Add support for Twofish family keys.

diff --git a/twofish.c b/twofish.c
index 4ba4860..566ee1e 100644 (file)
--- a/twofish.c
+++ b/twofish.c
@@ -1,6 +1,6 @@
 /* -*-c-*-
  *
- * $Id: twofish.c,v 1.2 2000/06/22 18:58:00 mdw Exp $
+ * $Id: twofish.c,v 1.3 2002/01/13 13:37:59 mdw Exp $
  *
  * Implementation of the Twofish cipher
  *
@@ -30,6 +30,9 @@
 /*----- Revision history --------------------------------------------------* 
  *
  * $Log: twofish.c,v $
+ * Revision 1.3  2002/01/13 13:37:59  mdw
+ * Add support for Twofish family keys.
+ *
  * Revision 1.2  2000/06/22 18:58:00  mdw
  * Twofish can handle keys with any byte-aligned size.
  *
@@ -102,19 +105,22 @@ static uint32 h(uint32 x, const uint32 *l, unsigned k)
          qmds[2][U8(x >> 16)] ^ qmds[3][U8(x >> 24)]);
 }
 
-/* --- @twofish_init@ --- *
+/* --- @twofish_initfk@ --- *
  *
  * Arguments:  @twofish_ctx *k@ = pointer to key block to fill in
  *             @const void *buf@ = pointer to buffer of key material
  *             @size_t sz@ = size of key material
+ *             @const twofish_fk *fk@ = family-key information
  *
  * Returns:    ---
  *
- * Use:                Initializes a Twofish key buffer.  Twofish accepts key sizes
- *             of up to 256 bits (32 bytes).
+ * Use:                Does the underlying Twofish key initialization with family
+ *             key.  Pass in a family-key structure initialized to
+ *             all-bits-zero for a standard key schedule.
  */
 
-void twofish_init(twofish_ctx *k, const void *buf, size_t sz)
+void twofish_initfk(twofish_ctx *k, const void *buf, size_t sz,
+                   const twofish_fk *fk)
 {
 # define KMAX 4
 
@@ -170,8 +176,8 @@ void twofish_init(twofish_ctx *k, const void *buf, size_t sz)
 
       /* --- Extract the easy subkeys --- */
 
-      me[i] = LOAD32_L(q);
-      mo[i] = LOAD32_L(q + 4);
+      me[i] = LOAD32_L(q) ^ fk->t0[2 * i];
+      mo[i] = LOAD32_L(q + 4) ^ fk->t0[2 * i + 1];
 
       /* --- Now do the Reed-Solomon thing --- */
 
@@ -181,8 +187,8 @@ void twofish_init(twofish_ctx *k, const void *buf, size_t sz)
        int k;
 
        for (k = 0; k < 8; k++) {
-         if (*qq)
-           a ^= rsexp[rslog[*qq] + *r];
+         unsigned char x = *qq ^ fk->t1[i * 8 + k];
+         if (x) a ^= rsexp[rslog[x] + *r];
          qq++;
          r++;
        }
@@ -215,6 +221,13 @@ void twofish_init(twofish_ctx *k, const void *buf, size_t sz)
       k->k[i + 1] = ROL32(b, 9);
       ip += 2 * p;
     }
+
+    for (i = 0; i < 8; i++)
+      k->k[i] ^= fk->t23[i];
+    for (i = 8; i < 40; i += 2) {
+      k->k[i] ^= fk->t4[0];
+      k->k[i + 1] ^= fk->t4[1];
+    }
   }
 
   /* --- Construct the S-box tables --- */
@@ -259,6 +272,64 @@ void twofish_init(twofish_ctx *k, const void *buf, size_t sz)
   BURN(s);
 }
 
