path: root/src/sw/hash_tester.py

#!/usr/bin/env python
# -*- coding: utf-8 -*-
#=======================================================================
#
# hash_tester.py
# --------------
# This program sends several commands to the coretest_hashed subsystem
# in order to verify the SHA-1 and SHA-256 hash function cores.
# The program uses the built in hash implementations in Python
# to do functional comparison and validation.
#
# Note: This program requires the PySerial module.
# http://pyserial.sourceforge.net/
#
# 
# Author: Joachim Strombergson
# Copyright (c) 2014, Secworks Sweden AB
# All rights reserved.
# 
# Redistribution and use in source and binary forms, with or 
# without modification, are permitted provided that the following 
# conditions are met: 
# 
# 1. Redistributions of source code must retain the above copyright 
#    notice, this list of conditions and the following disclaimer. 
# 
# 2. 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. 
# 
# 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 OWNER 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.
#
#=======================================================================
 
#-------------------------------------------------------------------
# Python module imports.
#-------------------------------------------------------------------
import sys
import serial
import os
import time
import threading

 
#-------------------------------------------------------------------
# Defines.
#-------------------------------------------------------------------
VERBOSE = False

# Memory map.
SOC                   = '\x55'
EOC                   = '\xaa'
READ_CMD              = '\x10'
WRITE_CMD             = '\x11'

UART_ADDR_PREFIX      = '\x00'

SHA1_ADDR_PREFIX      = '\x10'
SHA1_ADDR_NAME0       = '\x00'
SHA1_ADDR_NAME1       = '\x01'
SHA1_ADDR_VERSION     = '\x02'
SHA1_ADDR_CTRL        = '\x08'
SHA1_CTRL_INIT_BIT    = 0
SHA1_CTRL_NEXT_BIT    = 1
SHA1_ADDR_STATUS      = '\x09'
SHA1_STATUS_READY_BIT = 0
SHA1_STATUS_VALID_BIT = 1
SHA1_ADDR_BLOCK0      = '\x10'
SHA1_ADDR_BLOCK1      = '\x11'
SHA1_ADDR_BLOCK2      = '\x12'
SHA1_ADDR_BLOCK3      = '\x13'
SHA1_ADDR_BLOCK4      = '\x14'
SHA1_ADDR_BLOCK5      = '\x15'
SHA1_ADDR_BLOCK6      = '\x16'
SHA1_ADDR_BLOCK7      = '\x17'
SHA1_ADDR_BLOCK8      = '\x18'
SHA1_ADDR_BLOCK9      = '\x19'
SHA1_ADDR_BLOCK10     = '\x1a'
SHA1_ADDR_BLOCK11     = '\x1b'
SHA1_ADDR_BLOCK12     = '\x1c'
SHA1_ADDR_BLOCK13     = '\x1d'
SHA1_ADDR_BLOCK14     = '\x1e'
SHA1_ADDR_BLOCK15     = '\x1f'
SHA1_ADDR_DIGEST0     = '\x20'
SHA1_ADDR_DIGEST1     = '\x21'
SHA1_ADDR_DIGEST2     = '\x22'
SHA1_ADDR_DIGEST3     = '\x23'
SHA1_ADDR_DIGEST4     = '\x24'

SHA256_ADDR_PREFIX      = '\x20'
SHA256_ADDR_NAME0       = '\x00'
SHA256_ADDR_NAME1       = '\x01'
SHA256_ADDR_VERSION     = '\x02'
SHA256_ADDR_CTRL        = '\x08'
SHA256_CTRL_INIT_BIT    = 0
SHA256_CTRL_NEXT_BIT    = 1
SHA256_ADDR_STATUS      = '\x09'
SHA256_STATUS_READY_BIT = 0
SHA256_STATUS_VALID_BIT = 1
SHA256_ADDR_BLOCK0      = '\x10'
SHA256_ADDR_BLOCK1      = '\x11'
SHA256_ADDR_BLOCK2      = '\x12'
SHA256_ADDR_BLOCK3      = '\x13'
SHA256_ADDR_BLOCK4      = '\x14'
SHA256_ADDR_BLOCK5      = '\x15'
SHA256_ADDR_BLOCK6      = '\x16'
SHA256_ADDR_BLOCK7      = '\x17'
SHA256_ADDR_BLOCK8      = '\x18'
SHA256_ADDR_BLOCK9      = '\x19'
SHA256_ADDR_BLOCK10     = '\x1a'
SHA256_ADDR_BLOCK11     = '\x1b'
SHA256_ADDR_BLOCK12     = '\x1c'
SHA256_ADDR_BLOCK13     = '\x1d'
SHA256_ADDR_BLOCK14     = '\x1e'
SHA256_ADDR_BLOCK15     = '\x1f'
SHA256_ADDR_DIGEST0     = '\x20'
SHA256_ADDR_DIGEST1     = '\x21'
SHA256_ADDR_DIGEST2     = '\x22'
SHA256_ADDR_DIGEST3     = '\x23'
SHA256_ADDR_DIGEST4     = '\x24'
SHA256_ADDR_DIGEST5     = '\x25'
SHA256_ADDR_DIGEST6     = '\x26'
SHA256_ADDR_DIGEST7     = '\x27'

