->data_len + message->pad_len);
669 silc_buffer_format(tmp,
670 SILC_STR_UI_SHORT(message->flags),
671 SILC_STR_UI_SHORT(message->data_len),
672 SILC_STR_UI_XNSTRING(message->data, message->data_len),
673 SILC_STR_UI_SHORT(message->pad_len),
674 SILC_STR_UI_XNSTRING(message->pad, message->pad_len),
676 sign = silc_message_signed_encode_data(tmp->data, silc_buffer_len(tmp),
677 sig->pk_data, sig->pk_len,
679 silc_buffer_clear(tmp);
680 silc_buffer_free(tmp);
685 /* Verify the authentication data */
686 if (!silc_pkcs_verify(remote_public_key, sig->sign_data, sig->sign_len,
687 silc_buffer_data(sign), silc_buffer_len(sign), hash)) {
688 silc_buffer_clear(sign);
689 silc_buffer_free(sign);
690 SILC_LOG_DEBUG(("Signature verification failed"));
696 silc_buffer_clear(sign);
697 silc_buffer_free(sign);
699 SILC_LOG_DEBUG(("Signature verification successful"));
704 /* Return the public key from the payload */
707 silc_message_signed_get_public_key(SilcMessagePayload payload,
708 const unsigned char **pk_data,
709 SilcUInt32 *pk_data_len)
712 SilcMessageSignedPayload sig = &payload->sig;
717 if (!silc_pkcs_public_key_alloc(sig->pk_type, sig->pk_data,
722 *pk_data = sig->pk_data;
724 *pk_data_len = sig->pk_len;