src/misc/update_crypto.c

   1 /*****************************************************************************
   2  * update_crypto.c: DSA/SHA1 related functions used for updating
   3  *****************************************************************************
   4  * Copyright © 2008-2009 the VideoLAN team
   5  * $Id$
   6  *
   7  * Authors: Rafaël Carré <funman@videolanorg>
   8  *
   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; 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 General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU General Public License
  20  * along with this program; if not, write to the Free Software
  21  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111, 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
  77 /*
  78  * fill a public_key_packet_t structure from public key packet data
  79  * verify that it is a version 4 public key packet, using DSA
  80  */
  81 static int parse_public_key_packet( public_key_packet_t *p_key, uint8_t *p_buf,
  82                                     size_t i_packet_len )
  83 {
  84
  85     if( i_packet_len > 418 || i_packet_len < 6 )
  86         return VLC_EGENERIC;
  87
  88     size_t i_read = 0;
  89
  90     p_key->version   = *p_buf++; i_read++;
  91     if( p_key->version != 4 )
  92         return VLC_EGENERIC;
  93
  94     /* XXX: warn when timestamp is > date ? */
  95     memcpy( p_key->timestamp, p_buf, 4 ); p_buf += 4; i_read += 4;
  96
  97     p_key->algo      = *p_buf++; i_read++;
  98     if( p_key->algo != PUBLIC_KEY_ALGO_DSA )
  99         return VLC_EGENERIC;
 100
 101     /* read p */
 102     if( i_read + 2 > i_packet_len )
 103         return VLC_EGENERIC;
 104
 105     int i_p_len = mpi_len( p_buf );
 106
 107     if( i_p_len > 128 || i_read + 2 + i_p_len > i_packet_len )
 108         return VLC_EGENERIC;
 109
 110     memcpy( p_key->p, p_buf, 2+i_p_len );
 111     p_buf += 2+i_p_len; i_read += 2+i_p_len;
 112
 113     /* read q */
 114     if( i_read + 2 > i_packet_len )
 115         return VLC_EGENERIC;
 116
 117     int i_q_len = mpi_len( p_buf );
 118
 119     if( i_q_len > 20 || i_read+2+i_q_len > i_packet_len )
 120         return VLC_EGENERIC;
 121
 122     memcpy( p_key->q, p_buf, 2+i_q_len );
 123     p_buf += 2+i_q_len; i_read += 2+i_q_len;
 124
 125     /* read g */
 126     if( i_read + 2 > i_packet_len )
 127         return VLC_EGENERIC;
 128
 129     int i_g_len = mpi_len( p_buf );
 130
 131     if( i_g_len > 128 || i_read+2+i_g_len > i_packet_len )
 132         return VLC_EGENERIC;
 133
 134     memcpy( p_key->g, p_buf, 2+i_g_len );
 135     p_buf += 2+i_g_len; i_read += 2+i_g_len;
 136
 137     /* read y */
 138     if( i_read + 2 > i_packet_len )
 139         return VLC_EGENERIC;
 140
 141     int i_y_len = mpi_len( p_buf );
 142
 143
 144     if( i_y_len > 128 || i_read+2+i_y_len > i_packet_len )
 145         return VLC_EGENERIC;
 146
 147     memcpy( p_key->y, p_buf, 2+i_y_len );
 148     i_read += 2+i_y_len;
 149
 150     if( i_read != i_packet_len ) /* some extra data eh ? */
 151         return VLC_EGENERIC;
 152
 153     return VLC_SUCCESS;
 154 }
 155
 156
 157 static size_t parse_signature_v3_packet( signature_packet_t *p_sig,
 158                                       uint8_t *p_buf, size_t i_sig_len )
 159 {
 160     size_t i_read = 1; /* we already read the version byte */
 161
 162     if( i_sig_len < 19 ) /* signature is at least 19 bytes + the 2 MPIs */
 163         return 0;
 164
 165     p_sig->specific.v3.hashed_data_len = *p_buf++; i_read++;
 166     if( p_sig->specific.v3.hashed_data_len != 5 )
 167         return 0;
 168
 169     p_sig->type = *p_buf++; i_read++;
 170
 171     memcpy( p_sig->specific.v3.timestamp, p_buf, 4 );
 172     p_buf += 4; i_read += 4;
 173
 174     memcpy( p_sig->issuer_longid, p_buf, 8 );
 175     p_buf += 8; i_read += 8;
 176
 177     p_sig->public_key_algo = *p_buf++; i_read++;
 178
