gpg: Unify AEAD parameter retrieval.

* g10/pkclist.c (select_aead_from_pklist): Return the AEAD_algo.
* g10/encrypt.c (use_aead): Return the AEAD algo.
(encrypt_simple): Adjust for this change.
(encrypt_crypt): Ditto.
(encrypt_filter): Ditto.
* g10/sign.c (sign_symencrypt_file): Ditto.

* g10/misc.c (MY_GCRY_CIPHER_MODE_EAX): New.
(openpgp_aead_algo_info): New.
* g10/cipher-aead.c (MY_GCRY_CIPHER_MODE_EAX): Remove.
(write_header): Use new fucntion.
* g10/decrypt-data.c (MY_GCRY_CIPHER_MODE_EAX): Remove.
(decrypt_data): Use new function.  Also allow for chunkbytes other
than 10.
--

Note that other chunk bytes than 10 and in particular 0 (64 byte
chunks) have not yet been tested.

Signed-off-by: Werner Koch <[email protected]>

8 files changed, 63 insertions, 66 deletions

diff --git a/g10/cipher-aead.c b/g10/cipher-aead.c
index 1d7263419..637bd71a7 100644
--- a/g10/cipher-aead.c
+++ b/g10/cipher-aead.c
@@ -33,10 +33,6 @@
 #include "options.h"
 #include "main.h"
 
-/* FIXME: Libgcrypt 1.9 will support EAX.  Until we kame this a
- * requirement we hardwire the enum used for EAX.  */
-#define MY_GCRY_CIPHER_MODE_EAX 14
-
 
 /* The size of the buffer we allocate to encrypt the data.  This must
  * be a multiple of the OCB blocksize (16 byte).  */
@@ -149,23 +145,9 @@ write_header (cipher_filter_context_t *cfx, iobuf_t a)
   if (blocksize != 16 )
     log_fatal ("unsupported blocksize %u for AEAD\n", blocksize);
 
-  switch (cfx->dek->use_aead)
-    {
-    case AEAD_ALGO_OCB:
-      ciphermode = GCRY_CIPHER_MODE_OCB;
-      startivlen = 15;
-      break;
-
-    case AEAD_ALGO_EAX:
-      ciphermode = MY_GCRY_CIPHER_MODE_EAX;
-      startivlen = 16;
-      break;
-
-    default:
-      log_error ("unsupported AEAD algo %d\n", cfx->dek->use_aead);
-      err = gpg_error (GPG_ERR_NOT_IMPLEMENTED);
-      goto leave;
-    }
+  err = openpgp_aead_algo_info (cfx->dek->use_aead, &ciphermode, &startivlen);
+  if (err)
+    goto leave;
 
   cfx->chunkbyte = 10;
   cfx->chunksize = (uint64_t)1 << (cfx->chunkbyte + 6);
diff --git a/g10/decrypt-data.c b/g10/decrypt-data.c
index 79e255480..7ed0bf006 100644
--- a/g10/decrypt-data.c
+++ b/g10/decrypt-data.c
@@ -31,10 +31,6 @@
 #include "../common/status.h"
 #include "../common/compliance.h"
 
-/* FIXME: Libgcrypt 1.9 will support EAX.  Until we kame this a
- * requirement we hardwire the enum used for EAX.  */
-#define MY_GCRY_CIPHER_MODE_EAX 14
-
 
 static int aead_decode_filter (void *opaque, int control, iobuf_t a,
                                byte *buf, size_t *ret_len);
@@ -274,28 +270,15 @@ decrypt_data (ctrl_t ctrl, void *procctx, PKT_encrypted *ed, DEK *dek)
           goto leave;
         }
 
-      switch (ed->aead_algo)
-        {
-        case AEAD_ALGO_OCB:
-          startivlen = 15;
-          ciphermode = GCRY_CIPHER_MODE_OCB;
-          break;
-        case AEAD_ALGO_EAX:
-          startivlen = 16;
-          ciphermode = MY_GCRY_CIPHER_MODE_EAX;
-          break;
-        default:
-          log_error ("unknown AEAD algo %d\n", ed->aead_algo);
-          rc = gpg_error (GPG_ERR_INV_CIPHER_MODE);
-          goto leave;
-        }
+      rc = openpgp_aead_algo_info (ed->aead_algo, &ciphermode, &startivlen);
+      if (rc)
+        goto leave;
       log_assert (startivlen <= sizeof dfx->startiv);
 
