gpg-agent with preset passphrase

[Andreas Hartmann]

Hello Richard,

the problem is, that the passphrase supplied with gpg-preset-passphrase is
stored native and not as a hexstring. I did the following changes in agent.c:




--- command.c.old       2005-07-27 16:18:13.000000000 +0200
+++ command.c   2005-09-01 14:30:46.000000000 +0200
@@ -807,7 +807,10 @@
   unsigned char grip[20];
   char *grip_clear = NULL;
   char *passphrase = NULL;
+  char *hexstring;
   int ttl;
+  int i;
+  unsigned char *p;

   if (!opt.allow_preset_passphrase)
     return gpg_error (GPG_ERR_NOT_SUPPORTED);
@@ -843,7 +846,18 @@
   else
     return map_to_assuan_status (gpg_error (GPG_ERR_NOT_IMPLEMENTED));

-  rc = agent_put_cache (grip_clear, CACHE_MODE_ANY, passphrase, ttl);
+  /* map passphrase to hexstring */
+  hexstring = gcry_malloc_secure(strlen ((char*)passphrase)*2+1);
+  if (!hexstring)
+    {
+      xfree (passphrase);
+      return map_to_assuan_status (gpg_error (GPG_ERR_MISSING_VALUE));
+    }
+
+  for (i=0, p=passphrase; *p; p++, i+=2)
+    sprintf(hexstring+i,"%02X",*p);
+
+  rc = agent_put_cache (grip_clear, CACHE_MODE_ANY, hexstring, ttl);

   if (rc)
     log_error ("command preset_passwd failed: %s\n", gpg_strerror (rc));



These changes are probably not the best way, but they are working. The
developpers do have a better solution for sure :-).



But now, I have a question: How is it possible to get the KEYGRIP? If I do
the following, I'm allways getting errors:

andreas at athlon:~ > gpg-protect-tool --show-keygrip tmp_key.pub
gpg-protect-tool: invalid S-Expression in `tmp_key.pub' (off=919): Bad
hexadecimal character in S-expression
andreas at athlon:~ > gpg-protect-tool --show-keygrip tmp_key.sec
gpg-protect-tool: invalid S-Expression in `tmp_key.sec' (off=1017):
Invalid length specifier in S-expression


Probably wrong file format of the keys?



Kind regards,
Andreas Hartmann