LCOV - code coverage report
Current view: top level - sm - fingerprint.c (source / functions) Hit Total Coverage
Test: coverage.info Lines: 30 151 19.9 %
Date: 2016-09-12 13:01:59 Functions: 2 8 25.0 %

          Line data    Source code
       1             : /* fingerprint.c - Get the fingerprint
       2             :  *      Copyright (C) 2001 Free Software Foundation, Inc.
       3             :  *
       4             :  * This file is part of GnuPG.
       5             :  *
       6             :  * GnuPG is free software; you can redistribute it and/or modify
       7             :  * it under the terms of the GNU General Public License as published by
       8             :  * the Free Software Foundation; either version 3 of the License, or
       9             :  * (at your option) any later version.
      10             :  *
      11             :  * GnuPG is distributed in the hope that it will be useful,
      12             :  * but WITHOUT ANY WARRANTY; without even the implied warranty of
      13             :  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      14             :  * GNU General Public License for more details.
      15             :  *
      16             :  * You should have received a copy of the GNU General Public License
      17             :  * along with this program; if not, see <http://www.gnu.org/licenses/>.
      18             :  */
      19             : 
      20             : #include <config.h>
      21             : #include <stdio.h>
      22             : #include <stdlib.h>
      23             : #include <string.h>
      24             : #include <errno.h>
      25             : #include <unistd.h>
      26             : #include <time.h>
      27             : #include <assert.h>
      28             : 
      29             : 
      30             : #include "gpgsm.h"
      31             : #include <gcrypt.h>
      32             : #include <ksba.h>
      33             : 
      34             : #include "host2net.h"
      35             : 
      36             : 
      37             : /* Return the fingerprint of the certificate (we can't put this into
      38             :    libksba because we need libgcrypt support).  The caller must
      39             :    provide an array of sufficient length or NULL so that the function
      40             :    allocates the array.  If r_len is not NULL, the length of the
      41             :    digest is returned; well, this can also be done by using
      42             :    gcry_md_get_algo_dlen().  If algo is 0, a SHA-1 will be used.
      43             : 
      44             :    If there is a problem , the function does never return NULL but a
      45             :    digest of all 0xff.
      46             :  */
      47             : unsigned char *
      48           9 : gpgsm_get_fingerprint (ksba_cert_t cert, int algo,
      49             :                        unsigned char *array, int *r_len)
      50             : {
      51             :   gcry_md_hd_t md;
      52             :   int rc, len;
      53             : 
      54           9 :   if (!algo)
      55           3 :     algo = GCRY_MD_SHA1;
      56             : 
      57           9 :   len = gcry_md_get_algo_dlen (algo);
      58           9 :   assert (len);
      59           9 :   if (!array)
      60           0 :     array = xmalloc (len);
      61             : 
      62           9 :   if (r_len)
      63           0 :     *r_len = len;
      64             : 
      65             :   /* Fist check whether we have cached the fingerprint.  */
      66           9 :   if (algo == GCRY_MD_SHA1)
      67             :     {
      68             :       size_t buflen;
      69             : 
      70           9 :       assert (len >= 20);
      71           9 :       if (!ksba_cert_get_user_data (cert, "sha1-fingerprint",
      72             :                                     array, len, &buflen)
      73           6 :           && buflen == 20)
      74           6 :         return array;
      75             :     }
      76             : 
      77             :   /* No, need to compute it.  */
      78           3 :   rc = gcry_md_open (&md, algo, 0);
      79           3 :   if (rc)
      80             :     {
      81           0 :       log_error ("md_open failed: %s\n", gpg_strerror (rc));
      82           0 :       memset (array, 0xff, len); /* better return an invalid fpr than NULL */
      83           0 :       return array;
      84             :     }
      85             : 
      86           3 :   rc = ksba_cert_hash (cert, 0, HASH_FNC, md);
      87           3 :   if (rc)
      88             :     {
      89           0 :       log_error ("ksba_cert_hash failed: %s\n", gpg_strerror (rc));
      90           0 :       gcry_md_close (md);
      91           0 :       memset (array, 0xff, len); /* better return an invalid fpr than NULL */
      92           0 :       return array;
      93             :     }
      94           3 :   gcry_md_final (md);
      95           3 :   memcpy (array, gcry_md_read(md, algo), len );
      96           3 :   gcry_md_close (md);
      97             : 
      98             :   /* Cache an SHA-1 fingerprint.  */
      99           3 :   if ( algo == GCRY_MD_SHA1 )
     100           3 :     ksba_cert_set_user_data (cert, "sha1-fingerprint", array, 20);
     101             : 
     102           3 :   return array;
     103             : }
     104             : 
     105             : 
