src/misc/update_crypto.c

   1 /*****************************************************************************
   2  * update_crypto.c: OpenPGP related functions used for updating
   3  *****************************************************************************
   4  * Copyright © 2008-2009 VLC authors and VideoLAN
   5  *
   6  * Authors: Rafaël Carré <funman@videolanorg>
   7  *
   8  * This program is free software; you can redistribute it and/or modify it
   9  * under the terms of the GNU Lesser General Public License as published by
  10  * the Free Software Foundation; either release 2 of the License, or
  11  * (at your option) any later release.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  16  * GNU Lesser General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU Lesser General Public License
  19  * along with this program; if not, write to the Free Software Foundation,
  20  * Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
  21  *****************************************************************************/
  22
  23 /**
  24  *   \file
  25  *   This file contains functions related to OpenPGP in VLC update management
  26  */
  27
  28 /*****************************************************************************
  29  * Preamble
  30  *****************************************************************************/
  31
  32 #ifdef HAVE_CONFIG_H
  33 # include "config.h"
  34 #endif
  35
  36 #include <gcrypt.h>
  37 #include <assert.h>
  38 #include <limits.h>
  39
  40 #include "vlc_common.h"
  41 #include <vlc_stream.h>
  42 #include <vlc_strings.h>
  43 #include <vlc_fs.h>
  44
  45 #include "update.h"
  46
  47
  48 /*****************************************************************************
  49  * OpenPGP functions
  50  *****************************************************************************/
  51
  52 #define packet_type( c ) ( ( c & 0x3c ) >> 2 )      /* 0x3C = 00111100 */
  53 #define packet_header_len( c ) ( ( c & 0x03 ) + 1 ) /* number of bytes in a packet header */
  54
  55
  56 static inline int scalar_number( const uint8_t *p, int header_len )
  57 {
  58     assert( header_len == 1 || header_len == 2 || header_len == 4 );
  59
  60     if( header_len == 1 )
  61         return( p[0] );
  62     else if( header_len == 2 )
  63         return( (p[0] << 8) + p[1] );
  64     else if( header_len == 4 )
  65         return( (p[0] << 24) + (p[1] << 16) + (p[2] << 8) + p[3] );
  66     else
  67         abort();
  68 }
  69
  70
  71 /* number of data bytes in a MPI */
  72 static int mpi_len(const uint8_t *mpi)
  73 {
  74     return (scalar_number(mpi, 2) + 7) / 8;
  75 }
  76
  77 static size_t read_mpi(uint8_t *dst, const uint8_t *buf, size_t buflen, size_t bits)
  78 {
  79     if (buflen < 2)
  80         return 0;
  81
  82     size_t n = mpi_len(buf);
  83
  84     if (n * 8 > bits)
  85         return 0;
  86
  87     n += 2;
  88
  89     if (buflen < n)
  90         return 0;
  91
  92     memcpy(dst, buf, n);
  93     return n;
  94 }
  95
  96 #define READ_MPI(d, bits) do { \
  97     size_t n = read_mpi(d, p_buf, i_packet_len - i_read, bits); \
  98     if (!n) goto error; \
  99     p_buf += n; \
 100     i_read += n; \
 101 } while(0)
 102
 103 /*
 104  * fill a public_key_packet_t structure from public key packet data
 105  * verify that it is a version 4 public key packet, using DSA or RSA
 106  */
 107 static int parse_public_key_packet( public_key_packet_t *p_key,
 108                                     const uint8_t *p_buf, size_t i_packet_len )
 109 {
 110     if( i_packet_len < 6 )
 111         return VLC_EGENERIC;
 112
 113     size_t i_read = 0;
 114
 115     p_key->version   = *p_buf++; i_read++;
 116     if( p_key->version != 4 )
 117         return VLC_EGENERIC;
 118
 119     /* XXX: warn when timestamp is > date ? */
 120     memcpy( p_key->timestamp, p_buf, 4 ); p_buf += 4; i_read += 4;
 121
 122     p_key->algo      = *p_buf++; i_read++;
 123     if( p_key->algo == GCRY_PK_DSA ) {
 124         READ_MPI(p_key->sig.dsa.p, 3072);
 125         READ_MPI(p_key->sig.dsa.q, 256);
 126         READ_MPI(p_key->sig.dsa.g, 3072);
 127         READ_MPI(p_key->sig.dsa.y, 3072);
 128     } else if ( p_key->algo == GCRY_PK_RSA ) {
 129         READ_MPI(p_key->sig.rsa.n, 4096);
 130         READ_MPI(p_key->sig.rsa.e, 4096);
 131     } else
 132         return VLC_EGENERIC;
 133
 134     if( i_read == i_packet_len )
 135         return VLC_SUCCESS;
 136
 137     /* some extra data eh ? */
 138
 139 error:
 140     return VLC_EGENERIC;
 141 }
 142
 143
 144 static size_t parse_signature_v3_packet( signature_packet_t *p_sig,
 145                                       const uint8_t *p_buf, size_t i_sig_len )
 146 {
 147     size_t i_read = 1; /* we already read the version byte */
 148
 149     if( i_sig_len < 19 ) /* signature is at least 19 bytes + the 2 MPIs */
 150         return 0;
 151
 152     p_sig->specific.v3.hashed_data_len = *p_buf++; i_read++;
 153     if( p_sig->specific.v3.hashed_data_len != 5 )
 154         return 0;
 155
 156     p_sig->type = *p_buf++; i_read++;
 157
 158     memcpy( p_sig->specific.v3.timestamp, p_buf, 4 );
 159     p_buf += 4; i_read += 4;
 160
 161     memcpy( p_sig->issuer_longid, p_buf, 8 );
 162     p_buf += 8; i_read += 8;
 163
 164     p_sig->public_key_algo = *p_buf++; i_read++;
 165
 166     p_sig->digest_algo = *p_buf++; i_read++;
 167
 168     p_sig->hash_verification[0] = *p_buf++; i_read++;
 169     p_sig->hash_verification[1] = *p_buf++; i_read++;
 170
 171     assert( i_read == 19 );
 172
 173     return i_read;
 174 }
 175
 176
