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+//======================================================================
+//
+// trng_csprng.v
+// -------------
+// CSPRNG for the TRNG.
+//
+//
+// 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 trng_csprng(
+ // Clock and reset.
+ input wire clk,
+ input wire reset_n,
+
+ // Control, config and status.
+ input debug_mode,
+ input wire [4 : 0] num_rounds,
+ input wire [63 : 0] num_blocks,
+ input wire seed,
+ input wire enable,
+ output wire more_seed,
+ output wire ready,
+ output wire error,
+
+ // Seed input
+ input wire seed_syn,
+ input [511 : 0] seed_data,
+ output wire seed_ack,
+
+ // Random data output
+ output wire rnd_syn,
+ output wire [31 : 0] rnd_data,
+ input wire rnd_ack
+ );
+
+
+ //----------------------------------------------------------------
+ // Internal constant and parameter definitions.
+ //----------------------------------------------------------------
+ parameter CIPHER_KEYLEN256 = 1'b1; // 256 bit key.
+ parameter CIPHER_MAX_BLOCKS = 64'h1000000000000000;
+
+ parameter CTRL_IDLE = 4'h0;
+ parameter CTRL_SEED0 = 4'h1;
+ parameter CTRL_SEED1 = 4'h2;
+ parameter CTRL_INIT0 = 4'h3;
+ parameter CTRL_INIT1 = 4'h4;
+ parameter CTRL_NEXT0 = 4'h5;
+ parameter CTRL_NEXT1 = 4'h6;
+ parameter CTRL_MORE = 4'h7;
+ parameter CTRL_CANCEL = 4'hf;
+
+
+ //----------------------------------------------------------------
+ // Registers including update variables and write enable.
+ //----------------------------------------------------------------
+ reg [255 : 0] cipher_key_reg;
+ reg [255 : 0] cipher_key_new;
+ reg cipher_key_we;
+
+ reg [63 : 0] cipher_iv_reg;
+ reg [63 : 0] cipher_iv_new;
+ reg cipher_iv_we;
+
+ reg [63 : 0] cipher_ctr_reg;
+ reg [63 : 0] cipher_ctr_new;
+ reg cipher_ctr_we;
+
+ reg [511 : 0] cipher_block_reg;
+ reg [511 : 0] cipher_block_new;
+ reg cipher_block_we;
+
+ reg [63 : 0] block_ctr_reg;
+ reg [63 : 0] block_ctr_new;
+ reg block_ctr_inc;
+ reg block_ctr_rst;
+ reg block_ctr_we;
+ reg block_ctr_max;
+
+ reg error_reg;
+ reg error_new;
+ reg error_we;
+
+ reg [3 : 0] csprng_ctrl_reg;
+ reg [3 : 0] csprng_ctrl_new;
+ reg csprng_ctrl_we;
+
+ reg ready_reg;
+ reg ready_new;
+ reg ready_we;
+
+ reg more_seed_reg;
+ reg more_seed_new;
+
+ reg seed_ack_reg;
+ reg seed_ack_new;
+
+
+ //----------------------------------------------------------------
+ // Wires.
+ //----------------------------------------------------------------
+ reg cipher_init;
+ reg cipher_next;
+
+ wire [511 : 0] cipher_data_out;
+ wire cipher_data_out_valid;
+
+ reg discard_outputs;
+
+ wire fifo_more_data;
+ reg fifo_discard;
+ wire fifo_rnd_syn;
+ wire [31 : 0] fifo_rnd_data;
+ reg fifo_cipher_data_valid;
+
+
+ //----------------------------------------------------------------
+ // Concurrent connectivity for ports etc.
+ //----------------------------------------------------------------
+ assign seed_ack = seed_ack_reg;
+ assign more_seed = more_seed_reg;
+
+ assign ready = ready_reg;
+ assign error = error_reg;
+
+ assign rnd_syn = fifo_rnd_syn;
+ assign rnd_data = fifo_rnd_data;
+
+
+ //----------------------------------------------------------------
+ // core instantiation.
+ //----------------------------------------------------------------
+ chacha_core cipher(
+ .clk(clk),
+ .reset_n(reset_n),
+
+ .init(cipher_init),
+ .next(cipher_next),
+
+ .key(cipher_key_reg),
+ .keylen(CIPHER_KEYLEN256),
+ .iv(cipher_iv_reg),
+ .ctr(cipher_ctr_reg),
+ .rounds(num_rounds),
+
+ .data_in(cipher_block_reg),
+ .ready(cipher_ready),
+
+ .data_out(cipher_data_out),
+ .data_out_valid(cipher_data_out_valid)
+ );
+
+
+ trng_csprng_fifo fifo(
+ .clk(clk),
+ .reset_n(reset_n),
+
+ .csprng_data(cipher_data_out),
+ .csprng_data_valid(fifo_cipher_data_valid),
+ .discard(fifo_discard),
+ .more_data(fifo_more_data),
+
+ .rnd_syn(fifo_rnd_syn),
+ .rnd_data(fifo_rnd_data),
+ .rnd_ack(rnd_ack)
+ );
+
+
+ //----------------------------------------------------------------
+ // reg_update
+ //
+ // Update functionality for all registers in the core.
