[Cryptech-Commits] [core/util/keywrap] 52/95: Adding state and counter functionality to support unwrap. Changed name of define to something more comprehensible.

[git at cryptech.is]

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paul at psgd.org pushed a commit to branch master
in repository core/util/keywrap.

commit f7da70916565e8e11a69c9ed845b001acf224635
Author: Joachim Strömbergson <joachim at secworks.se>
AuthorDate: Thu Jul 5 15:15:14 2018 +0200

    Adding state and counter functionality to support unwrap. Changed name of define to something more comprehensible.
---
 src/rtl/keywrap_core.v | 66 ++++++++++++++++++++++++++++++++++++++++++++------
 1 file changed, 58 insertions(+), 8 deletions(-)

diff --git a/src/rtl/keywrap_core.v b/src/rtl/keywrap_core.v
index 28e8f74..91e5161 100644
--- a/src/rtl/keywrap_core.v
+++ b/src/rtl/keywrap_core.v
@@ -69,7 +69,7 @@ module keywrap_core (
   //----------------------------------------------------------------
   // Paramenters and local defines.
   //----------------------------------------------------------------
-  localparam OUTER_LOOP_MAX = 6 - 1;
+  localparam MAX_ITERATIONS = 6 - 1;
 
   localparam CTRL_IDLE          = 4'h0;
   localparam CTRL_INIT_WAIT     = 4'h1;
@@ -77,8 +77,9 @@ module keywrap_core (
   localparam CTRL_NEXT_WAIT0    = 4'h3;
   localparam CTRL_NEXT_WAIT     = 4'h4;
   localparam CTRL_NEXT_UPDATE   = 4'h5;
-  localparam CTRL_NEXT_CHECK    = 4'h6;
-  localparam CTRL_NEXT_FINALIZE = 4'h7;
+  localparam CTRL_NEXT_WRAP     = 4'h6;
+  localparam CTRL_NEXT_UNWRAP   = 4'h7;
+  localparam CTRL_NEXT_FINALIZE = 4'h8;
 
 
   //----------------------------------------------------------------
@@ -100,8 +101,10 @@ module keywrap_core (
   reg [12 : 0] block_ctr_reg;
   reg [12 : 0] block_ctr_new;
   reg          block_ctr_we;
+  reg          block_ctr_dec;
   reg          block_ctr_inc;
   reg          block_ctr_rst;
+  reg          block_ctr_set;
 
   reg [2 : 0]  iteration_ctr_reg;
   reg [2 : 0]  iteration_ctr_new;
@@ -264,6 +267,18 @@ module keywrap_core (
           block_ctr_we  = 1'h1;
         end
 
+      if (block_ctr_set)
+        begin
+          block_ctr_new = rlen;
+          block_ctr_we  = 1'h1;
+        end
+
+      if (block_ctr_dec)
+        begin
+          block_ctr_new = block_ctr_reg - 1'h1;
+          block_ctr_we  = 1'h1;
+        end
+
       if (block_ctr_inc)
         begin
           block_ctr_new = block_ctr_reg + 1'h1;
@@ -288,7 +303,7 @@ module keywrap_core (
 
       if (iteration_ctr_set)
         begin
-          iteration_ctr_new = 3'h5;
+          iteration_ctr_new = MAX_ITERATIONS;
           iteration_ctr_we  = 1'h1;
         end
 
@@ -320,8 +335,10 @@ module keywrap_core (
       update_state          = 1'h0;
       aes_init              = 1'h0;
       aes_next              = 1'h0;
+      block_ctr_dec         = 1'h0;
       block_ctr_inc         = 1'h0;
       block_ctr_rst         = 1'h0;
+      block_ctr_set         = 1'h0;
       iteration_ctr_inc     = 1'h0;
       iteration_ctr_dec     = 1'h0;
       iteration_ctr_set     = 1'h0;
@@ -398,12 +415,20 @@ module keywrap_core (
         CTRL_NEXT_UPDATE:
           begin
             update_state          = 1'h1;
-            keywrap_core_ctrl_new = CTRL_NEXT_CHECK;
-            keywrap_core_ctrl_we  = 1'h1;
+            if (encdec)
+              begin
+                keywrap_core_ctrl_new = CTRL_NEXT_WRAP;
+                keywrap_core_ctrl_we  = 1'h1;
+              end
+            else
+              begin
+                keywrap_core_ctrl_new = CTRL_NEXT_UNWRAP;
+                keywrap_core_ctrl_we  = 1'h1;
+              end
           end
 
 
-        CTRL_NEXT_CHECK:
+        CTRL_NEXT_WRAP:
           begin
             if (block_ctr_reg < rlen)
               begin
@@ -412,7 +437,7 @@ module keywrap_core (
                 keywrap_core_ctrl_we  = 1'h1;
               end
 
-            else if (iteration_ctr_reg < OUTER_LOOP_MAX)
+            else if (iteration_ctr_reg < MAX_ITERATIONS)
               begin
                 block_ctr_rst         = 1'h1;
                 iteration_ctr_inc     = 1'h1;
@@ -428,6 +453,31 @@ module keywrap_core (
           end
 
 
+        CTRL_NEXT_UNWRAP:
+          begin
+            if (block_ctr_reg > 0)
+              begin
+                block_ctr_dec         = 1'h1;
+                keywrap_core_ctrl_new = CTRL_NEXT_LOOP;
+                keywrap_core_ctrl_we  = 1'h1;
+              end
+
+            else if (iteration_ctr_reg > 0)
+              begin
+                block_ctr_set         = 1'h1;
+                iteration_ctr_dec     = 1'h1;
+                keywrap_core_ctrl_new = CTRL_NEXT_LOOP;
+                keywrap_core_ctrl_we  = 1'h1;
+              end
+
+            else
+              begin
+                keywrap_core_ctrl_new = CTRL_NEXT_FINALIZE;
+                keywrap_core_ctrl_we  = 1'h1;
+              end
+          end
+
+
         CTRL_NEXT_FINALIZE:
           begin
             ready_new             = 1'h1;