gpg: refactor cli

trezor_agent/gpg/README

@@ -0,0 +1,22 @@
+# Generate new stand-along GPG identity
+
+```
+$ USER_ID="Satoshi Nakamoto <satoshi@nakamoto.bit>"
+$ trezor-gpg create "${USER_ID}" > identity.pub           # create new TREZOR-based GPG identity
+$ gpg2 --import identity.pub                              # import into local GPG public keyring
+$ gpg2 --edit "${USER_ID}" trust                          # OPTIONAL: mark the key as trusted
+```
+
+# Generate new subkey for existing GPG identity
+```
+$ USER_ID="Satoshi Nakamoto <satoshi@nakamoto.bit>"
+$ gpg2 --list-keys "${USER_ID}"                           # make sure this identity already exists
+$ trezor-gpg create --subkey "${USER_ID}" > identity.pub  # create new TREZOR-based GPG public key
+$ gpg2 --import identity.pub                              # append it to existing identity
+```
+
+# Generate signatures using the TREZOR device
+```
+$ trezor-gpg sign EXAMPLE > EXAMPLE.sig					  # confirm signature using the device
+$ gpg2 --verify EXAMPLE.sig                               # verify using standard GPG binary
+```

trezor_agent/gpg/check.py

@@ -1,51 +0,0 @@
-#!/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()

trezor_agent/gpg/decode.py

@@ -1,4 +1,5 @@
 """Decoders for GPG v2 data structures."""
+import base64
 import functools
 import hashlib
 import io
@@ -268,6 +269,7 @@ def load_public_key(stream, use_custom=False):
         packet, signature = packets[:2]
         packets = packets[2:]
 
+    packet['user_id'] = userid['value']
     return packet
 
 
@@ -281,7 +283,8 @@ def load_signature(stream, original_data):
 
 def load_from_gpg(user_id, use_custom=False):
     """Load existing GPG public key for `user_id` from local keyring."""
-    pubkey_bytes = subprocess.check_output(['gpg2', '--export', user_id])
+    args = ['gpg2', '--export'] + ([user_id] if user_id else [])
+    pubkey_bytes = subprocess.check_output(args=args)
     if pubkey_bytes:
         return load_public_key(io.BytesIO(pubkey_bytes), use_custom=use_custom)
     else:
@@ -298,3 +301,19 @@ def verify_digest(pubkey, digest, signature, label):
     except ecdsa.keys.BadSignatureError:
         log.error('Bad %s!', label)
         raise
+
+
+def verify(pubkey, signature, original_data):
+    """Verify correctness of public key and signature."""
+    stream = io.BytesIO(signature)
+
+    # remove GPG armor
+    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 = load_signature(stream, original_data)
+    verify_digest(pubkey=pubkey, digest=digest,
+                  signature=signature['sig'], label='GPG signature')

trezor_agent/gpg/encode.py

@@ -125,8 +125,9 @@ class Signer(object):
             curve_name=curve_name, created=created,
             verifying_key=self.conn.pubkey())
 
-        log.info('%s GPG public key %s created at %s', curve_name,
-                 self.pubkey, util.time_format(self.pubkey.created))
+        log.info('%s GPG public key %s created at %s for "%s"',
+                 curve_name, self.pubkey,
+                 util.time_format(self.pubkey.created), user_id)
 
     @classmethod
     def from_public_key(cls, pubkey, user_id):

trezor_agent/gpg/signer.py

@@ -6,73 +6,65 @@ import subprocess as sp
 import sys
 import time
 
-from . import check, decode, encode
+from . import decode, encode
 
 log = logging.getLogger(__name__)
 
 
-def _open_output(filename):
-    return sys.stdout if filename == '-' else open(filename, 'wb')
+def run_create(args):
+    """Generate a new pubkey for a new/existing GPG identity."""
+    s = encode.Signer(user_id=args.user_id, created=args.time,
+                      curve_name=args.ecdsa_curve)
+    if args.subkey:
+        subkey = s.subkey()
+        primary = sp.check_output(['gpg2', '--export', args.user_id])
+        result = primary + subkey
+    else:
+        result = s.export()
+    s.close()
+
+    return encode.armor(result, 'PUBLIC KEY BLOCK')
+
 
