1 files changed, 52 insertions, 0 deletions

diff --git a/nacl/crypto_stream/salsa208/ref/xor.c b/nacl/crypto_stream/salsa208/ref/xor.c
new file mode 100644
index 00000000..c017ac42
--- /dev/null
+++ b/nacl/crypto_stream/salsa208/ref/xor.c
@@ -0,0 +1,52 @@
+/*
+version 20080913
+D. J. Bernstein
+Public domain.
+*/
+
+#include "crypto_core_salsa208.h"
+#include "crypto_stream.h"
+
+typedef unsigned int uint32;
+
+static const unsigned char sigma[16] = "expand 32-byte k";
+
+int crypto_stream_xor(
+        unsigned char *c,
+  const unsigned char *m,unsigned long long mlen,
+  const unsigned char *n,
+  const unsigned char *k
+)
+{
+  unsigned char in[16];
+  unsigned char block[64];
+  int i;
+  unsigned int u;
+
+  if (!mlen) return 0;
+
+  for (i = 0;i < 8;++i) in[i] = n[i];
+  for (i = 8;i < 16;++i) in[i] = 0;
+
+  while (mlen >= 64) {
+    crypto_core_salsa208(block,in,k,sigma);
+    for (i = 0;i < 64;++i) c[i] = m[i] ^ block[i];
+
+    u = 1;
+    for (i = 8;i < 16;++i) {
+      u += (unsigned int) in[i];
+      in[i] = u;
+      u >>= 8;
+    }
+
+    mlen -= 64;
+    c += 64;
+    m += 64;
+  }
+
+  if (mlen) {
+    crypto_core_salsa208(block,in,k,sigma);
+    for (i = 0;i < mlen;++i) c[i] = m[i] ^ block[i];
+  }
+  return 0;
+}