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update_crypto.c
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/*****************************************************************************
* update_crypto.c: OpenPGP related functions used for updating
*****************************************************************************
* Copyright © 2008-2009 VLC authors and VideoLAN
* $Id$
*
* Authors: Rafaël Carré <funman@videolanorg>
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation; either release 2 of the License, or
* (at your option) any later release.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this program; if not, write to the Free Software Foundation,
* Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
*****************************************************************************/
/**
* \file
* This file contains functions related to OpenPGP in VLC update management
*/
/*****************************************************************************
* Preamble
*****************************************************************************/
#ifdef HAVE_CONFIG_H
# include "config.h"
#endif
#ifdef UPDATE_CHECK
#include <gcrypt.h>
#include <assert.h>
#include <limits.h>
#include "vlc_common.h"
#include <vlc_stream.h>
#include <vlc_strings.h>
#include <vlc_fs.h>
#include "update.h"
/*****************************************************************************
* OpenPGP functions
*****************************************************************************/
#define packet_type( c ) ( ( c & 0x3c ) >> 2 ) /* 0x3C = 00111100 */
#define packet_header_len( c ) ( ( c & 0x03 ) + 1 ) /* number of bytes in a packet header */
static inline int scalar_number( const uint8_t *p, int header_len )
{
assert( header_len == 1 || header_len == 2 || header_len == 4 );
if( header_len == 1 )
return( p[0] );
else if( header_len == 2 )
return( (p[0] << 8) + p[1] );
else if( header_len == 4 )
return( (p[0] << 24) + (p[1] << 16) + (p[2] << 8) + p[3] );
else
abort();
}
/* number of data bytes in a MPI */
static int mpi_len(const uint8_t *mpi)
{
return (scalar_number(mpi, 2) + 7) / 8;
}
static size_t read_mpi(uint8_t *dst, const uint8_t *buf, size_t buflen, size_t bits)
{
if (buflen < 2)
return 0;
size_t n = mpi_len(buf);
if (n * 8 > bits)
return 0;
n += 2;
if (buflen < n)
return 0;
memcpy(dst, buf, n);
return n;
}
#define READ_MPI(d, bits) do { \
size_t n = read_mpi(d, p_buf, i_packet_len - i_read, bits); \
if (!n) goto error; \
p_buf += n; \
i_read += n; \
} while(0)
/*
* fill a public_key_packet_t structure from public key packet data
* verify that it is a version 4 public key packet, using DSA or RSA
*/
static int parse_public_key_packet( public_key_packet_t *p_key,
const uint8_t *p_buf, size_t i_packet_len )
{
if( i_packet_len < 6 )
return VLC_EGENERIC;
size_t i_read = 0;
p_key->version = *p_buf++; i_read++;
if( p_key->version != 4 )
return VLC_EGENERIC;
/* XXX: warn when timestamp is > date ? */
