Support offline signing of TAs.
Add generate-digest and stitch-ta support to script sign.py. One can
generate a digest for the loadable TA file, sign it offline and later
stitch the generated signature to the loadable TA binary file.
For this purpose sign.py gets an extra initial command argument to select
between sign/digest/stitch operations. If no command is provided, `sign`
is assumed, preserving previous usage.
Signed-off-by: Markus S. Wamser <markus.wamser@mixed-mode.de>
Acked-by: Etienne Carriere <etienne.carriere@linaro.org>
Reviewed-by: Jerome Forissier <jerome.forissier@linaro.org>
diff --git a/scripts/sign.py b/scripts/sign.py
index 84fd771..608d59c 100755
--- a/scripts/sign.py
+++ b/scripts/sign.py
@@ -4,6 +4,8 @@
#
# SPDX-License-Identifier: BSD-2-Clause
+import sys
+
def uuid_parse(s):
from uuid import UUID
@@ -14,65 +16,200 @@
return int(str, 0)
-def get_args():
- from argparse import ArgumentParser
+def get_args(logger):
+ from argparse import ArgumentParser, RawDescriptionHelpFormatter
+ import textwrap
+ command_base = ['sign', 'digest', 'stitch']
+ command_aliases_digest = ['generate-digest']
+ command_aliases_stitch = ['stitch-ta']
+ command_aliases = command_aliases_digest + command_aliases_stitch
+ command_choices = command_base + command_aliases
- parser = ArgumentParser()
+ dat = '[' + ', '.join(command_aliases_digest) + ']'
+ sat = '[' + ', '.join(command_aliases_stitch) + ']'
+
+ parser = ArgumentParser(
+ description='Sign a Tusted Application for OP-TEE.',
+ usage='\n %(prog)s command [ arguments ]\n\n'
+
+ ' command:\n' +
+ ' sign Generate signed loadable TA image file.\n' +
+ ' Takes arguments --uuid, --in, --out' +
+ ' and --key.\n' +
+ ' digest Generate loadable TA binary image digest' +
+ ' for offline\n' +
+ ' signing. Takes arguments --uuid, --in and' +
+ ' --dig.\n' +
+ ' stitch Generate loadable signed TA binary image' +
+ ' file from\n' +
+ ' TA raw image and its signature. Takes' +
+ ' arguments\n' +
+ ' --uuid, --in, --out, and --sig.\n\n' +
+ ' %(prog)s --help show available commands and arguments\n\n',
+ formatter_class=RawDescriptionHelpFormatter,
+ epilog=textwrap.dedent('''\
+ If no command is given, the script will default to "sign".
+
+ command aliases:
+ The command \'digest\' can be aliased by ''' + dat + '''
+ The command \'stitch\' can be aliased by ''' + sat + '\n' + '''
+ example offline signing command using OpenSSL:
+ base64 -d <UUID>.dig | \\
+ openssl pkeyutl -sign -inkey <KEYFILE>.pem \\
+ -pkeyopt digest:sha256 \\
+ -pkeyopt rsa_padding_mode:pkcs1 | \\
+ base64 > <UUID>.sig
+ '''))
+
+ parser.add_argument(
+ 'command', choices=command_choices, nargs='?',
+ default='sign',
+ help='Command, one of [' + ', '.join(command_base) + ']')
parser.add_argument('--uuid', required=True,
- type=uuid_parse, help='UUID of TA')
- parser.add_argument('--version', type=int_parse, default=0, help='Version')
- parser.add_argument('--key', required=True, help='Name of key file')
- parser.add_argument('--in', required=True, dest='inf',
- help='Name of in file')
- parser.add_argument('--out', required=True, help='Name of out file')
- return parser.parse_args()
+ type=uuid_parse, help='String UUID of the TA')
+ parser.add_argument('--key', required=True,
+ help='Name of key file (PEM format)')
+ parser.add_argument(
+ '--sig', required=False, dest='sigf',
+ help='Name of signature input file, defaults to <UUID>.sig')
+ parser.add_argument(
+ '--dig', required=False, dest='digf',
+ help='Name of digest output file, defaults to <UUID>.dig')
+ parser.add_argument(
+ '--in', required=False, dest='inf',
+ help='Name of application input file, defaults to <UUID>.stripped.elf')
+ parser.add_argument(
+ '--out', required=False, dest='outf',
+ help='Name of application output file, defaults to <UUID>.ta')
+
+ parsed = parser.parse_args()
+
+ # Check parameter combinations
+
+ if parsed.digf is None and \
+ parsed.outf is not None and \
+ parsed.command in ['digest'] + command_aliases_digest:
+ logger.error('A digest was requested, but argument --out was given.' +
+ ' Did you mean:\n ' +
+ parser.prog+' --dig ' + parsed.outf + ' ...')
