src/misc/update_crypto.c

   1 /*****************************************************************************
   2  * update_crypto.c: DSA/SHA1 related functions used for updating
   3  *****************************************************************************
   4  * Copyright © 2008-2009 VLC authors and VideoLAN
   5  * $Id$
   6  *
   7  * Authors: Rafaël Carré <funman@videolanorg>
   8  *
   9  * This program is free software; you can redistribute it and/or modify it
  10  * under the terms of the GNU Lesser General Public License as published by
  11  * the Free Software Foundation; either release 2 of the License, or
  12  * (at your option) any later release.
  13  *
  14  * This program is distributed in the hope that it will be useful,
  15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  17  * GNU Lesser General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU Lesser General Public License
  20  * along with this program; if not, write to the Free Software Foundation,
  21  * Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
  22  *****************************************************************************/
  23
  24 /**
  25  *   \file
  26  *   This file contains functions related to OpenPGP in VLC update management
  27  */
  28
  29 /*****************************************************************************
  30  * Preamble
  31  *****************************************************************************/
  32
  33 #ifdef HAVE_CONFIG_H
  34 # include "config.h"
  35 #endif
  36
  37 #ifdef UPDATE_CHECK
  38
  39 #include <gcrypt.h>
  40 #include <assert.h>
  41
  42 #include "vlc_common.h"
  43 #include <vlc_stream.h>
  44 #include <vlc_strings.h>
  45 #include <vlc_fs.h>
  46
  47 #include "update.h"
  48
  49
  50 /*****************************************************************************
  51  * OpenPGP functions
  52  *****************************************************************************/
  53
  54 #define packet_type( c ) ( ( c & 0x3c ) >> 2 )      /* 0x3C = 00111100 */
  55 #define packet_header_len( c ) ( ( c & 0x03 ) + 1 ) /* number of bytes in a packet header */
  56
  57
  58 static inline int scalar_number( uint8_t *p, int header_len )
  59 {
  60     assert( header_len == 1 || header_len == 2 || header_len == 4 );
  61
  62     if( header_len == 1 )
  63         return( p[0] );
  64     else if( header_len == 2 )
  65         return( (p[0] << 8) + p[1] );
  66     else if( header_len == 4 )
  67         return( (p[0] << 24) + (p[1] << 16) + (p[2] << 8) + p[3] );
  68     else
  69         abort();
  70 }
  71
  72
  73 /* number of data bytes in a MPI */
  74 #define mpi_len( mpi ) ( ( scalar_number( mpi, 2 ) + 7 ) / 8 )
  75
  76 #define READ_MPI(n, bits) do { \
  77     if( i_read + 2 > i_packet_len ) \
  78         goto error; \
  79     int len = mpi_len( p_buf ); \
  80     if( len > (bits)/8 || i_read + 2 + len > i_packet_len ) \
  81         goto error; \
  82     len += 2; \
  83     memcpy( n, p_buf, len ); \
  84     p_buf += len; i_read += len; \
  85     } while(0)
  86
  87 /*
  88  * fill a public_key_packet_t structure from public key packet data
  89  * verify that it is a version 4 public key packet, using DSA
  90  */
  91 static int parse_public_key_packet( public_key_packet_t *p_key, uint8_t *p_buf,
  92                                     size_t i_packet_len )
  93 {
  94
  95     if( i_packet_len > 418 || i_packet_len < 6 )
  96         return VLC_EGENERIC;
  97
  98     size_t i_read = 0;
  99
 100     p_key->version   = *p_buf++; i_read++;
 101     if( p_key->version != 4 )
 102         return VLC_EGENERIC;
 103
 104     /* XXX: warn when timestamp is > date ? */
 105     memcpy( p_key->timestamp, p_buf, 4 ); p_buf += 4; i_read += 4;
 106
 107     p_key->algo      = *p_buf++; i_read++;
 108     if( p_key->algo != PUBLIC_KEY_ALGO_DSA )
 109         return VLC_EGENERIC;
 110
 111     READ_MPI(p_key->p, 1024);
 112     READ_MPI(p_key->q, 160);
 113     READ_MPI(p_key->g, 1024);