 179     p_sig->digest_algo = *p_buf++; i_read++;
 180
 181     p_sig->hash_verification[0] = *p_buf++; i_read++;
 182     p_sig->hash_verification[1] = *p_buf++; i_read++;
 183
 184     assert( i_read == 19 );
 185
 186     return i_read;
 187 }
 188
 189
 190 /*
 191  * fill a signature_packet_v4_t from signature packet data
 192  * verify that it was used with a DSA public key, using SHA-1 digest
 193  */
 194 static size_t parse_signature_v4_packet( signature_packet_t *p_sig,
 195                                       uint8_t *p_buf, size_t i_sig_len )
 196 {
 197     size_t i_read = 1; /* we already read the version byte */
 198
 199     if( i_sig_len < 10 ) /* signature is at least 10 bytes + the 2 MPIs */
 200         return 0;
 201
 202     p_sig->type = *p_buf++; i_read++;
 203
 204     p_sig->public_key_algo = *p_buf++; i_read++;
 205
 206     p_sig->digest_algo = *p_buf++; i_read++;
 207
 208     memcpy( p_sig->specific.v4.hashed_data_len, p_buf, 2 );
 209     p_buf += 2; i_read += 2;
 210
 211     size_t i_hashed_data_len =
 212         scalar_number( p_sig->specific.v4.hashed_data_len, 2 );
 213     i_read += i_hashed_data_len;
 214     if( i_read + 4 > i_sig_len )
 215         return 0;
 216
 217     p_sig->specific.v4.hashed_data = (uint8_t*) malloc( i_hashed_data_len );
 218     if( !p_sig->specific.v4.hashed_data )
 219         return 0;
 220     memcpy( p_sig->specific.v4.hashed_data, p_buf, i_hashed_data_len );
 221     p_buf += i_hashed_data_len;
 222
 223     memcpy( p_sig->specific.v4.unhashed_data_len, p_buf, 2 );
 224     p_buf += 2; i_read += 2;
 225
 226     size_t i_unhashed_data_len =
 227         scalar_number( p_sig->specific.v4.unhashed_data_len, 2 );
 228     i_read += i_unhashed_data_len;
 229     if( i_read + 2 > i_sig_len )
 230         return 0;
 231
 232     p_sig->specific.v4.unhashed_data = (uint8_t*) malloc( i_unhashed_data_len );
 233     if( !p_sig->specific.v4.unhashed_data )
 234         return 0;
 235
 236     memcpy( p_sig->specific.v4.unhashed_data, p_buf, i_unhashed_data_len );
 237     p_buf += i_unhashed_data_len;
 238
 239     memcpy( p_sig->hash_verification, p_buf, 2 );
 240     p_buf += 2; i_read += 2;
 241
 242     uint8_t *p, *max_pos;
 243     p = p_sig->specific.v4.unhashed_data;
 244     max_pos = p + scalar_number( p_sig->specific.v4.unhashed_data_len, 2 );
 245
 246     for( ;; )
 247     {
 248         if( p > max_pos )
 249             return 0;
 250
 251         size_t i_subpacket_len;
 252         if( *p < 192 )
 253         {
 254             if( p + 1 > max_pos )
 255                 return 0;
 256             i_subpacket_len = *p++;
 257         }
 258         else if( *p < 255 )
 259         {
 260             if( p + 2 > max_pos )
 261                 return 0;
 262             i_subpacket_len = (*p++ - 192) << 8;
 263             i_subpacket_len += *p++ + 192;
 264         }
 265         else
 266         {
 267             if( p + 4 > max_pos )
 268                 return 0;
 269             i_subpacket_len = *++p << 24;
 270             i_subpacket_len += *++p << 16;
 271             i_subpacket_len += *++p << 8;
 272             i_subpacket_len += *++p;
 273         }
 274
 275         if( *p == ISSUER_SUBPACKET )
 276         {
 277             if( p + 9 > max_pos )
 278                 return 0;
 279
 280             memcpy( &p_sig->issuer_longid, p+1, 8 );
 281
 282             return i_read;
 283         }
 284
 285         p += i_subpacket_len;
 286     }
 287 }
 288
 289
 290 static int parse_signature_packet( signature_packet_t *p_sig,
 291                                    uint8_t *p_buf, size_t i_sig_len )
 292 {
 293     if( !i_sig_len ) /* 1st sanity check, we need at least the version */
 294         return VLC_EGENERIC;
 295
 296     p_sig->version = *p_buf++;
 297
 298     size_t i_read;
 299     switch( p_sig->version )
 300     {
 301         case 3:
 302             i_read = parse_signature_v3_packet( p_sig, p_buf, i_sig_len );
