Add HMAC and use void * instead of char * for binary data

Signed-off-by: Mattias Andrée <maandree@kth.se>

1 files changed, 37 insertions, 0 deletions

diff --git a/hmac_digest.c b/hmac_digest.c
new file mode 100644
index 0000000..caee756
--- /dev/null
+++ b/hmac_digest.c
@@ -0,0 +1,37 @@
+/* See LICENSE file for copyright and license details. */
+#include "common.h"
+
+
+/**
+ * Feed data into the HMAC algorithm and
+ * get the result
+ * 
+ * The state of the algorithm will be reset and
+ * `libsha2_hmac_update` and `libsha2_hmac_update`
+ * can be called again
+ * 
+ * @param   state   The state of the algorithm
+ * @param   data    Data to feed into the algorithm
+ * @param   n       The number of bytes to feed into the algorithm
+ * @param   output  The output buffer for the hash, it will be as
+ *                  large as for the underlaying hash algorithm
+ * @return          Zero on success, -1 on error
+ */
+int
+libsha2_hmac_digest(struct libsha2_hmac_state *restrict state, const void *data, size_t n, void *output)
+{
+	if (!state->inited) {
+		if (libsha2_init(&state->sha2_state, state->sha2_state.algorithm))
+			return -1;
+		libsha2_update(&state->sha2_state, state->ipad, state->sha2_state.chunk_size * 8);
+	}
+
+	libsha2_digest(&state->sha2_state, data, n, output);
+	if (libsha2_init(&state->sha2_state, state->sha2_state.algorithm))
+		return -1;
+
+	libsha2_update(&state->sha2_state, state->opad, state->sha2_state.chunk_size * 8);
+	libsha2_digest(&state->sha2_state, output, state->outsize, output);
+	state->inited = 0;
+	return 0;
+}