     106             : /* Return an allocated buffer with the formatted fingerprint */
     107             : char *
     108           0 : gpgsm_get_fingerprint_string (ksba_cert_t cert, int algo)
     109             : {
     110             :   unsigned char digest[MAX_DIGEST_LEN];
     111             :   char *buf;
     112             :   int len;
     113             : 
     114           0 :   if (!algo)
     115           0 :     algo = GCRY_MD_SHA1;
     116             : 
     117           0 :   len = gcry_md_get_algo_dlen (algo);
     118           0 :   assert (len <= MAX_DIGEST_LEN );
     119           0 :   gpgsm_get_fingerprint (cert, algo, digest, NULL);
     120           0 :   buf = xmalloc (len*3+1);
     121           0 :   bin2hexcolon (digest, len, buf);
     122           0 :   return buf;
     123             : }
     124             : 
     125             : /* Return an allocated buffer with the formatted fingerprint as one
     126             :    large hexnumber */
     127             : char *
     128           3 : gpgsm_get_fingerprint_hexstring (ksba_cert_t cert, int algo)
     129             : {
     130             :   unsigned char digest[MAX_DIGEST_LEN];
     131             :   char *buf;
     132             :   int len;
     133             : 
     134           3 :   if (!algo)
     135           0 :     algo = GCRY_MD_SHA1;
     136             : 
     137           3 :   len = gcry_md_get_algo_dlen (algo);
     138           3 :   assert (len <= MAX_DIGEST_LEN );
     139           3 :   gpgsm_get_fingerprint (cert, algo, digest, NULL);
     140           3 :   buf = xmalloc (len*2+1);
     141           3 :   bin2hex (digest, len, buf);
     142           3 :   return buf;
     143             : }
     144             : 
     145             : /* Return a certificate ID.  These are the last 4 bytes of the SHA-1
     146             :    fingerprint.  If R_HIGH is not NULL the next 4 bytes are stored
     147             :    there. */
     148             : unsigned long
     149           0 : gpgsm_get_short_fingerprint (ksba_cert_t cert, unsigned long *r_high)
     150             : {
     151             :   unsigned char digest[20];
     152             : 
     153           0 :   gpgsm_get_fingerprint (cert, GCRY_MD_SHA1, digest, NULL);
     154           0 :   if (r_high)
     155           0 :     *r_high = buf32_to_ulong (digest+12);
     156           0 :   return buf32_to_ulong (digest + 16);
     157             : }
     158             : 
     159             : 
     160             : /* Return the so called KEYGRIP which is the SHA-1 hash of the public
     161             :    key parameters expressed as an canoncial encoded S-Exp.  ARRAY must
     162             :    be 20 bytes long.  Returns ARRAY or a newly allocated buffer if ARRAY was
     163             :    given as NULL.  May return NULL on error.  */
     164             : unsigned char *
     165           0 : gpgsm_get_keygrip (ksba_cert_t cert, unsigned char *array)
     166             : {
     167             :   gcry_sexp_t s_pkey;
     168             :   int rc;
     169             :   ksba_sexp_t p;
     170             :   size_t n;
     171             : 
     172           0 :   p = ksba_cert_get_public_key (cert);
     173           0 :   if (!p)
     174           0 :     return NULL; /* oops */
     175             : 
     176           0 :   if (DBG_X509)
     177           0 :     log_debug ("get_keygrip for public key\n");
     178           0 :   n = gcry_sexp_canon_len (p, 0, NULL, NULL);
     179           0 :   if (!n)
     180             :     {
     181           0 :       log_error ("libksba did not return a proper S-Exp\n");
     182           0 :       return NULL;
     183             :     }
     184           0 :   rc = gcry_sexp_sscan ( &s_pkey, NULL, (char*)p, n);
     185           0 :   xfree (p);
     186           0 :   if (rc)
     187             :     {
     188           0 :       log_error ("gcry_sexp_scan failed: %s\n", gpg_strerror (rc));
     189           0 :       return NULL;
     190             :     }
     191           0 :   array = gcry_pk_get_keygrip (s_pkey, array);
     192           0 :   gcry_sexp_release (s_pkey);
     193           0 :   if (!array)
     194             :     {
     195           0 :       log_error ("can't calculate keygrip\n");
     196           0 :       return NULL;
     197             :     }
     198           0 :   if (DBG_X509)
     199           0 :     log_printhex ("keygrip=", array, 20);
     200             : 
     201           0 :   return array;
     202             : }
     203             : 
     204             : /* Return an allocated buffer with the keygrip of CERT encoded as a
     205             :    hexstring.  NULL is returned in case of error.  */
     206             : char *
     207           0 : gpgsm_get_keygrip_hexstring (ksba_cert_t cert)
     208             : {
     209             :   unsigned char grip[20];
     210             :   char *buf;
     211             : 
     212           0 :   if (!gpgsm_get_keygrip (cert, grip))
     213           0 :     return NULL;
     214           0 :   buf = xtrymalloc (20*2+1);
     215           0 :   if (buf)
     216           0 :     bin2hex (grip, 20, buf);
     217           0 :   return buf;
     218             : }
     219             : 
     220             : 
     221             : /* Return the PK algorithm used by CERT as well as the length in bits
     222             :    of the public key at NBITS. */