 303             break;
 304         case 4:
 305             p_sig->specific.v4.hashed_data = NULL;
 306             p_sig->specific.v4.unhashed_data = NULL;
 307             i_read = parse_signature_v4_packet( p_sig, p_buf, i_sig_len );
 308             break;
 309         default:
 310             return VLC_EGENERIC;
 311     }
 312
 313     if( i_read == 0 ) /* signature packet parsing has failed */
 314         goto error;
 315
 316     if( p_sig->public_key_algo != PUBLIC_KEY_ALGO_DSA )
 317         goto error;
 318
 319     if( p_sig->digest_algo != DIGEST_ALGO_SHA1 )
 320         goto error;
 321
 322     switch( p_sig->type )
 323     {
 324         case BINARY_SIGNATURE:
 325         case TEXT_SIGNATURE:
 326         case GENERIC_KEY_SIGNATURE:
 327         case PERSONA_KEY_SIGNATURE:
 328         case CASUAL_KEY_SIGNATURE:
 329         case POSITIVE_KEY_SIGNATURE:
 330             break;
 331         default:
 332             goto error;
 333     }
 334
 335     p_buf--; /* rewind to the version byte */
 336     p_buf += i_read;
 337
 338     if( i_read + 2 > i_sig_len )
 339         goto error;
 340
 341     size_t i_r_len = mpi_len( p_buf ); i_read += 2;
 342     if( i_read + i_r_len > i_sig_len || i_r_len > 20 )
 343         goto error;
 344
 345     memcpy( p_sig->r, p_buf, 2 + i_r_len );
 346     p_buf += 2 + i_r_len;
 347     i_read += i_r_len;
 348
 349     if( i_read + 2 > i_sig_len )
 350         goto error;
 351
 352     size_t i_s_len = mpi_len( p_buf ); i_read += 2;
 353     if( i_read + i_s_len > i_sig_len || i_s_len > 20 )
 354         goto error;
 355
 356     memcpy( p_sig->s, p_buf, 2 + i_s_len );
 357     p_buf += 2 + i_s_len;
 358     i_read += i_s_len;
 359
 360     assert( i_read == i_sig_len );
 361     if( i_read < i_sig_len ) /* some extra data, hm ? */
 362         goto error;
 363
 364     return VLC_SUCCESS;
 365
 366 error:
 367
 368     if( p_sig->version == 4 )
 369     {
 370         free( p_sig->specific.v4.hashed_data );
 371         free( p_sig->specific.v4.unhashed_data );
 372     }
 373
 374     return VLC_EGENERIC;
 375 }
 376
 377
 378 /*
 379  * crc_octets() was lamely copied from rfc 2440
 380  * Copyright (C) The Internet Society (1998).  All Rights Reserved.
 381  */
 382 #define CRC24_INIT 0xB704CEL
 383 #define CRC24_POLY 0x1864CFBL
 384
 385 static long crc_octets( uint8_t *octets, size_t len )
 386 {
 387     long crc = CRC24_INIT;
 388     int i;
 389     while (len--)
 390     {
 391         crc ^= (*octets++) << 16;
 392         for (i = 0; i < 8; i++)
 393         {
 394             crc <<= 1;
 395             if (crc & 0x1000000)
 396                 crc ^= CRC24_POLY;
 397         }
 398     }
 399     return crc & 0xFFFFFFL;
 400 }
 401
 402
 403 /*
 404  * Transform an armored document in binary format
 405  * Used on public keys and signatures
 406  */
 407 static int pgp_unarmor( char *p_ibuf, size_t i_ibuf_len,
 408                         uint8_t *p_obuf, size_t i_obuf_len )
 409 {
 410     char *p_ipos = p_ibuf;
 411     uint8_t *p_opos = p_obuf;
 412     int i_end = 0;
 413     int i_header_skipped = 0;
 414
 415     while( !i_end && p_ipos < p_ibuf + i_ibuf_len && *p_ipos != '=' )
 416     {
 417         if( *p_ipos == '\r' || *p_ipos == '\n' )
 418         {
 419             p_ipos++;
 420             continue;
 421         }
 422
 423         size_t i_line_len = strcspn( p_ipos, "\r\n" );
 424         if( i_line_len == 0 )
 425             continue;
 426
 427         if( !i_header_skipped )
 428         {
 429             if( !strncmp( p_ipos, "-----BEGIN PGP", 14 ) )
 430                 i_header_skipped = 1;
 431
 432             p_ipos += i_line_len + 1;
 433             continue;
 434         }
 435
 436         if( !strncmp( p_ipos, "Version:", 8 ) )
 437         {
 438             p_ipos += i_line_len + 1;
 439             continue;
 440         }
 441
