--- /dev/null
+#!/usr/bin/env python
+#
+# Copyright (C) 2016 The Android Open Source Project
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""
+Verify a given OTA package with the specifed certificate.
+"""
+
+from __future__ import print_function
+
+import argparse
+import common
+import re
+import subprocess
+import sys
+
+from hashlib import sha1
+from hashlib import sha256
+
+
+def cert_uses_sha256(cert):
+ """Check if the cert uses SHA-256 hashing algorithm."""
+
+ cmd = ['openssl', 'x509', '-text', '-noout', '-in', cert]
+ p1 = common.Run(cmd, stdout=subprocess.PIPE)
+ cert_dump, _ = p1.communicate()
+
+ algorithm = re.search(r'Signature Algorithm: ([a-zA-Z0-9]+)', cert_dump)
+ assert algorithm, "Failed to identify the signature algorithm."
+
+ assert not algorithm.group(1).startswith('ecdsa'), (
+ 'This script doesn\'t support verifying ECDSA signed package yet.')
+
+ return algorithm.group(1).startswith('sha256')
+
+
+def verify_package(cert, package):
+ """Verify the given package with the certificate.
+
+ (Comments from bootable/recovery/verifier.cpp:)
+
+ An archive with a whole-file signature will end in six bytes:
+
+ (2-byte signature start) $ff $ff (2-byte comment size)
+
+ (As far as the ZIP format is concerned, these are part of the
+ archive comment.) We start by reading this footer, this tells
+ us how far back from the end we have to start reading to find
+ the whole comment.
+ """
+
+ print('Package: %s' % (package,))
+ print('Certificate: %s' % (cert,))
+
+ # Read in the package.
+ with open(package) as package_file:
+ package_bytes = package_file.read()
+
+ length = len(package_bytes)
+ assert length >= 6, "Not big enough to contain footer."
+
+ footer = [ord(x) for x in package_bytes[-6:]]
+ assert footer[2] == 0xff and footer[3] == 0xff, "Footer is wrong."
+
+ signature_start_from_end = (footer[1] << 8) + footer[0]
+ assert signature_start_from_end > 6, "Signature start is in the footer."
+
+ signature_start = length - signature_start_from_end
+
+ # Determine how much of the file is covered by the signature. This is
+ # everything except the signature data and length, which includes all of the
+ # EOCD except for the comment length field (2 bytes) and the comment data.
+ comment_len = (footer[5] << 8) + footer[4]
+ signed_len = length - comment_len - 2
+
+ print('Package length: %d' % (length,))
+ print('Comment length: %d' % (comment_len,))
+ print('Signed data length: %d' % (signed_len,))
+ print('Signature start: %d' % (signature_start,))
+
+ use_sha256 = cert_uses_sha256(cert)
+ print('Use SHA-256: %s' % (use_sha256,))
+
+ if use_sha256:
+ h = sha256()
+ else:
+ h = sha1()
+ h.update(package_bytes[:signed_len])
+ package_digest = h.hexdigest().lower()
+
+ print('Digest: %s\n' % (package_digest,))
+
+ # Get the signature from the input package.
+ signature = package_bytes[signature_start:-6]
+ sig_file = common.MakeTempFile(prefix='sig-', suffix='')
+ with open(sig_file, 'wb') as f:
+ f.write(signature)
+
+ # Parse the signature and get the hash.
+ cmd = ['openssl', 'asn1parse', '-inform', 'DER', '-in', sig_file]
+ p1 = common.Run(cmd, stdout=subprocess.PIPE)
+ sig, _ = p1.communicate()
+ assert p1.returncode == 0, "Failed to parse the signature."
+
+ digest_line = sig.strip().split('\n')[-1]
+ digest_string = digest_line.split(':')[3]
+ digest_file = common.MakeTempFile(prefix='digest-', suffix='')
+ with open(digest_file, 'wb') as f:
+ f.write(digest_string.decode('hex'))
+
+ # Verify the digest by outputing the decrypted result in ASN.1 structure.
+ decrypted_file = common.MakeTempFile(prefix='decrypted-', suffix='')
+ cmd = ['openssl', 'rsautl', '-verify', '-certin', '-inkey', cert,
+ '-in', digest_file, '-out', decrypted_file]
+ p1 = common.Run(cmd, stdout=subprocess.PIPE)
+ p1.communicate()
+ assert p1.returncode == 0, "Failed to run openssl rsautl -verify."
+
+ # Parse the output ASN.1 structure.
+ cmd = ['openssl', 'asn1parse', '-inform', 'DER', '-in', decrypted_file]
+ p1 = common.Run(cmd, stdout=subprocess.PIPE)
+ decrypted_output, _ = p1.communicate()
+ assert p1.returncode == 0, "Failed to parse the output."
+
+ digest_line = decrypted_output.strip().split('\n')[-1]
+ digest_string = digest_line.split(':')[3].lower()
+
+ # Verify that the two digest strings match.
+ assert package_digest == digest_string, "Verification failed."
+
+ # Verified successfully upon reaching here.
+ print('VERIFIED\n')
+
+
+def main():
+ parser = argparse.ArgumentParser()
+ parser.add_argument('certificate', help='The certificate to be used.')
+ parser.add_argument('package', help='The OTA package to be verified.')
+ args = parser.parse_args()
+
+ verify_package(args.certificate, args.package)
+
+
+if __name__ == '__main__':
+ try:
+ main()
+ except AssertionError as err:
+ print('\n ERROR: %s\n' % (err,))
+ sys.exit(1)
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