+/* --- @twofish_init@ --- *
+ *
+ * Arguments:  @twofish_ctx *k@ = pointer to key block to fill in
+ *             @const void *buf@ = pointer to buffer of key material
+ *             @size_t sz@ = size of key material
+ *
+ * Returns:    ---
+ *
+ * Use:                Initializes a Twofish key buffer.  Twofish accepts key sizes
+ *             of up to 256 bits (32 bytes).
+ */
+
+void twofish_init(twofish_ctx *k, const void *buf, size_t sz)
+{
+  static twofish_fk fk = { { 0 } };
+  twofish_initfk(k, buf, sz, &fk);
+}
+
+/* --- @twofish_fkinit@ --- *
+ *
+ * Arguments:  @twofish_fk *fk@ = pointer to family key block
+ *             @const void *buf@ = pointer to buffer of key material
+ *             @size_t sz@ = size of key material
+ *
+ * Returns:    ---
+ *
+ * Use:                Initializes a family-key buffer.  This implementation allows
+ *             family keys of any size acceptable to the Twofish algorithm.
+ */
+
+void twofish_fkinit(twofish_fk *fk, const void *buf, size_t sz)
+{
+  twofish_ctx k;
+  uint32 pt[4], ct[4];
+  const octet *kk;
+  unsigned i;
+
+  twofish_init(&k, buf, sz);
+
+  for (i = 0; i < 4; i++) pt[i] = (uint32)-1;
+  twofish_eblk(&k, pt, fk->t0 + 4);
+
+  kk = buf; sz /= 4;
+  for (i = 0; i < sz; i++) { fk->t0[i] = LOAD32_L(kk); kk += 4; }
+
+  for (i = 0; i < 4; i++) pt[i] = 0; twofish_eblk(&k, pt, ct);
+  for (i = 0; i < 4; i++) STORE32_L(fk->t1 + i * 4, ct[i]);
+  pt[0] = 1; twofish_eblk(&k, pt, ct);
+  for (i = 0; i < 4; i++) STORE32_L(fk->t1 + 4 + i * 4, ct[i]);
+
+  pt[0] = 2; twofish_eblk(&k, pt, fk->t23 + 0);
+  pt[0] = 3; twofish_eblk(&k, pt, fk->t23 + 4);
+  pt[0] = 4; twofish_eblk(&k, pt, ct);
+  fk->t4[0] = ct[0]; fk->t4[1] = ct[1];
+
+  BURN(k);
+}
+
 /*----- Main encryption ---------------------------------------------------*/
 
 /* --- Feistel function --- */

diff --git a/twofish.h b/twofish.h
index 42736bd..79c697b 100644 (file)
--- a/twofish.h
+++ b/twofish.h
@@ -1,6 +1,6 @@
 /* -*-c-*-
  *
- * $Id: twofish.h,v 1.3 2001/04/29 18:12:43 mdw Exp $
+ * $Id: twofish.h,v 1.4 2002/01/13 13:37:59 mdw Exp $
  *
  * The Twofish block cipher
  *
@@ -30,6 +30,9 @@
 /*----- Revision history --------------------------------------------------* 
  *
  * $Log: twofish.h,v $
+ * Revision 1.4  2002/01/13 13:37:59  mdw
+ * Add support for Twofish family keys.
+ *
  * Revision 1.3  2001/04/29 18:12:43  mdw
  * Fix formatting.
  *
@@ -79,8 +82,30 @@ typedef struct twofish_ctx {
   uint32 g[4][256];
 } twofish_ctx;
 
+typedef struct twofish_fk {
+  uint32 t0[8], t23[8], t4[2];
+  octet t1[32];
+} twofish_fk;
+
 /*----- Functions provided ------------------------------------------------*/
 
+/* --- @twofish_initfk@ --- *
+ *
+ * Arguments:  @twofish_ctx *k@ = pointer to key block to fill in
+ *             @const void *buf@ = pointer to buffer of key material
+ *             @size_t sz@ = size of key material
+ *             @const twofish_fk *fk@ = family-key information
+ *
+ * Returns:    ---
+ *
+ * Use:                Does the underlying Twofish key initialization with family
+ *             key.  Pass in a family-key structure initialized to
+ *             all-bits-zero for a standard key schedule.
+ */
+
+extern void twofish_initfk(twofish_ctx */*k*/, const void */*buf*/,
+                          size_t /*sz*/, const twofish_fk */*fk*/);
+
 /* --- @twofish_init@ --- *
  *
  * Arguments:  @twofish_ctx *k@ = pointer to key block to fill in
@@ -96,6 +121,21 @@ typedef struct twofish_ctx {
 extern void twofish_init(twofish_ctx */*k*/,
                         const void */*buf*/, size_t /*sz*/);
 
+/* --- @twofish_fkinit@ --- *
+ *
+ * Arguments:  @twofish_fk *fk@ = pointer to family key block
+ *             @const void *buf@ = pointer to buffer of key material
+ *             @size_t sz@ = size of key material
+ *
+ * Returns:    ---
+ *
+ * Use:                Initializes a family-key buffer.  This implementation allows
+ *             family keys of any size acceptable to the Twofish algorithm.
+ */
+
+extern void twofish_fkinit(twofish_fk */*fk*/,
+                          const void */*buf*/, size_t /*sz*/);
+
 /* --- @twofish_eblk@, @twofish_dblk@ --- *
  *
  * Arguments:  @const twofish_ctx *k@ = pointer to key block