summaryrefslogtreecommitdiff
path: root/src/include/gnunet_crypto_lib.h
blob: 0be9611baed6170f83871aa33cdd79a04148fda2 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
/*
     This file is part of GNUnet.
     (C) 2001, 2002, 2003, 2004, 2005, 2006, 2007 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 include/gnunet_crypto_lib.h
 * @brief cryptographic primitives for GNUnet
 *
 * @author Christian Grothoff
 * @author Krista Bennett
 * @author Gerd Knorr <kraxel@bytesex.org>
 * @author Ioana Patrascu
 * @author Tzvetan Horozov
 */

#ifndef GNUNET_CRYPTO_LIB_H
#define GNUNET_CRYPTO_LIB_H

#ifdef __cplusplus
extern "C"
{
#if 0                           /* keep Emacsens' auto-indent happy */
}
#endif
#endif

#include "gnunet_common.h"
#include "gnunet_scheduler_lib.h"

/**
 * Desired quality level for cryptographic operations.
 */
enum GNUNET_CRYPTO_Quality
{
  /**
   * No good quality of the operation is needed (i.e.,
   * random numbers can be pseudo-random).
   */
  GNUNET_CRYPTO_QUALITY_WEAK,

  /**
   * High-quality operations are desired.
   */
  GNUNET_CRYPTO_QUALITY_STRONG,

  /**
   * Randomness for IVs etc. is required.
   */
  GNUNET_CRYPTO_QUALITY_NONCE
};


/**
 * @brief length of the sessionkey in bytes (256 BIT sessionkey)
 */
#define GNUNET_CRYPTO_AES_KEY_LENGTH (256/8)


/**
 * @brief Length of RSA encrypted data (2048 bit)
 *
 * We currently do not handle encryption of data
 * that can not be done in a single call to the
 * RSA methods (read: large chunks of data).
 * We should never need that, as we can use
 * the GNUNET_CRYPTO_hash for larger pieces of data for signing,
 * and for encryption, we only need to encode sessionkeys!
 */
#define GNUNET_CRYPTO_RSA_DATA_ENCODING_LENGTH 256


/**
 * Length of an RSA KEY (d,e,len), 2048 bit (=256 octests) key d, 2 byte e
 */
#define GNUNET_CRYPTO_RSA_KEY_LENGTH 258


/**
 * Length of a hash value
 */
#define GNUNET_CRYPTO_HASH_LENGTH 512/8

/**
 * The private information of an RSA key pair.
 */
struct GNUNET_CRYPTO_RsaPrivateKey;


/**
 * @brief 0-terminated ASCII encoding of a GNUNET_HashCode.
 */
struct GNUNET_CRYPTO_HashAsciiEncoded
{
  unsigned char encoding[104];
};



/**
 * @brief an RSA signature
 */
struct GNUNET_CRYPTO_RsaSignature
{
  unsigned char sig[GNUNET_CRYPTO_RSA_DATA_ENCODING_LENGTH];
};


GNUNET_NETWORK_STRUCT_BEGIN

/**
 * @brief header of what an RSA signature signs
 *        this must be followed by "size - 8" bytes of
 *        the actual signed data
 */
struct GNUNET_CRYPTO_RsaSignaturePurpose
{
  /**
   * How many bytes does this signature sign?
   * (including this purpose header); in network
   * byte order (!).
   */
  uint32_t size GNUNET_PACKED;

  /**
   * What does this signature vouch for?  This
   * must contain a GNUNET_SIGNATURE_PURPOSE_XXX
   * constant (from gnunet_signatures.h).  In
   * network byte order!
   */
  uint32_t purpose GNUNET_PACKED;

};


/**
 * @brief A public key.
 */
struct GNUNET_CRYPTO_RsaPublicKeyBinaryEncoded
{
  /**
   * In big-endian, must be GNUNET_CRYPTO_RSA_KEY_LENGTH+4
   */
  uint16_t len GNUNET_PACKED;

  /**
   * Size of n in key; in big-endian!
   */
  uint16_t sizen GNUNET_PACKED;

  /**
   * The key itself, contains n followed by e.
   */
  unsigned char key[GNUNET_CRYPTO_RSA_KEY_LENGTH];