 114     READ_MPI(p_key->y, 1024);
 115
 116     if( i_read != i_packet_len ) /* some extra data eh ? */
 117         return VLC_EGENERIC;
 118
 119     return VLC_SUCCESS;
 120
 121 error:
 122     return VLC_EGENERIC;
 123 }
 124
 125
 126 static size_t parse_signature_v3_packet( signature_packet_t *p_sig,
 127                                       uint8_t *p_buf, size_t i_sig_len )
 128 {
 129     size_t i_read = 1; /* we already read the version byte */
 130
 131     if( i_sig_len < 19 ) /* signature is at least 19 bytes + the 2 MPIs */
 132         return 0;
 133
 134     p_sig->specific.v3.hashed_data_len = *p_buf++; i_read++;
 135     if( p_sig->specific.v3.hashed_data_len != 5 )
 136         return 0;
 137
 138     p_sig->type = *p_buf++; i_read++;
 139
 140     memcpy( p_sig->specific.v3.timestamp, p_buf, 4 );
 141     p_buf += 4; i_read += 4;
 142
 143     memcpy( p_sig->issuer_longid, p_buf, 8 );
 144     p_buf += 8; i_read += 8;
 145
 146     p_sig->public_key_algo = *p_buf++; i_read++;
 147
 148     p_sig->digest_algo = *p_buf++; i_read++;
 149
 150     p_sig->hash_verification[0] = *p_buf++; i_read++;
 151     p_sig->hash_verification[1] = *p_buf++; i_read++;
 152
 153     assert( i_read == 19 );
 154
 155     return i_read;
 156 }
 157
 158
 159 /*
 160  * fill a signature_packet_v4_t from signature packet data
 161  * verify that it was used with a DSA public key, using SHA-1 digest
 162  */
 163 static size_t parse_signature_v4_packet( signature_packet_t *p_sig,
 164                                       uint8_t *p_buf, size_t i_sig_len )
 165 {
 166     size_t i_read = 1; /* we already read the version byte */
 167
 168     if( i_sig_len < 10 ) /* signature is at least 10 bytes + the 2 MPIs */
 169         return 0;
 170
 171     p_sig->type = *p_buf++; i_read++;
 172
 173     p_sig->public_key_algo = *p_buf++; i_read++;
 174
 175     p_sig->digest_algo = *p_buf++; i_read++;
 176
 177     memcpy( p_sig->specific.v4.hashed_data_len, p_buf, 2 );
 178     p_buf += 2; i_read += 2;
 179
 180     size_t i_hashed_data_len =
 181         scalar_number( p_sig->specific.v4.hashed_data_len, 2 );
 182     i_read += i_hashed_data_len;
 183     if( i_read + 4 > i_sig_len )
 184         return 0;
 185
 186     p_sig->specific.v4.hashed_data = (uint8_t*) malloc( i_hashed_data_len );
 187     if( !p_sig->specific.v4.hashed_data )
 188         return 0;
 189     memcpy( p_sig->specific.v4.hashed_data, p_buf, i_hashed_data_len );
 190     p_buf += i_hashed_data_len;
 191
 192     memcpy( p_sig->specific.v4.unhashed_data_len, p_buf, 2 );
 193     p_buf += 2; i_read += 2;
 194
 195     size_t i_unhashed_data_len =
 196         scalar_number( p_sig->specific.v4.unhashed_data_len, 2 );
 197     i_read += i_unhashed_data_len;
 198     if( i_read + 2 > i_sig_len )
 199         return 0;
 200
 201     p_sig->specific.v4.unhashed_data = (uint8_t*) malloc( i_unhashed_data_len );
 202     if( !p_sig->specific.v4.unhashed_data )
 203         return 0;
 204
 205     memcpy( p_sig->specific.v4.unhashed_data, p_buf, i_unhashed_data_len );
 206     p_buf += i_unhashed_data_len;
 207
 208     memcpy( p_sig->hash_verification, p_buf, 2 );
 209     p_buf += 2; i_read += 2;
 210
 211     uint8_t *p, *max_pos;
 212     p = p_sig->specific.v4.unhashed_data;
 213     max_pos = p + scalar_number( p_sig->specific.v4.unhashed_data_len, 2 );
 214
 215     for( ;; )
 216     {
 217         if( p > max_pos )
 218             return 0;
 219
 220         size_t i_subpacket_len;
 221         if( *p < 192 )
 222         {
 223             if( p + 1 > max_pos )
 224                 return 0;
 225             i_subpacket_len = *p++;
 226         }
 227         else if( *p < 255 )
 228         {
 229             if( p + 2 > max_pos )
 230                 return 0;
 231             i_subpacket_len = (*p++ - 192) << 8;
 232             i_subpacket_len += *p++ + 192;
 233         }
 234         else
 235         {
 236             if( p + 4 > max_pos )
 237                 return 0;
 238             i_subpacket_len = *++p << 24;
