1 files changed, 16 insertions, 1 deletions

diff --git a/src/lib/libcrypto/chacha/chacha.c b/src/lib/libcrypto/chacha/chacha.c
index a12c824fe6..141b3e99f6 100644
--- a/src/lib/libcrypto/chacha/chacha.c
+++ b/src/lib/libcrypto/chacha/chacha.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: chacha.c,v 1.4 2014/06/12 15:49:28 deraadt Exp $ */
+/* $OpenBSD: chacha.c,v 1.5 2014/06/24 18:12:09 jsing Exp $ */
 /*
  * Copyright (c) 2014 Joel Sing <jsing@openbsd.org>
  *
@@ -22,6 +22,7 @@ void
 ChaCha_set_key(ChaCha_ctx *ctx, const unsigned char *key, uint32_t keybits)
 {
         chacha_keysetup((chacha_ctx *)ctx, key, keybits);
+        ctx->unused = 0;
 }
 
 void
@@ -29,11 +30,25 @@ ChaCha_set_iv(ChaCha_ctx *ctx, const unsigned char *iv,
     const unsigned char *counter)
 {
         chacha_ivsetup((chacha_ctx *)ctx, iv, counter);
+        ctx->unused = 0;
 }
 
 void
 ChaCha(ChaCha_ctx *ctx, unsigned char *out, const unsigned char *in, size_t len)
 {
+        unsigned char *k;
+        int i, l;
+
+        /* Consume remaining keystream, if any exists. */
+        if (ctx->unused > 0) {
+                k = ctx->ks + 64 - ctx->unused;
+                l = (len > ctx->unused) ? ctx->unused : len;
+                for (i = 0; i < l; i++)
+                        *(out++) = *(in++) ^ *(k++);
+                ctx->unused -= l;
+                len -= l;
+        }
+
         chacha_encrypt_bytes((chacha_ctx *)ctx, in, out, (uint32_t)len);
 }