allow a key to be created with a known prefix (so that we can debug

birthday paradox problems).

keyring.c

@@ -1298,12 +1298,23 @@ static int keyring_commit_identity(keyring_file *k, keyring_identity *id)
   return 1;
 }
 
+
+int keyring_key_prefix_mismatch(keypair *kp, const char *prefix)
+{
+  if (!prefix[0]) return 0;
+  char hex[5];
+  snprintf(hex,5,"%02x%02x",kp->public_key[0],kp->public_key[1]);
+  int r=strncasecmp(hex,prefix,strlen(prefix));
+  return r;
+}
+
 /* Create a new identity in the specified context (which supplies the keyring pin) with the
  * specified PKR pin.  The crypto_box and crypto_sign key pairs are automatically created, and the
  * PKR is packed and written to a hithero unallocated slot which is then marked full.  Requires an
  * explicit call to keyring_commit()
 */
-keyring_identity *keyring_create_identity(keyring_file *k, const char *pin)
+keyring_identity *keyring_create_identity(keyring_file *k, const char *pin,
+					  const char *prefix)
 {
   DEBUGF(keyring, "k=%p", k);
   /* Check obvious abort conditions early */
@@ -1326,14 +1337,28 @@ keyring_identity *keyring_create_identity(keyring_file *k, const char *pin)
     goto kci_safeexit;
   }
 
-  /* Allocate key pairs */
+  /* Allocate key pairs.
+     The prefix input allows rejection of keys until the public key matches a 
+     given prefix.  The prefix lenth is not allowed to be more than 16 bits to
+     prevent abuse and excessive compromising of security.
+   */
   unsigned ktype;
   for (ktype = 1; ktype < NELS(keytypes); ++ktype) {
     if (keytypes[ktype].creator) {
-      keypair *kp = keyring_alloc_keypair(ktype, 0);
+      keypair *kp = NULL;
+      while (kp==NULL) {
+	kp = keyring_alloc_keypair(ktype, 0);
+	if (kp == NULL)
+	  goto kci_safeexit;
+	keytypes[ktype].creator(kp);
+	if (kp->public_key&&
+	    keyring_key_prefix_mismatch(kp,prefix)) {
+	  keyring_free_keypair(kp);
+	  kp=NULL;
+	} 
+      }
       if (kp == NULL)
 	goto kci_safeexit;
-      keytypes[ktype].creator(kp);
       keyring_identity_add_keypair(id, kp);
     }
   }
@@ -1950,7 +1975,7 @@ int keyring_seed(keyring_file *k)
   /* nothing to do if there is already an identity */
   if (k->identities)
     return 0;
-  keyring_identity *id=keyring_create_identity(k,"");
+  keyring_identity *id=keyring_create_identity(k,"","");
   if (!id)
     return WHY("Could not create new identity");
   if (keyring_commit(k))

keyring.h

@@ -109,7 +109,8 @@ struct keypair *keyring_find_sas_private(keyring_file *k, keyring_identity *iden
 int keyring_send_sas_request(struct subscriber *subscriber);
 
 int keyring_commit(keyring_file *k);
-keyring_identity *keyring_create_identity(keyring_file *k, const char *pin);
+keyring_identity *keyring_create_identity(keyring_file *k, const char *pin,
+					  const char *prefix);
 int keyring_seed(keyring_file *k);
 void keyring_identity_extract(const keyring_identity *id, const sid_t **sidp, const char **didp, const char **namep);
 int keyring_load_from_dump(keyring_file *k, unsigned entry_pinc, const char **entry_pinv, FILE *input);

keyring_cli.c

@@ -226,18 +226,20 @@ static int app_keyring_list2(const struct cli_parsed *parsed, struct cli_context
 
 DEFINE_CMD(app_keyring_add, 0,
   "Create a new identity in the keyring protected by the supplied PIN (empty PIN if not given)",
-  "keyring","add" KEYRING_PIN_OPTIONS,"[<pin>]");
+	   "keyring","add" KEYRING_PIN_OPTIONS,"[<pin>]","[<prefix>]");
 static int app_keyring_add(const struct cli_parsed *parsed, struct cli_context *context)
 {
   DEBUG_cli_parsed(verbose, parsed);
   const char *pin;
   cli_arg(parsed, "pin", &pin, NULL, "");
+  const char *prefix;
+  cli_arg(parsed, "prefix", &prefix, NULL, "");
   keyring_file *k = keyring_open_instance_cli(parsed);
   if (!k)
     return -1;
   keyring_enter_pin(k, pin);
 
-  const keyring_identity *id = keyring_create_identity(k, pin);
+  const keyring_identity *id = keyring_create_identity(k, pin, prefix);
   if (id == NULL) {
     keyring_free(k);
     return WHY("Could not create new identity");

keyring_restful.c

@@ -211,7 +211,7 @@ static int restful_keyring_add(httpd_request *r, const char *remainder)
   if (*remainder)
     return 404;
   const char *pin = http_request_get_query_param(&r->http, "pin");
-  const keyring_identity *id = keyring_create_identity(keyring, pin ? pin : "");
+  const keyring_identity *id = keyring_create_identity(keyring, pin ? pin : "", "");
   if (id == NULL)
     return http_request_keyring_response(r, 500, "Could not create identity");
   if (keyring_commit(keyring) == -1)