 177 /*
 178  * fill a signature_packet_v4_t from signature packet data
 179  * verify that it was used with a DSA or RSA public key
 180  */
 181 static size_t parse_signature_v4_packet( signature_packet_t *p_sig,
 182                                       const uint8_t *p_buf, size_t i_sig_len )
 183 {
 184     size_t i_read = 1; /* we already read the version byte */
 185
 186     if( i_sig_len < 10 ) /* signature is at least 10 bytes + the 2 MPIs */
 187         return 0;
 188
 189     p_sig->type = *p_buf++; i_read++;
 190
 191     p_sig->public_key_algo = *p_buf++; i_read++;
 192     if (p_sig->public_key_algo != GCRY_PK_DSA && p_sig->public_key_algo != GCRY_PK_RSA )
 193             return 0;
 194
 195     p_sig->digest_algo = *p_buf++; i_read++;
 196
 197     memcpy( p_sig->specific.v4.hashed_data_len, p_buf, 2 );
 198     p_buf += 2; i_read += 2;
 199
 200     size_t i_hashed_data_len =
 201         scalar_number( p_sig->specific.v4.hashed_data_len, 2 );
 202     i_read += i_hashed_data_len;
 203     if( i_read + 4 > i_sig_len )
 204         return 0;
 205
 206     p_sig->specific.v4.hashed_data = (uint8_t*) malloc( i_hashed_data_len );
 207     if( !p_sig->specific.v4.hashed_data )
 208         return 0;
 209     memcpy( p_sig->specific.v4.hashed_data, p_buf, i_hashed_data_len );
 210     p_buf += i_hashed_data_len;
 211
 212     memcpy( p_sig->specific.v4.unhashed_data_len, p_buf, 2 );
 213     p_buf += 2; i_read += 2;
 214
 215     size_t i_unhashed_data_len =
 216         scalar_number( p_sig->specific.v4.unhashed_data_len, 2 );
 217     i_read += i_unhashed_data_len;
 218     if( i_read + 2 > i_sig_len )
 219         return 0;
 220
 221     p_sig->specific.v4.unhashed_data = (uint8_t*) malloc( i_unhashed_data_len );
 222     if( !p_sig->specific.v4.unhashed_data )
 223         return 0;
 224
 225     memcpy( p_sig->specific.v4.unhashed_data, p_buf, i_unhashed_data_len );
 226     p_buf += i_unhashed_data_len;
 227
 228     memcpy( p_sig->hash_verification, p_buf, 2 );
 229     p_buf += 2; i_read += 2;
 230
 231     uint8_t *p, *max_pos;
 232     p = p_sig->specific.v4.unhashed_data;
 233     max_pos = p + scalar_number( p_sig->specific.v4.unhashed_data_len, 2 );
 234
 235     for( ;; )
 236     {
 237         if( p > max_pos )
 238             return 0;
 239
 240         size_t i_subpacket_len;
 241         if( *p < 192 )
 242         {
 243             if( p + 1 > max_pos )
 244                 return 0;
 245             i_subpacket_len = *p++;
 246         }
 247         else if( *p < 255 )
 248         {
 249             if( p + 2 > max_pos )
 250                 return 0;
 251             i_subpacket_len = (*p++ - 192) << 8;
 252             i_subpacket_len += *p++ + 192;
 253         }
 254         else
 255         {
 256             if( ++p + 4 > max_pos )
 257                 return 0;
 258             i_subpacket_len = U32_AT(p);
 259             p += 4;
 260         }
 261
 262         if( *p == ISSUER_SUBPACKET )
 263         {
 264             if( p + 9 > max_pos )
 265                 return 0;
 266
 267             memcpy( &p_sig->issuer_longid, p+1, 8 );
 268
 269             return i_read;
 270         }
 271
 272         p += i_subpacket_len;
 273     }
 274 }
 275
 276
 277 static int parse_signature_packet( signature_packet_t *p_sig,
 278                                    const uint8_t *p_buf, size_t i_packet_len )
 279 {
 280     if( !i_packet_len ) /* 1st sanity check, we need at least the version */
 281         return VLC_EGENERIC;
 282
 283     p_sig->version = *p_buf++;
 284
 285     size_t i_read;
 286     switch( p_sig->version )
 287     {
 288         case 3:
 289             i_read = parse_signature_v3_packet( p_sig, p_buf, i_packet_len );
 290             break;
 291         case 4:
 292             p_sig->specific.v4.hashed_data = NULL;
 293             p_sig->specific.v4.unhashed_data = NULL;
 294             i_read = parse_signature_v4_packet( p_sig, p_buf, i_packet_len );
 295             break;
 296         default:
 297             return VLC_EGENERIC;
 298     }
 299
 300     if( i_read == 0 ) /* signature packet parsing has failed */
 301         goto error;
 302
 303     if( p_sig->public_key_algo != GCRY_PK_DSA && p_sig->public_key_algo != GCRY_PK_RSA )
 304         goto error;
 305
 306     switch( p_sig->type )
 307     {
 308         case BINARY_SIGNATURE:
 309         case TEXT_SIGNATURE:
 310         case GENERIC_KEY_SIGNATURE:
 311         case PERSONA_KEY_SIGNATURE:
 312         case CASUAL_KEY_SIGNATURE:
 313         case POSITIVE_KEY_SIGNATURE:
 314             break;
 315         default:
 316             goto error;
 317     }
 318
 319     p_buf--; /* rewind to the version byte */
 320     p_buf += i_read;
 321
 322     if( p_sig->public_key_algo == GCRY_PK_DSA ) {
 323         READ_MPI(p_sig->algo_specific.dsa.r, 256);
 324         READ_MPI(p_sig->algo_specific.dsa.s, 256);
 325     } else if ( p_sig->public_key_algo == GCRY_PK_RSA ) {
 326         READ_MPI(p_sig->algo_specific.rsa.s, 4096);
 327     } else
 328         goto error;
 329
 330     assert( i_read == i_packet_len );
 331     if( i_read < i_packet_len ) /* some extra data, hm ? */
 332         goto error;
 333
 334     return VLC_SUCCESS;
 335
 336 error:
 337
 338     if( p_sig->version == 4 )
 339     {
 340         free( p_sig->specific.v4.hashed_data );
 341         free( p_sig->specific.v4.unhashed_data );
 342     }
 343
 344     return VLC_EGENERIC;
 345 }
 346
 347
 348 /*
 349  * crc_octets() was lamely copied from rfc 2440
 350  * Copyright (C) The Internet Society (1998).  All Rights Reserved.
