scripts: imgtool: compression

Adds LZMA2 compression to imgtool.
Python lzma library is unable to compress with proper parameters while using
"ALONE" container, therefore 2 header bytes are calculated and added
to payload by imgtool.

Signed-off-by: Mateusz Michalek <mateusz.michalek@nordicsemi.no>

scripts/imgtool/image.py

@@ -20,7 +20,14 @@
 Image signing and management.
 """
 
+from . import version as versmod
+from .boot_record import create_sw_component_data
+import click
+from enum import Enum
+import array
+from intelhex import IntelHex
 import hashlib
+import array
 import os.path
 import struct
 from enum import Enum
@@ -58,6 +65,8 @@
  'NON_BOOTABLE': 0x0000010,
  'RAM_LOAD': 0x0000020,
  'ROM_FIXED': 0x0000100,
+ 'COMPRESSED_LZMA1': 0x0000200,
+ 'COMPRESSED_LZMA2': 0x0000400,
 }
 
 TLV_VALUES = {
@@ -76,6 +85,9 @@
  'DEPENDENCY': 0x40,
  'SEC_CNT': 0x50,
  'BOOT_RECORD': 0x60,
+ 'DECOMP_SIZE': 0x70,
+ 'DECOMP_SHA': 0x71,
+ 'DECOMP_SIGNATURE': 0x72,
 }
 
 TLV_SIZE = 4
@@ -165,6 +177,8 @@ def __init__(self, version=None, header_size=IMAGE_HEADER_SIZE,
  if load_addr and rom_fixed:
  raise click.UsageError("Can not set rom_fixed and load_addr at the same time")
 
+ self.image_hash = None
+ self.image_size = None
  self.version = version or versmod.decode_version("0")
  self.header_size = header_size
  self.pad_header = pad_header
@@ -228,7 +242,7 @@ def __repr__(self):
  self.__class__.__name__,
  len(self.payload))
 
- def load(self, path):
+ def load(self, path, compression_header=None):
  """Load an image from a given file"""
  ext = os.path.splitext(path)[1][1:].lower()
  try:
@@ -239,8 +253,26 @@ def load(self, path):
  else:
  with open(path, 'rb') as f:
  self.payload = f.read()
+ if compression_header is not None:
+ self.payload = compression_header + self.payload
  except FileNotFoundError:
  raise click.UsageError("Input file not found")
+ self.image_size = len(self.payload)
+
+ # Add the image header if needed.
+ if self.pad_header and self.header_size > 0:
+ if self.base_addr:
+ # Adjust base_addr for new header
+ self.base_addr -= self.header_size
+ self.payload = bytes([self.erased_val] * self.header_size) + \
+ self.payload
+
+ self.check_header()
+
+ def load_compressed(self, data, compression_header):
+ """Load an image from buffer"""
+ self.payload = compression_header + data
+ self.image_size = len(self.payload)
 
  # Add the image header if needed.
  if self.pad_header and self.header_size > 0:
@@ -335,8 +367,8 @@ def ecies_hkdf(self, enckey, plainkey):
  return cipherkey, ciphermac, pubk
 
  def create(self, key, public_key_format, enckey, dependencies=None,
- sw_type=None, custom_tlvs=None, encrypt_keylen=128, clear=False,
- fixed_sig=None, pub_key=None, vector_to_sign=None):
+ sw_type=None, custom_tlvs=None, compression_tlvs=None, compression_type=None, encrypt_keylen=128,
+ clear=False, fixed_sig=None, pub_key=None, vector_to_sign=None):
  self.enckey = enckey
 
  # Check what hashing algorithm should be used
@@ -402,6 +434,9 @@ def create(self, key, public_key_format, enckey, dependencies=None,
  dependencies_num = len(dependencies[DEP_IMAGES_KEY])
  protected_tlv_size += (dependencies_num * 16)
 
+ if compression_tlvs is not None:
+ for value in compression_tlvs.values():
+ protected_tlv_size += TLV_SIZE + len(value)
  if custom_tlvs is not None:
  for value in custom_tlvs.values():
  protected_tlv_size += TLV_SIZE + len(value)
@@ -423,11 +458,15 @@ def create(self, key, public_key_format, enckey, dependencies=None,
  else:
  self.payload.extend(pad)
 
