symm/keccak1600.c: Add new function to overwrite the state.

[catacomb] / symm / keccak1600.c

diff --git a/symm/keccak1600.c b/symm/keccak1600.c
index 499ab4f..c2d8292 100644 (file)
--- a/symm/keccak1600.c
+++ b/symm/keccak1600.c
@@ -589,6 +589,35 @@ void keccak1600_mix(keccak1600_state *s, const kludge64 *p, size_t n)
     { a = TO_LANE(p[i]); XOR_LANE(s->S[i], s->S[i], a); }
 }
 
+/* --- @keccak1600_set@ --- *
+ *
+ * Arguments:  @keccak1600_state *s@ = a state to update
+ *             @const kludge64 *p@ = pointer to 64-bit words to mix in
+ *             @size_t n@ = size of the input, in 64-bit words
+ *
+ * Returns:    ---
+ *
+ * Use:                Stores data into a %$\Keccak[r, 1600 - r]$% state.  Note that
+ *             it's the caller's responsibility to pass in no more than
+ *             %$r$% bits of data.
+ *
+ *             This is not the operation you wanted for ordinary hashing.
+ *             It's provided for the use of higher-level protocols which use
+ *             duplexing and other fancy sponge features.
+ */
+
+void keccak1600_set(keccak1600_state *s, const kludge64 *p, size_t n)
+{
+  uint32 m = COMPL_MASK;
+  unsigned i;
+  lane a;
+
+  for (i = 0; i < n; i++) {
+    a = TO_LANE(p[i]); if (m&1) NOT_LANE(a, a);
+    s->S[i] = a; m >>= 1;
+  }
+}
+
 /* --- @keccak1600_extract@ --- *
  *
  * Arguments:  @const keccak1600_state *s@ = a state to extract output from