memcpy( p_key->timestamp, p_buf, 4 ); p_buf += 4; i_read += 4;
p_key->algo = *p_buf++; i_read++;
if( p_key->algo == GCRY_PK_DSA ) {
READ_MPI(p_key->sig.dsa.p, 3072);
READ_MPI(p_key->sig.dsa.q, 256);
READ_MPI(p_key->sig.dsa.g, 3072);
READ_MPI(p_key->sig.dsa.y, 3072);
} else if ( p_key->algo == GCRY_PK_RSA ) {
READ_MPI(p_key->sig.rsa.n, 4096);
READ_MPI(p_key->sig.rsa.e, 4096);
} else
return VLC_EGENERIC;
if( i_read == i_packet_len )
return VLC_SUCCESS;
/* some extra data eh ? */
error:
return VLC_EGENERIC;
}
static size_t parse_signature_v3_packet( signature_packet_t *p_sig,
const uint8_t *p_buf, size_t i_sig_len )
{
size_t i_read = 1; /* we already read the version byte */
if( i_sig_len < 19 ) /* signature is at least 19 bytes + the 2 MPIs */
return 0;
p_sig->specific.v3.hashed_data_len = *p_buf++; i_read++;
if( p_sig->specific.v3.hashed_data_len != 5 )
return 0;
p_sig->type = *p_buf++; i_read++;
memcpy( p_sig->specific.v3.timestamp, p_buf, 4 );
p_buf += 4; i_read += 4;
memcpy( p_sig->issuer_longid, p_buf, 8 );
p_buf += 8; i_read += 8;
p_sig->public_key_algo = *p_buf++; i_read++;
p_sig->digest_algo = *p_buf++; i_read++;
p_sig->hash_verification[0] = *p_buf++; i_read++;
p_sig->hash_verification[1] = *p_buf++; i_read++;
assert( i_read == 19 );
return i_read;
}
/*
* fill a signature_packet_v4_t from signature packet data
* verify that it was used with a DSA or RSA public key
*/
static size_t parse_signature_v4_packet( signature_packet_t *p_sig,
const uint8_t *p_buf, size_t i_sig_len )
{
size_t i_read = 1; /* we already read the version byte */
if( i_sig_len < 10 ) /* signature is at least 10 bytes + the 2 MPIs */
return 0;
p_sig->type = *p_buf++; i_read++;
p_sig->public_key_algo = *p_buf++; i_read++;
if (p_sig->public_key_algo != GCRY_PK_DSA && p_sig->public_key_algo != GCRY_PK_RSA )
return 0;
p_sig->digest_algo = *p_buf++; i_read++;
memcpy( p_sig->specific.v4.hashed_data_len, p_buf, 2 );
p_buf += 2; i_read += 2;
size_t i_hashed_data_len =
scalar_number( p_sig->specific.v4.hashed_data_len, 2 );
i_read += i_hashed_data_len;
if( i_read + 4 > i_sig_len )
return 0;
p_sig->specific.v4.hashed_data = (uint8_t*) malloc( i_hashed_data_len );
if( !p_sig->specific.v4.hashed_data )
return 0;
memcpy( p_sig->specific.v4.hashed_data, p_buf, i_hashed_data_len );
p_buf += i_hashed_data_len;
memcpy( p_sig->specific.v4.unhashed_data_len, p_buf, 2 );
p_buf += 2; i_read += 2;
size_t i_unhashed_data_len =
scalar_number( p_sig->specific.v4.unhashed_data_len, 2 );
i_read += i_unhashed_data_len;
if( i_read + 2 > i_sig_len )
return 0;
p_sig->specific.v4.unhashed_data = (uint8_t*) malloc( i_unhashed_data_len );
if( !p_sig->specific.v4.unhashed_data )
return 0;
memcpy( p_sig->specific.v4.unhashed_data, p_buf, i_unhashed_data_len );
p_buf += i_unhashed_data_len;
memcpy( p_sig->hash_verification, p_buf, 2 );
p_buf += 2; i_read += 2;
uint8_t *p, *max_pos;
p = p_sig->specific.v4.unhashed_data;
max_pos = p + scalar_number( p_sig->specific.v4.unhashed_data_len, 2 );