-      if (ed->chunkbyte != 10)
+      if (ed->chunkbyte > 56)
         {
-          /* FIXME */
-          log_error ("unsupported chunkbyte %u\n", ed->chunkbyte);
-          rc = gpg_error (GPG_ERR_NOT_IMPLEMENTED);
+          log_error ("invalid AEAD chunkbyte %u\n", ed->chunkbyte);
+          rc = gpg_error (GPG_ERR_INV_PACKET);
           goto leave;
         }
 
diff --git a/g10/encrypt.c b/g10/encrypt.c
index ab745cee8..4cc4b1a29 100644
--- a/g10/encrypt.c
+++ b/g10/encrypt.c
@@ -139,8 +139,9 @@ encrypt_seskey (DEK *dek, DEK **r_seskey, void **r_enckey, size_t *r_enckeylen)
 }
 
 
-/* Return true if we shall use AEAD mode.  */
-int
+/* Return the AEAD algo if we shall use AEAD mode.  Returns 0 if AEAD
+ * shall not be used.  */
+aead_algo_t
 use_aead (pk_list_t pk_list, int algo)
 {
   int can_use;
@@ -168,7 +169,7 @@ use_aead (pk_list_t pk_list, int algo)
                     openpgp_cipher_algo_name (algo));
           return 0;
         }
-      return 1;
+      return default_aead_algo ();
     }
 
   /* AEAD does only work with 128 bit cipher blocklength.  */
@@ -176,10 +177,7 @@ use_aead (pk_list_t pk_list, int algo)
     return 0;
 
   /* If all keys support AEAD we can use it.  */
-  if (select_aead_from_pklist (pk_list))
-    return 1;
-
-  return 0; /* No AEAD. */
+  return select_aead_from_pklist (pk_list);
 }
 
 
@@ -328,7 +326,7 @@ encrypt_simple (const char *filename, int mode, int use_seskey)
         }
 
       /* See whether we want to use AEAD.  */
-      aead_algo = use_aead (NULL, cfx.dek->algo)? default_aead_algo () : 0;
+      aead_algo = use_aead (NULL, cfx.dek->algo);
 
       if ( use_seskey )
         {
@@ -784,9 +782,8 @@ encrypt_crypt (ctrl_t ctrl, int filefd, const char *filename,
                           gnupg_status_compliance_flag (CO_DE_VS),
                           NULL);
 
-  if (use_aead (pk_list, cfx.dek->algo))
-    cfx.dek->use_aead = 1;
-  else
+  cfx.dek->use_aead = use_aead (pk_list, cfx.dek->algo);
+  if (!cfx.dek->use_aead)
     cfx.dek->use_mdc = !!use_mdc (pk_list, cfx.dek->algo);
 
   /* Only do the is-file-already-compressed check if we are using a
@@ -1002,9 +999,8 @@ encrypt_filter (void *opaque, int control,
 	      efx->cfx.dek->algo = opt.def_cipher_algo;
 	    }
 
-          if (use_aead (efx->pk_list, efx->cfx.dek->algo))
-            efx->cfx.dek->use_aead = 1;
-          else
+          efx->cfx.dek->use_aead = use_aead (efx->pk_list, efx->cfx.dek->algo);
+          if (!efx->cfx.dek->use_aead)
             efx->cfx.dek->use_mdc = !!use_mdc (efx->pk_list,efx->cfx.dek->algo);
 
           make_session_key ( efx->cfx.dek );
diff --git a/g10/keydb.h b/g10/keydb.h
index 9f6064b41..f2ea8a7d2 100644
--- a/g10/keydb.h
+++ b/g10/keydb.h
@@ -232,7 +232,7 @@ int  algo_available( preftype_t preftype, int algo,
 int  select_algo_from_prefs( PK_LIST pk_list, int preftype,
 			     int request, const union pref_hint *hint);
 int  select_mdc_from_pklist (PK_LIST pk_list);
-int  select_aead_from_pklist (pk_list_t pk_list);
+aead_algo_t select_aead_from_pklist (pk_list_t pk_list);
 void warn_missing_mdc_from_pklist (PK_LIST pk_list);
 void warn_missing_aes_from_pklist (PK_LIST pk_list);
 
diff --git a/g10/main.h b/g10/main.h
index 509126c65..96899acf5 100644
--- a/g10/main.h
+++ b/g10/main.h
@@ -127,6 +127,9 @@ const char *openpgp_cipher_algo_name (cipher_algo_t algo);
 
 gpg_error_t openpgp_aead_test_algo (aead_algo_t algo);
 const char *openpgp_aead_algo_name (aead_algo_t algo);
+gpg_error_t openpgp_aead_algo_info (aead_algo_t algo,
+                                    enum gcry_cipher_modes *r_mode,
+                                    unsigned int *r_noncelen);
 