 239             i_subpacket_len += *++p << 16;
 240             i_subpacket_len += *++p << 8;
 241             i_subpacket_len += *++p;
 242         }
 243
 244         if( *p == ISSUER_SUBPACKET )
 245         {
 246             if( p + 9 > max_pos )
 247                 return 0;
 248
 249             memcpy( &p_sig->issuer_longid, p+1, 8 );
 250
 251             return i_read;
 252         }
 253
 254         p += i_subpacket_len;
 255     }
 256 }
 257
 258
 259 static int parse_signature_packet( signature_packet_t *p_sig,
 260                                    uint8_t *p_buf, size_t i_packet_len )
 261 {
 262     if( !i_packet_len ) /* 1st sanity check, we need at least the version */
 263         return VLC_EGENERIC;
 264
 265     p_sig->version = *p_buf++;
 266
 267     size_t i_read;
 268     switch( p_sig->version )
 269     {
 270         case 3:
 271             i_read = parse_signature_v3_packet( p_sig, p_buf, i_packet_len );
 272             break;
 273         case 4:
 274             p_sig->specific.v4.hashed_data = NULL;
 275             p_sig->specific.v4.unhashed_data = NULL;
 276             i_read = parse_signature_v4_packet( p_sig, p_buf, i_packet_len );
 277             break;
 278         default:
 279             return VLC_EGENERIC;
 280     }
 281
 282     if( i_read == 0 ) /* signature packet parsing has failed */
 283         goto error;
 284
 285     if( p_sig->public_key_algo != PUBLIC_KEY_ALGO_DSA )
 286         goto error;
 287
 288     if( p_sig->digest_algo != DIGEST_ALGO_SHA1 )
 289         goto error;
 290
 291     switch( p_sig->type )
 292     {
 293         case BINARY_SIGNATURE:
 294         case TEXT_SIGNATURE:
 295         case GENERIC_KEY_SIGNATURE:
 296         case PERSONA_KEY_SIGNATURE:
 297         case CASUAL_KEY_SIGNATURE:
 298         case POSITIVE_KEY_SIGNATURE:
 299             break;
 300         default:
 301             goto error;
 302     }
 303
 304     p_buf--; /* rewind to the version byte */
 305     p_buf += i_read;
 306
 307     READ_MPI(p_sig->r, 160);
 308     READ_MPI(p_sig->s, 160);
 309
 310     assert( i_read == i_packet_len );
 311     if( i_read < i_packet_len ) /* some extra data, hm ? */
 312         goto error;
 313
 314     return VLC_SUCCESS;
 315
 316 error:
 317
 318     if( p_sig->version == 4 )
 319     {
 320         free( p_sig->specific.v4.hashed_data );
 321         free( p_sig->specific.v4.unhashed_data );
 322     }
 323
 324     return VLC_EGENERIC;
 325 }
 326
 327
 328 /*
 329  * crc_octets() was lamely copied from rfc 2440
 330  * Copyright (C) The Internet Society (1998).  All Rights Reserved.
 331  */
 332 #define CRC24_INIT 0xB704CEL
 333 #define CRC24_POLY 0x1864CFBL
 334
 335 static long crc_octets( uint8_t *octets, size_t len )
 336 {
 337     long crc = CRC24_INIT;
 338     int i;
 339     while (len--)
 340     {
 341         crc ^= (*octets++) << 16;
 342         for (i = 0; i < 8; i++)
 343         {
 344             crc <<= 1;
 345             if (crc & 0x1000000)
 346                 crc ^= CRC24_POLY;
 347         }
 348     }
 349     return crc & 0xFFFFFFL;
 350 }
 351
 352
 353 /*
 354  * Transform an armored document in binary format
 355  * Used on public keys and signatures
 356  */
 357 static int pgp_unarmor( char *p_ibuf, size_t i_ibuf_len,
 358                         uint8_t *p_obuf, size_t i_obuf_len )
 359 {
 360     char *p_ipos = p_ibuf;
 361     uint8_t *p_opos = p_obuf;
 362     int i_end = 0;
 363     int i_header_skipped = 0;
 364
 365     while( !i_end && p_ipos < p_ibuf + i_ibuf_len && *p_ipos != '=' )
 366     {
 367         if( *p_ipos == '\r' || *p_ipos == '\n' )
 368         {
 369             p_ipos++;
 370             continue;
 371         }
 372
 373         size_t i_line_len = strcspn( p_ipos, "\r\n" );
 374         if( i_line_len == 0 )
 375             continue;
 376
 377         if( !i_header_skipped )
 378         {
 379             if( !strncmp( p_ipos, "-----BEGIN PGP", 14 ) )
 380                 i_header_skipped = 1;