     223             : int
     224           0 : gpgsm_get_key_algo_info (ksba_cert_t cert, unsigned int *nbits)
     225             : {
     226             :   gcry_sexp_t s_pkey;
     227             :   int rc;
     228             :   ksba_sexp_t p;
     229             :   size_t n;
     230             :   gcry_sexp_t l1, l2;
     231             :   const char *name;
     232             :   char namebuf[128];
     233             : 
     234           0 :   if (nbits)
     235           0 :     *nbits = 0;
     236             : 
     237           0 :   p = ksba_cert_get_public_key (cert);
     238           0 :   if (!p)
     239           0 :     return 0;
     240           0 :   n = gcry_sexp_canon_len (p, 0, NULL, NULL);
     241           0 :   if (!n)
     242             :     {
     243           0 :       xfree (p);
     244           0 :       return 0;
     245             :     }
     246           0 :   rc = gcry_sexp_sscan (&s_pkey, NULL, (char *)p, n);
     247           0 :   xfree (p);
     248           0 :   if (rc)
     249           0 :     return 0;
     250             : 
     251           0 :   if (nbits)
     252           0 :     *nbits = gcry_pk_get_nbits (s_pkey);
     253             : 
     254             :   /* Breaking the algorithm out of the S-exp is a bit of a challenge ... */
     255           0 :   l1 = gcry_sexp_find_token (s_pkey, "public-key", 0);
     256           0 :   if (!l1)
     257             :     {
     258           0 :       gcry_sexp_release (s_pkey);
     259           0 :       return 0;
     260             :     }
     261           0 :   l2 = gcry_sexp_cadr (l1);
     262           0 :   gcry_sexp_release (l1);
     263           0 :   l1 = l2;
     264           0 :   name = gcry_sexp_nth_data (l1, 0, &n);
     265           0 :   if (name)
     266             :     {
     267           0 :       if (n > sizeof namebuf -1)
     268           0 :         n = sizeof namebuf -1;
     269           0 :       memcpy (namebuf, name, n);
     270           0 :       namebuf[n] = 0;
     271             :     }
     272             :   else
     273           0 :     *namebuf = 0;
     274           0 :   gcry_sexp_release (l1);
     275           0 :   gcry_sexp_release (s_pkey);
     276           0 :   return gcry_pk_map_name (namebuf);
     277             : }
     278             : 
     279             : 
     280             : 
     281             : 
     282             : /* For certain purposes we need a certificate id which has an upper
     283             :    limit of the size.  We use the hash of the issuer name and the
     284             :    serial number for this.  In most cases the serial number is not
     285             :    that large and the resulting string can be passed on an assuan
     286             :    command line.  Everything is hexencoded with the serialnumber
     287             :    delimited from the hash by a dot.
     288             : 
     289             :    The caller must free the string.
     290             : */
     291             : char *
     292           0 : gpgsm_get_certid (ksba_cert_t cert)
     293             : {
     294             :   ksba_sexp_t serial;
     295             :   char *p;
     296             :   char *endp;
     297             :   unsigned char hash[20];
     298             :   unsigned long n;
     299             :   char *certid;
     300             :   int i;
     301             : 
     302           0 :   p = ksba_cert_get_issuer (cert, 0);
     303           0 :   if (!p)
     304           0 :     return NULL; /* Ooops: No issuer */
     305           0 :   gcry_md_hash_buffer (GCRY_MD_SHA1, hash, p, strlen (p));
     306           0 :   xfree (p);
     307             : 
     308           0 :   serial = ksba_cert_get_serial (cert);
     309           0 :   if (!serial)
     310           0 :     return NULL; /* oops: no serial number */
     311           0 :   p = (char *)serial;
     312           0 :   if (*p != '(')
     313             :     {
     314           0 :       log_error ("Ooops: invalid serial number\n");
     315           0 :       xfree (serial);
     316           0 :       return NULL;
     317             :     }
     318           0 :   p++;
     319           0 :   n = strtoul (p, &endp, 10);
     320           0 :   p = endp;
     321           0 :   if (*p != ':')
     322             :     {
     323           0 :       log_error ("Ooops: invalid serial number (no colon)\n");
     324           0 :       xfree (serial);
     325           0 :       return NULL;
     326             :     }
     327           0 :   p++;
     328             : 
     329           0 :   certid = xtrymalloc ( 40 + 1 + n*2 + 1);
     330           0 :   if (!certid)
     331             :     {
     332           0 :       xfree (serial);
     333           0 :       return NULL; /* out of core */
     334             :     }
     335             : 
     336           0 :   for (i=0, endp = certid; i < 20; i++, endp += 2 )
     337           0 :     sprintf (endp, "%02X", hash[i]);
     338           0 :   *endp++ = '.';
     339           0 :   for (i=0; i < n; i++, endp += 2)
     340           0 :     sprintf (endp, "%02X", ((unsigned char*)p)[i]);
     341           0 :   *endp = 0;
     342             : 
     343           0 :   xfree (serial);
     344           0 :   return certid;
     345             : }

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