+ // All registers are positive edge triggered with synchronous
+ // active low reset. All registers have write enable.
+ //----------------------------------------------------------------
+ always @ (posedge clk or negedge reset_n)
+ begin
+ if (!reset_n)
+ begin
+ cipher_key_reg <= {8{32'h00000000}};
+ cipher_iv_reg <= {2{32'h00000000}};
+ cipher_ctr_reg <= {2{32'h00000000}};
+ cipher_block_reg <= {16{32'h00000000}};
+ block_ctr_reg <= {2{32'h00000000}};
+ more_seed_reg <= 0;
+ seed_ack_reg <= 0;
+ ready_reg <= 0;
+ error_reg <= 0;
+ csprng_ctrl_reg <= CTRL_IDLE;
+ end
+ else
+ begin
+ more_seed_reg <= more_seed_new;
+ seed_ack_reg <= seed_ack_new;
+
+ if (cipher_key_we)
+ begin
+ cipher_key_reg <= cipher_key_new;
+ end
+
+ if (cipher_iv_we)
+ begin
+ cipher_iv_reg <= cipher_iv_new;
+ end
+
+ if (cipher_ctr_we)
+ begin
+ cipher_ctr_reg <= cipher_ctr_new;
+ end
+
+ if (cipher_block_we)
+ begin
+ cipher_block_reg <= cipher_block_new;
+ end
+
+ if (block_ctr_we)
+ begin
+ block_ctr_reg <= block_ctr_new;
+ end
+
+ if (ready_we)
+ begin
+ ready_reg <= ready_new;
+ end
+
+ if (error_we)
+ begin
+ error_reg <= error_new;
+ end
+
+ if (csprng_ctrl_we)
+ begin
+ csprng_ctrl_reg <= csprng_ctrl_new;
+ end
+ end
+ end // reg_update
+
+
+ //----------------------------------------------------------------
+ // block_ctr
+ //
+ // Logic to implement the block counter. This includes the
+ // ability to detect that maximum allowed number of blocks
+ // has been reached. Either as defined by the application
+ // or the hard coded CIPHER_MAX_BLOCKS value.
+ //----------------------------------------------------------------
+ always @*
+ begin : block_ctr
+ block_ctr_new = 64'h0000000000000000;
+ block_ctr_we = 0;
+ block_ctr_max = 0;
+
+ if (block_ctr_rst)
+ begin
+ block_ctr_new = 64'h0000000000000000;
+ block_ctr_we = 1;
+ end
+
+ if (block_ctr_inc)
+ begin
+ block_ctr_new = block_ctr_reg + 1'b1;
+ block_ctr_we = 1;
+ end
+
+ if ((block_ctr_reg == num_blocks) || (block_ctr_reg == CIPHER_MAX_BLOCKS))
+ begin
+ block_ctr_max = 1;
+ end
+ end // block_ctr
+
+
+ //----------------------------------------------------------------
+ // csprng_ctrl_fsm
+ //
+ // Control FSM for the CSPRNG.