  /**
   * Padding (must be 0)
   */
  uint16_t padding GNUNET_PACKED;
};


/**
 * RSA Encrypted data.
 */
struct GNUNET_CRYPTO_RsaEncryptedData
{
  unsigned char encoding[GNUNET_CRYPTO_RSA_DATA_ENCODING_LENGTH];
};


/**
 * @brief type for session keys
 */
struct GNUNET_CRYPTO_AesSessionKey
{
  /**
   * Actual key.
   */
  unsigned char key[GNUNET_CRYPTO_AES_KEY_LENGTH];

  /**
   * checksum!
   */
  uint32_t crc32 GNUNET_PACKED;
};
GNUNET_NETWORK_STRUCT_END

/**
 * @brief IV for sym cipher
 *
 * NOTE: must be smaller (!) in size than the
 * GNUNET_HashCode.
 */
struct GNUNET_CRYPTO_AesInitializationVector
{
  unsigned char iv[GNUNET_CRYPTO_AES_KEY_LENGTH / 2];
};


/**
 * @brief type for (message) authentication keys
 */
struct GNUNET_CRYPTO_AuthKey
{
  unsigned char key[GNUNET_CRYPTO_HASH_LENGTH];
};


/* **************** Functions and Macros ************* */

/**
 * Seed a weak random generator. Only GNUNET_CRYPTO_QUALITY_WEAK-mode generator
 * can be seeded.
 *
 * @param seed the seed to use
 */
void
GNUNET_CRYPTO_seed_weak_random (int32_t seed);


/**
 * Perform an incremental step in a CRC16 (for TCP/IP) calculation.
 *
 * @param sum current sum, initially 0
 * @param hdr buffer to calculate CRC over (must be 16-bit aligned)
 * @param len number of bytes in hdr, must be multiple of 2
 * @return updated crc sum (must be subjected to GNUNET_CRYPTO_crc16_finish to get actual crc16)
 */
uint32_t
GNUNET_CRYPTO_crc16_step (uint32_t sum, uint16_t * hdr, size_t len);


/**
 * Convert results from GNUNET_CRYPTO_crc16_step to final crc16.
 *
 * @param sum cummulative sum
 * @return crc16 value
 */
uint16_t
GNUNET_CRYPTO_crc16_finish (uint32_t sum);


/**
 * Calculate the checksum of a buffer in one step.
 *
 * @param hdr buffer to  calculate CRC over (must be 16-bit aligned)
 * @param len number of bytes in hdr, must be multiple of 2
 * @return crc16 value
 */
uint16_t
GNUNET_CRYPTO_crc16_n (uint16_t *hdr, size_t len);


/**
 * Compute the CRC32 checksum for the first len
 * bytes of the buffer.
 *
 * @param buf the data over which we're taking the CRC
 * @param len the length of the buffer in bytes
 * @return the resulting CRC32 checksum
 */
int32_t
GNUNET_CRYPTO_crc32_n (const void *buf, size_t len);


/**
 * Produce a random value.
 *
 * @param mode desired quality of the random number
 * @param i the upper limit (exclusive) for the random number
 * @return a random value in the interval [0,i) (exclusive).
 */
uint32_t
GNUNET_CRYPTO_random_u32 (enum GNUNET_CRYPTO_Quality mode, uint32_t i);


/**
 * Random on unsigned 64-bit values.
 *
 * @param mode desired quality of the random number
 * @param max value returned will be in range [0,max) (exclusive)
 * @return random 64-bit number
 */
uint64_t
GNUNET_CRYPTO_random_u64 (enum GNUNET_CRYPTO_Quality mode, uint64_t max);


/**
 * Get an array with a random permutation of the
 * numbers 0...n-1.
 * @param mode GNUNET_CRYPTO_QUALITY_STRONG if the strong (but expensive) PRNG should be used, GNUNET_CRYPTO_QUALITY_WEAK otherwise
 * @param n the size of the array
 * @return the permutation array (allocated from heap)
 */
unsigned int *
GNUNET_CRYPTO_random_permute (enum GNUNET_CRYPTO_Quality mode, unsigned int n);


/**
 * Create a new Session key.
 *
 * @param key key to initialize
 */
void
GNUNET_CRYPTO_aes_create_session_key (struct GNUNET_CRYPTO_AesSessionKey *key);