 pubkey_algo_t map_pk_gcry_to_openpgp (enum gcry_pk_algos algo);
 int openpgp_pk_test_algo (pubkey_algo_t algo);
@@ -234,7 +237,7 @@ void display_online_help( const char *keyword );
 int setup_symkey (STRING2KEY **symkey_s2k,DEK **symkey_dek);
 gpg_error_t encrypt_seskey (DEK *dek, DEK **r_seskey,
                             void **r_enckey, size_t *r_enckeylen);
-int use_aead (pk_list_t pk_list, int algo);
+aead_algo_t use_aead (pk_list_t pk_list, int algo);
 int use_mdc (pk_list_t pk_list,int algo);
 int encrypt_symmetric (const char *filename );
 int encrypt_store (const char *filename );
diff --git a/g10/misc.c b/g10/misc.c
index f7ac3c708..36d3bdc36 100644
--- a/g10/misc.c
+++ b/g10/misc.c
@@ -70,6 +70,11 @@
 #include "../common/zb32.h"
 
 
+/* FIXME: Libgcrypt 1.9 will support EAX.  Until we kame this a
+ * requirement we hardwire the enum used for EAX.  */
+#define MY_GCRY_CIPHER_MODE_EAX 14
+
+
 #ifdef ENABLE_SELINUX_HACKS
 /* A object and a global variable to keep track of files marked as
    secured. */
@@ -616,6 +621,34 @@ openpgp_aead_algo_name (aead_algo_t algo)
 }
 
 
+/* Return information for the AEAD algorithm ALGO.  The corresponding
+ * Libgcrypt ciphermode is stored at R_MODE and the required number of
+ * octets for the nonce at R_NONCELEN.  On error and error code is
+ * returned.  Note that the taglen is always 128 bits.  */
+gpg_error_t
+openpgp_aead_algo_info (aead_algo_t algo, enum gcry_cipher_modes *r_mode,
+                        unsigned int *r_noncelen)
+{
+  switch (algo)
+    {
+    case AEAD_ALGO_OCB:
+      *r_mode = GCRY_CIPHER_MODE_OCB;
+      *r_noncelen = 15;
+      break;
+
+    case AEAD_ALGO_EAX:
+      *r_mode = MY_GCRY_CIPHER_MODE_EAX;
+      *r_noncelen = 16;
+      break;
+
+    default:
+      log_error ("unsupported AEAD algo %d\n", algo);
+      return gpg_error (GPG_ERR_INV_CIPHER_MODE);
+    }
+  return 0;
+}
+
+
 /* Return 0 if ALGO is a supported OpenPGP public key algorithm.  */
 int
 openpgp_pk_test_algo (pubkey_algo_t algo)
diff --git a/g10/pkclist.c b/g10/pkclist.c
index b85efa4cd..6ec5537f5 100644
--- a/g10/pkclist.c
+++ b/g10/pkclist.c
@@ -1652,8 +1652,9 @@ select_mdc_from_pklist (PK_LIST pk_list)
 
 
 /* Select the AEAD flag from the pk_list.  We can only use AEAD if all
- * recipients support this feature.  Returns true if AEAD can be used.  */
-int
+ * recipients support this feature.  Returns the AEAD to be used or 0
+ * if AEAD shall not be used.  */
+aead_algo_t
 select_aead_from_pklist (PK_LIST pk_list)
 {
   pk_list_t pkr;
@@ -1672,7 +1673,7 @@ select_aead_from_pklist (PK_LIST pk_list)
         return 0;  /* At least one recipient does not support it. */
     }
 
-  return 1; /* Can be used. */
+  return default_aead_algo (); /* Yes, AEAD can be used. */
 }
 
 
diff --git a/g10/sign.c b/g10/sign.c
index 051ab594d..7045e8cad 100644
--- a/g10/sign.c
+++ b/g10/sign.c
@@ -1337,9 +1337,8 @@ sign_symencrypt_file (ctrl_t ctrl, const char *fname, strlist_t locusr)
         goto leave;
     }
 
-    if (use_aead (NULL, cfx.dek->algo))
-      cfx.dek->use_aead = 1;
-    else
+    cfx.dek->use_aead = use_aead (NULL, cfx.dek->algo);
+    if (!cfx.dek->use_aead)
       cfx.dek->use_mdc = !!use_mdc (NULL, cfx.dek->algo);
 
     /* now create the outfile */