1 files changed, 38 insertions, 0 deletions
diff --git a/libkeccak_hmac_copy.c b/libkeccak_hmac_copy.c
new file mode 100644
index 0000000..49fc1e7
--- /dev/null
+++ b/libkeccak_hmac_copy.c
@@ -0,0 +1,38 @@
+/* See LICENSE file for copyright and license details. */
+#include "common.h"
+
+
+/**
+ * Make a copy of an HMAC hashing-state
+ * 
+ * @param   dest  The slot for the duplicate, must not be initialised (memory leak otherwise)
+ * @param   src   The state to duplicate
+ * @return        Zero on success, -1 on error
+ */
+int
+libkeccak_hmac_copy(libkeccak_hmac_state_t *restrict dest, const libkeccak_hmac_state_t *restrict src)
+{
+	size_t size;
+
+	dest->key_opad = NULL;
+	dest->key_ipad = NULL;
+
+	if (libkeccak_state_copy(&dest->sponge, &src->sponge) < 0)
+		return -1;
+
+	dest->key_length = src->key_length;
+	dest->leftover = src->leftover;
+
+	size = (src->key_length + 7) >> 3;
+	dest->key_opad = malloc(2 * size);
+	if (dest->key_opad == NULL) {
+		libkeccak_state_destroy(&dest->sponge);
+		return -1;
+	}
+	dest->key_ipad = dest->key_opad + size / sizeof(char);
+
+	memcpy(dest->key_opad, src->key_opad, size);
+	memcpy(dest->key_ipad, src->key_ipad, size);
+
+	return 0;
+}