/**
 * Check that a new session key is well-formed.
 *
 * @param key key to check
 * @return GNUNET_OK if the key is valid
 */
int
GNUNET_CRYPTO_aes_check_session_key (const struct GNUNET_CRYPTO_AesSessionKey
                                     *key);


/**
 * Encrypt a block with the public key of another
 * host that uses the same cyper.
 *
 * @param block the block to encrypt
 * @param len the size of the block
 * @param sessionkey the key used to encrypt
 * @param iv the initialization vector to use, use INITVALUE
 *        for streams.
 * @return the size of the encrypted block, -1 for errors
 */
ssize_t
GNUNET_CRYPTO_aes_encrypt (const void *block, size_t len,
                           const struct GNUNET_CRYPTO_AesSessionKey *sessionkey,
                           const struct GNUNET_CRYPTO_AesInitializationVector
                           *iv, void *result);


/**
 * Decrypt a given block with the sessionkey.
 *
 * @param block the data to decrypt, encoded as returned by encrypt
 * @param size how big is the block?
 * @param sessionkey the key used to decrypt
 * @param iv the initialization vector to use
 * @param result address to store the result at
 * @return -1 on failure, size of decrypted block on success
 */
ssize_t
GNUNET_CRYPTO_aes_decrypt (const void *block, size_t size,
                           const struct GNUNET_CRYPTO_AesSessionKey *sessionkey,
                           const struct GNUNET_CRYPTO_AesInitializationVector
                           *iv, void *result);


/**
 * @brief Derive an IV
 * @param iv initialization vector
 * @param skey session key
 * @param salt salt for the derivation
 * @param salt_len size of the salt
 * @param ... pairs of void * & size_t for context chunks, terminated by NULL
 */
void
GNUNET_CRYPTO_aes_derive_iv (struct GNUNET_CRYPTO_AesInitializationVector *iv,
                             const struct GNUNET_CRYPTO_AesSessionKey *skey,
                             const void *salt, size_t salt_len, ...);


/**
 * @brief Derive an IV
 * @param iv initialization vector
 * @param skey session key
 * @param salt salt for the derivation
 * @param salt_len size of the salt
 * @param argp pairs of void * & size_t for context chunks, terminated by NULL
 */
void
GNUNET_CRYPTO_aes_derive_iv_v (struct GNUNET_CRYPTO_AesInitializationVector *iv,
                               const struct GNUNET_CRYPTO_AesSessionKey *skey,
                               const void *salt, size_t salt_len, va_list argp);


/**
 * Convert hash to ASCII encoding.
 * @param block the hash code
 * @param result where to store the encoding (struct GNUNET_CRYPTO_HashAsciiEncoded can be
 *  safely cast to char*, a '\\0' termination is set).
 */
void
GNUNET_CRYPTO_hash_to_enc (const GNUNET_HashCode * block,
                           struct GNUNET_CRYPTO_HashAsciiEncoded *result);


/**
 * Convert ASCII encoding back to GNUNET_CRYPTO_hash
 * @param enc the encoding
 * @param result where to store the GNUNET_CRYPTO_hash code
 * @return GNUNET_OK on success, GNUNET_SYSERR if result has the wrong encoding
 */
int
GNUNET_CRYPTO_hash_from_string (const char *enc, GNUNET_HashCode * result);


/**
 * Compute the distance between 2 hashcodes.
 * The computation must be fast, not involve
 * a.a or a.e (they're used elsewhere), and
 * be somewhat consistent. And of course, the
 * result should be a positive number.
 *
 * @param a some hash code
 * @param b some hash code
 * @return number between 0 and UINT32_MAX
 */
uint32_t
GNUNET_CRYPTO_hash_distance_u32 (const GNUNET_HashCode * a,
                                 const GNUNET_HashCode * b);


/**
 * Compute hash of a given block.
 *
 * @param block the data to hash
 * @param size size of the block
 * @param ret pointer to where to write the hashcode
 */
void
GNUNET_CRYPTO_hash (const void *block, size_t size, GNUNET_HashCode * ret);


