--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/libtomcrypt/src/stream/rc4/rc4_stream.c	Fri Feb 09 21:44:05 2018 +0800
@@ -0,0 +1,111 @@
+/* LibTomCrypt, modular cryptographic library -- Tom St Denis
+ *
+ * LibTomCrypt is a library that provides various cryptographic
+ * algorithms in a highly modular and flexible manner.
+ *
+ * The library is free for all purposes without any express
+ * guarantee it works.
+ */
+
+#include "tomcrypt.h"
+
+#ifdef LTC_RC4_STREAM
+
+/**
+   Initialize an RC4 context (only the key)
+   @param st        [out] The destination of the RC4 state
+   @param key       The secret key
+   @param keylen    The length of the secret key (8 - 256 bytes)
+   @return CRYPT_OK if successful
+*/
+int rc4_stream_setup(rc4_state *st, const unsigned char *key, unsigned long keylen)
+{
+   unsigned char tmp, *s;
+   int x, y;
+   unsigned long j;
+
+   LTC_ARGCHK(st  != NULL);
+   LTC_ARGCHK(key != NULL);
+   LTC_ARGCHK(keylen >= 5); /* 40-2048 bits */
+
+   s = st->buf;
+   for (x = 0; x < 256; x++) {
+      s[x] = x;
+   }
+
+   for (j = x = y = 0; x < 256; x++) {
+      y = (y + s[x] + key[j++]) & 255;
+      if (j == keylen) {
+         j = 0;
+      }
+      tmp = s[x]; s[x] = s[y]; s[y] = tmp;
+   }
+   st->x = 0;
+   st->y = 0;
+
+   return CRYPT_OK;
+}
+
+/**
+   Encrypt (or decrypt) bytes of ciphertext (or plaintext) with RC4
+   @param st      The RC4 state
+   @param in      The plaintext (or ciphertext)
+   @param inlen   The length of the input (octets)
+   @param out     [out] The ciphertext (or plaintext), length inlen
+   @return CRYPT_OK if successful
+*/
+int rc4_stream_crypt(rc4_state *st, const unsigned char *in, unsigned long inlen, unsigned char *out)
+{
+   unsigned char x, y, *s, tmp;
+
+   LTC_ARGCHK(st  != NULL);
+   LTC_ARGCHK(in  != NULL);
+   LTC_ARGCHK(out != NULL);
+
+   x = st->x;
+   y = st->y;
+   s = st->buf;
+   while (inlen--) {
+      x = (x + 1) & 255;
+      y = (y + s[x]) & 255;
+      tmp = s[x]; s[x] = s[y]; s[y] = tmp;
+      tmp = (s[x] + s[y]) & 255;
+      *out++ = *in++ ^ s[tmp];
+   }
+   st->x = x;
+   st->y = y;
+   return CRYPT_OK;
+}
+
+/**
+  Generate a stream of random bytes via RC4
+  @param st      The RC420 state
+  @param out     [out] The output buffer
+  @param outlen  The output length
+  @return CRYPT_OK on success
+ */
+int rc4_stream_keystream(rc4_state *st, unsigned char *out, unsigned long outlen)
+{
+   if (outlen == 0) return CRYPT_OK; /* nothing to do */
+   LTC_ARGCHK(out != NULL);
+   XMEMSET(out, 0, outlen);
+   return rc4_stream_crypt(st, out, outlen, out);
+}
+
+/**
+  Terminate and clear RC4 state
+  @param st      The RC4 state
+  @return CRYPT_OK on success
+*/
+int rc4_stream_done(rc4_state *st)
+{
+   LTC_ARGCHK(st != NULL);
+   XMEMSET(st, 0, sizeof(rc4_state));
+   return CRYPT_OK;
+}
+
+#endif
+
+/* ref:         $Format:%D$ */
+/* git commit:  $Format:%H$ */
+/* commit time: $Format:%ai$ */