diff --git a/NEWS b/NEWS
index 0a76003d..33118413 100644
--- a/NEWS
+++ b/NEWS
@@ -4,9 +4,14 @@ Noteworthy changes in version 0.4.3 (unreleased)
  * gpgme_get_key fails with GPG_ERR_AMBIGUOUS_NAME if the key ID
    provided was not unique, instead returning the first matching key.
 
+ * gpgme_key_t and gpgme_subkey_t have a new field, can_authenticate,
+   that indicates if the key can be used for authentication.
+
  * Interface changes relative to the 0.4.3 release:
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 gpgme_get_key			CHANGED: Fails correctly if key ID not unique.
+gpgme_key_t			EXTENDED: New field can_authenticate.
+gpgme_subkey_t			EXTENDED: New field can_authenticate.
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 
diff --git a/doc/ChangeLog b/doc/ChangeLog
index 60336a8f..b06ffd72 100644
--- a/doc/ChangeLog
+++ b/doc/ChangeLog
@@ -1,5 +1,7 @@
 2003-07-31  Marcus Brinkmann  <marcus@g10code.de>
 
+	* gpgme.texi (Key Management): Add can_authenticate flag.
+
 	* gpgme.texi (Listing Keys): Document GPG_ERR_AMBIGUOUS_NAME for
 	gpgme_get_key.
 
diff --git a/doc/gpgme.texi b/doc/gpgme.texi
index 4a97e8de..018102b2 100644
--- a/doc/gpgme.texi
+++ b/doc/gpgme.texi
@@ -2023,6 +2023,9 @@ This is true if the subkey can be used to create data signatures.
 @item unsigned int can_certify : 1
 This is true if the subkey can be used to create key certificates.
 
+@item unsigned int can_authenticate : 1
+This is true if the subkey can be used for authentication.
+
 @item unsigned int secret : 1
 This is true if the subkey is a secret key.
 
@@ -2181,6 +2184,10 @@ data signatures.
 This is true if the key (ie one of its subkeys) can be used to create
 key certificates.
 
+@item unsigned int can_authenticate : 1
+This is true if the key (ie one of its subkeys) can be used for
+authentication.
+
 @item unsigned int secret : 1
 This is true if the key is a secret key.
 
diff --git a/gpgme/ChangeLog b/gpgme/ChangeLog
index 7108693f..eaa9b8a8 100644
--- a/gpgme/ChangeLog
+++ b/gpgme/ChangeLog
@@ -1,5 +1,11 @@
 2003-07-31  Marcus Brinkmann  <marcus@g10code.de>
 
+	* gpgme.h (struct _gpgme_subkey): Add flag CAN_AUTHENTICATE.
+	Lower _UNUSED to 23 bits.
+	(struct _gpgme_key): Likewise.
+	* keylist.c (set_mainkey_capability): Support 'a' and 'A'.
+	(set_subkey_capability): Support 'a'.
+
 	* keylist.c (gpgme_get_key): Check if there is more than one key
 	listed, and return GPG_ERR_AMBIGUOUS_NAME in that case.
 
diff --git a/gpgme/gpgme.h b/gpgme/gpgme.h
index 42b4ec2b..2320f900 100644
--- a/gpgme/gpgme.h
+++ b/gpgme/gpgme.h
@@ -421,8 +421,11 @@ struct _gpgme_subkey
   /* True if subkey is secret.  */
   unsigned int secret : 1;
 
+  /* True if subkey can be used for authentication.  */
+  unsigned int can_authenticate : 1;
+
   /* Internal to GPGME, do not use.  */
-  unsigned int _unused : 24;
+  unsigned int _unused : 23;
   
   /* Public key algorithm supported by this subkey.  */
   gpgme_pubkey_algo_t pubkey_algo;
@@ -572,8 +575,11 @@ struct _gpgme_key
   /* True if key is secret.  */
   unsigned int secret : 1;
 
+  /* True if key can be used for authentication.  */
+  unsigned int can_authenticate : 1;
+
   /* Internal to GPGME, do not use.  */
-  unsigned int _unused : 24;
+  unsigned int _unused : 23;
 
   /* This is the protocol supported by this key.  */
   gpgme_protocol_t protocol;
diff --git a/gpgme/keylist.c b/gpgme/keylist.c
index c47f3865..07c9385c 100644
--- a/gpgme/keylist.c
+++ b/gpgme/keylist.c
@@ -245,6 +245,10 @@ set_mainkey_capability (gpgme_key_t key, const char *src)
 	  key->subkeys->can_certify = 1;
 	  break;
 
+	case 'a':
+	  key->subkeys->can_authenticate = 1;
+	  break;
+
         case 'd':
         case 'D':
           /* Note, that this flag is also set using the key validity
@@ -266,6 +270,10 @@ set_mainkey_capability (gpgme_key_t key, const char *src)
 	case 'C':
 	  key->can_certify = 1;
 	  break;
+
+	case 'A':
+	  key->can_authenticate = 1;
+	  break;
         }
       src++;
     }
@@ -290,6 +298,10 @@ set_subkey_capability (gpgme_subkey_t subkey, const char *src)
 	case 'c':
 	  subkey->can_certify = 1;
 	  break;
+
+	case 'a':
+	  subkey->can_authenticate = 1;
+	  break;
         }
       src++;
     }