NAME0_ADDR            = '\x00'
NAME1_ADDR            = '\x01'
VERSION_ADDR          = '\x02'


#-------------------------------------------------------------------
# print_response()
#
# Parses a received buffer and prints the response.
#-------------------------------------------------------------------
def print_response(buffer):
    if VERBOSE:
        print "Length of response: %d" % len(buffer)
        if buffer[0] == '\xaa':
            print "Response contains correct Start of Response (SOR)"
        if buffer[-1] == '\x55':
            print "Response contains correct End of Response (EOR)"

    response_code = ord(buffer[1])

    if response_code == 0xfe:
        print "UNKNOWN response code received."

    elif response_code == 0xfd:
        print "ERROR response code received."

    elif response_code == 0x7f:
        read_addr = ord(buffer[2]) * 256 + ord(buffer[3])
        read_data = (ord(buffer[4]) * 16777216) + (ord(buffer[5]) * 65536) +\
                    (ord(buffer[6]) * 256) + ord(buffer[7])
        print "READ_OK. address 0x%02x = 0x%08x." % (read_addr, read_data)

    elif response_code == 0x7e:
        read_addr = ord(buffer[2]) * 256 + ord(buffer[3])
        print "WRITE_OK. address 0x%02x." % (read_addr)

    elif response_code == 0x7d:
        print "RESET_OK."

    else:
        print "Response 0x%02x is unknown." % response_code
        print buffer
        

#-------------------------------------------------------------------
# read_serial_thread()
#
# Function used in a thread to read from the serial port and
# collect response from coretest.
#-------------------------------------------------------------------
def read_serial_thread(serialport):
    if VERBOSE:
        print "Serial port response thread started. Waiting for response..."
        
    buffer = []
    while True:
        response = serialport.read()
        buffer.append(response)
        if response == '\x55':
            print_response(buffer)
            buffer = []


#-------------------------------------------------------------------
# write_serial_bytes()
#
# Send the bytes in the buffer to coretest over the serial port.
#-------------------------------------------------------------------
def write_serial_bytes(tx_cmd, serialport):
    if VERBOSE:
        print "Command to be sent:", tx_cmd
    
    for tx_byte in tx_cmd:
        serialport.write(tx_byte)

    # Allow the device to complete the transaction.
    time.sleep(0.1)
    
    
#-------------------------------------------------------------------
# main()
#
# Parse any arguments and run the tests.
#-------------------------------------------------------------------
def main():
    # Open device
    ser = serial.Serial()
    ser.port='/dev/cu.usbserial-A801SA6T'
    ser.baudrate=9600
    ser.bytesize=8
    ser.parity='N'
    ser.stopbits=1
    ser.timeout=1
    ser.writeTimeout=0

    if VERBOSE:
        print "Setting up a serial port and starting a receive thread."

    try:
        ser.open()
    except:
        print "Error: Can't open serial device."
        sys.exit(1)

    try:
        my_thread = threading.Thread(target=read_serial_thread, args=(ser,))
    except:
        print "Error: Can't start thread."
        sys.exit()
        
    my_thread.daemon = True
    my_thread.start()