 351  */
 352 #define CRC24_INIT 0xB704CEL
 353 #define CRC24_POLY 0x1864CFBL
 354
 355 static long crc_octets( uint8_t *octets, size_t len )
 356 {
 357     long crc = CRC24_INIT;
 358     int i;
 359     while (len--)
 360     {
 361         crc ^= (*octets++) << 16;
 362         for (i = 0; i < 8; i++)
 363         {
 364             crc <<= 1;
 365             if (crc & 0x1000000)
 366                 crc ^= CRC24_POLY;
 367         }
 368     }
 369     return crc & 0xFFFFFFL;
 370 }
 371
 372
 373 /*
 374  * Transform an armored document in binary format
 375  * Used on public keys and signatures
 376  */
 377 static int pgp_unarmor( const char *p_ibuf, size_t i_ibuf_len,
 378                         uint8_t *p_obuf, size_t i_obuf_len )
 379 {
 380     const char *p_ipos = p_ibuf;
 381     uint8_t *p_opos = p_obuf;
 382     int i_end = 0;
 383     int i_header_skipped = 0;
 384
 385     while( !i_end && p_ipos < p_ibuf + i_ibuf_len && *p_ipos != '=' )
 386     {
 387         if( *p_ipos == '\r' || *p_ipos == '\n' )
 388         {
 389             p_ipos++;
 390             continue;
 391         }
 392
 393         size_t i_line_len = strcspn( p_ipos, "\r\n" );
 394         if( i_line_len == 0 )
 395             continue;
 396
 397         if( !i_header_skipped )
 398         {
 399             if( !strncmp( p_ipos, "-----BEGIN PGP", 14 ) )
 400                 i_header_skipped = 1;
 401
 402             p_ipos += i_line_len + 1;
 403             continue;
 404         }
 405
 406         if( !strncmp( p_ipos, "Version:", 8 ) )
 407         {
 408             p_ipos += i_line_len + 1;
 409             continue;
 410         }
 411
 412         if( p_ipos[i_line_len - 1] == '=' )
 413         {
 414             i_end = 1;
 415         }
 416
 417         p_opos += vlc_b64_decode_binary_to_buffer(  p_opos,
 418                         p_obuf - p_opos + i_obuf_len, p_ipos );
 419         p_ipos += i_line_len + 1;
 420     }
 421
 422     /* XXX: the CRC is OPTIONAL, really require it ? */
 423     if( p_ipos + 5 > p_ibuf + i_ibuf_len || *p_ipos++ != '=' )
 424         return 0;
 425
 426     uint8_t p_crc[3];
 427     if( vlc_b64_decode_binary_to_buffer( p_crc, 3, p_ipos ) != 3 )
 428         return 0;
 429
 430     long l_crc = crc_octets( p_obuf, p_opos - p_obuf );
 431     long l_crc2 = ( 0 << 24 ) + ( p_crc[0] << 16 ) + ( p_crc[1] << 8 ) + p_crc[2];
 432
 433     return l_crc2 == l_crc ? p_opos - p_obuf : 0;
 434 }
 435
 436 static int rsa_pkcs1_encode_sig(gcry_mpi_t *r_result, size_t size,
 437                                 const uint8_t *hash, int algo)
 438 {
 439     uint8_t asn[100];
 440     uint8_t frame[4096/8];
 441
 442     size_t asnlen = sizeof(asn);
 443     size_t hashlen = gcry_md_get_algo_dlen(algo);
 444
 445     if (gcry_md_algo_info(algo, GCRYCTL_GET_ASNOID, asn, &asnlen))
 446         return VLC_EGENERIC;
 447
 448     if (!hashlen || hashlen + asnlen + 4 > size)
 449         return VLC_EGENERIC;
 450
 451     frame[0] = 0;
 452     frame[1] = 1; /* block type */
 453     int pad = size - hashlen - asnlen - 3 ;
 454     memset (&frame[2], 0xff, pad );
 455     frame[2+pad] = 0;
 456     memcpy(&frame[3+pad], asn, asnlen);
 457     memcpy(&frame[3+pad+asnlen], hash, hashlen);
 458
 459     if (gcry_mpi_scan(r_result, GCRYMPI_FMT_USG, frame, size, &size))
 460         return VLC_EGENERIC;
 461     return VLC_SUCCESS;
 462 }
 463
 464 /*
 465  * Verify an OpenPGP signature made with some RSA public key
 466  */
 467 static int verify_signature_rsa( signature_packet_t *sign, public_key_packet_t *p_key,
 468                       uint8_t *p_hash )
 469 {
 470     int ret = VLC_EGENERIC;
 471     /* the data to be verified (a hash) */
 472     const char *hash_sexp_s = "(data(flags raw)(value %m))";
 473     /* the public key */
 474     const char *key_sexp_s = "(public-key(rsa(n %m)(e %m)))";
 475     /* the signature */
 476     const char *sig_sexp_s = "(sig-val(rsa(s%m)))";
 477
 478     size_t erroff;
 479     gcry_mpi_t n, e, s, hash;
 480     n = e = s = hash = NULL;
 481     gcry_sexp_t key_sexp, hash_sexp, sig_sexp;
 482     key_sexp = hash_sexp = sig_sexp = NULL;
 483
 484     int i_n_len = mpi_len( p_key->sig.rsa.n );
 485     int i_e_len = mpi_len( p_key->sig.rsa.e );
 486     if( gcry_mpi_scan( &n, GCRYMPI_FMT_USG, p_key->sig.rsa.n + 2, i_n_len, NULL ) ||