 381
 382             p_ipos += i_line_len + 1;
 383             continue;
 384         }
 385
 386         if( !strncmp( p_ipos, "Version:", 8 ) )
 387         {
 388             p_ipos += i_line_len + 1;
 389             continue;
 390         }
 391
 392         if( p_ipos[i_line_len - 1] == '=' )
 393         {
 394             i_end = 1;
 395             p_ipos[i_line_len - 1] = '\0';
 396         }
 397         else
 398             p_ipos[i_line_len] = '\0';
 399
 400         p_opos += vlc_b64_decode_binary_to_buffer(  p_opos,
 401                         p_obuf - p_opos + i_obuf_len, p_ipos );
 402         p_ipos += i_line_len + 1;
 403     }
 404
 405     /* XXX: the CRC is OPTIONAL, really require it ? */
 406     if( p_ipos + 5 > p_ibuf + i_ibuf_len || *p_ipos++ != '=' )
 407         return 0;
 408
 409     uint8_t p_crc[3];
 410     if( vlc_b64_decode_binary_to_buffer( p_crc, 3, p_ipos ) != 3 )
 411         return 0;
 412
 413     long l_crc = crc_octets( p_obuf, p_opos - p_obuf );
 414     long l_crc2 = ( 0 << 24 ) + ( p_crc[0] << 16 ) + ( p_crc[1] << 8 ) + p_crc[2];
 415
 416     return l_crc2 == l_crc ? p_opos - p_obuf : 0;
 417 }
 418
 419
 420 /*
 421  * Verify an OpenPGP signature made on some SHA-1 hash, with some DSA public key
 422  */
 423 int verify_signature( uint8_t *p_r, uint8_t *p_s, public_key_packet_t *p_key,
 424                       uint8_t *p_hash )
 425 {
 426     /* the data to be verified (a SHA-1 hash) */
 427     const char *hash_sexp_s = "(data(flags raw)(value %m))";
 428     /* the public key */
 429     const char *key_sexp_s = "(public-key(dsa(p %m)(q %m)(g %m)(y %m)))";
 430     /* the signature */
 431     const char *sig_sexp_s = "(sig-val(dsa(r %m )(s %m )))";
 432
 433     size_t erroff;
 434     gcry_mpi_t p, q, g, y, r, s, hash;
 435     p = q = g = y = r = s = hash = NULL;
 436     gcry_sexp_t key_sexp, hash_sexp, sig_sexp;
 437     key_sexp = hash_sexp = sig_sexp = NULL;
 438
 439     int i_p_len = mpi_len( p_key->p );
 440     int i_q_len = mpi_len( p_key->q );
 441     int i_g_len = mpi_len( p_key->g );
 442     int i_y_len = mpi_len( p_key->y );
 443     if( gcry_mpi_scan( &p, GCRYMPI_FMT_USG, p_key->p + 2, i_p_len, NULL ) ||
 444         gcry_mpi_scan( &q, GCRYMPI_FMT_USG, p_key->q + 2, i_q_len, NULL ) ||
 445         gcry_mpi_scan( &g, GCRYMPI_FMT_USG, p_key->g + 2, i_g_len, NULL ) ||
 446         gcry_mpi_scan( &y, GCRYMPI_FMT_USG, p_key->y + 2, i_y_len, NULL ) ||
 447         gcry_sexp_build( &key_sexp, &erroff, key_sexp_s, p, q, g, y ) )
 448         goto problem;
 449
 450     int i_r_len = mpi_len( p_r );
 451     int i_s_len = mpi_len( p_s );
 452     if( gcry_mpi_scan( &r, GCRYMPI_FMT_USG, p_r + 2, i_r_len, NULL ) ||
 453         gcry_mpi_scan( &s, GCRYMPI_FMT_USG, p_s + 2, i_s_len, NULL ) ||
 454         gcry_sexp_build( &sig_sexp, &erroff, sig_sexp_s, r, s ) )
 455         goto problem;
 456
 457     int i_hash_len = 20;
 458     if( gcry_mpi_scan( &hash, GCRYMPI_FMT_USG, p_hash, i_hash_len, NULL ) ||
 459         gcry_sexp_build( &hash_sexp, &erroff, hash_sexp_s, hash ) )
 460         goto problem;
 461
 462     if( gcry_pk_verify( sig_sexp, hash_sexp, key_sexp ) )
 463         goto problem;
 464
 465     return VLC_SUCCESS;
 466
 467 problem:
 468     if( p ) gcry_mpi_release( p );
 469     if( q ) gcry_mpi_release( q );
 470     if( g ) gcry_mpi_release( g );
 471     if( y ) gcry_mpi_release( y );
 472     if( r ) gcry_mpi_release( r );
 473     if( s ) gcry_mpi_release( s );
 474     if( hash ) gcry_mpi_release( hash );
 475     if( key_sexp ) gcry_sexp_release( key_sexp );
 476     if( sig_sexp ) gcry_sexp_release( sig_sexp );
 477     if( hash_sexp ) gcry_sexp_release( hash_sexp );
 478     return VLC_EGENERIC;
 479 }
 480
 481
 482 /*
 483  * fill a public_key_t with public key data, including:
 484  *   * public key packet
 485  *   * signature packet issued by key which long id is p_sig_issuer
 486  *   * user id packet
 487  */
 488 int parse_public_key( const uint8_t *p_key_data, size_t i_key_len,