 442         if( p_ipos[i_line_len - 1] == '=' )
 443         {
 444             i_end = 1;
 445             p_ipos[i_line_len - 1] = '\0';
 446         }
 447         else
 448             p_ipos[i_line_len] = '\0';
 449
 450         p_opos += vlc_b64_decode_binary_to_buffer(  p_opos,
 451                         p_obuf - p_opos + i_obuf_len, p_ipos );
 452         p_ipos += i_line_len + 1;
 453     }
 454
 455     /* XXX: the CRC is OPTIONAL, really require it ? */
 456     if( p_ipos + 5 > p_ibuf + i_ibuf_len || *p_ipos++ != '=' )
 457         return 0;
 458
 459     uint8_t p_crc[3];
 460     if( vlc_b64_decode_binary_to_buffer( p_crc, 3, p_ipos ) != 3 )
 461         return 0;
 462
 463     long l_crc = crc_octets( p_obuf, p_opos - p_obuf );
 464     long l_crc2 = ( 0 << 24 ) + ( p_crc[0] << 16 ) + ( p_crc[1] << 8 ) + p_crc[2];
 465
 466     return l_crc2 == l_crc ? p_opos - p_obuf : 0;
 467 }
 468
 469
 470 /*
 471  * Verify an OpenPGP signature made on some SHA-1 hash, with some DSA public key
 472  */
 473 int verify_signature( uint8_t *p_r, uint8_t *p_s, public_key_packet_t *p_key,
 474                       uint8_t *p_hash )
 475 {
 476     /* the data to be verified (a SHA-1 hash) */
 477     const char *hash_sexp_s = "(data(flags raw)(value %m))";
 478     /* the public key */
 479     const char *key_sexp_s = "(public-key(dsa(p %m)(q %m)(g %m)(y %m)))";
 480     /* the signature */
 481     const char *sig_sexp_s = "(sig-val(dsa(r %m )(s %m )))";
 482
 483     size_t erroff;
 484     gcry_mpi_t p, q, g, y, r, s, hash;
 485     p = q = g = y = r = s = hash = NULL;
 486     gcry_sexp_t key_sexp, hash_sexp, sig_sexp;
 487     key_sexp = hash_sexp = sig_sexp = NULL;
 488
 489     int i_p_len = mpi_len( p_key->p );
 490     int i_q_len = mpi_len( p_key->q );
 491     int i_g_len = mpi_len( p_key->g );
 492     int i_y_len = mpi_len( p_key->y );
 493     if( gcry_mpi_scan( &p, GCRYMPI_FMT_USG, p_key->p + 2, i_p_len, NULL ) ||
 494         gcry_mpi_scan( &q, GCRYMPI_FMT_USG, p_key->q + 2, i_q_len, NULL ) ||
 495         gcry_mpi_scan( &g, GCRYMPI_FMT_USG, p_key->g + 2, i_g_len, NULL ) ||
 496         gcry_mpi_scan( &y, GCRYMPI_FMT_USG, p_key->y + 2, i_y_len, NULL ) ||
 497         gcry_sexp_build( &key_sexp, &erroff, key_sexp_s, p, q, g, y ) )
 498         goto problem;
 499
 500     int i_r_len = mpi_len( p_r );
 501     int i_s_len = mpi_len( p_s );
 502     if( gcry_mpi_scan( &r, GCRYMPI_FMT_USG, p_r + 2, i_r_len, NULL ) ||
 503         gcry_mpi_scan( &s, GCRYMPI_FMT_USG, p_s + 2, i_s_len, NULL ) ||
 504         gcry_sexp_build( &sig_sexp, &erroff, sig_sexp_s, r, s ) )
 505         goto problem;
 506
 507     int i_hash_len = 20;
 508     if( gcry_mpi_scan( &hash, GCRYMPI_FMT_USG, p_hash, i_hash_len, NULL ) ||
 509         gcry_sexp_build( &hash_sexp, &erroff, hash_sexp_s, hash ) )
 510         goto problem;
 511
 512     if( gcry_pk_verify( sig_sexp, hash_sexp, key_sexp ) )
 513         goto problem;
 514
 515     return VLC_SUCCESS;
 516
 517 problem:
 518     if( p ) gcry_mpi_release( p );
 519     if( q ) gcry_mpi_release( q );
 520     if( g ) gcry_mpi_release( g );
 521     if( y ) gcry_mpi_release( y );
 522     if( r ) gcry_mpi_release( r );
 523     if( s ) gcry_mpi_release( s );
 524     if( hash ) gcry_mpi_release( hash );
 525     if( key_sexp ) gcry_sexp_release( key_sexp );
 526     if( sig_sexp ) gcry_sexp_release( sig_sexp );
 527     if( hash_sexp ) gcry_sexp_release( hash_sexp );
 528     return VLC_EGENERIC;
 529 }
 530
 531
 532 /*
 533  * fill a public_key_t with public key data, including:
 534  *   * public key packet
 535  *   * signature packet issued by key which long id is p_sig_issuer
 536  *   * user id packet
 537  */
 538 int parse_public_key( const uint8_t *p_key_data, size_t i_key_len,
 539                       public_key_t *p_key, const uint8_t *p_sig_issuer )
 540 {
 541     uint8_t *pos = (uint8_t*) p_key_data;
 542     uint8_t *max_pos = pos + i_key_len;
