From c236e66d628ec4a7d24612dd5c94c35c6b170af8 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ulf=20M=C3=B6ller?= <ulf@openssl.org>
Date: Sat, 5 Feb 2000 10:41:05 +0000
Subject: [PATCH] Document RC4.

---
 crypto/rc4/rc4.h      |  4 +--
 crypto/rc4/rc4_enc.c  |  2 +-
 crypto/rc4/rc4_skey.c |  2 +-
 doc/crypto/rc4.pod    | 58 +++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 62 insertions(+), 4 deletions(-)
 create mode 100644 doc/crypto/rc4.pod

diff --git a/crypto/rc4/rc4.h b/crypto/rc4/rc4.h
index 7418c2a9a2..8556dddab0 100644
--- a/crypto/rc4/rc4.h
+++ b/crypto/rc4/rc4.h
@@ -77,8 +77,8 @@ typedef struct rc4_key_st
 
  
 const char *RC4_options(void);
-void RC4_set_key(RC4_KEY *key, int len, unsigned char *data);
-void RC4(RC4_KEY *key, unsigned long len, unsigned char *indata,
+void RC4_set_key(RC4_KEY *key, int len, const unsigned char *data);
+void RC4(RC4_KEY *key, unsigned long len, const unsigned char *indata,
 		unsigned char *outdata);
 
 #ifdef  __cplusplus
diff --git a/crypto/rc4/rc4_enc.c b/crypto/rc4/rc4_enc.c
index 35dbc7c47e..d5f18a3a70 100644
--- a/crypto/rc4/rc4_enc.c
+++ b/crypto/rc4/rc4_enc.c
@@ -67,7 +67,7 @@
  * Date: Wed, 14 Sep 1994 06:35:31 GMT
  */
 
-void RC4(RC4_KEY *key, unsigned long len, unsigned char *indata,
+void RC4(RC4_KEY *key, unsigned long len, const unsigned char *indata,
 	     unsigned char *outdata)
 	{
         register RC4_INT *d;
diff --git a/crypto/rc4/rc4_skey.c b/crypto/rc4/rc4_skey.c
index c67a445f1f..bb10c1ebe2 100644
--- a/crypto/rc4/rc4_skey.c
+++ b/crypto/rc4/rc4_skey.c
@@ -85,7 +85,7 @@ const char *RC4_options(void)
  * Date: Wed, 14 Sep 1994 06:35:31 GMT
  */
 
-void RC4_set_key(RC4_KEY *key, int len, register unsigned char *data)
+void RC4_set_key(RC4_KEY *key, int len, const unsigned char *data)
 	{
         register RC4_INT tmp;
         register int id1,id2;
diff --git a/doc/crypto/rc4.pod b/doc/crypto/rc4.pod
new file mode 100644
index 0000000000..e380045dbf
--- /dev/null
+++ b/doc/crypto/rc4.pod
@@ -0,0 +1,58 @@
+=pod
+
+=head1 NAME
+
+RC4_set_key, RC4 - RC4 encryption
+
+=head1 SYNOPSIS
+
+ #include <openssl/rc4.h>
+
+ void RC4_set_key(RC4_KEY *key, int len, const unsigned char *data);
+
+ void RC4(RC4_KEY *key, unsigned long len, const unsigned char *indata,
+          unsigned char *outdata);
+
+=head1 DESCRIPTION
+
+This library implements the Alleged RC4 cipher, which is described for
+example in I<Applied Cryptography>.  It is believed to be compatible
+with RC4[TM], a proprietary cipher of RSA Security Inc.
+
+RC4 is a stream cipher with variable key length.  Typically, 128 bit
+(16 byte) keys are used for strong encryption, but shorter insecure
+key sizes have been widely used due to export restrictions.
+
+RC4 consists of a key setup phase and the actual encryption or
+decryption phase.
+
+RC4_set_key() sets up the B<RC4_KEY> B<key> using the B<len> bytes long
+key at B<data>.
+
+RC4() encrypts or decrypts the B<len> bytes of data at B<indata> using
+B<key> and places the result at B<outdata>.  Repeated RC4() calls with
+the same B<key> yield a continuous key stream.
+
+Since RC4 is a stream cipher (the input is XORed with a pseudo-random
+key stream to produce the output), decryption uses the same function
+calls as encryption.
+
+=head1 RETURN VALUES
+
+RC4_set_key() and RC4() do not return values.
+
+=head1 NOTE
+
+Certain conditions have to be observed to securely use stream ciphers.
+It is not permissible to perform multiple encryptions using the same
+key stream.
+
+=head1 SEE ALSO
+
+L<blowfish(3)|blowfish(3)>, L<des(3)|des(3)>, L<rc2(3)|rc2(3)>
+
+=head1 HISTORY
+
+RC4_set_key() and RC4() are available in all versions of SSLeay and OpenSSL.
+
+=cut
-- 
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