 489                       public_key_t *p_key, const uint8_t *p_sig_issuer )
 490 {
 491     uint8_t *pos = (uint8_t*) p_key_data;
 492     uint8_t *max_pos = pos + i_key_len;
 493
 494     int i_status = 0;
 495 #define PUBLIC_KEY_FOUND    0x01
 496 #define USER_ID_FOUND       0x02
 497 #define SIGNATURE_FOUND     0X04
 498
 499     uint8_t *p_key_unarmored = NULL;
 500
 501     p_key->psz_username = NULL;
 502     p_key->sig.specific.v4.hashed_data = NULL;
 503     p_key->sig.specific.v4.unhashed_data = NULL;
 504
 505     if( !( *pos & 0x80 ) )
 506     {   /* first byte is ASCII, unarmoring */
 507         p_key_unarmored = (uint8_t*)malloc( i_key_len );
 508         if( !p_key_unarmored )
 509             return VLC_ENOMEM;
 510         int i_len = pgp_unarmor( (char*)p_key_data, i_key_len,
 511                                  p_key_unarmored, i_key_len );
 512
 513         if( i_len == 0 )
 514             goto error;
 515
 516         pos = p_key_unarmored;
 517         max_pos = pos + i_len;
 518     }
 519
 520     while( pos < max_pos )
 521     {
 522         if( !(*pos & 0x80) || *pos & 0x40 )
 523             goto error;
 524
 525         int i_type = packet_type( *pos );
 526
 527         int i_header_len = packet_header_len( *pos++ );
 528         if( pos + i_header_len > max_pos ||
 529             ( i_header_len != 1 && i_header_len != 2 && i_header_len != 4 ) )
 530             goto error;
 531
 532         int i_packet_len = scalar_number( pos, i_header_len );
 533         pos += i_header_len;
 534
 535         if( pos + i_packet_len > max_pos )
 536             goto error;
 537
 538         switch( i_type )
 539         {
 540             case PUBLIC_KEY_PACKET:
 541                 i_status |= PUBLIC_KEY_FOUND;
 542                 if( parse_public_key_packet( &p_key->key, pos, i_packet_len ) != VLC_SUCCESS )
 543                     goto error;
 544                 break;
 545
 546             case SIGNATURE_PACKET: /* we accept only v4 signatures here */
 547                 if( i_status & SIGNATURE_FOUND || !p_sig_issuer )
 548                     break;
 549                 int i_ret = parse_signature_packet( &p_key->sig, pos,
 550                                                     i_packet_len );
 551                 if( i_ret == VLC_SUCCESS )
 552                 {
 553                     if( p_key->sig.version != 4 )
 554                         break;
 555                     if( memcmp( p_key->sig.issuer_longid, p_sig_issuer, 8 ) )
 556                     {
 557                         free( p_key->sig.specific.v4.hashed_data );
 558                         free( p_key->sig.specific.v4.unhashed_data );
 559                         p_key->sig.specific.v4.hashed_data = NULL;
 560                         p_key->sig.specific.v4.unhashed_data = NULL;
 561                         break;
 562                     }
 563                     i_status |= SIGNATURE_FOUND;
 564                 }
 565                 break;
 566
 567             case USER_ID_PACKET:
 568                 if( p_key->psz_username ) /* save only the first User ID */
 569                     break;
 570                 i_status |= USER_ID_FOUND;
 571                 p_key->psz_username = (uint8_t*)malloc( i_packet_len + 1);
 572                 if( !p_key->psz_username )
 573                     goto error;
 574
 575                 memcpy( p_key->psz_username, pos, i_packet_len );
 576                 p_key->psz_username[i_packet_len] = '\0';
 577                 break;
 578
 579             default:
 580                 break;
 581         }
 582         pos += i_packet_len;
 583     }
 584     free( p_key_unarmored );
 585
 586     if( !( i_status & ( PUBLIC_KEY_FOUND | USER_ID_FOUND ) ) )
 587         return VLC_EGENERIC;
 588
 589     if( p_sig_issuer && !( i_status & SIGNATURE_FOUND ) )
 590         return VLC_EGENERIC;
 591
 592     return VLC_SUCCESS;
 593
 594 error:
 595     if( p_key->sig.version == 4 )
 596     {
 597         free( p_key->sig.specific.v4.hashed_data );