 487         gcry_mpi_scan( &e, GCRYMPI_FMT_USG, p_key->sig.rsa.e + 2, i_e_len, NULL ) ||
 488         gcry_sexp_build( &key_sexp, &erroff, key_sexp_s, n, e ) )
 489         goto out;
 490
 491     uint8_t *p_s = sign->algo_specific.rsa.s;
 492     int i_s_len = mpi_len( p_s );
 493     if( gcry_mpi_scan( &s, GCRYMPI_FMT_USG, p_s + 2, i_s_len, NULL ) ||
 494         gcry_sexp_build( &sig_sexp, &erroff, sig_sexp_s, s ) )
 495         goto out;
 496
 497     if( rsa_pkcs1_encode_sig (&hash, i_n_len, p_hash, sign->digest_algo) ||
 498         gcry_sexp_build( &hash_sexp, &erroff, hash_sexp_s, hash ) )
 499         goto out;
 500
 501     if( gcry_pk_verify( sig_sexp, hash_sexp, key_sexp ) )
 502         goto out;
 503
 504     ret = VLC_SUCCESS;
 505
 506 out:
 507     if( n ) gcry_mpi_release( n );
 508     if( e ) gcry_mpi_release( e );
 509     if( s ) gcry_mpi_release( s );
 510     if( hash ) gcry_mpi_release( hash );
 511     if( key_sexp ) gcry_sexp_release( key_sexp );
 512     if( sig_sexp ) gcry_sexp_release( sig_sexp );
 513     if( hash_sexp ) gcry_sexp_release( hash_sexp );
 514     return ret;
 515 }
 516
 517 /*
 518  * Verify an OpenPGP signature made with some DSA public key
 519  */
 520 static int verify_signature_dsa( signature_packet_t *sign, public_key_packet_t *p_key,
 521                       uint8_t *p_hash )
 522 {
 523     int ret = VLC_EGENERIC;
 524
 525     /* the data to be verified (a hash) */
 526     const char *hash_sexp_s = "(data(flags raw)(value %m))";
 527     /* the public key */
 528     const char *key_sexp_s = "(public-key(dsa(p %m)(q %m)(g %m)(y %m)))";
 529     /* the signature */
 530     const char *sig_sexp_s = "(sig-val(dsa(r %m )(s %m )))";
 531
 532     size_t erroff;
 533     gcry_mpi_t p, q, g, y, r, s, hash;
 534     p = q = g = y = r = s = hash = NULL;
 535     gcry_sexp_t key_sexp, hash_sexp, sig_sexp;
 536     key_sexp = hash_sexp = sig_sexp = NULL;
 537
 538     int i_p_len = mpi_len( p_key->sig.dsa.p );
 539     int i_q_len = mpi_len( p_key->sig.dsa.q );
 540     int i_g_len = mpi_len( p_key->sig.dsa.g );
 541     int i_y_len = mpi_len( p_key->sig.dsa.y );
 542     if( gcry_mpi_scan( &p, GCRYMPI_FMT_USG, p_key->sig.dsa.p + 2, i_p_len, NULL ) ||
 543         gcry_mpi_scan( &q, GCRYMPI_FMT_USG, p_key->sig.dsa.q + 2, i_q_len, NULL ) ||
 544         gcry_mpi_scan( &g, GCRYMPI_FMT_USG, p_key->sig.dsa.g + 2, i_g_len, NULL ) ||
 545         gcry_mpi_scan( &y, GCRYMPI_FMT_USG, p_key->sig.dsa.y + 2, i_y_len, NULL ) ||
 546         gcry_sexp_build( &key_sexp, &erroff, key_sexp_s, p, q, g, y ) )
 547         goto out;
 548
 549     uint8_t *p_r = sign->algo_specific.dsa.r;
 550     uint8_t *p_s = sign->algo_specific.dsa.s;
 551     int i_r_len = mpi_len( p_r );
 552     int i_s_len = mpi_len( p_s );
 553     if( gcry_mpi_scan( &r, GCRYMPI_FMT_USG, p_r + 2, i_r_len, NULL ) ||
 554         gcry_mpi_scan( &s, GCRYMPI_FMT_USG, p_s + 2, i_s_len, NULL ) ||
 555         gcry_sexp_build( &sig_sexp, &erroff, sig_sexp_s, r, s ) )
 556         goto out;
 557
 558     int i_hash_len = gcry_md_get_algo_dlen (sign->digest_algo);
 559     if (i_hash_len > i_q_len)
 560         i_hash_len = i_q_len;
 561     if( gcry_mpi_scan( &hash, GCRYMPI_FMT_USG, p_hash, i_hash_len, NULL ) ||
 562         gcry_sexp_build( &hash_sexp, &erroff, hash_sexp_s, hash ) )
 563         goto out;
 564
 565     if( gcry_pk_verify( sig_sexp, hash_sexp, key_sexp ) )
 566         goto out;
 567
 568     ret = VLC_SUCCESS;
 569
 570 out:
 571     if( p ) gcry_mpi_release( p );
 572     if( q ) gcry_mpi_release( q );
 573     if( g ) gcry_mpi_release( g );
 574     if( y ) gcry_mpi_release( y );
 575     if( r ) gcry_mpi_release( r );
 576     if( s ) gcry_mpi_release( s );
 577     if( hash ) gcry_mpi_release( hash );
 578     if( key_sexp ) gcry_sexp_release( key_sexp );
 579     if( sig_sexp ) gcry_sexp_release( sig_sexp );
 580     if( hash_sexp ) gcry_sexp_release( hash_sexp );
 581
 582     return ret;
 583 }
 584
 585 /*
 586  * Verify an OpenPGP signature made with some public key
 587  */
 588 int verify_signature( signature_packet_t *sign, public_key_packet_t *p_key,
 589                       uint8_t *p_hash )
 590 {
 591     if (sign->public_key_algo == GCRY_PK_DSA)
 592         return verify_signature_dsa(sign, p_key, p_hash);
 593     else if (sign->public_key_algo == GCRY_PK_RSA)
 594         return verify_signature_rsa(sign, p_key, p_hash);