for( ;; )
{
if( p > max_pos )
return 0;
size_t i_subpacket_len;
if( *p < 192 )
{
if( p + 1 > max_pos )
return 0;
i_subpacket_len = *p++;
}
else if( *p < 255 )
{
if( p + 2 > max_pos )
return 0;
i_subpacket_len = (*p++ - 192) << 8;
i_subpacket_len += *p++ + 192;
}
else
{
if( ++p + 4 > max_pos )
return 0;
i_subpacket_len = U32_AT(p);
p += 4;
}
if( *p == ISSUER_SUBPACKET )
{
if( p + 9 > max_pos )
return 0;
memcpy( &p_sig->issuer_longid, p+1, 8 );
return i_read;
}
p += i_subpacket_len;
}
}
static int parse_signature_packet( signature_packet_t *p_sig,
const uint8_t *p_buf, size_t i_packet_len )
{
if( !i_packet_len ) /* 1st sanity check, we need at least the version */
return VLC_EGENERIC;
p_sig->version = *p_buf++;
size_t i_read;
switch( p_sig->version )
{
case 3:
i_read = parse_signature_v3_packet( p_sig, p_buf, i_packet_len );
break;
case 4:
p_sig->specific.v4.hashed_data = NULL;
p_sig->specific.v4.unhashed_data = NULL;
i_read = parse_signature_v4_packet( p_sig, p_buf, i_packet_len );
break;
default:
return VLC_EGENERIC;
}
if( i_read == 0 ) /* signature packet parsing has failed */
goto error;
if( p_sig->public_key_algo != GCRY_PK_DSA && p_sig->public_key_algo != GCRY_PK_RSA )
goto error;
switch( p_sig->type )
{
case BINARY_SIGNATURE:
case TEXT_SIGNATURE:
case GENERIC_KEY_SIGNATURE:
case PERSONA_KEY_SIGNATURE:
case CASUAL_KEY_SIGNATURE:
case POSITIVE_KEY_SIGNATURE:
break;
default:
goto error;
}
p_buf--; /* rewind to the version byte */
p_buf += i_read;
if( p_sig->public_key_algo == GCRY_PK_DSA ) {
READ_MPI(p_sig->algo_specific.dsa.r, 256);
READ_MPI(p_sig->algo_specific.dsa.s, 256);
} else if ( p_sig->public_key_algo == GCRY_PK_RSA ) {
READ_MPI(p_sig->algo_specific.rsa.s, 4096);
} else
goto error;
assert( i_read == i_packet_len );
if( i_read < i_packet_len ) /* some extra data, hm ? */
goto error;
return VLC_SUCCESS;
error:
if( p_sig->version == 4 )
{
free( p_sig->specific.v4.hashed_data );
free( p_sig->specific.v4.unhashed_data );
}
return VLC_EGENERIC;
}
/*
* crc_octets() was lamely copied from rfc 2440
* Copyright (C) The Internet Society (1998). All Rights Reserved.
*/
#define CRC24_INIT 0xB704CEL
#define CRC24_POLY 0x1864CFBL
static long crc_octets( uint8_t *octets, size_t len )
{
long crc = CRC24_INIT;
int i;
while (len--)
{
crc ^= (*octets++) << 16;
for (i = 0; i < 8; i++)
{
crc <<= 1;
if (crc & 0x1000000)
crc ^= CRC24_POLY;
}
}
return crc & 0xFFFFFFL;
}
/*
* Transform an armored document in binary format
* Used on public keys and signatures
*/
static int pgp_unarmor( const char *p_ibuf, size_t i_ibuf_len,
uint8_t *p_obuf, size_t i_obuf_len )
{
const char *p_ipos = p_ibuf;
uint8_t *p_opos = p_obuf;
int i_end = 0;
int i_header_skipped = 0;
while( !i_end && p_ipos < p_ibuf + i_ibuf_len && *p_ipos != '=' )
{
if( *p_ipos == '\r' || *p_ipos == '\n' )
{
p_ipos++;
continue;
}
size_t i_line_len = strcspn( p_ipos, "\r\n" );
if( i_line_len == 0 )
continue;
if( !i_header_skipped )
{
if( !strncmp( p_ipos, "-----BEGIN PGP", 14 ) )