 598         free( p_key->sig.specific.v4.unhashed_data );
 599     }
 600     free( p_key->psz_username );
 601     free( p_key_unarmored );
 602     return VLC_EGENERIC;
 603 }
 604
 605
 606 /* hash a binary file */
 607 static int hash_from_binary_file( const char *psz_file, gcry_md_hd_t hd )
 608 {
 609     uint8_t buffer[4096];
 610     size_t i_read;
 611
 612     FILE *f = vlc_fopen( psz_file, "r" );
 613     if( !f )
 614         return -1;
 615
 616     while( ( i_read = fread( buffer, 1, sizeof(buffer), f ) ) > 0 )
 617         gcry_md_write( hd, buffer, i_read );
 618
 619     fclose( f );
 620
 621     return 0;
 622 }
 623
 624
 625 /* final part of the hash */
 626 static uint8_t *hash_finish( gcry_md_hd_t hd, signature_packet_t *p_sig )
 627 {
 628     if( p_sig->version == 3 )
 629     {
 630         gcry_md_putc( hd, p_sig->type );
 631         gcry_md_write( hd, &p_sig->specific.v3.timestamp, 4 );
 632     }
 633     else if( p_sig->version == 4 )
 634     {
 635         gcry_md_putc( hd, p_sig->version );
 636         gcry_md_putc( hd, p_sig->type );
 637         gcry_md_putc( hd, p_sig->public_key_algo );
 638         gcry_md_putc( hd, p_sig->digest_algo );
 639         gcry_md_write( hd, p_sig->specific.v4.hashed_data_len, 2 );
 640         size_t i_len = scalar_number( p_sig->specific.v4.hashed_data_len, 2 );
 641         gcry_md_write( hd, p_sig->specific.v4.hashed_data, i_len );
 642
 643         gcry_md_putc( hd, 0x04 );
 644         gcry_md_putc( hd, 0xFF );
 645
 646         i_len += 6; /* hashed data + 6 bytes header */
 647
 648         gcry_md_putc( hd, (i_len >> 24) & 0xff );
 649         gcry_md_putc( hd, (i_len >> 16) & 0xff );
 650         gcry_md_putc( hd, (i_len >> 8) & 0xff );
 651         gcry_md_putc( hd, (i_len) & 0xff );
 652     }
 653     else
 654     {   /* RFC 4880 only tells about versions 3 and 4 */
 655         return NULL;
 656     }
 657
 658     gcry_md_final( hd );
 659
 660     uint8_t *p_tmp = (uint8_t*) gcry_md_read( hd, GCRY_MD_SHA1);
 661     uint8_t *p_hash = malloc( 20 );
 662     if( p_hash )
 663         memcpy( p_hash, p_tmp, 20 );
 664     gcry_md_close( hd );
 665     return p_hash;
 666 }
 667
 668
 669 /*
 670  * return a sha1 hash of a text
 671  */
 672 uint8_t *hash_sha1_from_text( const char *psz_string,
 673         signature_packet_t *p_sig )
 674 {
 675     gcry_md_hd_t hd;
 676     if( gcry_md_open( &hd, GCRY_MD_SHA1, 0 ) )
 677         return NULL;
 678
 679     if( p_sig->type == TEXT_SIGNATURE )
 680     while( *psz_string )
 681     {
 682         size_t i_len = strcspn( psz_string, "\r\n" );
 683
 684         if( i_len )
 685         {
 686             gcry_md_write( hd, psz_string, i_len );
 687             psz_string += i_len;
 688         }
 689         gcry_md_putc( hd, '\r' );
 690         gcry_md_putc( hd, '\n' );
 691
 692         if( *psz_string == '\r' )
 693             psz_string++;
 694         if( *psz_string == '\n' )
 695             psz_string++;
 696     }
 697     else
 698         gcry_md_write( hd, psz_string, strlen( psz_string ) );
 699
 700     return hash_finish( hd, p_sig );
 701 }
 702
 703
 704 /*
 705  * return a sha1 hash of a file
 706  */
 707 uint8_t *hash_sha1_from_file( const char *psz_file, signature_packet_t *p_sig )
 708 {
 709     gcry_md_hd_t hd;
 710     if( gcry_md_open( &hd, GCRY_MD_SHA1, 0 ) )
 711         return NULL;
 712
 713     if( hash_from_binary_file( psz_file, hd ) < 0 )
 714     {
 715         gcry_md_close( hd );
 716         return NULL;
 717     }
 718
 719     return hash_finish( hd, p_sig );
 720 }
 721
 722
 723 /*
 724  * Generate a SHA1 hash on a public key, to verify a signature made on that hash
 725  * Note that we need the signature (v4) to compute the hash
 726  */
 727 uint8_t *hash_sha1_from_public_key( public_key_t *p_pkey )
 728 {
 729     if( p_pkey->sig.version != 4 )
 730         return NULL;
 731
 732     if( p_pkey->sig.type < GENERIC_KEY_SIGNATURE ||
 733         p_pkey->sig.type > POSITIVE_KEY_SIGNATURE )