 543
 544     int i_status = 0;
 545 #define PUBLIC_KEY_FOUND    0x01
 546 #define USER_ID_FOUND       0x02
 547 #define SIGNATURE_FOUND     0X04
 548
 549     uint8_t *p_key_unarmored = NULL;
 550
 551     p_key->psz_username = NULL;
 552     p_key->sig.specific.v4.hashed_data = NULL;
 553     p_key->sig.specific.v4.unhashed_data = NULL;
 554
 555     if( !( *pos & 0x80 ) )
 556     {   /* first byte is ASCII, unarmoring */
 557         p_key_unarmored = (uint8_t*)malloc( i_key_len );
 558         if( !p_key_unarmored )
 559             return VLC_ENOMEM;
 560         int i_len = pgp_unarmor( (char*)p_key_data, i_key_len,
 561                                  p_key_unarmored, i_key_len );
 562
 563         if( i_len == 0 )
 564             goto error;
 565
 566         pos = p_key_unarmored;
 567         max_pos = pos + i_len;
 568     }
 569
 570     while( pos < max_pos )
 571     {
 572         if( !(*pos & 0x80) || *pos & 0x40 )
 573             goto error;
 574
 575         int i_type = packet_type( *pos );
 576
 577         int i_header_len = packet_header_len( *pos++ );
 578         if( pos + i_header_len > max_pos ||
 579             ( i_header_len != 1 && i_header_len != 2 && i_header_len != 4 ) )
 580             goto error;
 581
 582         int i_packet_len = scalar_number( pos, i_header_len );
 583         pos += i_header_len;
 584
 585         if( pos + i_packet_len > max_pos )
 586             goto error;
 587
 588         switch( i_type )
 589         {
 590             case PUBLIC_KEY_PACKET:
 591                 i_status |= PUBLIC_KEY_FOUND;
 592                 if( parse_public_key_packet( &p_key->key, pos, i_packet_len ) != VLC_SUCCESS )
 593                     goto error;
 594                 break;
 595
 596             case SIGNATURE_PACKET: /* we accept only v4 signatures here */
 597                 if( i_status & SIGNATURE_FOUND || !p_sig_issuer )
 598                     break;
 599                 int i_ret = parse_signature_packet( &p_key->sig, pos,
 600                                                     i_packet_len );
 601                 if( i_ret == VLC_SUCCESS )
 602                 {
 603                     if( p_key->sig.version != 4 )
 604                         break;
 605                     if( memcmp( p_key->sig.issuer_longid, p_sig_issuer, 8 ) )
 606                     {
 607                         free( p_key->sig.specific.v4.hashed_data );
 608                         free( p_key->sig.specific.v4.unhashed_data );
 609                         p_key->sig.specific.v4.hashed_data = NULL;
 610                         p_key->sig.specific.v4.unhashed_data = NULL;
 611                         break;
 612                     }
 613                     i_status |= SIGNATURE_FOUND;
 614                 }
 615                 break;
 616
 617             case USER_ID_PACKET:
 618                 if( p_key->psz_username ) /* save only the first User ID */
 619                     break;
 620                 i_status |= USER_ID_FOUND;
 621                 p_key->psz_username = (uint8_t*)malloc( i_packet_len + 1);
 622                 if( !p_key->psz_username )
 623                     goto error;
 624
 625                 memcpy( p_key->psz_username, pos, i_packet_len );
 626                 p_key->psz_username[i_packet_len] = '\0';
 627                 break;
 628
 629             default:
 630                 break;
 631         }
 632         pos += i_packet_len;
 633     }
 634     free( p_key_unarmored );
 635
 636     if( !( i_status & ( PUBLIC_KEY_FOUND | USER_ID_FOUND ) ) )
 637         return VLC_EGENERIC;
 638
 639     if( p_sig_issuer && !( i_status & SIGNATURE_FOUND ) )
 640         return VLC_EGENERIC;
 641
 642     return VLC_SUCCESS;
 643
 644 error:
 645     if( p_key->sig.version == 4 )
 646     {
 647         free( p_key->sig.specific.v4.hashed_data );
 648         free( p_key->sig.specific.v4.unhashed_data );
 649     }
