add support for xchacha20 and xchacha20-poly1305

xchacha is a chacha stream that allows for an extended nonce, which
in turn makes it feasible to use random nonces.

ok tb@

1 files changed, 11 insertions, 1 deletions

diff --git a/src/lib/libcrypto/chacha/chacha.c b/src/lib/libcrypto/chacha/chacha.c
index 0c384ab88a..6a2dddf055 100644
--- a/src/lib/libcrypto/chacha/chacha.c
+++ b/src/lib/libcrypto/chacha/chacha.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: chacha.c,v 1.7 2015/12/09 14:07:55 bcook Exp $ */
+/* $OpenBSD: chacha.c,v 1.8 2019/01/22 00:59:21 dlg Exp $ */
 /*
  * Copyright (c) 2014 Joel Sing <jsing@openbsd.org>
  *
@@ -75,3 +75,13 @@ CRYPTO_chacha_20(unsigned char *out, const unsigned char *in, size_t len,
 
         chacha_encrypt_bytes(&ctx, in, out, (uint32_t)len);
 }
+
+void
+CRYPTO_xchacha_20(unsigned char *out, const unsigned char *in, size_t len,
+    const unsigned char key[32], const unsigned char iv[24])
+{
+        uint8_t subkey[32];
+
+        CRYPTO_hchacha_20(subkey, key, iv);
+        CRYPTO_chacha_20(out, in, len, subkey, iv + 16, 0);
+}