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/*
* Copyright (C) 2003 Philip Blundell <philb@gnu.org>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <glib.h>
#include "libdisplaymigration/auth.h"
#include "libdisplaymigration/crypt.h"
#define CHALLENGE_LEN 64
gchar *displaymigration_auth_challenge_string;
static unsigned char challenge_bytes[CHALLENGE_LEN];
static unsigned long challenge_seq;
#define hexbyte(x) ((x) >= 10 ? (x) + 'a' - 10 : (x) + '0')
void
displaymigration_auth_update_challenge (void)
{
int i;
unsigned char *p;
if (displaymigration_auth_challenge_string == NULL)
displaymigration_auth_challenge_string = g_malloc ((CHALLENGE_LEN * 2) + 9);
p = displaymigration_auth_challenge_string;
for (i = 0; i < CHALLENGE_LEN; i++)
{
*p++ = hexbyte (challenge_bytes[i] >> 4);
*p++ = hexbyte (challenge_bytes[i] & 15);
}
sprintf (p, "%08lx", challenge_seq++);
}
void
displaymigration_auth_generate_challenge (void)
{
gcry_randomize (challenge_bytes, sizeof (challenge_bytes), GCRY_STRONG_RANDOM);
displaymigration_auth_update_challenge ();
}
static struct rsa_key *
parse_pubkey (char *s)
{
struct rsa_key *r;
gcry_mpi_t n, e;
gchar *sp;
sp = strtok (s, " \n");
gcry_mpi_scan (&e, GCRYMPI_FMT_HEX, sp, 0, NULL);
sp = strtok (NULL, " \n");
gcry_mpi_scan (&n, GCRYMPI_FMT_HEX, sp, 0, NULL);
r = g_malloc0 (sizeof (struct rsa_key));
r->e = e;
r->n = n;
return r;
}
static struct rsa_key *
lookup_pubkey (u_int32_t id)
{
const gchar *home_dir = g_get_home_dir ();
gchar *filename = g_strdup_printf ("%s/.gpe/migrate/public", home_dir);
FILE *fp = fopen (filename, "r");
struct rsa_key *r = NULL;
if (fp)
{
while (!feof (fp))
{
char buffer[4096];
if (fgets (buffer, 4096, fp))
{
char *p;
u_int32_t this_id = strtoul (buffer, &p, 16);
if (p != buffer && *p == ' ')
{
#ifdef DEBUG
fprintf (stderr, "found id %x\n", this_id);
#endif
if (this_id == id)
{
r = parse_pubkey (++p);
break;
}
}
}
}
fclose (fp);
}
g_free (filename);
return r;
}
static void
free_pubkey (struct rsa_key *k)
{
gcry_mpi_release (k->n);
gcry_mpi_release (k->e);
g_free (k);
}
gboolean
displaymigration_auth_validate_request (char *display, char *data)
{
u_int32_t key_id;
char *ep;
char *p;
struct rsa_key *k;
char hash[20];
gboolean rc;
p = strchr (data, ' ');
if (p == NULL)
return FALSE;
*p++ = 0;
key_id = strtoul (data, &ep, 16);
if (*ep)
return FALSE;
k = lookup_pubkey (key_id);
if (k == NULL)
return FALSE;
displaymigration_crypt_create_hash (display, displaymigration_auth_challenge_string,
strlen (displaymigration_auth_challenge_string), hash);
rc = displaymigration_crypt_check_signature (k, hash, p);
free_pubkey (k);
return rc;
}
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