/**
 * Calculate HMAC of a message (RFC 2104)
 *
 * @param key secret key
 * @param plaintext input plaintext
 * @param plaintext_len length of plaintext
 * @param hmac where to store the hmac
 */
void
GNUNET_CRYPTO_hmac (const struct GNUNET_CRYPTO_AuthKey *key,
                    const void *plaintext, size_t plaintext_len,
                    GNUNET_HashCode * hmac);


/**
 * Function called once the hash computation over the
 * specified file has completed.
 *
 * @param cls closure
 * @param res resulting hash, NULL on error
 */
typedef void (*GNUNET_CRYPTO_HashCompletedCallback) (void *cls,
                                                     const GNUNET_HashCode *
                                                     res);


/**
 * Handle to file hashing operation.
 */
struct GNUNET_CRYPTO_FileHashContext;

/**
 * Compute the hash of an entire file.
 *
 * @param priority scheduling priority to use
 * @param filename name of file to hash
 * @param blocksize number of bytes to process in one task
 * @param callback function to call upon completion
 * @param callback_cls closure for callback
 * @return NULL on (immediate) errror
 */
struct GNUNET_CRYPTO_FileHashContext *
GNUNET_CRYPTO_hash_file (enum GNUNET_SCHEDULER_Priority priority,
                         const char *filename, size_t blocksize,
                         GNUNET_CRYPTO_HashCompletedCallback callback,
                         void *callback_cls);


/**
 * Cancel a file hashing operation.
 *
 * @param fhc operation to cancel (callback must not yet have been invoked)
 */
void
GNUNET_CRYPTO_hash_file_cancel (struct GNUNET_CRYPTO_FileHashContext *fhc);


/**
 * Create a random hash code.
 *
 * @param mode desired quality level
 * @param result hash code that is randomized
 */
void
GNUNET_CRYPTO_hash_create_random (enum GNUNET_CRYPTO_Quality mode,
                                  GNUNET_HashCode * result);


/**
 * compute result(delta) = b - a
 *
 * @param a some hash code
 * @param b some hash code
 * @param result set to b - a
 */
void
GNUNET_CRYPTO_hash_difference (const GNUNET_HashCode * a,
                               const GNUNET_HashCode * b,
                               GNUNET_HashCode * result);


/**
 * compute result(b) = a + delta
 *
 * @param a some hash code
 * @param delta some hash code
 * @param result set to a + delta
 */
void
GNUNET_CRYPTO_hash_sum (const GNUNET_HashCode * a,
                        const GNUNET_HashCode * delta,
                        GNUNET_HashCode * result);


/**
 * compute result = a ^ b
 *
 * @param a some hash code
 * @param b some hash code
 * @param result set to a ^ b
 */
void
GNUNET_CRYPTO_hash_xor (const GNUNET_HashCode * a, const GNUNET_HashCode * b,
                        GNUNET_HashCode * result);


/**
 * Convert a hashcode into a key.
 *
 * @param hc hash code that serves to generate the key
 * @param skey set to a valid session key
 * @param iv set to a valid initialization vector
 */
void
GNUNET_CRYPTO_hash_to_aes_key (const GNUNET_HashCode * hc,
                               struct GNUNET_CRYPTO_AesSessionKey *skey,
                               struct GNUNET_CRYPTO_AesInitializationVector
                               *iv);


/**
 * Obtain a bit from a hashcode.
 *
 * @param code the GNUNET_CRYPTO_hash to index bit-wise
 * @param bit index into the hashcode, [0...159]
 * @return Bit \a bit from hashcode \a code, -1 for invalid index
 */
int
GNUNET_CRYPTO_hash_get_bit (const GNUNET_HashCode * code, unsigned int bit);

/**
 * Determine how many low order bits match in two
 * GNUNET_HashCodes.  i.e. - 010011 and 011111 share
 * the first two lowest order bits, and therefore the
 * return value is two (NOT XOR distance, nor how many
 * bits match absolutely!).
 *
 * @param first the first hashcode
 * @param second the hashcode to compare first to
 *
 * @return the number of bits that match
 */
unsigned int
GNUNET_CRYPTO_hash_matching_bits (const GNUNET_HashCode * first,
                                  const GNUNET_HashCode * second);