 734         return NULL;
 735
 736     gcry_error_t error = 0;
 737     gcry_md_hd_t hd;
 738
 739     error = gcry_md_open( &hd, GCRY_MD_SHA1, 0 );
 740     if( error )
 741         return NULL;
 742
 743     gcry_md_putc( hd, 0x99 );
 744
 745     size_t i_p_len = mpi_len( p_pkey->key.p );
 746     size_t i_g_len = mpi_len( p_pkey->key.g );
 747     size_t i_q_len = mpi_len( p_pkey->key.q );
 748     size_t i_y_len = mpi_len( p_pkey->key.y );
 749
 750     size_t i_size = 6 + 2*4 + i_p_len + i_g_len + i_q_len + i_y_len;
 751
 752     gcry_md_putc( hd, (i_size >> 8) & 0xff );
 753     gcry_md_putc( hd, i_size & 0xff );
 754
 755     gcry_md_putc( hd, p_pkey->key.version );
 756     gcry_md_write( hd, p_pkey->key.timestamp, 4 );
 757     gcry_md_putc( hd, p_pkey->key.algo );
 758
 759     gcry_md_write( hd, (uint8_t*)&p_pkey->key.p, 2 );
 760     gcry_md_write( hd, (uint8_t*)&p_pkey->key.p + 2, i_p_len );
 761
 762     gcry_md_write( hd, (uint8_t*)&p_pkey->key.q, 2 );
 763     gcry_md_write( hd, (uint8_t*)&p_pkey->key.q + 2, i_q_len );
 764
 765     gcry_md_write( hd, (uint8_t*)&p_pkey->key.g, 2 );
 766     gcry_md_write( hd, (uint8_t*)&p_pkey->key.g + 2, i_g_len );
 767
 768     gcry_md_write( hd, (uint8_t*)&p_pkey->key.y, 2 );
 769     gcry_md_write( hd, (uint8_t*)&p_pkey->key.y + 2, i_y_len );
 770
 771     gcry_md_putc( hd, 0xb4 );
 772
 773     size_t i_len = strlen((char*)p_pkey->psz_username);
 774
 775     gcry_md_putc( hd, (i_len >> 24) & 0xff );
 776     gcry_md_putc( hd, (i_len >> 16) & 0xff );
 777     gcry_md_putc( hd, (i_len >> 8) & 0xff );
 778     gcry_md_putc( hd, (i_len) & 0xff );
 779
 780     gcry_md_write( hd, p_pkey->psz_username, i_len );
 781
 782     uint8_t *p_hash = hash_finish( hd, &p_pkey->sig );
 783     if( !p_hash ||
 784         p_hash[0] != p_pkey->sig.hash_verification[0] ||
 785         p_hash[1] != p_pkey->sig.hash_verification[1] )
 786     {
 787         free(p_hash);
 788         return NULL;
 789     }
 790
 791     return p_hash;
 792 }
 793
 794
 795 /*
 796  * download a public key (the last one) from videolan server, and parse it
 797  */
 798 public_key_t *download_key( vlc_object_t *p_this,
 799                     const uint8_t *p_longid, const uint8_t *p_signature_issuer )
 800 {
 801     char *psz_url;
 802     if( asprintf( &psz_url, "http://download.videolan.org/pub/keys/%.2X%.2X%.2X%.2X%.2X%.2X%.2X%.2X.asc",
 803                     p_longid[0], p_longid[1], p_longid[2], p_longid[3],
 804                     p_longid[4], p_longid[5], p_longid[6], p_longid[7] ) == -1 )
 805         return NULL;
 806
 807     stream_t *p_stream = stream_UrlNew( p_this, psz_url );
 808     free( psz_url );
 809     if( !p_stream )
 810         return NULL;
 811
 812     int64_t i_size = stream_Size( p_stream );
 813     if( i_size < 0 )
 814     {
 815         stream_Delete( p_stream );
 816         return NULL;
 817     }
 818
 819     uint8_t *p_buf = (uint8_t*)malloc( i_size );
 820     if( !p_buf )
 821     {
 822         stream_Delete( p_stream );
 823         return NULL;
 824     }
 825
 826     int i_read = stream_Read( p_stream, p_buf, (int)i_size );
 827     stream_Delete( p_stream );
 828
 829     if( i_read != (int)i_size )
 830     {
 831         msg_Dbg( p_this, "Couldn't read full GPG key" );
 832         free( p_buf );
 833         return NULL;
 834     }
 835
 836     public_key_t *p_pkey = (public_key_t*) malloc( sizeof( public_key_t ) );
 837     if( !p_pkey )
 838     {
 839         free( p_buf );
 840         return NULL;
 841     }
 842
 843     memcpy( p_pkey->longid, p_longid, 8 );
 844
 845     int i_error = parse_public_key( p_buf, i_read, p_pkey, p_signature_issuer );
 846     free( p_buf );
 847
 848     if( i_error != VLC_SUCCESS )
 849     {
 850         msg_Dbg( p_this, "Couldn't parse GPG key" );
 851         free( p_pkey );
 852         return NULL;
 853     }
 854
 855     return p_pkey;
 856 }
 857
 858
 859 /*
 860  * Download the signature associated to a document or a binary file.