 595     else
 596         return VLC_EGENERIC;
 597 }
 598
 599
 600 /*
 601  * fill a public_key_t with public key data, including:
 602  *   * public key packet
 603  *   * signature packet issued by key which long id is p_sig_issuer
 604  *   * user id packet
 605  */
 606 int parse_public_key( const uint8_t *p_key_data, size_t i_key_len,
 607                       public_key_t *p_key, const uint8_t *p_sig_issuer )
 608 {
 609     const uint8_t *pos = p_key_data;
 610     const uint8_t *max_pos = pos + i_key_len;
 611
 612     int i_status = 0;
 613 #define PUBLIC_KEY_FOUND    0x01
 614 #define USER_ID_FOUND       0x02
 615 #define SIGNATURE_FOUND     0X04
 616
 617     uint8_t *p_key_unarmored = NULL;
 618
 619     p_key->psz_username = NULL;
 620     p_key->sig.specific.v4.hashed_data = NULL;
 621     p_key->sig.specific.v4.unhashed_data = NULL;
 622
 623     if( !( *pos & 0x80 ) )
 624     {   /* first byte is ASCII, unarmoring */
 625         p_key_unarmored = (uint8_t*)malloc( i_key_len );
 626         if( !p_key_unarmored )
 627             return VLC_ENOMEM;
 628         int i_len = pgp_unarmor( (char*)p_key_data, i_key_len,
 629                                  p_key_unarmored, i_key_len );
 630
 631         if( i_len == 0 )
 632             goto error;
 633
 634         pos = p_key_unarmored;
 635         max_pos = pos + i_len;
 636     }
 637
 638     while( pos < max_pos )
 639     {
 640         if( !(*pos & 0x80) || *pos & 0x40 )
 641             goto error;
 642
 643         int i_type = packet_type( *pos );
 644
 645         int i_header_len = packet_header_len( *pos++ );
 646         if( pos + i_header_len > max_pos ||
 647             ( i_header_len != 1 && i_header_len != 2 && i_header_len != 4 ) )
 648             goto error;
 649
 650         int i_packet_len = scalar_number( pos, i_header_len );
 651         pos += i_header_len;
 652
 653         if( pos + i_packet_len > max_pos )
 654             goto error;
 655
 656         switch( i_type )
 657         {
 658             case PUBLIC_KEY_PACKET:
 659                 i_status |= PUBLIC_KEY_FOUND;
 660                 if( parse_public_key_packet( &p_key->key, pos, i_packet_len ) != VLC_SUCCESS )
 661                     goto error;
 662                 break;
 663
 664             case SIGNATURE_PACKET: /* we accept only v4 signatures here */
 665                 if( i_status & SIGNATURE_FOUND || !p_sig_issuer )
 666                     break;
 667                 int i_ret = parse_signature_packet( &p_key->sig, pos,
 668                                                     i_packet_len );
 669                 if( i_ret == VLC_SUCCESS )
 670                 {
 671                     if( p_key->sig.version != 4 )
 672                         break;
 673                     if( memcmp( p_key->sig.issuer_longid, p_sig_issuer, 8 ) )
 674                     {
 675                         free( p_key->sig.specific.v4.hashed_data );
 676                         free( p_key->sig.specific.v4.unhashed_data );
 677                         p_key->sig.specific.v4.hashed_data = NULL;
 678                         p_key->sig.specific.v4.unhashed_data = NULL;
 679                         break;
 680                     }
 681                     i_status |= SIGNATURE_FOUND;
 682                 }
 683                 break;
 684
 685             case USER_ID_PACKET:
 686                 if( p_key->psz_username ) /* save only the first User ID */
 687                     break;
 688                 i_status |= USER_ID_FOUND;
 689                 p_key->psz_username = (uint8_t*)malloc( i_packet_len + 1);
 690                 if( !p_key->psz_username )
 691                     goto error;
 692
 693                 memcpy( p_key->psz_username, pos, i_packet_len );
 694                 p_key->psz_username[i_packet_len] = '\0';
 695                 break;
 696
 697             default:
 698                 break;
 699         }
 700         pos += i_packet_len;
 701     }
 702     free( p_key_unarmored );
 703
 704     if( !( i_status & ( PUBLIC_KEY_FOUND | USER_ID_FOUND ) ) )
 705         return VLC_EGENERIC;
 706
 707     if( p_sig_issuer && !( i_status & SIGNATURE_FOUND ) )
 708         return VLC_EGENERIC;
 709
 710     return VLC_SUCCESS;
 711
 712 error:
 713     if( p_key->sig.version == 4 )
 714     {
 715         free( p_key->sig.specific.v4.hashed_data );
