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