    # TC1-1: Read name and version from SHA-1 core.
    print "TC1-1: Reading name, type and version words from SHA-1 core."
    write_serial_bytes([SOC, READ_CMD, SHA1_ADDR_PREFIX, SHA1_ADDR_NAME0, EOC], ser)
    write_serial_bytes([SOC, READ_CMD, SHA1_ADDR_PREFIX, SHA1_ADDR_NAME1, EOC], ser)
    write_serial_bytes([SOC, READ_CMD, SHA1_ADDR_PREFIX, SHA1_ADDR_VERSION, EOC], ser)
    print""

    # TC1-2: Writing and reading a block into the SHA-1 core.
    print "TC1-2: Writing and reading a block into the SHA-1 core."
    write_serial_bytes([SOC, WRITE_CMD, SHA1_ADDR_PREFIX, SHA1_ADDR_BLOCK0,  '\x61', '\x62', '\x63', '\x80', EOC], ser)
    write_serial_bytes([SOC, WRITE_CMD, SHA1_ADDR_PREFIX, SHA1_ADDR_BLOCK1,  '\x00', '\x00', '\x00', '\x00', EOC], ser)
    write_serial_bytes([SOC, WRITE_CMD, SHA1_ADDR_PREFIX, SHA1_ADDR_BLOCK2,  '\x00', '\x00', '\x00', '\x00', EOC], ser)
    write_serial_bytes([SOC, WRITE_CMD, SHA1_ADDR_PREFIX, SHA1_ADDR_BLOCK3,  '\x00', '\x00', '\x00', '\x00', EOC], ser)
    write_serial_bytes([SOC, WRITE_CMD, SHA1_ADDR_PREFIX, SHA1_ADDR_BLOCK4,  '\x00', '\x00', '\x00', '\x00', EOC], ser)
    write_serial_bytes([SOC, WRITE_CMD, SHA1_ADDR_PREFIX, SHA1_ADDR_BLOCK5,  '\x00', '\x00', '\x00', '\x00', EOC], ser)
    write_serial_bytes([SOC, WRITE_CMD, SHA1_ADDR_PREFIX, SHA1_ADDR_BLOCK6,  '\x00', '\x00', '\x00', '\x00', EOC], ser)
    write_serial_bytes([SOC, WRITE_CMD, SHA1_ADDR_PREFIX, SHA1_ADDR_BLOCK7,  '\x00', '\x00', '\x00', '\x00', EOC], ser)
    write_serial_bytes([SOC, WRITE_CMD, SHA1_ADDR_PREFIX, SHA1_ADDR_BLOCK8,  '\x00', '\x00', '\x00', '\x00', EOC], ser)
    write_serial_bytes([SOC, WRITE_CMD, SHA1_ADDR_PREFIX, SHA1_ADDR_BLOCK9,  '\x00', '\x00', '\x00', '\x00', EOC], ser)
    write_serial_bytes([SOC, WRITE_CMD, SHA1_ADDR_PREFIX, SHA1_ADDR_BLOCK10, '\x00', '\x00', '\x00', '\x00', EOC], ser)
    write_serial_bytes([SOC, WRITE_CMD, SHA1_ADDR_PREFIX, SHA1_ADDR_BLOCK11, '\x00', '\x00', '\x00', '\x00', EOC], ser)
    write_serial_bytes([SOC, WRITE_CMD, SHA1_ADDR_PREFIX, SHA1_ADDR_BLOCK12, '\x00', '\x00', '\x00', '\x00', EOC], ser)
    write_serial_bytes([SOC, WRITE_CMD, SHA1_ADDR_PREFIX, SHA1_ADDR_BLOCK13, '\x00', '\x00', '\x00', '\x00', EOC], ser)
    write_serial_bytes([SOC, WRITE_CMD, SHA1_ADDR_PREFIX, SHA1_ADDR_BLOCK14, '\x00', '\x00', '\x00', '\x00', EOC], ser)
    write_serial_bytes([SOC, WRITE_CMD, SHA1_ADDR_PREFIX, SHA1_ADDR_BLOCK15, '\x00', '\x00', '\x00', '\x18', EOC], ser)
    print "TC1-2: All block words written. Time to read."