 716         free( p_key->sig.specific.v4.unhashed_data );
 717     }
 718     free( p_key->psz_username );
 719     free( p_key_unarmored );
 720     return VLC_EGENERIC;
 721 }
 722
 723
 724 /* hash a binary file */
 725 static int hash_from_binary_file( const char *psz_file, gcry_md_hd_t hd )
 726 {
 727     uint8_t buffer[4096];
 728     size_t i_read;
 729
 730     FILE *f = vlc_fopen( psz_file, "r" );
 731     if( !f )
 732         return -1;
 733
 734     while( ( i_read = fread( buffer, 1, sizeof(buffer), f ) ) > 0 )
 735         gcry_md_write( hd, buffer, i_read );
 736
 737     fclose( f );
 738
 739     return 0;
 740 }
 741
 742
 743 /* final part of the hash */
 744 static uint8_t *hash_finish( gcry_md_hd_t hd, signature_packet_t *p_sig )
 745 {
 746     if( p_sig->version == 3 )
 747     {
 748         gcry_md_putc( hd, p_sig->type );
 749         gcry_md_write( hd, &p_sig->specific.v3.timestamp, 4 );
 750     }
 751     else if( p_sig->version == 4 )
 752     {
 753         gcry_md_putc( hd, p_sig->version );
 754         gcry_md_putc( hd, p_sig->type );
 755         gcry_md_putc( hd, p_sig->public_key_algo );
 756         gcry_md_putc( hd, p_sig->digest_algo );
 757         gcry_md_write( hd, p_sig->specific.v4.hashed_data_len, 2 );
 758         size_t i_len = scalar_number( p_sig->specific.v4.hashed_data_len, 2 );
 759         gcry_md_write( hd, p_sig->specific.v4.hashed_data, i_len );
 760
 761         gcry_md_putc( hd, 0x04 );
 762         gcry_md_putc( hd, 0xFF );
 763
 764         i_len += 6; /* hashed data + 6 bytes header */
 765
 766         gcry_md_putc( hd, (i_len >> 24) & 0xff );
 767         gcry_md_putc( hd, (i_len >> 16) & 0xff );
 768         gcry_md_putc( hd, (i_len >> 8) & 0xff );
 769         gcry_md_putc( hd, (i_len) & 0xff );
 770     }
 771     else
 772     {   /* RFC 4880 only tells about versions 3 and 4 */
 773         return NULL;
 774     }
 775
 776     gcry_md_final( hd );
 777
 778     uint8_t *p_tmp = (uint8_t*) gcry_md_read( hd, p_sig->digest_algo) ;
 779     unsigned int hash_len = gcry_md_get_algo_dlen (p_sig->digest_algo);
 780     uint8_t *p_hash = malloc(hash_len);
 781     if( p_hash )
 782         memcpy(p_hash, p_tmp, hash_len);
 783     gcry_md_close( hd );
 784     return p_hash;
 785 }
 786
 787
 788 /*
 789  * return a hash of a text
 790  */
 791 uint8_t *hash_from_text( const char *psz_string,
 792         signature_packet_t *p_sig )
 793 {
 794     gcry_md_hd_t hd;
 795     if( gcry_md_open( &hd, p_sig->digest_algo, 0 ) )
 796         return NULL;
 797
 798     if( p_sig->type == TEXT_SIGNATURE )
 799     while( *psz_string )
 800     {
 801         size_t i_len = strcspn( psz_string, "\r\n" );
 802
 803         if( i_len )
 804         {
 805             gcry_md_write( hd, psz_string, i_len );
 806             psz_string += i_len;
 807         }
 808         gcry_md_putc( hd, '\r' );
 809         gcry_md_putc( hd, '\n' );
 810
 811         if( *psz_string == '\r' )
 812             psz_string++;
 813         if( *psz_string == '\n' )
 814             psz_string++;
 815     }
 816     else
 817         gcry_md_write( hd, psz_string, strlen( psz_string ) );
 818
 819     return hash_finish( hd, p_sig );
 820 }
 821
 822
 823 /*
 824  * return a hash of a file
 825  */
 826 uint8_t *hash_from_file( const char *psz_file, signature_packet_t *p_sig )
 827 {
 828     gcry_md_hd_t hd;
 829     if( gcry_md_open( &hd, p_sig->digest_algo, 0 ) )
 830         return NULL;
 831
 832     if( hash_from_binary_file( psz_file, hd ) < 0 )
 833     {
 834         gcry_md_close( hd );
 835         return NULL;
 836     }
 837
 838     return hash_finish( hd, p_sig );
 839 }
 840
 841
 842 /*
 843  * Generate a hash on a public key, to verify a signature made on that hash
 844  * Note that we need the signature (v4) to compute the hash
 845  */
 846 uint8_t *hash_from_public_key( public_key_t *p_pkey )
 847 {
 848     const uint8_t pk_algo = p_pkey->key.algo;
 849     size_t i_size;
 850     size_t i_p_len, i_g_len, i_q_len, i_y_len;
 851     size_t i_n_len, i_e_len;
 852
 853     if( p_pkey->sig.version != 4 )
 854         return NULL;
 855
 856     if( p_pkey->sig.type < GENERIC_KEY_SIGNATURE ||
 857         p_pkey->sig.type > POSITIVE_KEY_SIGNATURE )
 858         return NULL;
 859
 860     if( p_pkey->psz_username == NULL )
 861         return NULL;
 862