i_header_skipped = 1;
p_ipos += i_line_len + 1;
continue;
}
if( !strncmp( p_ipos, "Version:", 8 ) )
{
p_ipos += i_line_len + 1;
continue;
}
if( p_ipos[i_line_len - 1] == '=' )
{
i_end = 1;
}
p_opos += vlc_b64_decode_binary_to_buffer( p_opos,
p_obuf - p_opos + i_obuf_len, p_ipos );
p_ipos += i_line_len + 1;
}
/* XXX: the CRC is OPTIONAL, really require it ? */
if( p_ipos + 5 > p_ibuf + i_ibuf_len || *p_ipos++ != '=' )
return 0;
uint8_t p_crc[3];
if( vlc_b64_decode_binary_to_buffer( p_crc, 3, p_ipos ) != 3 )
return 0;
long l_crc = crc_octets( p_obuf, p_opos - p_obuf );
long l_crc2 = ( 0 << 24 ) + ( p_crc[0] << 16 ) + ( p_crc[1] << 8 ) + p_crc[2];
return l_crc2 == l_crc ? p_opos - p_obuf : 0;
}
static int rsa_pkcs1_encode_sig(gcry_mpi_t *r_result, size_t size,
const uint8_t *hash, int algo)
{
uint8_t asn[100];
uint8_t frame[4096/8];
size_t asnlen = sizeof(asn);
size_t hashlen = gcry_md_get_algo_dlen(algo);
if (gcry_md_algo_info(algo, GCRYCTL_GET_ASNOID, asn, &asnlen))
return VLC_EGENERIC;
if (!hashlen || hashlen + asnlen + 4 > size)
return VLC_EGENERIC;
frame[0] = 0;
frame[1] = 1; /* block type */
int pad = size - hashlen - asnlen - 3 ;
memset (&frame[2], 0xff, pad );
frame[2+pad] = 0;
memcpy(&frame[3+pad], asn, asnlen);
memcpy(&frame[3+pad+asnlen], hash, hashlen);
if (gcry_mpi_scan(r_result, GCRYMPI_FMT_USG, frame, size, &size))
return VLC_EGENERIC;
return VLC_SUCCESS;
}
/*
* Verify an OpenPGP signature made with some RSA public key
*/
static int verify_signature_rsa( signature_packet_t *sign, public_key_packet_t *p_key,
uint8_t *p_hash )
{
int ret = VLC_EGENERIC;
/* the data to be verified (a hash) */
const char *hash_sexp_s = "(data(flags raw)(value %m))";
/* the public key */
const char *key_sexp_s = "(public-key(rsa(n %m)(e %m)))";
/* the signature */
const char *sig_sexp_s = "(sig-val(rsa(s%m)))";
size_t erroff;
gcry_mpi_t n, e, s, hash;
n = e = s = hash = NULL;
gcry_sexp_t key_sexp, hash_sexp, sig_sexp;
key_sexp = hash_sexp = sig_sexp = NULL;
int i_n_len = mpi_len( p_key->sig.rsa.n );
int i_e_len = mpi_len( p_key->sig.rsa.e );
if( gcry_mpi_scan( &n, GCRYMPI_FMT_USG, p_key->sig.rsa.n + 2, i_n_len, NULL ) ||
gcry_mpi_scan( &e, GCRYMPI_FMT_USG, p_key->sig.rsa.e + 2, i_e_len, NULL ) ||
gcry_sexp_build( &key_sexp, &erroff, key_sexp_s, n, e ) )
goto out;
uint8_t *p_s = sign->algo_specific.rsa.s;
int i_s_len = mpi_len( p_s );
if( gcry_mpi_scan( &s, GCRYMPI_FMT_USG, p_s + 2, i_s_len, NULL ) ||
gcry_sexp_build( &sig_sexp, &erroff, sig_sexp_s, s ) )
goto out;
if( rsa_pkcs1_encode_sig (&hash, i_n_len, p_hash, sign->digest_algo) ||
gcry_sexp_build( &hash_sexp, &erroff, hash_sexp_s, hash ) )
goto out;
if( gcry_pk_verify( sig_sexp, hash_sexp, key_sexp ) )
goto out;
ret = VLC_SUCCESS;
out:
if( n ) gcry_mpi_release( n );
if( e ) gcry_mpi_release( e );
if( s ) gcry_mpi_release( s );
if( hash ) gcry_mpi_release( hash );
if( key_sexp ) gcry_sexp_release( key_sexp );
if( sig_sexp ) gcry_sexp_release( sig_sexp );
