--- /dev/null
+#ifndef TESTS_ARC4_H
+#define TESTS_ARC4_H
+
+#include <stddef.h>
+#include <stdint.h>
+
+/* Alleged RC4 algorithm encryption state. */
+struct arc4
+ {
+ uint8_t s[256];
+ uint8_t i, j;
+ };
+
+void arc4_init (struct arc4 *, const void *, size_t);
+void arc4_crypt (struct arc4 *, void *, size_t);
+
+#endif /* tests/arc4.h */