/**
 * Compare function for HashCodes, producing a total ordering
 * of all hashcodes.
 *
 * @param h1 some hash code
 * @param h2 some hash code
 * @return 1 if h1 > h2, -1 if h1 < h2 and 0 if h1 == h2.
 */
int
GNUNET_CRYPTO_hash_cmp (const GNUNET_HashCode * h1, const GNUNET_HashCode * h2);


/**
 * Find out which of the two GNUNET_CRYPTO_hash codes is closer to target
 * in the XOR metric (Kademlia).
 *
 * @param h1 some hash code
 * @param h2 some hash code
 * @param target some hash code
 * @return -1 if h1 is closer, 1 if h2 is closer and 0 if h1==h2.
 */
int
GNUNET_CRYPTO_hash_xorcmp (const GNUNET_HashCode * h1,
                           const GNUNET_HashCode * h2,
                           const GNUNET_HashCode * target);


/**
 * @brief Derive an authentication key
 * @param key authentication key
 * @param rkey root key
 * @param salt salt
 * @param salt_len size of the salt
 * @param argp pair of void * & size_t for context chunks, terminated by NULL
 */
void
GNUNET_CRYPTO_hmac_derive_key_v (struct GNUNET_CRYPTO_AuthKey *key,
                                 const struct GNUNET_CRYPTO_AesSessionKey *rkey,
                                 const void *salt, size_t salt_len,
                                 va_list argp);


/**
 * @brief Derive an authentication key
 * @param key authentication key
 * @param rkey root key
 * @param salt salt
 * @param salt_len size of the salt
 * @param ... pair of void * & size_t for context chunks, terminated by NULL
 */
void
GNUNET_CRYPTO_hmac_derive_key (struct GNUNET_CRYPTO_AuthKey *key,
                               const struct GNUNET_CRYPTO_AesSessionKey *rkey,
                               const void *salt, size_t salt_len, ...);

/**
 * @brief Derive key
 * @param result buffer for the derived key, allocated by caller
 * @param out_len desired length of the derived key
 * @param xtr_algo hash algorithm for the extraction phase, GCRY_MD_...
 * @param prf_algo hash algorithm for the expansion phase, GCRY_MD_...
 * @param xts salt
 * @param xts_len length of xts
 * @param skm source key material
 * @param skm_len length of skm
 * @return GNUNET_YES on success
 */
int
GNUNET_CRYPTO_hkdf (void *result, size_t out_len, int xtr_algo, int prf_algo,
                    const void *xts, size_t xts_len, const void *skm,
                    size_t skm_len, ...);


/**
 * @brief Derive key
 * @param result buffer for the derived key, allocated by caller
 * @param out_len desired length of the derived key
 * @param xtr_algo hash algorithm for the extraction phase, GCRY_MD_...
 * @param prf_algo hash algorithm for the expansion phase, GCRY_MD_...
 * @param xts salt
 * @param xts_len length of xts
 * @param skm source key material
 * @param skm_len length of skm
 * @param argp va_list of void * & size_t pairs for context chunks
 * @return GNUNET_YES on success
 */
int
GNUNET_CRYPTO_hkdf_v (void *result, size_t out_len, int xtr_algo, int prf_algo,
                      const void *xts, size_t xts_len, const void *skm,
                      size_t skm_len, va_list argp);


/**
 * @brief Derive key
 * @param result buffer for the derived key, allocated by caller
 * @param out_len desired length of the derived key
 * @param xts salt
 * @param xts_len length of xts
 * @param skm source key material
 * @param skm_len length of skm
 * @param argp va_list of void * & size_t pairs for context chunks
 * @return GNUNET_YES on success
 */
int
GNUNET_CRYPTO_kdf_v (void *result, size_t out_len, const void *xts,
                     size_t xts_len, const void *skm, size_t skm_len,
                     va_list argp);


/**
 * @brief Derive key
 * @param result buffer for the derived key, allocated by caller
 * @param out_len desired length of the derived key
 * @param xts salt
 * @param xts_len length of xts
 * @param skm source key material
 * @param skm_len length of skm
 * @param ... void * & size_t pairs for context chunks
 * @return GNUNET_YES on success
 */
int
GNUNET_CRYPTO_kdf (void *result, size_t out_len, const void *xts,
                   size_t xts_len, const void *skm, size_t skm_len, ...);