if( hash_sexp ) gcry_sexp_release( hash_sexp );
return ret;
}
/*
* Verify an OpenPGP signature made with some DSA public key
*/
static int verify_signature_dsa( signature_packet_t *sign, public_key_packet_t *p_key,
uint8_t *p_hash )
{
int ret = VLC_EGENERIC;
/* the data to be verified (a hash) */
const char *hash_sexp_s = "(data(flags raw)(value %m))";
/* the public key */
const char *key_sexp_s = "(public-key(dsa(p %m)(q %m)(g %m)(y %m)))";
/* the signature */
const char *sig_sexp_s = "(sig-val(dsa(r %m )(s %m )))";
size_t erroff;
gcry_mpi_t p, q, g, y, r, s, hash;
p = q = g = y = r = s = hash = NULL;
gcry_sexp_t key_sexp, hash_sexp, sig_sexp;
key_sexp = hash_sexp = sig_sexp = NULL;
int i_p_len = mpi_len( p_key->sig.dsa.p );
int i_q_len = mpi_len( p_key->sig.dsa.q );
int i_g_len = mpi_len( p_key->sig.dsa.g );
int i_y_len = mpi_len( p_key->sig.dsa.y );
if( gcry_mpi_scan( &p, GCRYMPI_FMT_USG, p_key->sig.dsa.p + 2, i_p_len, NULL ) ||
gcry_mpi_scan( &q, GCRYMPI_FMT_USG, p_key->sig.dsa.q + 2, i_q_len, NULL ) ||
gcry_mpi_scan( &g, GCRYMPI_FMT_USG, p_key->sig.dsa.g + 2, i_g_len, NULL ) ||
gcry_mpi_scan( &y, GCRYMPI_FMT_USG, p_key->sig.dsa.y + 2, i_y_len, NULL ) ||
gcry_sexp_build( &key_sexp, &erroff, key_sexp_s, p, q, g, y ) )
goto out;
uint8_t *p_r = sign->algo_specific.dsa.r;
uint8_t *p_s = sign->algo_specific.dsa.s;
int i_r_len = mpi_len( p_r );
int i_s_len = mpi_len( p_s );
if( gcry_mpi_scan( &r, GCRYMPI_FMT_USG, p_r + 2, i_r_len, NULL ) ||
gcry_mpi_scan( &s, GCRYMPI_FMT_USG, p_s + 2, i_s_len, NULL ) ||
gcry_sexp_build( &sig_sexp, &erroff, sig_sexp_s, r, s ) )
goto out;
int i_hash_len = gcry_md_get_algo_dlen (sign->digest_algo);
if (i_hash_len > i_q_len)
i_hash_len = i_q_len;
if( gcry_mpi_scan( &hash, GCRYMPI_FMT_USG, p_hash, i_hash_len, NULL ) ||
gcry_sexp_build( &hash_sexp, &erroff, hash_sexp_s, hash ) )
goto out;
if( gcry_pk_verify( sig_sexp, hash_sexp, key_sexp ) )
goto out;
ret = VLC_SUCCESS;
out:
if( p ) gcry_mpi_release( p );
if( q ) gcry_mpi_release( q );
if( g ) gcry_mpi_release( g );
if( y ) gcry_mpi_release( y );
if( r ) gcry_mpi_release( r );
if( s ) gcry_mpi_release( s );
if( hash ) gcry_mpi_release( hash );
if( key_sexp ) gcry_sexp_release( key_sexp );
if( sig_sexp ) gcry_sexp_release( sig_sexp );
if( hash_sexp ) gcry_sexp_release( hash_sexp );
return ret;
}
/*
* Verify an OpenPGP signature made with some public key
*/
int verify_signature( signature_packet_t *sign, public_key_packet_t *p_key,
uint8_t *p_hash )
{
if (sign->public_key_algo == GCRY_PK_DSA)
return verify_signature_dsa(sign, p_key, p_hash);
else if (sign->public_key_algo == GCRY_PK_RSA)
return verify_signature_rsa(sign, p_key, p_hash);
else
return VLC_EGENERIC;
}
/*
* fill a public_key_t with public key data, including:
* * public key packet
* * signature packet issued by key which long id is p_sig_issuer
* * user id packet
*/
int parse_public_key( const uint8_t *p_key_data, size_t i_key_len,
public_key_t *p_key, const uint8_t *p_sig_issuer )