    write_serial_bytes([SOC, READ_CMD, SHA1_ADDR_PREFIX, SHA1_ADDR_BLOCK0,  EOC], ser)
    write_serial_bytes([SOC, READ_CMD, SHA1_ADDR_PREFIX, SHA1_ADDR_BLOCK1,  EOC], ser)
    write_serial_bytes([SOC, READ_CMD, SHA1_ADDR_PREFIX, SHA1_ADDR_BLOCK2,  EOC], ser)
    write_serial_bytes([SOC, READ_CMD, SHA1_ADDR_PREFIX, SHA1_ADDR_BLOCK3,  EOC], ser)
    write_serial_bytes([SOC, READ_CMD, SHA1_ADDR_PREFIX, SHA1_ADDR_BLOCK4,  EOC], ser)
    write_serial_bytes([SOC, READ_CMD, SHA1_ADDR_PREFIX, SHA1_ADDR_BLOCK5,  EOC], ser)
    write_serial_bytes([SOC, READ_CMD, SHA1_ADDR_PREFIX, SHA1_ADDR_BLOCK6,  EOC], ser)
    write_serial_bytes([SOC, READ_CMD, SHA1_ADDR_PREFIX, SHA1_ADDR_BLOCK7,  EOC], ser)
    write_serial_bytes([SOC, READ_CMD, SHA1_ADDR_PREFIX, SHA1_ADDR_BLOCK8,  EOC], ser)
    write_serial_bytes([SOC, READ_CMD, SHA1_ADDR_PREFIX, SHA1_ADDR_BLOCK9,  EOC], ser)
    write_serial_bytes([SOC, READ_CMD, SHA1_ADDR_PREFIX, SHA1_ADDR_BLOCK10, EOC], ser)
    write_serial_bytes([SOC, READ_CMD, SHA1_ADDR_PREFIX, SHA1_ADDR_BLOCK11, EOC], ser)
    write_serial_bytes([SOC, READ_CMD, SHA1_ADDR_PREFIX, SHA1_ADDR_BLOCK12, EOC], ser)
    write_serial_bytes([SOC, READ_CMD, SHA1_ADDR_PREFIX, SHA1_ADDR_BLOCK13, EOC], ser)
    write_serial_bytes([SOC, READ_CMD, SHA1_ADDR_PREFIX, SHA1_ADDR_BLOCK14, EOC], ser)
    write_serial_bytes([SOC, READ_CMD, SHA1_ADDR_PREFIX, SHA1_ADDR_BLOCK15, EOC], ser)
    print "TC1-2: All block words read."
    print""

    # TC1-3: Running single block procssing on SHA-1 with the current block.
    print "TC1-3: Starting the SHA-1 core on single block procssing with the current block."
    write_serial_bytes([SOC, WRITE_CMD, SHA1_ADDR_PREFIX, SHA1_ADDR_CTRL, '\x00', '\x00', '\x00', '\x01', EOC], ser)
    time.sleep(0.1)
    print "TC1-3: Reading SHA-1 status and digest."
    write_serial_bytes([SOC, READ_CMD, SHA1_ADDR_PREFIX, SHA1_ADDR_STATUS,   EOC], ser)
    write_serial_bytes([SOC, READ_CMD, SHA1_ADDR_PREFIX, SHA1_ADDR_DIGEST0,  EOC], ser)
    write_serial_bytes([SOC, READ_CMD, SHA1_ADDR_PREFIX, SHA1_ADDR_DIGEST1,  EOC], ser)
    write_serial_bytes([SOC, READ_CMD, SHA1_ADDR_PREFIX, SHA1_ADDR_DIGEST2,  EOC], ser)
    write_serial_bytes([SOC, READ_CMD, SHA1_ADDR_PREFIX, SHA1_ADDR_DIGEST3,  EOC], ser)
    write_serial_bytes([SOC, READ_CMD, SHA1_ADDR_PREFIX, SHA1_ADDR_DIGEST4,  EOC], ser)
    print""
    
    # TC2-1: Read name and version from SHA-256 core.
    print "TC2-1: Reading name, type and version words from SHA-256 core."
    my_cmd = [SOC, READ_CMD, SHA256_ADDR_PREFIX, NAME0_ADDR, EOC]
    write_serial_bytes(my_cmd, ser)
    my_cmd = [SOC, READ_CMD, SHA256_ADDR_PREFIX, NAME1_ADDR, EOC]
    write_serial_bytes(my_cmd, ser)
    my_cmd = [SOC, READ_CMD, SHA256_ADDR_PREFIX, VERSION_ADDR, EOC]
    write_serial_bytes(my_cmd, ser)
    print""


