1 files changed, 78 insertions, 0 deletions
diff --git a/g10/misc.c b/g10/misc.c
index 291d36f2d..22ed47e7c 100644
--- a/g10/misc.c
+++ b/g10/misc.c
@@ -70,6 +70,10 @@
 #include "../common/i18n.h"
 #include "../common/zb32.h"
 
+/* FIXME: Libgcrypt 1.9 will support EAX.  Until we name 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
@@ -602,6 +606,80 @@ openpgp_cipher_algo_name (cipher_algo_t algo)
 }
 
 
+/* Return 0 if ALGO is supported.  Return an error if not. */
+gpg_error_t
+openpgp_aead_test_algo (aead_algo_t algo)
+{
+  /* FIXME: We currently have no easy way to test whether libgcrypt
+   * implements a mode.  The only way we can do this is to open a
+   * cipher context with that mode and close it immediately.  That is
+   * a bit costly.  So we look at the libgcrypt version and assume
+   * nothing has been patched out.  */
+  switch (algo)
+    {
+    case AEAD_ALGO_NONE:
+      break;
+
+    case AEAD_ALGO_EAX:
+#if GCRYPT_VERSION_NUMBER < 0x010900
+      break;
+#else
+      return 0;
+#endif
+
+    case AEAD_ALGO_OCB:
+      return 0;
+    }
+
+  return gpg_error (GPG_ERR_INV_CIPHER_MODE);
+}
+
+
+/* Map the OpenPGP AEAD algorithm with ID ALGO to a string
+ * representation of the algorithm name.  For unknown algorithm IDs
+ * this function returns "?".  */
+const char *
+openpgp_aead_algo_name (aead_algo_t algo)
+{
+  switch (algo)
+    {
+    case AEAD_ALGO_NONE:  break;
+    case AEAD_ALGO_EAX:   return "EAX";
+    case AEAD_ALGO_OCB:   return "OCB";
+    }
+
+  return "?";
+}
+
+
+/* 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)