{
const uint8_t *pos = p_key_data;
const uint8_t *max_pos = pos + i_key_len;
int i_status = 0;
#define PUBLIC_KEY_FOUND 0x01
#define USER_ID_FOUND 0x02
#define SIGNATURE_FOUND 0X04
uint8_t *p_key_unarmored = NULL;
p_key->psz_username = NULL;
p_key->sig.specific.v4.hashed_data = NULL;
p_key->sig.specific.v4.unhashed_data = NULL;
if( !( *pos & 0x80 ) )
{ /* first byte is ASCII, unarmoring */
p_key_unarmored = (uint8_t*)malloc( i_key_len );
if( !p_key_unarmored )
return VLC_ENOMEM;
int i_len = pgp_unarmor( (char*)p_key_data, i_key_len,
p_key_unarmored, i_key_len );
if( i_len == 0 )
goto error;
pos = p_key_unarmored;
max_pos = pos + i_len;
}
while( pos < max_pos )
{
if( !(*pos & 0x80) || *pos & 0x40 )
goto error;
int i_type = packet_type( *pos );
int i_header_len = packet_header_len( *pos++ );
if( pos + i_header_len > max_pos ||
( i_header_len != 1 && i_header_len != 2 && i_header_len != 4 ) )
goto error;
int i_packet_len = scalar_number( pos, i_header_len );
pos += i_header_len;
if( pos + i_packet_len > max_pos )
goto error;
switch( i_type )
{
case PUBLIC_KEY_PACKET:
i_status |= PUBLIC_KEY_FOUND;
if( parse_public_key_packet( &p_key->key, pos, i_packet_len ) != VLC_SUCCESS )
goto error;
break;
case SIGNATURE_PACKET: /* we accept only v4 signatures here */
if( i_status & SIGNATURE_FOUND || !p_sig_issuer )
break;
int i_ret = parse_signature_packet( &p_key->sig, pos,
i_packet_len );
if( i_ret == VLC_SUCCESS )
{
if( p_key->sig.version != 4 )
break;
if( memcmp( p_key->sig.issuer_longid, p_sig_issuer, 8 ) )
{
free( p_key->sig.specific.v4.hashed_data );
free( p_key->sig.specific.v4.unhashed_data );
p_key->sig.specific.v4.hashed_data = NULL;
p_key->sig.specific.v4.unhashed_data = NULL;
break;
}
i_status |= SIGNATURE_FOUND;
}
break;
case USER_ID_PACKET:
if( p_key->psz_username ) /* save only the first User ID */
break;
i_status |= USER_ID_FOUND;
p_key->psz_username = (uint8_t*)malloc( i_packet_len + 1);
if( !p_key->psz_username )
goto error;
memcpy( p_key->psz_username, pos, i_packet_len );
p_key->psz_username[i_packet_len] = '\0';
break;
default:
break;
}
pos += i_packet_len;
}
free( p_key_unarmored );
if( !( i_status & ( PUBLIC_KEY_FOUND | USER_ID_FOUND ) ) )
return VLC_EGENERIC;
if( p_sig_issuer && !( i_status & SIGNATURE_FOUND ) )
return VLC_EGENERIC;
return VLC_SUCCESS;
error:
if( p_key->sig.version == 4 )
{
free( p_key->sig.specific.v4.hashed_data );
free( p_key->sig.specific.v4.unhashed_data );
}
free( p_key->psz_username );
free( p_key_unarmored );
return VLC_EGENERIC;
}
/* hash a binary file */
static int hash_from_binary_file( const char *psz_file, gcry_md_hd_t hd )
{
uint8_t buffer[4096];
size_t i_read;
FILE *f = vlc_fopen( psz_file, "r" );
if( !f )
return -1;
while( ( i_read = fread( buffer, 1, sizeof(buffer), f ) ) > 0 )
gcry_md_write( hd, buffer, i_read );
fclose( f );
return 0;
}
/* final part of the hash */
static uint8_t *hash_finish( gcry_md_hd_t hd, signature_packet_t *p_sig )
{