 863     gcry_error_t error = 0;
 864     gcry_md_hd_t hd;
 865
 866     if (pk_algo == GCRY_PK_DSA) {
 867         i_p_len = mpi_len( p_pkey->key.sig.dsa.p );
 868         i_g_len = mpi_len( p_pkey->key.sig.dsa.g );
 869         i_q_len = mpi_len( p_pkey->key.sig.dsa.q );
 870         i_y_len = mpi_len( p_pkey->key.sig.dsa.y );
 871
 872         i_size = 6 + 2*4 + i_p_len + i_g_len + i_q_len + i_y_len;
 873     } else if (pk_algo == GCRY_PK_RSA) {
 874         i_n_len = mpi_len( p_pkey->key.sig.rsa.n );
 875         i_e_len = mpi_len( p_pkey->key.sig.rsa.e );
 876
 877         i_size = 6 + 2*2 + i_n_len + i_e_len;
 878     } else
 879         return NULL;
 880
 881     error = gcry_md_open( &hd, p_pkey->sig.digest_algo, 0 );
 882     if( error )
 883         return NULL;
 884
 885     gcry_md_putc( hd, 0x99 );
 886
 887     gcry_md_putc( hd, (i_size >> 8) & 0xff );
 888     gcry_md_putc( hd, i_size & 0xff );
 889
 890     gcry_md_putc( hd, p_pkey->key.version );
 891     gcry_md_write( hd, p_pkey->key.timestamp, 4 );
 892     gcry_md_putc( hd, p_pkey->key.algo );
 893
 894     if (pk_algo == GCRY_PK_DSA) {
 895         gcry_md_write( hd, (uint8_t*)&p_pkey->key.sig.dsa.p, 2 + i_p_len );
 896         gcry_md_write( hd, (uint8_t*)&p_pkey->key.sig.dsa.q, 2 + i_q_len );
 897         gcry_md_write( hd, (uint8_t*)&p_pkey->key.sig.dsa.g, 2 + i_g_len );
 898         gcry_md_write( hd, (uint8_t*)&p_pkey->key.sig.dsa.y, 2 + i_y_len );
 899     } else if (pk_algo == GCRY_PK_RSA) {
 900         gcry_md_write( hd, (uint8_t*)&p_pkey->key.sig.rsa.n, 2 + i_n_len );
 901         gcry_md_write( hd, (uint8_t*)&p_pkey->key.sig.rsa.e, 2 + i_e_len );
 902     }
 903
 904     gcry_md_putc( hd, 0xb4 );
 905
 906     size_t i_len = strlen((char*)p_pkey->psz_username);
 907
 908     gcry_md_putc( hd, (i_len >> 24) & 0xff );
 909     gcry_md_putc( hd, (i_len >> 16) & 0xff );
 910     gcry_md_putc( hd, (i_len >> 8) & 0xff );
 911     gcry_md_putc( hd, (i_len) & 0xff );
 912
 913     gcry_md_write( hd, p_pkey->psz_username, i_len );
 914
 915     uint8_t *p_hash = hash_finish( hd, &p_pkey->sig );
 916     if( !p_hash ||
 917         p_hash[0] != p_pkey->sig.hash_verification[0] ||
 918         p_hash[1] != p_pkey->sig.hash_verification[1] )
 919     {
 920         free(p_hash);
 921         return NULL;
 922     }
 923
 924     return p_hash;
 925 }
 926
 927
 928 /*
 929  * download a public key (the last one) from videolan server, and parse it
 930  */
 931 public_key_t *download_key( vlc_object_t *p_this,
 932                     const uint8_t *p_longid, const uint8_t *p_signature_issuer )
 933 {
 934     char *psz_url;
 935     if( asprintf( &psz_url, "http://download.videolan.org/pub/keys/%.2X%.2X%.2X%.2X%.2X%.2X%.2X%.2X.asc",
 936                     p_longid[0], p_longid[1], p_longid[2], p_longid[3],
 937                     p_longid[4], p_longid[5], p_longid[6], p_longid[7] ) == -1 )
 938         return NULL;
 939
 940     stream_t *p_stream = vlc_stream_NewURL( p_this, psz_url );
 941     free( psz_url );
 942     if( !p_stream )
 943         return NULL;
 944
 945     uint64_t i_size;
 946     if( vlc_stream_GetSize( p_stream, &i_size ) || i_size > INT_MAX )
 947     {
 948         vlc_stream_Delete( p_stream );
 949         return NULL;
 950     }
 951
 952     uint8_t *p_buf = (uint8_t*)malloc( i_size );
 953     if( !p_buf )
 954     {
 955         vlc_stream_Delete( p_stream );
 956         return NULL;
 957     }
 958
 959     int i_read = vlc_stream_Read( p_stream, p_buf, (int)i_size );
 960     vlc_stream_Delete( p_stream );
 961
 962     if( i_read != (int)i_size )
 963     {
 964         msg_Dbg( p_this, "Couldn't read full GPG key" );
 965         free( p_buf );
 966         return NULL;
 967     }
 968
 969     public_key_t *p_pkey = (public_key_t*) malloc( sizeof( public_key_t ) );
 970     if( !p_pkey )
 971     {
 972         free( p_buf );
 973         return NULL;
 974     }
 975
 976     memcpy( p_pkey->longid, p_longid, 8 );
 977
 978     int i_error = parse_public_key( p_buf, i_read, p_pkey, p_signature_issuer );
 979     free( p_buf );
 980
 981     if( i_error != VLC_SUCCESS )
 982     {
 983         msg_Dbg( p_this, "Couldn't parse GPG key" );
 984         free( p_pkey );
 985         return NULL;
 986     }
 987
 988     return p_pkey;
 989 }
 990
 991
 992 /*
 993  * Download the signature associated to a document or a binary file.
