| #!/usr/bin/env python3 |
| # SPDX-License-Identifier: BSD-2-Clause |
| # |
| # Copyright (c) 2015, 2017, 2019, Linaro Limited |
| # |
| |
| import sys |
| |
| |
| def uuid_parse(s): |
| from uuid import UUID |
| return UUID(s) |
| |
| |
| def int_parse(str): |
| return int(str, 0) |
| |
| |
| def get_args(logger): |
| from argparse import ArgumentParser, RawDescriptionHelpFormatter |
| import textwrap |
| command_base = ['sign-enc', '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 |
| |
| dat = '[' + ', '.join(command_aliases_digest) + ']' |
| sat = '[' + ', '.join(command_aliases_stitch) + ']' |
| |
| parser = ArgumentParser( |
| description='Sign and encrypt (optional) a Tusted Application for' + |
| ' OP-TEE.', |
| usage='\n %(prog)s command [ arguments ]\n\n' |
| |
| ' command:\n' + |
| ' sign-enc Generate signed and optionally encrypted loadable' + |
| ' TA image file.\n' + |
| ' Takes arguments --uuid, --ta-version, --in, --out,' + |
| ' --key\n' + |
| ' and --enc-key (optional).\n' + |
| ' digest Generate loadable TA binary image digest' + |
| ' for offline\n' + |
| ' signing. Takes arguments --uuid, --ta-version,' + |
| ' --in, --key,\n' |
| ' --enc-key (optional) and --dig.\n' + |
| ' stitch Generate loadable signed and encrypted TA binary' + |
| ' image file from\n' + |
| ' TA raw image and its signature. Takes' + |
| ' arguments\n' + |
| ' --uuid, --in, --key, --enc-key (optional), --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-enc". |
| |
| 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-enc', |
| help='Command, one of [' + ', '.join(command_base) + ']') |
| parser.add_argument('--uuid', required=True, |
| type=uuid_parse, help='String UUID of the TA') |
| parser.add_argument('--key', required=True, |
| help='Name of signing key file (PEM format)') |
| parser.add_argument('--enc-key', required=False, |
| help='Encryption key string') |
| parser.add_argument( |
| '--ta-version', required=False, type=int_parse, default=0, |
| help='TA version stored as a 32-bit unsigned integer and used for\n' + |
| 'rollback protection of TA install in the secure database.\n' + |
| 'Defaults to 0.') |
| 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=True, 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 Cryptodome.Signature import pss |
| from Cryptodome.Hash import SHA256 |
| from Cryptodome.PublicKey import RSA |
| import base64 |
| import logging |
| import os |
| import struct |
| |
| logging.basicConfig() |
| logger = logging.getLogger(os.path.basename(__file__)) |
| |
| args = get_args(logger) |
| |
| with open(args.key, 'rb') as f: |
| key = RSA.importKey(f.read()) |
| |
| with open(args.inf, 'rb') as f: |
| img = f.read() |
| |
| h = SHA256.new() |
| |
| digest_len = h.digest_size |
| sig_len = key.size_in_bytes() |
| |
| img_size = len(img) |
| |
| hdr_version = args.ta_version # struct shdr_bootstrap_ta::ta_version |
| |
| magic = 0x4f545348 # SHDR_MAGIC |
| if args.enc_key: |
| img_type = 2 # SHDR_ENCRYPTED_TA |
| else: |
| img_type = 1 # SHDR_BOOTSTRAP_TA |
| algo = 0x70414930 # TEE_ALG_RSASSA_PKCS1_PSS_MGF1_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', hdr_version) |
| |
| if args.enc_key: |
| from Cryptodome.Cipher import AES |
| cipher = AES.new(bytearray.fromhex(args.enc_key), AES.MODE_GCM) |
| ciphertext, tag = cipher.encrypt_and_digest(img) |
| |
| enc_algo = 0x40000810 # TEE_ALG_AES_GCM |
| flags = 0 # SHDR_ENC_KEY_DEV_SPECIFIC |
| ehdr = struct.pack('<IIHH', |
| enc_algo, flags, len(cipher.nonce), len(tag)) |
| |
| h.update(shdr) |
| h.update(shdr_uuid) |
| h.update(shdr_version) |
| if args.enc_key: |
| h.update(ehdr) |
| h.update(cipher.nonce) |
| h.update(tag) |
| h.update(img) |
| img_digest = h.digest() |
| |
| 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) |
| if args.enc_key: |
| f.write(ehdr) |
| f.write(cipher.nonce) |
| f.write(tag) |
| f.write(ciphertext) |
| else: |
| f.write(img) |
| |
| def sign_encrypt_ta(): |
| if not key.has_private(): |
| logger.error('Provided key cannot be used for signing, ' + |
| 'please use offline-signing mode.') |
| sys.exit(1) |
| else: |
| signer = pss.new(key) |
| sig = signer.sign(h) |
| if len(sig) != sig_len: |
| raise Exception(("Actual signature length is not equal to ", |
| "the computed one: {} != {}"). |
| format(len(sig), sig_len)) |
| 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.exists(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) |
| sys.exit(1) |
| else: |
| verifier = pss.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.') |
| sys.exit(1) |
| |
| # dispatch command |
| { |
| 'sign-enc': sign_encrypt_ta, |
| 'digest': generate_digest, |
| 'generate-digest': generate_digest, |
| 'stitch': stitch_ta, |
| 'stitch-ta': stitch_ta |
| }.get(args.command, 'sign_encrypt_ta')() |
| |
| |
| if __name__ == "__main__": |
| main() |