 650     free( p_key->psz_username );
 651     free( p_key_unarmored );
 652     return VLC_EGENERIC;
 653 }
 654
 655
 656 /* hash a binary file */
 657 static int hash_from_binary_file( const char *psz_file, gcry_md_hd_t hd )
 658 {
 659     uint8_t buffer[4096];
 660     size_t i_read;
 661
 662     FILE *f = vlc_fopen( psz_file, "r" );
 663     if( !f )
 664         return -1;
 665
 666     while( ( i_read = fread( buffer, 1, sizeof(buffer), f ) ) > 0 )
 667         gcry_md_write( hd, buffer, i_read );
 668
 669     fclose( f );
 670
 671     return 0;
 672 }
 673
 674
 675 /* final part of the hash */
 676 static uint8_t *hash_finish( gcry_md_hd_t hd, signature_packet_t *p_sig )
 677 {
 678     if( p_sig->version == 3 )
 679     {
 680         gcry_md_putc( hd, p_sig->type );
 681         gcry_md_write( hd, &p_sig->specific.v3.timestamp, 4 );
 682     }
 683     else if( p_sig->version == 4 )
 684     {
 685         gcry_md_putc( hd, p_sig->version );
 686         gcry_md_putc( hd, p_sig->type );
 687         gcry_md_putc( hd, p_sig->public_key_algo );
 688         gcry_md_putc( hd, p_sig->digest_algo );
 689         gcry_md_write( hd, p_sig->specific.v4.hashed_data_len, 2 );
 690         size_t i_len = scalar_number( p_sig->specific.v4.hashed_data_len, 2 );
 691         gcry_md_write( hd, p_sig->specific.v4.hashed_data, i_len );
 692
 693         gcry_md_putc( hd, 0x04 );
 694         gcry_md_putc( hd, 0xFF );
 695
 696         i_len += 6; /* hashed data + 6 bytes header */
 697
 698         gcry_md_putc( hd, (i_len >> 24) & 0xff );
 699         gcry_md_putc( hd, (i_len >> 16) & 0xff );
 700         gcry_md_putc( hd, (i_len >> 8) & 0xff );
 701         gcry_md_putc( hd, (i_len) & 0xff );
 702     }
 703     else
 704     {   /* RFC 4880 only tells about versions 3 and 4 */
 705         return NULL;
 706     }
 707
 708     gcry_md_final( hd );
 709
 710     uint8_t *p_tmp = (uint8_t*) gcry_md_read( hd, GCRY_MD_SHA1);
 711     uint8_t *p_hash = malloc( 20 );
 712     if( p_hash )
 713         memcpy( p_hash, p_tmp, 20 );
 714     gcry_md_close( hd );
 715     return p_hash;
 716 }
 717
 718
 719 /*
 720  * return a sha1 hash of a text
 721  */
 722 uint8_t *hash_sha1_from_text( const char *psz_string,
 723         signature_packet_t *p_sig )
 724 {
 725     gcry_md_hd_t hd;
 726     if( gcry_md_open( &hd, GCRY_MD_SHA1, 0 ) )
 727         return NULL;
 728
 729     if( p_sig->type == TEXT_SIGNATURE )
 730     while( *psz_string )
 731     {
 732         size_t i_len = strcspn( psz_string, "\r\n" );
 733         if( !i_len )
 734             break;
 735
 736         gcry_md_write( hd, psz_string, i_len );
 737         gcry_md_putc( hd, '\r' );
 738         gcry_md_putc( hd, '\n' );
 739
 740         psz_string += i_len;
 741         while( *psz_string == '\r' || *psz_string == '\n' )
 742             psz_string++;
 743     }
 744     else
 745         gcry_md_write( hd, psz_string, strlen( psz_string ) );
 746
 747     return hash_finish( hd, p_sig );
 748 }
 749
 750
 751 /*
 752  * return a sha1 hash of a file
 753  */
 754 uint8_t *hash_sha1_from_file( const char *psz_file, signature_packet_t *p_sig )
 755 {
 756     gcry_md_hd_t hd;
 757     if( gcry_md_open( &hd, GCRY_MD_SHA1, 0 ) )
 758         return NULL;
 759
 760     if( hash_from_binary_file( psz_file, hd ) < 0 )
 761     {
 762         gcry_md_close( hd );
 763         return NULL;
 764     }
 765
 766     return hash_finish( hd, p_sig );
 767 }
 768
 769
 770 /*
 771  * Generate a SHA1 hash on a public key, to verify a signature made on that hash
 772  * Note that we need the signature (v4) to compute the hash
 773  */
 774 uint8_t *hash_sha1_from_public_key( public_key_t *p_pkey )
 775 {
 776     if( p_pkey->sig.version != 4 )
 777         return NULL;
 778
 779     if( p_pkey->sig.type < GENERIC_KEY_SIGNATURE ||
 780         p_pkey->sig.type > POSITIVE_KEY_SIGNATURE )
 781         return NULL;
 782