 861  * We're given the file's url, we just append ".asc" to it and download
 862  */
 863 int download_signature( vlc_object_t *p_this, signature_packet_t *p_sig,
 864                         const char *psz_url )
 865 {
 866     char *psz_sig = (char*) malloc( strlen( psz_url ) + 4 + 1 ); /* ".asc" + \0 */
 867     if( !psz_sig )
 868         return VLC_ENOMEM;
 869
 870     strcpy( psz_sig, psz_url );
 871     strcat( psz_sig, ".asc" );
 872
 873     stream_t *p_stream = stream_UrlNew( p_this, psz_sig );
 874     free( psz_sig );
 875
 876     if( !p_stream )
 877         return VLC_ENOMEM;
 878
 879     int64_t i_size = stream_Size( p_stream );
 880
 881     msg_Dbg( p_this, "Downloading signature (%"PRId64" bytes)", i_size );
 882     uint8_t *p_buf = (uint8_t*)malloc( i_size );
 883     if( !p_buf )
 884     {
 885         stream_Delete( p_stream );
 886         return VLC_ENOMEM;
 887     }
 888
 889     int i_read = stream_Read( p_stream, p_buf, (int)i_size );
 890
 891     stream_Delete( p_stream );
 892
 893     if( i_read != (int)i_size )
 894     {
 895         msg_Dbg( p_this,
 896             "Couldn't download full signature (only %d bytes)", i_read );
 897         free( p_buf );
 898         return VLC_EGENERIC;
 899     }
 900
 901     if( (uint8_t)*p_buf < 0x80 ) /* ASCII */
 902     {
 903         msg_Dbg( p_this, "Unarmoring signature" );
 904
 905         uint8_t* p_unarmored = (uint8_t*) malloc( ( i_size * 3 ) / 4 + 1 );
 906         if( !p_unarmored )
 907         {
 908             free( p_buf );
 909             return VLC_EGENERIC;
 910         }
 911
 912         int i_bytes = pgp_unarmor( (char*)p_buf, i_size, p_unarmored, i_size );
 913         free( p_buf );
 914
 915         p_buf = p_unarmored;
 916         i_size = i_bytes;
 917
 918         if( i_bytes < 2 )
 919         {
 920             free( p_buf );
 921             msg_Dbg( p_this, "Unarmoring failed : corrupted signature ?" );
 922             return VLC_EGENERIC;
 923         }
 924     }
 925
 926     if( packet_type( *p_buf ) != SIGNATURE_PACKET )
 927     {
 928         free( p_buf );
 929         msg_Dbg( p_this, "Not a signature: %d", *p_buf );
 930         return VLC_EGENERIC;
 931     }
 932
 933     size_t i_header_len = packet_header_len( *p_buf );
 934     if( ( i_header_len != 1 && i_header_len != 2 && i_header_len != 4 ) ||
 935         i_header_len + 1 > (size_t)i_size )
 936     {
 937         free( p_buf );
 938         msg_Dbg( p_this, "Invalid signature packet header" );
 939         return VLC_EGENERIC;
 940     }
 941
 942     size_t i_len = scalar_number( p_buf+1, i_header_len );
 943     if( i_len + i_header_len + 1 != (size_t)i_size )
 944     {
 945         free( p_buf );
 946         msg_Dbg( p_this, "Invalid signature packet" );
 947         return VLC_EGENERIC;
 948     }
 949
 950     int i_ret = parse_signature_packet( p_sig, p_buf+1+i_header_len, i_len );
 951     free( p_buf );
 952     if( i_ret != VLC_SUCCESS )
 953     {
 954         msg_Dbg( p_this, "Couldn't parse signature" );
 955         return i_ret;
 956     }
 957
 958     if( p_sig->type != BINARY_SIGNATURE && p_sig->type != TEXT_SIGNATURE )
 959     {
 960         msg_Dbg( p_this, "Invalid signature type: %d", p_sig->type );
 961         if( p_sig->version == 4 )
 962         {
 963             free( p_sig->specific.v4.hashed_data );
 964             free( p_sig->specific.v4.unhashed_data );
 965         }
 966         return VLC_EGENERIC;
 967     }
 968
 969     return VLC_SUCCESS;
 970 }
 971
 972 #endif /* UPDATE_CHECK */