+ sys.exit(1)
+
+ if parsed.digf is not None \
+ and parsed.outf is not None \
+ and parsed.command in ['digest'] + command_aliases_digest:
+ logger.warn('A digest was requested, but arguments --dig and ' +
+ '--out were given.\n' +
+ ' --out will be ignored.')
+
+ # Set defaults for optional arguments.
+
+ if parsed.sigf is None:
+ parsed.sigf = str(parsed.uuid)+'.sig'
+ if parsed.digf is None:
+ parsed.digf = str(parsed.uuid)+'.dig'
+ if parsed.inf is None:
+ parsed.inf = str(parsed.uuid)+'.stripped.elf'
+ if parsed.outf is None:
+ parsed.outf = str(parsed.uuid)+'.ta'
+
+ return parsed
def main():
from Crypto.Signature import PKCS1_v1_5
from Crypto.Hash import SHA256
from Crypto.PublicKey import RSA
+ from Crypto.Util.number import ceil_div
+ import base64
+ import logging
+ import os
import struct
- args = get_args()
+ logging.basicConfig()
+ logger = logging.getLogger(os.path.basename(__file__))
- f = open(args.key, 'rb')
- key = RSA.importKey(f.read())
- f.close()
+ args = get_args(logger)
- f = open(args.inf, 'rb')
- img = f.read()
- f.close()
+ with open(args.key, 'rb') as f:
+ key = RSA.importKey(f.read())
- signer = PKCS1_v1_5.new(key)
+ with open(args.inf, 'rb') as f:
+ img = f.read()
+
h = SHA256.new()
digest_len = h.digest_size
- sig_len = len(signer.sign(h))
+ sig_len = ceil_div(key.size() + 1, 8)
img_size = len(img)
- magic = 0x4f545348 # SHDR_MAGIC
- img_type = 1 # SHDR_BOOTSTRAP_TA
+ hdr_version = 0 # SHDR_VERSION (always 0)
+ magic = 0x4f545348 # SHDR_MAGIC
+ img_type = 1 # SHDR_BOOTSTRAP_TA
algo = 0x70004830 # TEE_ALG_RSASSA_PKCS1_V1_5_SHA256
shdr = struct.pack('<IIIIHH',
magic, img_type, img_size, algo, digest_len, sig_len)
shdr_uuid = args.uuid.bytes
- shdr_version = struct.pack('<I', args.version)
+ shdr_version = struct.pack('<I', hdr_version)
h.update(shdr)
h.update(shdr_uuid)
h.update(shdr_version)
h.update(img)
- sig = signer.sign(h)
+ img_digest = h.digest()
- f = open(args.out, 'wb')
- f.write(shdr)
- f.write(h.digest())
- f.write(sig)
- f.write(shdr_uuid)
- f.write(shdr_version)
- f.write(img)
- f.close()
+ def write_image_with_signature(sig):
+ with open(args.outf, 'wb') as f:
+ f.write(shdr)
+ f.write(img_digest)
+ f.write(sig)
+ f.write(shdr_uuid)
+ f.write(shdr_version)
+ f.write(img)
+
+ def sign_ta():
+ if not key.has_private():
+ logger.error('Provided key cannot be used for signing, ' +
+ 'please use offline-signing mode.')
+ else:
+ signer = PKCS1_v1_5.new(key)
+ sig = signer.sign(h)
+ write_image_with_signature(sig)
+ logger.info('Successfully signed application.')
+
+ def generate_digest():
+ with open(args.digf, 'wb+') as digfile:
+ digfile.write(base64.b64encode(img_digest))
+
+ def stitch_ta():
+ try:
+ with open(args.sigf, 'r') as sigfile:
+ sig = base64.b64decode(sigfile.read())
+ except IOError:
+ if not os.path.exits(args.digf):
+ generate_digest()
+ logger.error('No signature file found. Please sign\n %s\n' +
+ 'offline and place the signature at \n %s\n' +
+ 'or pass a different location ' +
+ 'using the --sig argument.\n',
+ args.digf, args.sigf)
+ else:
+ verifier = PKCS1_v1_5.new(key)
+ if verifier.verify(h, sig):
+ write_image_with_signature(sig)
+ logger.info('Successfully applied signature.')
+ else:
+ logger.error('Verification failed, ignoring given signature.')
+
+ command_dict = {
+ 'sign': sign_ta,
+ 'digest': generate_digest,
+ 'generate-digest': generate_digest,
+ 'stitch': stitch_ta,
+ 'stitch-ta': stitch_ta
+ }
+
+ fun = command_dict.get(args.command, 'sign_ta')
+ fun()
if __name__ == "__main__":