+def run_sign(args):
+    """Generate a GPG signature using hardware-based device."""
+    pubkey = decode.load_from_gpg(user_id=None, use_custom=True)
+    s = encode.Signer.from_public_key(pubkey=pubkey, user_id=pubkey['user_id'])
+    if args.filename:
+        data = open(args.filename, 'rb').read()
+    else:
+        data = sys.stdin.read()
+    sig = s.sign(data)
+    s.close()
 
-def _call_with_input(args, blob):
-    p = sp.Popen(args=args, stdin=sp.PIPE)
-    p.stdin.write(blob)
-    p.stdin.close()
-    exit_code = p.wait()
-    assert exit_code == 0, exit_code
+    sig = encode.armor(sig, 'SIGNATURE')
+    decode.verify(pubkey=pubkey, signature=sig, original_data=data)
+    return sig
 
 
 def main():
     """Main function."""
     p = argparse.ArgumentParser()
-    p.add_argument('user_id')
-    p.add_argument('filename', nargs='?')
-    p.add_argument('-t', '--time', type=int, default=int(time.time()))
-    p.add_argument('-a', '--armor', action='store_true', default=False)
     p.add_argument('-v', '--verbose', action='store_true', default=False)
-    p.add_argument('-s', '--subkey', action='store_true', default=False)
-    p.add_argument('-e', '--ecdsa-curve', default='nist256p1')
-    p.add_argument('-o', '--output',
-                   help='Output file name for the results. '
-                   'Use "-" to write the results to stdout or "GPG" '
-                   'to import a public key into the local keyring.')
+    subparsers = p.add_subparsers()
+
+    create = subparsers.add_parser('create')
+    create.add_argument('user_id', help='e.g. '
+                        '"Satoshi Nakamoto <satoshi@nakamoto.bit>"')
+    create.add_argument('-s', '--subkey', action='store_true', default=False)
+    create.add_argument('-e', '--ecdsa-curve', default='nist256p1')
+    create.add_argument('-t', '--time', type=int, default=int(time.time()))
+    create.set_defaults(run=run_create)
+
+    sign = subparsers.add_parser('sign')
+    sign.add_argument('filename', nargs='?')
+    sign.set_defaults(run=run_sign)
 
     args = p.parse_args()
     logging.basicConfig(level=logging.DEBUG if args.verbose else logging.INFO,
                         format='%(asctime)s %(levelname)-10s %(message)s')
-    user_id = args.user_id.encode('ascii')
-    if not args.filename:
-        s = encode.Signer(user_id=user_id, created=args.time,
-                          curve_name=args.ecdsa_curve)
-        if args.subkey:
-            pubkey = s.subkey()
-        else:
-            pubkey = s.export()
-
-        ext = '.pub'
-        if args.armor:
-            pubkey = encode.armor(pubkey, 'PUBLIC KEY BLOCK')
-            ext = '.asc'
-        filename = args.output or '-'  # use stdout if no file specified
-        if filename == 'GPG':
-            log.info('importing public key to local keyring')
-            _call_with_input(['gpg2', '--import'], pubkey)
-        else:
-            _open_output(filename).write(pubkey)
-    else:
-        pubkey = decode.load_from_gpg(user_id, use_custom=True)
-        s = encode.Signer.from_public_key(pubkey=pubkey, user_id=user_id)
-        data = open(args.filename, 'rb').read()
-        sig, ext = s.sign(data), '.sig'
-        if args.armor:
-            sig = encode.armor(sig, 'SIGNATURE')
-            ext = '.asc'
-        filename = args.output or (args.filename + ext)
-        _open_output(filename).write(sig)
-        check.verify(pubkey=pubkey, sig_file=filename)
-
-    s.close()
+    result = args.run(args)
+    sys.stdout.write(result)
 
 
 if __name__ == '__main__':