symm/* (aead): Implement the `szok' methods.

[catacomb] / symm / gaead.c

diff --git a/symm/gaead.c b/symm/gaead.c
index 45aeb61..d513069 100644 (file)
--- a/symm/gaead.c
+++ b/symm/gaead.c
@@ -31,6 +31,27 @@
 
 /*----- Main code ---------------------------------------------------------*/
 
+/* --- @gaead_szokcommon@ --- *
+ *
+ * Arguments:  @const gcaead *aec@ = pointer to AEAD class
+ *             @size_t nsz@, @size_t hsz@, @size_t msz@, @size_t tsz@ =
+ *                     nonce, header, message, and tag sizes
+ *
+ * Returns:    Nonzero if the sizes are acceptable to the AEAD scheme in
+ *             combination.
+ *
+ * Use:                Generic implementation for sensible AEAD schemes.
+ */
+
+int gaead_szokcommon(const gcaead *aec,
+                    size_t nsz, size_t hsz, size_t msz, size_t tsz)
+{
+  if (keysz(nsz, aec->noncesz) != nsz) return (0);
+  if (keysz(tsz, aec->tagsz) != tsz) return (0);
+  if (hsz && (aec->f&AEADF_NOAAD)) return (0);
+  return (1);
+}
+
 /* --- @gaead_encrypt@ --- *
  *
  * Arguments:  @const gaead_key *k@ = the AEAD key, already prepared