1 files changed, 44 insertions, 0 deletions
diff --git a/libkeccak/sha3.h b/libkeccak/sha3.h
new file mode 100644
index 0000000..7d75ace
--- /dev/null
+++ b/libkeccak/sha3.h
@@ -0,0 +1,44 @@
+/* See LICENSE file for copyright and license details. */
+
+
+/**
+ * Message suffix for SHA3 hashing
+ */
+#define LIBKECCAK_SHA3_SUFFIX "01"
+
+
+/**
+ * Fill in a `struct libkeccak_spec` for a SHA3-x hashing
+ * 
+ * @param  spec  The specifications datastructure to fill in
+ * @param  x     The value of x in `SHA3-x`, the output size
+ */
+LIBKECCAK_GCC_ONLY(__attribute__((__nonnull__, __nothrow__)))
+inline void
+libkeccak_spec_sha3(struct libkeccak_spec *spec, long int x)
+{
+	spec->bitrate = 1600 - 2 * x;
+	spec->capacity = 2 * x;
+	spec->output = x;
+}
+
+
+/**
+ * Calculate the SHA3 hashsum of a file,
+ * the content of the file is assumed non-sensitive
+ * 
+ * @param   fd       The file descriptor of the file to hash
+ * @param   state    The hashing state, should not be initialised (memory leak otherwise)
+ * @param   output   The output size parameter for the hashing algorithm
+ * @param   hashsum  Output array for the hashsum, have an allocation size of
+ *                   at least `((output + 7) / 8) * sizeof(char)`, may be `NULL`
+ * @return           Zero on success, -1 on error
+ */
+LIBKECCAK_GCC_ONLY(__attribute__((__nonnull__(2), __artificial__)))
+inline int
+libkeccak_sha3sum_fd(int fd, struct libkeccak_state *restrict state, long output, void *restrict hashsum)
+{
+	struct libkeccak_spec spec;
+	libkeccak_spec_sha3(&spec, output);
+	return libkeccak_generalised_sum_fd(fd, state, &spec, LIBKECCAK_SHA3_SUFFIX, hashsum);
+}