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#!/usr/bin/env python

"""
Somewhere, the HSM has to have a last-gasp default PIN, even if it's
only the null string, because there has to be **some** way to
initialize the poor thing.  Absent a better plan (feel free to
suggest one!), this last-gasp default is compiled in.

The normal value of this last-gasp PIN is deliberately chosen to be
annoying, so that people will change it, but since the derevation
requires running PBKDF2 and you might want a different default if
you're compiling this for yourself, we provide the script that
generates the default.
"""

# Author: Rob Austein
# Copyright (c) 2016, 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.

from argparse                   import ArgumentParser, ArgumentDefaultsHelpFormatter
from os                         import urandom
from Crypto.Protocol.KDF        import PBKDF2
from Crypto.Hash                import SHA256, HMAC

parser = ArgumentParser(description = __doc__, formatter_class = ArgumentDefaultsHelpFormatter)
parser.add_argument("-p", "--pin",
                    default = "YouReallyNeedToChangeThisPINRightNowWeAreNotKidding",
                    help    = "PIN plaintext before PBKDF2 processing")
parser.add_argument("-i", "--iterations",
                    type    = int,
                    default = 10000,
                    help    = "PBKDF2 iteration count")
parser.add_argument("-d", "--derived-key-length",
                    type    = int,
                    default = 64,
                    help    = "length of PBKDF2 output (must match libhal)")
args = parser.parse_args()

def HMAC_SHA256(pin, salt):
    return HMAC.new(pin, salt, SHA256).digest()

def hexify(value):
    return ", ".join("0x%02x" % ord(v) for v in value)

salt = urandom(16)

pin  = PBKDF2(password = args.pin,
              salt     = salt,
              dkLen    = args.derived_key_length,
              count    = args.iterations,
              prf      = HMAC_SHA256)

print '''\
/*
 * Automatically generated by a script, do not edit.
 */

static const hal_ks_pin_t hal_last_gasp_pin = {{
  {iterations},
  {{{pin}}},
  {{{salt}}}
}};'''.format(iterations = args.iterations,
              pin        = hexify(pin),
              salt       = hexify(salt))
.".format(args.device)) while True: try: dst = serial.Serial(args.device, 921600, timeout=0.1) except serial.SerialException: time.sleep(0.2) continue dst.write('\r') response = _read(dst, args.verbose) if 'OK' in response: dst.timeout=2 break print('\nUploading firmware\n') crc = 0 counter = 0 # 1. Write size of file (4 bytes) _write(dst, struct.pack('<I', size)) _read(dst, args.verbose) # 2. Write file contents while calculating CRC-32 while True: data = src.read(chunk_size) if not data: break dst.write(data) print("Wrote {!s} bytes (chunk {!s}/{!s})".format(len(data), counter, int(size / chunk_size))) # read ACK (a counter of number of 4k chunks received) while True: ack_bytes = dst.read(4) if len(ack_bytes) == 4: break print('ERROR: Did not receive an ACK, got {!r}'.format(ack_bytes)) dst.write('\r') # eventually get back to the CLI prompt ack = struct.unpack('<I', ack_bytes)[0] if ack != counter + 1: print('ERROR: Did not receive the expected counter as ACK (got {!r}/{!r}, not {!r})'.format(ack, ack_bytes, counter)) flush = dst.read(100) print('FLUSH data: {!r}'.format(flush)) return False counter += 1 crc = crc32(data, crc) & 0xffffffff _read(dst, args.verbose) # 3. Write CRC-32 (4 bytes) _write(dst, struct.pack('<I', crc)) if args.verbose: print('\nFinished - this command might hang now depending on the firmware loaded') _read(dst, args.verbose) else: print('\nFinished uploading firmware') src.close() dst.close() return True def main(args): send_file(args.filename, args) return True if __name__ == '__main__': try: args = parse_args() if main(args): sys.exit(0) sys.exit(1) except KeyboardInterrupt: pass