    # TC2-2: Writing and reading a block into the SHA-256 core.
    print "TC2-2: Writing and reading a block into the SHA-256 core."
    write_serial_bytes([SOC, WRITE_CMD, SHA256_ADDR_PREFIX, SHA256_ADDR_BLOCK0,  '\x61', '\x62', '\x63', '\x80', EOC], ser)
    write_serial_bytes([SOC, WRITE_CMD, SHA256_ADDR_PREFIX, SHA256_ADDR_BLOCK1,  '\x00', '\x00', '\x00', '\x00', EOC], ser)
    write_serial_bytes([SOC, WRITE_CMD, SHA256_ADDR_PREFIX, SHA256_ADDR_BLOCK2,  '\x00', '\x00', '\x00', '\x00', EOC], ser)
    write_serial_bytes([SOC, WRITE_CMD, SHA256_ADDR_PREFIX, SHA256_ADDR_BLOCK3,  '\x00', '\x00', '\x00', '\x00', EOC], ser)
    write_serial_bytes([SOC, WRITE_CMD, SHA256_ADDR_PREFIX, SHA256_ADDR_BLOCK4,  '\x00', '\x00', '\x00', '\x00', EOC], ser)
    write_serial_bytes([SOC, WRITE_CMD, SHA256_ADDR_PREFIX, SHA256_ADDR_BLOCK5,  '\x00', '\x00', '\x00', '\x00', EOC], ser)
    write_serial_bytes([SOC, WRITE_CMD, SHA256_ADDR_PREFIX, SHA256_ADDR_BLOCK6,  '\x00', '\x00', '\x00', '\x00', EOC], ser)
    write_serial_bytes([SOC, WRITE_CMD, SHA256_ADDR_PREFIX, SHA256_ADDR_BLOCK7,  '\x00', '\x00', '\x00', '\x00', EOC], ser)
    write_serial_bytes([SOC, WRITE_CMD, SHA256_ADDR_PREFIX, SHA256_ADDR_BLOCK8,  '\x00', '\x00', '\x00', '\x00', EOC], ser)
    write_serial_bytes([SOC, WRITE_CMD, SHA256_ADDR_PREFIX, SHA256_ADDR_BLOCK9,  '\x00', '\x00', '\x00', '\x00', EOC], ser)
    write_serial_bytes([SOC, WRITE_CMD, SHA256_ADDR_PREFIX, SHA256_ADDR_BLOCK10, '\x00', '\x00', '\x00', '\x00', EOC], ser)
    write_serial_bytes([SOC, WRITE_CMD, SHA256_ADDR_PREFIX, SHA256_ADDR_BLOCK11, '\x00', '\x00', '\x00', '\x00', EOC], ser)
    write_serial_bytes([SOC, WRITE_CMD, SHA256_ADDR_PREFIX, SHA256_ADDR_BLOCK12, '\x00', '\x00', '\x00', '\x00', EOC], ser)
    write_serial_bytes([SOC, WRITE_CMD, SHA256_ADDR_PREFIX, SHA256_ADDR_BLOCK13, '\x00', '\x00', '\x00', '\x00', EOC], ser)
    write_serial_bytes([SOC, WRITE_CMD, SHA256_ADDR_PREFIX, SHA256_ADDR_BLOCK14, '\x00', '\x00', '\x00', '\x00', EOC], ser)
    write_serial_bytes([SOC, WRITE_CMD, SHA256_ADDR_PREFIX, SHA256_ADDR_BLOCK15, '\x00', '\x00', '\x00', '\x18', EOC], ser)
    print "TC1-2: All block words written. Time to read."