 783     gcry_error_t error = 0;
 784     gcry_md_hd_t hd;
 785
 786     error = gcry_md_open( &hd, GCRY_MD_SHA1, 0 );
 787     if( error )
 788         return NULL;
 789
 790     gcry_md_putc( hd, 0x99 );
 791
 792     size_t i_p_len = mpi_len( p_pkey->key.p );
 793     size_t i_g_len = mpi_len( p_pkey->key.g );
 794     size_t i_q_len = mpi_len( p_pkey->key.q );
 795     size_t i_y_len = mpi_len( p_pkey->key.y );
 796
 797     size_t i_size = 6 + 2*4 + i_p_len + i_g_len + i_q_len + i_y_len;
 798
 799     gcry_md_putc( hd, (i_size >> 8) & 0xff );
 800     gcry_md_putc( hd, i_size & 0xff );
 801
 802     gcry_md_putc( hd, p_pkey->key.version );
 803     gcry_md_write( hd, p_pkey->key.timestamp, 4 );
 804     gcry_md_putc( hd, p_pkey->key.algo );
 805
 806     gcry_md_write( hd, (uint8_t*)&p_pkey->key.p, 2 );
 807     gcry_md_write( hd, (uint8_t*)&p_pkey->key.p + 2, i_p_len );
 808
 809     gcry_md_write( hd, (uint8_t*)&p_pkey->key.q, 2 );
 810     gcry_md_write( hd, (uint8_t*)&p_pkey->key.q + 2, i_q_len );
 811
 812     gcry_md_write( hd, (uint8_t*)&p_pkey->key.g, 2 );
 813     gcry_md_write( hd, (uint8_t*)&p_pkey->key.g + 2, i_g_len );
 814
 815     gcry_md_write( hd, (uint8_t*)&p_pkey->key.y, 2 );
 816     gcry_md_write( hd, (uint8_t*)&p_pkey->key.y + 2, i_y_len );
 817
 818     gcry_md_putc( hd, 0xb4 );
 819
 820     size_t i_len = strlen((char*)p_pkey->psz_username);
 821
 822     gcry_md_putc( hd, (i_len >> 24) & 0xff );
 823     gcry_md_putc( hd, (i_len >> 16) & 0xff );
 824     gcry_md_putc( hd, (i_len >> 8) & 0xff );
 825     gcry_md_putc( hd, (i_len) & 0xff );
 826
 827     gcry_md_write( hd, p_pkey->psz_username, i_len );
 828
 829     uint8_t *p_hash = hash_finish( hd, &p_pkey->sig );
 830     if( !p_hash ||
 831         p_hash[0] != p_pkey->sig.hash_verification[0] ||
 832         p_hash[1] != p_pkey->sig.hash_verification[1] )
 833     {
 834         return NULL;
 835     }
 836
 837     return p_hash;
 838 }
 839
 840
 841 /*
 842  * download a public key (the last one) from videolan server, and parse it
 843  */
 844 public_key_t *download_key( vlc_object_t *p_this,
 845                     const uint8_t *p_longid, const uint8_t *p_signature_issuer )
 846 {
 847     char *psz_url;
 848     if( asprintf( &psz_url, "http://download.videolan.org/pub/keys/%.2X%.2X%.2X%.2X%.2X%.2X%.2X%.2X.asc",
 849                     p_longid[0], p_longid[1], p_longid[2], p_longid[3],
 850                     p_longid[4], p_longid[5], p_longid[6], p_longid[7] ) == -1 )
 851         return NULL;
 852
 853     stream_t *p_stream = stream_UrlNew( p_this, psz_url );
 854     free( psz_url );
 855     if( !p_stream )
 856         return NULL;
 857
 858     int64_t i_size = stream_Size( p_stream );
 859     if( i_size < 0 )
 860     {
 861         stream_Delete( p_stream );
 862         return NULL;
 863     }
 864
 865     uint8_t *p_buf = (uint8_t*)malloc( i_size );
 866     if( !p_buf )
 867     {
 868         stream_Delete( p_stream );
 869         return NULL;
 870     }
 871
 872     int i_read = stream_Read( p_stream, p_buf, (int)i_size );
 873     stream_Delete( p_stream );
 874
 875     if( i_read != (int)i_size )
 876     {
 877         msg_Dbg( p_this, "Couldn't read full GPG key" );
 878         free( p_buf );
 879         return NULL;
 880     }
 881
 882     public_key_t *p_pkey = (public_key_t*) malloc( sizeof( public_key_t ) );
 883     if( !p_pkey )
 884     {
 885         free( p_buf );
 886         return NULL;
 887     }
 888
 889     memcpy( p_pkey->longid, p_longid, 8 );
 890
 891     int i_error = parse_public_key( p_buf, i_read, p_pkey, p_signature_issuer );
 892     free( p_buf );
 893
 894     if( i_error != VLC_SUCCESS )
 895     {
 896         msg_Dbg( p_this, "Couldn't parse GPG key" );
 897         free( p_pkey );
 898         return NULL;
 899     }
 900
 901     return p_pkey;
 902 }
 903
 904
 905 /*
 906  * Download the signature associated to a document or a binary file.
