From 4b8968ddae4a750b87d9f1a64a9833ee530bd398 Mon Sep 17 00:00:00 2001
From: mdw <mdw>
Date: Sat, 17 Jun 2000 11:55:22 +0000
Subject: [PATCH] New key size interface.  Allow key material to be combined
 with an existing initialized context.  Use secure arena for memory
 allocation.

---
 rc4.c | 78 +++++++++++++++++++++++++++++++++++++++++++++++--------------------
 1 file changed, 55 insertions(+), 23 deletions(-)

diff --git a/rc4.c b/rc4.c
index a4e595f..69adcc6 100644
--- a/rc4.c
+++ b/rc4.c
@@ -1,6 +1,6 @@
 /* -*-c-*-
  *
- * $Id: rc4.c,v 1.3 1999/12/13 15:34:01 mdw Exp $
+ * $Id: rc4.c,v 1.4 2000/06/17 11:55:22 mdw Exp $
  *
  * The alleged RC4 stream cipher
  *
@@ -30,6 +30,10 @@
 /*----- Revision history --------------------------------------------------* 
  *
  * $Log: rc4.c,v $
+ * Revision 1.4  2000/06/17 11:55:22  mdw
+ * New key size interface.  Allow key material to be combined with an
+ * existing initialized context.  Use secure arena for memory allocation.
+ *
  * Revision 1.3  1999/12/13 15:34:01  mdw
  * Add support for seeding from a generic pseudorandom source.
  *
@@ -50,35 +54,38 @@
 #include <mLib/bits.h>
 #include <mLib/sub.h>
 
+#include "arena.h"
 #include "gcipher.h"
 #include "grand.h"
+#include "paranoia.h"
 #include "rc4.h"
 
+/*----- Global variables --------------------------------------------------*/
+
+const octet rc4_keysz[] = { KSZ_RANGE, RC4_KEYSZ, 1, 255, 1 };
+
 /*----- Main code ---------------------------------------------------------*/
 
-/* --- @rc4_init@ --- *
+/* --- @rc4_addkey@ --- *
  *
- * Arguments:	@rc4_ctx *ctx@ = pointer to context to initialize
+ * Arguments:	@rc4_ctx *ctx@ = pointer to context to key
  *		@const void *k@ = pointer to key data to use
  *		@size_t sz@ = size of the key data
  *
  * Returns:	---
  *
- * Use:		Initializes an RC4 context ready for use.
+ * Use:		Mixes key data with an RC4 context.  The RC4 context is not
+ *		reset before mixing.  This may be used to mix new key
+ *		material with an existing RC4 context.
  */
 
-void rc4_init(rc4_ctx *ctx, const void *k, size_t sz)
+void rc4_addkey(rc4_ctx *ctx, const void *k, size_t sz)
 {
   unsigned i, j;
   const octet *p = k, *q = p + sz;
 
-  assert(((void)"RC4 does not support zero length keys", sz != 0));
+  KSZ_ASSERT(rc4, sz);
 
-  for (i = 0; i < 256; i++)
-    ctx->s[i] = i;
-  ctx->f = 0;
-  ctx->i = ctx->j = 0;
-  
   for (i = j = 0; i < 256; i++) {
     unsigned si = ctx->s[i];
     j = (j + si + *p++) & 0xff;
@@ -86,7 +93,30 @@ void rc4_init(rc4_ctx *ctx, const void *k, size_t sz)
     ctx->s[j] = si;
     if (p == q)
       p = k;
-  }
+  }  
+
+  ctx->i = ctx->j = 0;
+}
+
+/* --- @rc4_init@ --- *
+ *
+ * Arguments:	@rc4_ctx *ctx@ = pointer to context to initialize
+ *		@const void *k@ = pointer to key data to use
+ *		@size_t sz@ = size of the key data
+ *
+ * Returns:	---
+ *
+ * Use:		Initializes an RC4 context ready for use.
+ */
+
+void rc4_init(rc4_ctx *ctx, const void *k, size_t sz)
+{
+  unsigned i;
+
+  for (i = 0; i < 256; i++)
+    ctx->s[i] = i;
+  ctx->f = 0;
+  rc4_addkey(ctx, k, sz);
 }
 
 /* --- @rc4_encrypt@ --- *
@@ -131,7 +161,7 @@ static const gcipher_ops gops;
 
 static gcipher *ginit(const void *k, size_t sz)
 {
-  gctx *g = CREATE(gctx);
+  gctx *g = S_CREATE(gctx);
   g->c.ops = &gops;
   rc4_init(&g->rc4, k, sz);
   return (&g->c);
@@ -146,16 +176,17 @@ static void gencrypt(gcipher *c, const void *s, void *t, size_t sz)
 static void gdestroy(gcipher *c)
 {
   gctx *g = (gctx *)c;
-  DESTROY(g);
+  BURN(*g);
+  S_DESTROY(g);
 }
 
 static const gcipher_ops gops = {
-  &rc4.b,
+  &rc4,
   gencrypt, gencrypt, gdestroy, 0, 0
 };
 
 const gccipher rc4 = {
-  { "rc4", 0, 0 },
+  "rc4", rc4_keysz, 0,
   ginit
 };
 
@@ -169,7 +200,8 @@ typedef struct grctx {
 static void grdestroy(grand *r)
 {
   grctx *g = (grctx *)r;
-  DESTROY(g);
+  BURN(*g);
+  S_DESTROY(g);
 }
 
 static int grmisc(grand *r, unsigned op, ...)
@@ -197,22 +229,22 @@ static int grmisc(grand *r, unsigned op, ...)
       break;
     case GRAND_SEEDINT:
       STORE32(buf, va_arg(ap, unsigned));
-      rc4_init(&g->rc4, buf, sizeof(buf));
+      rc4_addkey(&g->rc4, buf, sizeof(buf));
       break;
     case GRAND_SEEDUINT32:
       STORE32(buf, va_arg(ap, uint32));
-      rc4_init(&g->rc4, buf, sizeof(buf));
+      rc4_addkey(&g->rc4, buf, sizeof(buf));
       break;
     case GRAND_SEEDBLOCK: {
       const void *p = va_arg(ap, const void *);
       size_t sz = va_arg(ap, size_t);
-      rc4_init(&g->rc4, p, sz);
+      rc4_addkey(&g->rc4, p, sz);
     } break;
     case GRAND_SEEDRAND: {
       grand *rr = va_arg(ap, grand *);
       octet buf[16];
       rr->ops->fill(rr, buf, sizeof(buf));
-      rc4_init(&g->rc4, buf, sizeof(buf));
+      rc4_addkey(&g->rc4, buf, sizeof(buf));
     } break;
     default:
       GRAND_BADOP;
@@ -250,7 +282,7 @@ static void grfill(grand *r, void *p, size_t sz)
 
 static const grand_ops grops = {
   "rc4",
-  0,
+  GRAND_CRYPTO, 0,
   grmisc, grdestroy,
   grword, grbyte, grword, grand_range, grfill
 };
@@ -268,7 +300,7 @@ static const grand_ops grops = {
 
 grand *rc4_rand(const void *k, size_t sz)
 {
-  grctx *g = CREATE(grctx);
+  grctx *g = S_CREATE(grctx);
   g->r.ops = &grops;
   rc4_init(&g->rc4, k, sz);
   return (&g->r);
-- 
2.11.0