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trezor-agent/trezor_agent/gpg/check.py

52 lines
1.6 KiB
Python

#!/usr/bin/env python
"""Check GPG v2 signature for a given public key."""
import argparse
import base64
import io
import logging
from . import decode
from .. import util
log = logging.getLogger(__name__)
def original_data(filename):
"""Locate and load original file data, whose signature is provided."""
parts = filename.rsplit('.', 1)
if len(parts) == 2 and parts[1] in ('sig', 'asc'):
log.debug('loading file %s', parts[0])
return open(parts[0], 'rb').read()
def verify(pubkey, sig_file):
"""Verify correctness of public key and signature."""
stream = open(sig_file, 'rb')
if stream.name.endswith('.asc'):
lines = stream.readlines()[3:-1]
data = base64.b64decode(''.join(lines))
payload, checksum = data[:-3], data[-3:]
assert util.crc24(payload) == checksum
stream = io.BytesIO(payload)
signature, digest = decode.load_signature(stream, original_data(sig_file))
decode.verify_digest(pubkey=pubkey, digest=digest,
signature=signature['sig'], label='GPG signature')
log.info('%s OK', sig_file)
def main():
"""Main function."""
p = argparse.ArgumentParser()
p.add_argument('pubkey')
p.add_argument('signature')
p.add_argument('-v', '--verbose', action='store_true', default=False)
args = p.parse_args()
logging.basicConfig(level=logging.DEBUG if args.verbose else logging.INFO,
format='%(asctime)s %(levelname)-10s %(message)s')
verify(pubkey=decode.load_public_key(open(args.pubkey, 'rb')),
sig_file=args.signature)
if __name__ == '__main__':
main()