 907  * We're given the file's url, we just append ".asc" to it and download
 908  */
 909 int download_signature( vlc_object_t *p_this, signature_packet_t *p_sig,
 910                         const char *psz_url )
 911 {
 912     char *psz_sig = (char*) malloc( strlen( psz_url ) + 4 + 1 ); /* ".asc" + \0 */
 913     if( !psz_sig )
 914         return VLC_ENOMEM;
 915
 916     strcpy( psz_sig, psz_url );
 917     strcat( psz_sig, ".asc" );
 918
 919     stream_t *p_stream = stream_UrlNew( p_this, psz_sig );
 920     free( psz_sig );
 921
 922     if( !p_stream )
 923         return VLC_ENOMEM;
 924
 925     int64_t i_size = stream_Size( p_stream );
 926
 927     msg_Dbg( p_this, "Downloading signature (%"PRId64" bytes)", i_size );
 928     uint8_t *p_buf = (uint8_t*)malloc( i_size );
 929     if( !p_buf )
 930     {
 931         stream_Delete( p_stream );
 932         return VLC_ENOMEM;
 933     }
 934
 935     int i_read = stream_Read( p_stream, p_buf, (int)i_size );
 936
 937     stream_Delete( p_stream );
 938
 939     if( i_read != (int)i_size )
 940     {
 941         msg_Dbg( p_this,
 942             "Couldn't download full signature (only %d bytes)", i_read );
 943         free( p_buf );
 944         return VLC_EGENERIC;
 945     }
 946
 947     if( (uint8_t)*p_buf < 0x80 ) /* ASCII */
 948     {
 949         msg_Dbg( p_this, "Unarmoring signature" );
 950
 951         uint8_t* p_unarmored = (uint8_t*) malloc( ( i_size * 3 ) / 4 + 1 );
 952         if( !p_unarmored )
 953         {
 954             free( p_buf );
 955             return VLC_EGENERIC;
 956         }
 957
 958         int i_bytes = pgp_unarmor( (char*)p_buf, i_size, p_unarmored, i_size );
 959         free( p_buf );
 960
 961         p_buf = p_unarmored;
 962         i_size = i_bytes;
 963
 964         if( i_bytes < 2 )
 965         {
 966             free( p_buf );
 967             msg_Dbg( p_this, "Unarmoring failed : corrupted signature ?" );
 968             return VLC_EGENERIC;
 969         }
 970     }
 971
 972     if( packet_type( *p_buf ) != SIGNATURE_PACKET )
 973     {
 974         free( p_buf );
 975         msg_Dbg( p_this, "Not a signature: %d", *p_buf );
 976         return VLC_EGENERIC;
 977     }
 978
 979     size_t i_header_len = packet_header_len( *p_buf );
 980     if( ( i_header_len != 1 && i_header_len != 2 && i_header_len != 4 ) ||
 981         i_header_len + 1 > (size_t)i_size )
 982     {
 983         free( p_buf );
 984         msg_Dbg( p_this, "Invalid signature packet header" );
 985         return VLC_EGENERIC;
 986     }
 987
 988     size_t i_len = scalar_number( p_buf+1, i_header_len );
 989     if( i_len + i_header_len + 1 != (size_t)i_size )
 990     {
 991         free( p_buf );
 992         msg_Dbg( p_this, "Invalid signature packet" );
 993         return VLC_EGENERIC;
 994     }
 995
 996     int i_ret = parse_signature_packet( p_sig, p_buf+1+i_header_len, i_len );
 997     free( p_buf );
 998     if( i_ret != VLC_SUCCESS )
 999     {
1000         msg_Dbg( p_this, "Couldn't parse signature" );
1001         return i_ret;
1002     }
1003
1004     if( p_sig->type != BINARY_SIGNATURE && p_sig->type != TEXT_SIGNATURE )
1005     {
1006         msg_Dbg( p_this, "Invalid signature type: %d", p_sig->type );
1007         if( p_sig->version == 4 )
1008         {
1009             free( p_sig->specific.v4.hashed_data );
1010             free( p_sig->specific.v4.unhashed_data );
1011         }
1012         return VLC_EGENERIC;
1013     }
1014
1015     return VLC_SUCCESS;
1016 }
1017
1018 #endif /* UPDATE_CHECK */