//======================================================================
//
// aes.core.v
// ----------
// The AES core. This core supports key size of 128, and 256 bits.
// Most of the functionality is within the submodules.
//
//
// Author: Joachim Strombergson
// Copyright (c) 2014, NORDUnet A/S
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
// - Redistributions of source code must retain the above copyright notice,
// this list of conditions and the following disclaimer.
//
// - Redistributions in binary form must reproduce the above copyright
// notice, this list of conditions and the following disclaimer in the
// documentation and/or other materials provided with the distribution.
//
// - Neither the name of the NORDUnet nor the names of its contributors may
// be used to endorse or promote products derived from this software
// without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
// IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
// TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
// PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
// TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
// PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
// LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
// NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
// SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
//
//======================================================================
module aes_core(
input wire clk,
input wire reset_n,
input wire encdec,
input wire init,
input wire next,
output wire ready,
input wire [255 : 0] key,
input wire keylen,
input wire [127 : 0] block,
output wire [127 : 0] result,
output wire result_valid
);
//----------------------------------------------------------------
// Internal constant and parameter definitions.
//----------------------------------------------------------------
localparam CTRL_IDLE = 2'h0;
localparam CTRL_INIT = 2'h1;
localparam CTRL_NEXT = 2'h2;
//----------------------------------------------------------------
// Registers including update variables and write enable.
//----------------------------------------------------------------
reg [1 : 0] aes_core_ctrl_reg;
reg [1 : 0] aes_core_ctrl_new;
reg aes_core_ctrl_we;
reg result_valid_reg;
reg result_valid_new;
reg result_valid_we;
reg ready_reg;
reg ready_new;
reg ready_we;
//----------------------------------------------------------------
// Wires.
//----------------------------------------------------------------
wire [127 : 0] round_key;
wire key_ready;
reg enc_next;
wire [3 : 0] enc_round_nr;
wire [127 : 0] enc_new_block;
wire enc_ready;
reg dec_next;
wire [3 : 0] dec_round_nr;
wire [127 : 0] dec_new_block;
wire dec_ready;
reg [127 : 0] muxed_new_block;
reg [3 : 0] muxed_round_nr;
reg muxed_ready;
//----------------------------------------------------------------
// Instantiations.
//----------------------------------------------------------------
aes_encipher_block enc_block(
.clk(clk),
.reset_n(reset_n),
.next(enc_next),
.keylen(keylen),
.round(enc_round_nr),
.round_key(round_key),
.block(block),
.new_block(enc_new_block),
.ready(enc_ready)
);
aes_decipher_block dec_block(
.clk(clk),
.reset_n(reset_n),
.next(dec_next),
.keylen(keylen),
.round(dec_round_nr),
.round_key(round_key),
.block(block),
.new_block(dec_new_block),
.ready(dec_ready)
);
aes_key_mem keymem(
.clk(clk),
.reset_n(reset_n),
.key(key),
.keylen(keylen),
.init(init),
.round(muxed_round_nr),
.round_key(round_key),
.ready(key_ready)
);
//----------------------------------------------------------------
// Concurrent connectivity for ports etc.
//----------------------------------------------------------------
assign ready = ready_reg;
assign result = muxed_new_block;
assign result_valid = result_valid_reg;
//----------------------------------------------------------------
// reg_update
//
// Update functionality for all registers in the core.
// All registers are positive edge triggered with asynchronous
// active low reset. All registers have write enable.
//----------------------------------------------------------------
always @ (posedge clk or negedge reset_n)
begin: reg_update
if (!reset_n)
begin
result_valid_reg <= 1'b0;
ready_reg <= 1'b1;
aes_core_ctrl_reg <= CTRL_IDLE;
end
else
begin
if (result_valid_we)
result_valid_reg <= result_valid_new;
if (ready_we)
ready_reg <= ready_new;
if (aes_core_ctrl_we)
aes_core_ctrl_reg <= aes_core_ctrl_new;
end
end // reg_update
//----------------------------------------------------------------
// encdex_mux
//
// Controls which of the datapaths that get the next signal, have
// access to the memory as well as the block processing result.
//----------------------------------------------------------------
always @*
begin : encdec_mux
enc_next = 1'b0;
dec_next = 1'b0;
if (encdec)
begin
// Encipher operations
enc_next = next;
muxed_round_nr = enc_round_nr;
muxed_new_block = enc_new_block;
muxed_ready = enc_ready;
end
else
begin
// Decipher operations
dec_next = next;
muxed_round_nr = dec_round_nr;
muxed_new_block = dec_new_block;
muxed_ready = dec_ready;
end
end // encdec_mux
//----------------------------------------------------------------
// aes_core_ctrl
//
// Control FSM for aes core. Basically tracks if we are in
// key init, encipher or decipher modes and connects the
// different submodules to shared resources and interface ports.
//----------------------------------------------------------------
always @*
begin : aes_core_ctrl
ready_new = 1'b0;
ready_we = 1'b0;
result_valid_new = 1'b0;
result_valid_we = 1'b0;
aes_core_ctrl_new = CTRL_IDLE;
aes_core_ctrl_we = 1'b0;
case (aes_core_ctrl_reg)
CTRL_IDLE:
begin
if (init)
begin
ready_new = 1'b0;
ready_we = 1'b1;
result_valid_new = 1'b0;
result_valid_we = 1'b1;
aes_core_ctrl_new = CTRL_INIT;
aes_core_ctrl_we = 1'b1;
end
else if (next)
begin
ready_new = 1'b0;
ready_we = 1'b1;
result_valid_new = 1'b0;
result_valid_we = 1'b1;
aes_core_ctrl_new = CTRL_NEXT;
aes_core_ctrl_we = 1'b1;
end
end
CTRL_INIT:
begin
if (key_ready)
begin
ready_new = 1'b1;
ready_we = 1'b1;
aes_core_ctrl_new = CTRL_IDLE;
aes_core_ctrl_we = 1'b1;
end
end
CTRL_NEXT:
begin
if (muxed_ready)
begin
ready_new = 1'b1;
ready_we = 1'b1;
result_valid_new = 1'b1;
result_valid_we = 1'b1;
aes_core_ctrl_new = CTRL_IDLE;
aes_core_ctrl_we = 1'b1;
end
end
default:
begin
end
endcase // case (aes_core_ctrl_reg)
end // aes_core_ctrl
endmodule // aes_core
//======================================================================
// EOF aes_core.v
//======================================================================