 994  * We're given the file's url, we just append ".asc" to it and download
 995  */
 996 int download_signature( vlc_object_t *p_this, signature_packet_t *p_sig,
 997                         const char *psz_url )
 998 {
 999     char *psz_sig = (char*) malloc( strlen( psz_url ) + 4 + 1 ); /* ".asc" + \0 */
1000     if( !psz_sig )
1001         return VLC_ENOMEM;
1002
1003     strcpy( psz_sig, psz_url );
1004     strcat( psz_sig, ".asc" );
1005
1006     stream_t *p_stream = vlc_stream_NewURL( p_this, psz_sig );
1007     free( psz_sig );
1008
1009     if( !p_stream )
1010         return VLC_ENOMEM;
1011
1012     uint64_t i_size;
1013     if( vlc_stream_GetSize( p_stream, &i_size ) || i_size > INT_MAX )
1014     {
1015         vlc_stream_Delete( p_stream );
1016         return VLC_EGENERIC;
1017     }
1018
1019     msg_Dbg( p_this, "Downloading signature (%"PRIu64" bytes)", i_size );
1020     uint8_t *p_buf = (uint8_t*)malloc( i_size );
1021     if( !p_buf )
1022     {
1023         vlc_stream_Delete( p_stream );
1024         return VLC_ENOMEM;
1025     }
1026
1027     int i_read = vlc_stream_Read( p_stream, p_buf, (int)i_size );
1028
1029     vlc_stream_Delete( p_stream );
1030
1031     if( i_read != (int)i_size )
1032     {
1033         msg_Dbg( p_this,
1034             "Couldn't download full signature (only %d bytes)", i_read );
1035         free( p_buf );
1036         return VLC_EGENERIC;
1037     }
1038
1039     if( (uint8_t)*p_buf < 0x80 ) /* ASCII */
1040     {
1041         msg_Dbg( p_this, "Unarmoring signature" );
1042
1043         uint8_t* p_unarmored = (uint8_t*) malloc( ( i_size * 3 ) / 4 + 1 );
1044         if( !p_unarmored )
1045         {
1046             free( p_buf );
1047             return VLC_EGENERIC;
1048         }
1049
1050         int i_bytes = pgp_unarmor( (char*)p_buf, i_size, p_unarmored, i_size );
1051         free( p_buf );
1052
1053         p_buf = p_unarmored;
1054         i_size = i_bytes;
1055
1056         if( i_bytes < 2 )
1057         {
1058             free( p_buf );
1059             msg_Dbg( p_this, "Unarmoring failed : corrupted signature ?" );
1060             return VLC_EGENERIC;
1061         }
1062     }
1063
1064     if( packet_type( *p_buf ) != SIGNATURE_PACKET )
1065     {
1066         msg_Dbg( p_this, "Not a signature: %d", *p_buf );
1067         free( p_buf );
1068         return VLC_EGENERIC;
1069     }
1070
1071     size_t i_header_len = packet_header_len( *p_buf );
1072     if( ( i_header_len != 1 && i_header_len != 2 && i_header_len != 4 ) ||
1073         i_header_len + 1 > (size_t)i_size )
1074     {
1075         free( p_buf );
1076         msg_Dbg( p_this, "Invalid signature packet header" );
1077         return VLC_EGENERIC;
1078     }
1079
1080     size_t i_len = scalar_number( p_buf+1, i_header_len );
1081     if( i_len + i_header_len + 1 != (size_t)i_size )
1082     {
1083         free( p_buf );
1084         msg_Dbg( p_this, "Invalid signature packet" );
1085         return VLC_EGENERIC;
1086     }
1087
1088     int i_ret = parse_signature_packet( p_sig, p_buf+1+i_header_len, i_len );
1089     free( p_buf );
1090     if( i_ret != VLC_SUCCESS )
1091     {
1092         msg_Dbg( p_this, "Couldn't parse signature" );
1093         return i_ret;
1094     }
1095
1096     if( p_sig->type != BINARY_SIGNATURE && p_sig->type != TEXT_SIGNATURE )
1097     {
1098         msg_Dbg( p_this, "Invalid signature type: %d", p_sig->type );
1099         if( p_sig->version == 4 )
1100         {
1101             free( p_sig->specific.v4.hashed_data );
1102             free( p_sig->specific.v4.unhashed_data );
1103         }
1104         return VLC_EGENERIC;
1105     }
1106
1107     return VLC_SUCCESS;
1108 }