    write_serial_bytes([SOC, READ_CMD, SHA256_ADDR_PREFIX, SHA256_ADDR_BLOCK0,  EOC], ser)
    write_serial_bytes([SOC, READ_CMD, SHA256_ADDR_PREFIX, SHA256_ADDR_BLOCK1,  EOC], ser)
    write_serial_bytes([SOC, READ_CMD, SHA256_ADDR_PREFIX, SHA256_ADDR_BLOCK2,  EOC], ser)
    write_serial_bytes([SOC, READ_CMD, SHA256_ADDR_PREFIX, SHA256_ADDR_BLOCK3,  EOC], ser)
    write_serial_bytes([SOC, READ_CMD, SHA256_ADDR_PREFIX, SHA256_ADDR_BLOCK4,  EOC], ser)
    write_serial_bytes([SOC, READ_CMD, SHA256_ADDR_PREFIX, SHA256_ADDR_BLOCK5,  EOC], ser)
    write_serial_bytes([SOC, READ_CMD, SHA256_ADDR_PREFIX, SHA256_ADDR_BLOCK6,  EOC], ser)
    write_serial_bytes([SOC, READ_CMD, SHA256_ADDR_PREFIX, SHA256_ADDR_BLOCK7,  EOC], ser)
    write_serial_bytes([SOC, READ_CMD, SHA256_ADDR_PREFIX, SHA256_ADDR_BLOCK8,  EOC], ser)
    write_serial_bytes([SOC, READ_CMD, SHA256_ADDR_PREFIX, SHA256_ADDR_BLOCK9,  EOC], ser)
    write_serial_bytes([SOC, READ_CMD, SHA256_ADDR_PREFIX, SHA256_ADDR_BLOCK10, EOC], ser)
    write_serial_bytes([SOC, READ_CMD, SHA256_ADDR_PREFIX, SHA256_ADDR_BLOCK11, EOC], ser)
    write_serial_bytes([SOC, READ_CMD, SHA256_ADDR_PREFIX, SHA256_ADDR_BLOCK12, EOC], ser)
    write_serial_bytes([SOC, READ_CMD, SHA256_ADDR_PREFIX, SHA256_ADDR_BLOCK13, EOC], ser)
    write_serial_bytes([SOC, READ_CMD, SHA256_ADDR_PREFIX, SHA256_ADDR_BLOCK14, EOC], ser)
    write_serial_bytes([SOC, READ_CMD, SHA256_ADDR_PREFIX, SHA256_ADDR_BLOCK15, EOC], ser)
    print "TC2-2: All block words read."
    print""


    # TC2-3: Running single block procssing on SHA-256 with the current block.
    print "TC2-3: Starting the SHA-256 core on single block procssing with the current block."
    write_serial_bytes([SOC, WRITE_CMD, SHA256_ADDR_PREFIX, SHA256_ADDR_CTRL, '\x00', '\x00', '\x00', '\x01', EOC], ser)
    time.sleep(0.1)
    print "TC2-3: Reading SHA-256 status and digest."
    write_serial_bytes([SOC, READ_CMD, SHA256_ADDR_PREFIX, SHA256_ADDR_STATUS,   EOC], ser)
    write_serial_bytes([SOC, READ_CMD, SHA256_ADDR_PREFIX, SHA256_ADDR_DIGEST0,  EOC], ser)
    write_serial_bytes([SOC, READ_CMD, SHA256_ADDR_PREFIX, SHA256_ADDR_DIGEST1,  EOC], ser)
    write_serial_bytes([SOC, READ_CMD, SHA256_ADDR_PREFIX, SHA256_ADDR_DIGEST2,  EOC], ser)
    write_serial_bytes([SOC, READ_CMD, SHA256_ADDR_PREFIX, SHA256_ADDR_DIGEST3,  EOC], ser)
    write_serial_bytes([SOC, READ_CMD, SHA256_ADDR_PREFIX, SHA256_ADDR_DIGEST4,  EOC], ser)
    write_serial_bytes([SOC, READ_CMD, SHA256_ADDR_PREFIX, SHA256_ADDR_DIGEST5,  EOC], ser)
    write_serial_bytes([SOC, READ_CMD, SHA256_ADDR_PREFIX, SHA256_ADDR_DIGEST6,  EOC], ser)
    write_serial_bytes([SOC, READ_CMD, SHA256_ADDR_PREFIX, SHA256_ADDR_DIGEST7,  EOC], ser)
    print""
    
    # Exit nicely.
    if VERBOSE:
        print "Done. Closing device."
    ser.close()


#-------------------------------------------------------------------
# __name__
# Python thingy which allows the file to be run standalone as
# well as parsed from within a Python interpreter.
#-------------------------------------------------------------------
if __name__=="__main__": 
    # Run the main function.
    sys.exit(main())


#=======================================================================
# EOF hash_tester.py
#=======================================================================