imgtool: Add clear image generation with encryption capability
Create an option to generate a clear image with encryption capability
that can be installed on a primary slot. Since image has encryption
capability image can be swapped encrypted in secondary slot
Signed-off-by: Michel Jaouen <michel.jaouen@st.com>
diff --git a/scripts/imgtool/image.py b/scripts/imgtool/image.py
index 2f0a1fa..d04333e 100644
--- a/scripts/imgtool/image.py
+++ b/scripts/imgtool/image.py
@@ -305,7 +305,7 @@
return cipherkey, ciphermac, pubk
def create(self, key, public_key_format, enckey, dependencies=None,
- sw_type=None, custom_tlvs=None, encrypt_keylen=128):
+ sw_type=None, custom_tlvs=None, encrypt_keylen=128, clear=False):
self.enckey = enckey
# Calculate the hash of the public key
@@ -472,13 +472,14 @@
else:
tlv.add('ENCX25519', enctlv)
- nonce = bytes([0] * 16)
- cipher = Cipher(algorithms.AES(plainkey), modes.CTR(nonce),
- backend=default_backend())
- encryptor = cipher.encryptor()
- img = bytes(self.payload[self.header_size:])
- self.payload[self.header_size:] = \
- encryptor.update(img) + encryptor.finalize()
+ if not clear:
+ nonce = bytes([0] * 16)
+ cipher = Cipher(algorithms.AES(plainkey), modes.CTR(nonce),
+ backend=default_backend())
+ encryptor = cipher.encryptor()
+ img = bytes(self.payload[self.header_size:])
+ self.payload[self.header_size:] = \
+ encryptor.update(img) + encryptor.finalize()
self.payload += prot_tlv.get()
self.payload += tlv.get()
diff --git a/scripts/imgtool/main.py b/scripts/imgtool/main.py
index 87eccd9..e3f2775 100755
--- a/scripts/imgtool/main.py
+++ b/scripts/imgtool/main.py
@@ -254,6 +254,10 @@
type=click.Choice(['128','256']),
help='When encrypting the image using AES, select a 128 bit or '
'256 bit key len.')
+@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 '
+ 'when swapped to the secondary.')
@click.option('-e', '--endian', type=click.Choice(['little', 'big']),
default='little', help="Select little or big endian")
@click.option('--overwrite-only', default=False, is_flag=True,
@@ -303,7 +307,7 @@
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):
+ boot_record, custom_tlv, rom_fixed, max_align, clear):
if confirm:
# Confirmed but non-padded images don't make much sense, because
@@ -350,7 +354,7 @@
custom_tlvs[tag] = value.encode('utf-8')
img.create(key, public_key_format, enckey, dependencies, boot_record,
- custom_tlvs, int(encrypt_keylen))
+ custom_tlvs, int(encrypt_keylen), clear)
img.save(outfile, hex_addr)