+ compression_flags = 0x0
+ if compression_tlvs is not None:
+ if compression_type == "lzma2":
+ compression_flags = IMAGE_F['COMPRESSED_LZMA2']
  # This adds the header to the payload as well
  if encrypt_keylen == 256:
- self.add_header(enckey, protected_tlv_size, 256)
+ self.add_header(enckey, protected_tlv_size, compression_flags, 256)
  else:
- self.add_header(enckey, protected_tlv_size)
+ self.add_header(enckey, protected_tlv_size, compression_flags)
 
  prot_tlv = TLV(self.endian, TLV_PROT_INFO_MAGIC)
 
@@ -457,6 +496,9 @@ def create(self, key, public_key_format, enckey, dependencies=None,
  )
  prot_tlv.add('DEPENDENCY', payload)
 
+ if compression_tlvs is not None:
+ for tag, value in compression_tlvs.items():
+ prot_tlv.add(tag, value)
  if custom_tlvs is not None:
  for tag, value in custom_tlvs.items():
  prot_tlv.add(tag, value)
@@ -472,6 +514,7 @@ def create(self, key, public_key_format, enckey, dependencies=None,
  sha.update(self.payload)
  digest = sha.digest()
  tlv.add(hash_tlv, digest)
+ self.image_hash = digest
 
  if vector_to_sign == 'payload':
  # Stop amending data to the image
@@ -551,10 +594,13 @@ def create(self, key, public_key_format, enckey, dependencies=None,
 
  self.check_trailer()
 
+ def get_struct_endian(self):
+ return STRUCT_ENDIAN_DICT[self.endian]
+
  def get_signature(self):
  return self.signature
 
- def add_header(self, enckey, protected_tlv_size, aes_length=128):
+ def add_header(self, enckey, protected_tlv_size, compression_flags, aes_length=128):
  """Install the image header."""
 
  flags = 0
@@ -592,7 +638,7 @@ def add_header(self, enckey, protected_tlv_size, aes_length=128):
  protected_tlv_size, # TLV Info header +
  # Protected TLVs
  len(self.payload) - self.header_size, # ImageSz
- flags,
+ flags | compression_flags,
  self.version.major,
  self.version.minor or 0,
  self.version.revision or 0,

scripts/imgtool/main.py

@@ -22,13 +22,24 @@
 import getpass
 import imgtool.keys as keys
 import sys
+import struct
+import os
+import lzma
+import hashlib
 import base64
 from imgtool import image, imgtool_version
 from imgtool.version import decode_version
 from imgtool.dumpinfo import dump_imginfo
 from .keys import (
  RSAUsageError, ECDSAUsageError, Ed25519UsageError, X25519UsageError)
 
+comp_default_dictsize=131072
+comp_default_pb=2
+comp_default_lc=3
+comp_default_lp=1
+comp_default_preset=9
+
+
 MIN_PYTHON_VERSION = (3, 6)
 if sys.version_info < MIN_PYTHON_VERSION:
  sys.exit("Python %s.%s or newer is required by imgtool."
@@ -299,6 +310,14 @@ def get_dependencies(ctx, param, value):
  dependencies[image.DEP_VERSIONS_KEY] = versions
  return dependencies
 
+def create_lzma2_header(dictsize, pb, lc, lp):
+ header = bytearray()
+ for i in range(0, 40):
+ if dictsize <= ((2 | ((i) & 1)) << int((i) / 2 + 11)):
+ header.append(i)
+ break
+ header.append( ( pb * 5 + lp) * 9 + lc)
+ return header
 