if( p_sig->version == 3 )
{
gcry_md_putc( hd, p_sig->type );
gcry_md_write( hd, &p_sig->specific.v3.timestamp, 4 );
}
else if( p_sig->version == 4 )
{
gcry_md_putc( hd, p_sig->version );
gcry_md_putc( hd, p_sig->type );
gcry_md_putc( hd, p_sig->public_key_algo );
gcry_md_putc( hd, p_sig->digest_algo );
gcry_md_write( hd, p_sig->specific.v4.hashed_data_len, 2 );
size_t i_len = scalar_number( p_sig->specific.v4.hashed_data_len, 2 );
gcry_md_write( hd, p_sig->specific.v4.hashed_data, i_len );
gcry_md_putc( hd, 0x04 );
gcry_md_putc( hd, 0xFF );
i_len += 6; /* hashed data + 6 bytes header */
gcry_md_putc( hd, (i_len >> 24) & 0xff );
gcry_md_putc( hd, (i_len >> 16) & 0xff );
gcry_md_putc( hd, (i_len >> 8) & 0xff );
gcry_md_putc( hd, (i_len) & 0xff );
}
else
{ /* RFC 4880 only tells about versions 3 and 4 */
return NULL;
}
gcry_md_final( hd );
uint8_t *p_tmp = (uint8_t*) gcry_md_read( hd, p_sig->digest_algo) ;
unsigned int hash_len = gcry_md_get_algo_dlen (p_sig->digest_algo);
uint8_t *p_hash = malloc(hash_len);
if( p_hash )
memcpy(p_hash, p_tmp, hash_len);
gcry_md_close( hd );
return p_hash;
}
/*
* return a hash of a text
*/
uint8_t *hash_from_text( const char *psz_string,
signature_packet_t *p_sig )
{
gcry_md_hd_t hd;
if( gcry_md_open( &hd, p_sig->digest_algo, 0 ) )
return NULL;
if( p_sig->type == TEXT_SIGNATURE )
while( *psz_string )
{
size_t i_len = strcspn( psz_string, "\r\n" );
if( i_len )
{
gcry_md_write( hd, psz_string, i_len );
psz_string += i_len;
}
gcry_md_putc( hd, '\r' );
gcry_md_putc( hd, '\n' );
if( *psz_string == '\r' )
psz_string++;
if( *psz_string == '\n' )
psz_string++;
}
else
gcry_md_write( hd, psz_string, strlen( psz_string ) );
return hash_finish( hd, p_sig );
}
/*
* return a hash of a file
*/
uint8_t *hash_from_file( const char *psz_file, signature_packet_t *p_sig )
{
gcry_md_hd_t hd;
if( gcry_md_open( &hd, p_sig->digest_algo, 0 ) )
return NULL;
if( hash_from_binary_file( psz_file, hd ) < 0 )
{
gcry_md_close( hd );
return NULL;
}
return hash_finish( hd, p_sig );
}
/*
* Generate a hash on a public key, to verify a signature made on that hash
* Note that we need the signature (v4) to compute the hash
*/
uint8_t *hash_from_public_key( public_key_t *p_pkey )
{
const uint8_t pk_algo = p_pkey->key.algo;
size_t i_size;
size_t i_p_len, i_g_len, i_q_len, i_y_len;
size_t i_n_len, i_e_len;
if( p_pkey->sig.version != 4 )
return NULL;
if( p_pkey->sig.type < GENERIC_KEY_SIGNATURE ||
p_pkey->sig.type > POSITIVE_KEY_SIGNATURE )
return NULL;
gcry_error_t error = 0;
gcry_md_hd_t hd;
if (pk_algo == GCRY_PK_DSA) {
i_p_len = mpi_len( p_pkey->key.sig.dsa.p );
i_g_len = mpi_len( p_pkey->key.sig.dsa.g );
i_q_len = mpi_len( p_pkey->key.sig.dsa.q );
i_y_len = mpi_len( p_pkey->key.sig.dsa.y );
i_size = 6 + 2*4 + i_p_len + i_g_len + i_q_len + i_y_len;
} else if (pk_algo == GCRY_PK_RSA) {
i_n_len = mpi_len( p_pkey->key.sig.rsa.n );
i_e_len = mpi_len( p_pkey->key.sig.rsa.e );
i_size = 6 + 2*2 + i_n_len + i_e_len;
} else