/**
 * Create a new private key. Caller must free return value.
 *
 * @return fresh private key
 */
struct GNUNET_CRYPTO_RsaPrivateKey *
GNUNET_CRYPTO_rsa_key_create (void);

/**
 * Decode the private key from the data-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'
 */
struct GNUNET_CRYPTO_RsaPrivateKey *
GNUNET_CRYPTO_rsa_decode_key (const char *buf, uint16_t len);

/**
 * 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.
 *
 * @param filename name of file to use for storage
 * @return new private key, NULL on error (for example,
 *   permission denied)
 */
struct GNUNET_CRYPTO_RsaPrivateKey *
GNUNET_CRYPTO_rsa_key_create_from_file (const char *filename);


/**
 * Deterministically (!) create a private key using only the
 * given HashCode as input to the PRNG.
 *
 * @param hc "random" input to PRNG
 * @return some private key purely dependent on input
 */
struct GNUNET_CRYPTO_RsaPrivateKey *
GNUNET_CRYPTO_rsa_key_create_from_hash (const GNUNET_HashCode * hc);


/**
 * Free memory occupied by the private key.
 * @param hostkey pointer to the memory to free
 */
void
GNUNET_CRYPTO_rsa_key_free (struct GNUNET_CRYPTO_RsaPrivateKey *hostkey);


/**
 * Extract the public key of the host.
 *
 * @param priv the private key
 * @param pub where to write the public key
 */
void
GNUNET_CRYPTO_rsa_key_get_public (const struct GNUNET_CRYPTO_RsaPrivateKey
                                  *priv,
                                  struct GNUNET_CRYPTO_RsaPublicKeyBinaryEncoded
                                  *pub);


/**
 * Encrypt a block with the public key of another host that uses the
 * same cyper.
 *
 * @param block the block to encrypt
 * @param size the size of block
 * @param publicKey the encoded public key used to encrypt
 * @param target where to store the encrypted block
 * @return GNUNET_SYSERR on error, GNUNET_OK if ok
 */
int
GNUNET_CRYPTO_rsa_encrypt (const void *block, size_t size,
                           const struct GNUNET_CRYPTO_RsaPublicKeyBinaryEncoded
                           *publicKey,
                           struct GNUNET_CRYPTO_RsaEncryptedData *target);


/**
 * Decrypt a given block with the hostkey.
 *
 * @param key the key to use
 * @param block the data to decrypt, encoded as returned by encrypt, not consumed
 * @param result pointer to a location where the result can be stored
 * @param max how many bytes of a result are expected? Must be exact.
 * @return the size of the decrypted block (that is, size) or -1 on error
 */
ssize_t
GNUNET_CRYPTO_rsa_decrypt (const struct GNUNET_CRYPTO_RsaPrivateKey *key,
                           const struct GNUNET_CRYPTO_RsaEncryptedData *block,
                           void *result, size_t max);


/**
 * 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_rsa_sign (const struct GNUNET_CRYPTO_RsaPrivateKey *key,
                        const struct GNUNET_CRYPTO_RsaSignaturePurpose *purpose,
                        struct GNUNET_CRYPTO_RsaSignature *sig);


/**
 * Verify signature.  Note that the caller MUST have already
 * checked that "validate->size" bytes are actually available.
 *
 * @param purpose what is the purpose that validate should have?
 * @param validate block to validate (size, purpose, data)
 * @param sig signature that is being validated
 * @param publicKey public key of the signer
 * @return GNUNET_OK if ok, GNUNET_SYSERR if invalid
 */
int
GNUNET_CRYPTO_rsa_verify (uint32_t purpose,
                          const struct GNUNET_CRYPTO_RsaSignaturePurpose
                          *validate,
                          const struct GNUNET_CRYPTO_RsaSignature *sig,
                          const struct GNUNET_CRYPTO_RsaPublicKeyBinaryEncoded
                          *publicKey);



/**
 * This function should only be called in testcases
 * where strong entropy gathering is not desired
 * (for example, for hostkey generation).
 */
void
GNUNET_CRYPTO_random_disable_entropy_gathering (void);

#if 0                           /* keep Emacsens' auto-indent happy */
{
#endif
#ifdef __cplusplus
}
#endif


/* ifndef GNUNET_CRYPTO_LIB_H */
#endif
/* end of gnunet_crypto_lib.h */