+ //----------------------------------------------------------------
+ always @*
+ begin : csprng_ctrl_fsm
+ cipher_key_new = {8{32'h00000000}};
+ cipher_key_we = 0;
+ cipher_iv_new = {2{32'h00000000}};
+ cipher_iv_we = 0;
+ cipher_ctr_new = {2{32'h00000000}};
+ cipher_ctr_we = 0;
+ cipher_block_new = {16{32'h00000000}};
+ cipher_block_we = 0;
+ cipher_init = 0;
+ cipher_next = 0;
+ block_ctr_rst = 0;
+ block_ctr_inc = 0;
+ ready_new = 0;
+ ready_we = 0;
+ error_new = 0;
+ error_we = 0;
+ discard_outputs = 0;
+ seed_ack_new = 0;
+ more_seed_new = 0;
+ fifo_discard = 0;
+ fifo_cipher_data_valid = 0;
+ csprng_ctrl_new = CTRL_IDLE;
+ csprng_ctrl_we = 0;
+
+ case (csprng_ctrl_reg)
+ CTRL_IDLE:
+ begin
+ if (!enable)
+ begin
+ csprng_ctrl_new = CTRL_CANCEL;
+ csprng_ctrl_we = 1;
+ end
+ else if (fifo_more_data)
+ begin
+ more_seed_new = 1;
+ csprng_ctrl_new = CTRL_SEED0;
+ csprng_ctrl_we = 1;
+ end
+ end
+
+ CTRL_SEED0:
+ begin
+ if ((!enable) || (seed))
+ begin
+ csprng_ctrl_new = CTRL_CANCEL;
+ csprng_ctrl_we = 1;
+ end
+ else if (seed_syn)
+ begin
+ more_seed_new = 1;
+ seed_ack_new = 1;
+ cipher_block_new = seed_data;
+ cipher_block_we = 1;
+ csprng_ctrl_new = CTRL_SEED1;
+ csprng_ctrl_we = 1;
+ end
+ end
+
+ CTRL_SEED1:
+ begin
+ if ((!enable) || (seed))
+ begin
+ csprng_ctrl_new = CTRL_CANCEL;
+ csprng_ctrl_we = 1;
+ end
+ else if (seed_syn)
+ begin
+ seed_ack_new = 1;
+ cipher_key_new = seed_data[255 : 0];
+ cipher_key_we = 1;
+ cipher_iv_new = seed_data[319 : 256];
+ cipher_iv_we = 1;
+ cipher_ctr_new = seed_data[383 : 320];
+ cipher_ctr_we = 1;
+ csprng_ctrl_new = CTRL_INIT0;
+ csprng_ctrl_we = 1;
+ end
+ else
+ begin
+ more_seed_new = 1;
+ end
+ end
+
+ CTRL_INIT0:
+ begin
+ if ((!enable) || (seed))
+ begin
+ csprng_ctrl_new = CTRL_CANCEL;
+ csprng_ctrl_we = 1;
+ end
+ else
+ begin
+ cipher_init = 1;
+ block_ctr_rst = 1;
+ csprng_ctrl_new = CTRL_INIT1;
+ csprng_ctrl_we = 1;
+ end
+ end
+
+ CTRL_INIT1:
+ begin
+ if ((!enable) || (seed))
+ begin
+ csprng_ctrl_new = CTRL_CANCEL;
+ csprng_ctrl_we = 1;
+ end
+ else if (cipher_ready)
+ begin
+ csprng_ctrl_new = CTRL_NEXT0;
+ csprng_ctrl_we = 1;
+ end
+ end
+
+ CTRL_NEXT0:
+ begin
+ if ((!enable) || (seed))
+ begin
+ csprng_ctrl_new = CTRL_CANCEL;
+ csprng_ctrl_we = 1;
+ end
+ else
+ begin
+ cipher_next = 1;
+ csprng_ctrl_new = CTRL_NEXT1;
+ csprng_ctrl_we = 1;
+ end
+ end
+
+ CTRL_NEXT1:
+ if ((!enable) || (seed))
+ begin
+ csprng_ctrl_new = CTRL_CANCEL;
+ csprng_ctrl_we = 1;
+ end
+ else if (cipher_ready)
+ begin
+ block_ctr_inc = 1;
+ fifo_cipher_data_valid = 1;
+ csprng_ctrl_new = CTRL_MORE;
+ csprng_ctrl_we = 1;
+ end
+
+ CTRL_MORE:
+ begin
+ if ((!enable) || (seed))
+ begin
+ csprng_ctrl_new = CTRL_CANCEL;
+ csprng_ctrl_we = 1;
+ end
+ else if (fifo_more_data)
+ begin
+ if (block_ctr_max)
+ begin
+ more_seed_new = 1;
+ csprng_ctrl_new = CTRL_SEED0;
+ csprng_ctrl_we = 1;
+ end
+ else
+ begin
+ csprng_ctrl_new = CTRL_NEXT0;
+ csprng_ctrl_we = 1;
+ end
+ end
+ end
+
+ CTRL_CANCEL:
+ begin
+ fifo_discard = 1;
+ cipher_key_new = {8{32'h00000000}};
+ cipher_key_we = 1;
+ cipher_iv_new = {2{32'h00000000}};
+ cipher_iv_we = 1;
+ cipher_ctr_new = {2{32'h00000000}};
+ cipher_ctr_we = 1;
+ cipher_block_new = {16{32'h00000000}};
+ cipher_block_we = 1;
+ block_ctr_rst = 1;
+ discard_outputs = 1;
+ csprng_ctrl_new = CTRL_IDLE;
+ csprng_ctrl_we = 1;
+ end
+
+ endcase // case (cspng_ctrl_reg)
+ end // csprng_ctrl_fsm
+
+endmodule // trng_csprng
+
+//======================================================================
+// EOF trng_csprng.v
+//======================================================================
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