return NULL;
error = gcry_md_open( &hd, p_pkey->sig.digest_algo, 0 );
if( error )
return NULL;
gcry_md_putc( hd, 0x99 );
gcry_md_putc( hd, (i_size >> 8) & 0xff );
gcry_md_putc( hd, i_size & 0xff );
gcry_md_putc( hd, p_pkey->key.version );
gcry_md_write( hd, p_pkey->key.timestamp, 4 );
gcry_md_putc( hd, p_pkey->key.algo );
if (pk_algo == GCRY_PK_DSA) {
gcry_md_write( hd, (uint8_t*)&p_pkey->key.sig.dsa.p, 2 + i_p_len );
gcry_md_write( hd, (uint8_t*)&p_pkey->key.sig.dsa.q, 2 + i_q_len );
gcry_md_write( hd, (uint8_t*)&p_pkey->key.sig.dsa.g, 2 + i_g_len );
gcry_md_write( hd, (uint8_t*)&p_pkey->key.sig.dsa.y, 2 + i_y_len );
} else if (pk_algo == GCRY_PK_RSA) {
gcry_md_write( hd, (uint8_t*)&p_pkey->key.sig.rsa.n, 2 + i_n_len );
gcry_md_write( hd, (uint8_t*)&p_pkey->key.sig.rsa.e, 2 + i_e_len );
}
gcry_md_putc( hd, 0xb4 );
size_t i_len = strlen((char*)p_pkey->psz_username);
gcry_md_putc( hd, (i_len >> 24) & 0xff );
gcry_md_putc( hd, (i_len >> 16) & 0xff );
gcry_md_putc( hd, (i_len >> 8) & 0xff );
gcry_md_putc( hd, (i_len) & 0xff );
gcry_md_write( hd, p_pkey->psz_username, i_len );
uint8_t *p_hash = hash_finish( hd, &p_pkey->sig );
if( !p_hash ||
p_hash[0] != p_pkey->sig.hash_verification[0] ||
p_hash[1] != p_pkey->sig.hash_verification[1] )
{
free(p_hash);
return NULL;
}
return p_hash;
}
/*
* download a public key (the last one) from videolan server, and parse it
*/
public_key_t *download_key( vlc_object_t *p_this,
const uint8_t *p_longid, const uint8_t *p_signature_issuer )
{
char *psz_url;
if( asprintf( &psz_url, "http://download.videolan.org/pub/keys/%.2X%.2X%.2X%.2X%.2X%.2X%.2X%.2X.asc",
p_longid[0], p_longid[1], p_longid[2], p_longid[3],
p_longid[4], p_longid[5], p_longid[6], p_longid[7] ) == -1 )
return NULL;
stream_t *p_stream = stream_UrlNew( p_this, psz_url );
free( psz_url );
if( !p_stream )
return NULL;
uint64_t i_size;
if( stream_GetSize( p_stream, &i_size ) || i_size > INT_MAX )
{
stream_Delete( p_stream );
return NULL;
}
uint8_t *p_buf = (uint8_t*)malloc( i_size );
if( !p_buf )
{
stream_Delete( p_stream );
return NULL;
}
int i_read = stream_Read( p_stream, p_buf, (int)i_size );
stream_Delete( p_stream );
if( i_read != (int)i_size )
{
msg_Dbg( p_this, "Couldn't read full GPG key" );
free( p_buf );
return NULL;
}
public_key_t *p_pkey = (public_key_t*) malloc( sizeof( public_key_t ) );
if( !p_pkey )
{
free( p_buf );
return NULL;
}
memcpy( p_pkey->longid, p_longid, 8 );
int i_error = parse_public_key( p_buf, i_read, p_pkey, p_signature_issuer );
free( p_buf );
if( i_error != VLC_SUCCESS )
{
msg_Dbg( p_this, "Couldn't parse GPG key" );
free( p_pkey );
return NULL;
}
return p_pkey;
}
/*
* Download the signature associated to a document or a binary file.
* We're given the file's url, we just append ".asc" to it and download
*/
int download_signature( vlc_object_t *p_this, signature_packet_t *p_sig,
const char *psz_url )
{
char *psz_sig = (char*) malloc( strlen( psz_url ) + 4 + 1 ); /* ".asc" + \0 */
if( !psz_sig )