 class BasedIntParamType(click.ParamType):
  name = 'integer'
@@ -342,6 +361,11 @@ def convert(self, value, param, ctx):
  type=click.Choice(['128', '256']),
  help='When encrypting the image using AES, select a 128 bit or '
  '256 bit key len.')
+@click.option('--compression', default='lzma2',
+ type=click.Choice(['disabled', 'lzma2']),
+ help='Enable image compression using specified type. '
+ 'Will fall back without image compression automatically '
+ 'if the compression increases the image size.')
 @click.option('-c', '--clear', required=False, is_flag=True, default=False,
  help='Output a non-encrypted image with encryption capabilities,'
  'so it can be installed in the primary slot, and encrypted '
@@ -410,10 +434,11 @@ def convert(self, value, param, ctx):
  .hex extension, otherwise binary format is used''')
 def sign(key, public_key_format, align, version, pad_sig, header_size,
  pad_header, slot_size, pad, confirm, max_sectors, overwrite_only,
- endian, encrypt_keylen, encrypt, infile, outfile, dependencies,
- load_addr, hex_addr, erased_val, save_enctlv, security_counter,
- boot_record, custom_tlv, rom_fixed, max_align, clear, fix_sig,
- fix_sig_pubkey, sig_out, vector_to_sign, non_bootable):
+ endian, encrypt_keylen, encrypt, compression, infile, outfile,
+ dependencies, load_addr, hex_addr, erased_val, save_enctlv,
+ security_counter, boot_record, custom_tlv, rom_fixed, max_align,
+ clear, fix_sig, fix_sig_pubkey, sig_out, vector_to_sign,
+ non_bootable):
 
  if confirm:
  # Confirmed but non-padded images don't make much sense, because
@@ -427,6 +452,7 @@ def sign(key, public_key_format, align, version, pad_sig, header_size,
  erased_val=erased_val, save_enctlv=save_enctlv,
  security_counter=security_counter, max_align=max_align,
  non_bootable=non_bootable)
+ compression_tlvs = {}
  img.load(infile)
  key = load_key(key) if key else None
  enckey = load_key(encrypt) if encrypt else None
@@ -480,10 +506,51 @@ def sign(key, public_key_format, align, version, pad_sig, header_size,
  }
 
  img.create(key, public_key_format, enckey, dependencies, boot_record,
- custom_tlvs, int(encrypt_keylen), clear, baked_signature,
+ custom_tlvs, compression_tlvs, int(encrypt_keylen), clear,
+ baked_signature, pub_key, vector_to_sign)
+
+ if compression == "lzma2" :
+ compressed_img = image.Image(version=decode_version(version),
+ header_size=header_size, pad_header=pad_header,
+ pad=pad, confirm=confirm, align=int(align),
+ slot_size=slot_size, max_sectors=max_sectors,
+ overwrite_only=overwrite_only, endian=endian,
+ load_addr=load_addr, rom_fixed=rom_fixed,
+ erased_val=erased_val, save_enctlv=save_enctlv,
+ security_counter=security_counter, max_align=max_align)
+ compressed_file = re.sub('bin$', 'compressed.bin', infile)
+ compression_filters = [
+ {"id": lzma.FILTER_LZMA2, "preset": comp_default_preset,
+ "dict_size": comp_default_dictsize, "lp": comp_default_lp,
+ "lc": comp_default_lc}
+ ]
+ in_fd=open(infile, "rb")
+ compressed_data = lzma.compress(in_fd.read(),filters=compression_filters,
+ format=lzma.FORMAT_RAW)
+ in_fd.close()
+ uncompressed_size = os.path.getsize(infile)
+ compressed_size = len(compressed_data)
+ print("compressed image size:", compressed_size,
+ "bytes\noriginal image size:", uncompressed_size, "bytes")
+ compression_tlvs["DECOMP_SIZE"] = struct.pack(
+ img.get_struct_endian() + 'L', img.image_size)
+ compression_tlvs["DECOMP_SHA"] = img.image_hash
+ compression_tlvs["DECOMP_SIGNATURE"] = img.signature
+ compression_tlvs_size = len(compression_tlvs["DECOMP_SIZE"])
+ compression_tlvs_size += len(compression_tlvs["DECOMP_SHA"])
+ compression_tlvs_size += len(compression_tlvs["DECOMP_SIGNATURE"])
+ if (compressed_size + compression_tlvs_size) < uncompressed_size:
+ compression_header = create_lzma2_header(
+ dictsize = comp_default_dictsize, pb = comp_default_pb,
+ lc = comp_default_lc, lp = comp_default_lp)
+ compressed_img.load_compressed(compressed_data, compression_header)
+ compressed_img.base_addr = img.base_addr
+ compressed_img.create(key, public_key_format, enckey,
+ dependencies, boot_record, custom_tlvs, compression_tlvs,
+ compression, int(encrypt_keylen), clear, baked_signature,
  pub_key, vector_to_sign)
+ img = compressed_img
  img.save(outfile, hex_addr)
-
  if sig_out is not None:
  new_signature = img.get_signature()
  save_signature(sig_out, new_signature)