ChaCha20-Poly1305 support.
diff --git a/crypto/chacha/chacha.h b/crypto/chacha/chacha.h
new file mode 100644
index 0000000..ce53d49
--- /dev/null
+++ b/crypto/chacha/chacha.h
@@ -0,0 +1,37 @@
+/* Copyright (c) 2014, Google Inc.
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
+ * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
+ * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
+ * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */
+
+#ifndef OPENSSL_HEADER_CHACHA_H
+#define OPENSSL_HEADER_CHACHA_H
+
+#include <openssl/base.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+
+/* CRYPTO_chacha_20 encrypts |in_len| bytes from |in| with the given key and
+ * nonce and writes the result to |out|, which may be equal to |in|. The
+ * initial block counter is specified by |counter|. */
+void CRYPTO_chacha_20(uint8_t *out, const uint8_t *in,
+ size_t in_len, const uint8_t key[32],
+ const uint8_t nonce[8], size_t counter);
+
+
+#if defined(__cplusplus)
+} /* extern C */
+#endif
+
+#endif /* OPENSSL_HEADER_CHACHA_H */
