src/misc/update.h

   1 /*****************************************************************************
   2  * update.h: VLC PGP update private API
   3  *****************************************************************************
   4  * Copyright © 2007-2008 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 /* Go reading the rfc 4880 ! NOW !! */
  24
  25 /*
  26  * XXX
  27  *  When PGP-signing a file, we only sign a SHA-1 hash of this file
  28  *  The DSA key size requires that we use an algorithm which produce
  29  *  a 160 bits long hash
  30  *  An alternative is RIPEMD160 , which you can use by giving the option
  31  *      --digest-algo RIPEMD160 to GnuPG
  32  *
  33  *  As soon as SHA-1 is broken, this method is not secure anymore, because an
  34  *  attacker could generate a file with the same SHA-1 hash.
  35  *
  36  *  Whenever this happens, we need to use another algorithm / type of key.
  37  * XXX
  38  */
  39
  40 #include <vlc_update.h>
  41
  42 enum    /* Public key algorithms */
  43 {
  44     /* we will only use DSA public keys */
  45     PUBLIC_KEY_ALGO_DSA = 0x11
  46 };
  47
  48 enum    /* Digest algorithms */
  49 {
  50     /* and DSA use SHA-1 digest */
  51     DIGEST_ALGO_SHA1    = 0x02
  52 };
  53
  54 enum    /* Packet types */
  55 {
  56     SIGNATURE_PACKET    = 0x02,
  57     PUBLIC_KEY_PACKET   = 0x06,
  58     USER_ID_PACKET      = 0x0d
  59 };
  60
  61 enum    /* Signature types */
  62 {
  63     BINARY_SIGNATURE        = 0x00,
  64     TEXT_SIGNATURE          = 0x01,
  65
  66     /* Public keys signatures */
  67     GENERIC_KEY_SIGNATURE   = 0x10, /* No assumption of verification */
  68     PERSONA_KEY_SIGNATURE   = 0x11, /* No verification has been made */
  69     CASUAL_KEY_SIGNATURE    = 0x12, /* Some casual verification */
  70     POSITIVE_KEY_SIGNATURE  = 0x13  /* Substantial verification */
  71 };
  72
  73 enum    /* Signature subpacket types */
  74 {
  75     ISSUER_SUBPACKET    = 0x10
  76 };
  77
  78 struct public_key_packet_t
  79 { /* a public key packet (DSA/SHA-1) is 418 bytes */
  80
  81     uint8_t version;      /* we use only version 4 */
  82     uint8_t timestamp[4]; /* creation time of the key */
  83     uint8_t algo;         /* we only use DSA */
  84     /* the multi precision integers, with their 2 bytes length header */
  85     uint8_t p[2+128];
  86     uint8_t q[2+20];
  87     uint8_t g[2+128];
  88     uint8_t y[2+128];
  89 };
  90
  91 /* used for public key and file signatures */
  92 struct signature_packet_t
  93 {
  94     uint8_t version; /* 3 or 4 */
  95
  96     uint8_t type;
  97     uint8_t public_key_algo;    /* DSA only */
  98     uint8_t digest_algo;        /* SHA-1 only */
  99
 100     uint8_t hash_verification[2];
 101     uint8_t issuer_longid[8];
 102
 103     union   /* version specific data */
 104     {
 105         struct
 106         {
 107             uint8_t hashed_data_len[2];     /* scalar number */
 108             uint8_t *hashed_data;           /* hashed_data_len bytes */
 109             uint8_t unhashed_data_len[2];   /* scalar number */
 110             uint8_t *unhashed_data;         /* unhashed_data_len bytes */
 111         } v4;
 112         struct
 113         {
 114             uint8_t hashed_data_len;    /* MUST be 5 */
 115             uint8_t timestamp[4];       /* 4 bytes scalar number */
 116         } v3;
 117     } specific;
 118
 119 /* The part below is made of consecutive MPIs, their number and size being
 120  * public-key-algorithm dependent.
 121  *
 122  * Since we use DSA signatures only, there is 2 integers, r & s, made of:
 123  *      2 bytes for the integer length (scalar number)
 124  *      160 bits (20 bytes) for the integer itself
 125  *
 126  * Note: the integers may be less than 160 significant bits
 127  */
 128     uint8_t r[2+20];
 129     uint8_t s[2+20];
 130 };
 131
 132 typedef struct public_key_packet_t public_key_packet_t;
 133 typedef struct signature_packet_t signature_packet_t;
 134
 135 struct public_key_t
 136 {
 137     uint8_t longid[8];       /* Long id */
 138     uint8_t *psz_username;    /* USER ID */
 139
 140     public_key_packet_t key;       /* Public key packet */
 141
 142     signature_packet_t sig;     /* Signature packet, by the embedded key */
 143 };
 144
 145 typedef struct public_key_t public_key_t;
 146
 147 /**
 148  * Non blocking binary download
 149  */
 150 typedef struct
 151 {
 152     VLC_COMMON_MEMBERS
 153
 154     vlc_thread_t thread;
 155     update_t *p_update;
 156     char *psz_destdir;
 157 } update_download_thread_t;
 158
 159 /**
 160  * Non blocking update availability verification
 161  */
 162 typedef struct
 163 {
 164     vlc_thread_t thread;
 165
 166     update_t *p_update;
 167     void (*pf_callback)( void *, bool );
 168     void *p_data;
 169 } update_check_thread_t;
 170
 171 /**
 172  * The update object. Stores (and caches) all information relative to updates
 173  */
 174 struct update_t
 175 {
 176     libvlc_int_t *p_libvlc;
 177     vlc_mutex_t lock;
 178     struct update_release_t release;    ///< Release (version)
 179     public_key_t *p_pkey;
 180     update_download_thread_t *p_download;
 181     update_check_thread_t *p_check;
 182 };
 183
 184 /*
 185  * download a public key (the last one) from videolan server, and parse it
 186  */
 187 public_key_t *
 188 download_key(
 189         vlc_object_t *p_this, const uint8_t *p_longid,
 190         const uint8_t *p_signature_issuer );
 191
 192 /*
 193  * fill a public_key_t with public key data, including:
 194  *   * public key packet
 195  *   * signature packet issued by key which long id is p_sig_issuer
 196  *   * user id packet
 197  */
 198 int
 199 parse_public_key(
 200         const uint8_t *p_key_data, size_t i_key_len, public_key_t *p_key,
 201         const uint8_t *p_sig_issuer );
 202
 203 /*
 204  * Verify an OpenPGP signature made on some SHA-1 hash, with some DSA public key
 205  */
 206 int
 207 verify_signature(
 208         uint8_t *p_r, uint8_t *p_s, public_key_packet_t *p_key,
 209         uint8_t *p_hash );
 210
 211 /*
 212  * Download the signature associated to a document or a binary file.
 213  * We're given the file's url, we just append ".asc" to it and download
 214  */
 215 int
 216 download_signature(
 217         vlc_object_t *p_this, signature_packet_t *p_sig, const char *psz_url );
 218
 219 /*
 220  * return a sha1 hash of a text
 221  */
 222 uint8_t *
 223 hash_sha1_from_text(
 224         const char *psz_text, signature_packet_t *p_sig );
 225
 226 /*
 227  * return a sha1 hash of a file
 228  */
 229 uint8_t *
 230 hash_sha1_from_file(
 231         const char *psz_file, signature_packet_t *p_sig );
 232
 233 /*
 234  * return a sha1 hash of a public key
 235  */
 236 uint8_t *
 237 hash_sha1_from_public_key( public_key_t *p_pkey );
 238