From 447faf973c5487e0d720b6066b6fb142f926a08d Mon Sep 17 00:00:00 2001
From: Roman Zeyde <romanzeyde@google.com>
Date: Sun, 17 Apr 2016 23:03:41 +0300
Subject: [PATCH] signer should export public key or sign a file

---
 gpg/check.py  |  4 ++--
 gpg/decode.py |  8 ++++----
 gpg/demo.sh   | 11 ++++++++---
 gpg/signer.py | 27 ++++++++++++++++++++++-----
 4 files changed, 36 insertions(+), 14 deletions(-)

diff --git a/gpg/check.py b/gpg/check.py
index 25a82dd..db4e0e1 100755
--- a/gpg/check.py
+++ b/gpg/check.py
@@ -28,7 +28,7 @@ def check(pubkey, sig_file):
     parser = decode.Parser(decode.Reader(d), original_data(sig_file))
     signature, = list(parser)
     decode.verify_digest(pubkey=pubkey, digest=signature['digest'],
-                         signature=signature['sig'], label=sig_file)
+                         signature=signature['sig'], label='GPG signature')
 
 
 def main():
@@ -38,7 +38,7 @@ def main():
     p.add_argument('pubkey')
     p.add_argument('signature')
     args = p.parse_args()
-    check(pubkey=decode.load_public_key(args.pubkey),
+    check(pubkey=decode.load_public_key(open(args.pubkey, 'rb')),
           sig_file=args.signature)
 
 if __name__ == '__main__':
diff --git a/gpg/decode.py b/gpg/decode.py
index ec89336..c936c03 100644
--- a/gpg/decode.py
+++ b/gpg/decode.py
@@ -224,12 +224,12 @@ class Parser(object):
     next = __next__
 
 
-def load_public_key(filename):
-    parser = Parser(Reader(open(filename, 'rb')))
+def load_public_key(stream):
+    parser = Parser(Reader(stream))
     pubkey, userid, signature = list(parser)
     log.info('loaded %s public key', userid['value'])
     verify_digest(pubkey=pubkey, digest=signature['digest'],
-                  signature=signature['sig'], label=filename)
+                  signature=signature['sig'], label='GPG public key')
     return pubkey
 
 
@@ -246,5 +246,5 @@ def verify_digest(pubkey, digest, signature, label):
                         sigdecode=lambda rs, order: rs)
         log.info('%s is OK', label)
     except ecdsa.keys.BadSignatureError:
-        log.error('%s has bad signature!', label)
+        log.error('Bad %s!', label)
         raise
diff --git a/gpg/demo.sh b/gpg/demo.sh
index 6bc7480..a012157 100755
--- a/gpg/demo.sh
+++ b/gpg/demo.sh
@@ -4,11 +4,16 @@ CREATED=1460731897  # needed for consistent public key creation
 NAME="trezor_key"  # will be used as GPG user id and public key name
 
 echo "Hello GPG World!" > EXAMPLE
-./signer.py $NAME --time $CREATED --public-key --file EXAMPLE --verbose
-./check.py $NAME.pub EXAMPLE.sig  # pure Python verification
+# Create, sign and export the public key
+./signer.py $NAME --time $CREATED --public-key --verbose
 
-# Install GPG v2.1 (modern) and verify the signature
+# Install GPG v2.1 (modern) and import the public key
 gpg2 --import $NAME.pub
 gpg2 --list-keys $NAME
+
+# Perform actual GPG signature using TREZOR
+./signer.py $NAME --file EXAMPLE --verbose
+./check.py $NAME.pub EXAMPLE.sig  # pure Python verification
+
 # gpg2 --edit-key trezor_key trust  # optional: mark it as trusted
 gpg2 --verify EXAMPLE.sig
diff --git a/gpg/signer.py b/gpg/signer.py
index 310711c..ac64fe3 100755
--- a/gpg/signer.py
+++ b/gpg/signer.py
@@ -3,12 +3,15 @@ import argparse
 import base64
 import binascii
 import hashlib
+import io
 import logging
 import struct
+import subprocess
 import time
 
 import ecdsa
 
+import decode
 import trezor_agent.client
 import trezor_agent.formats
 import trezor_agent.util
@@ -196,20 +199,29 @@ def armor(blob, type_str):
     return head + split_lines(body, 64) + '=' + checksum + '\n' + tail
 
 
+def load_from_gpg(user_id):
+    pubkey_bytes = subprocess.check_output(['gpg2', '--export', user_id])
+    pubkey = decode.load_public_key(io.BytesIO(pubkey_bytes))
+    return pubkey
+
+
 def main():
     p = argparse.ArgumentParser()
     p.add_argument('user_id')
     p.add_argument('-t', '--time', type=int, default=int(time.time()))
-    p.add_argument('-f', '--filename')
     p.add_argument('-a', '--armor', action='store_true', default=False)
-    p.add_argument('-p', '--public-key', action='store_true', default=False)
     p.add_argument('-v', '--verbose', action='store_true', default=False)
 
+    g = p.add_mutually_exclusive_group()
+    g.add_argument('-f', '--filename', help='File to sign')
+    g.add_argument('-p', '--public-key', 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')
-    s = Signer(user_id=args.user_id.encode('ascii'), created=args.time)
+    user_id = args.user_id.encode('ascii')
     if args.public_key:
+        s = Signer(user_id=user_id, created=args.time)
         pubkey = s.export()
         ext = '.pub'
         if args.armor:
@@ -217,11 +229,16 @@ def main():
             ext = '.asc'
         open(args.user_id + ext, 'wb').write(pubkey)
 
-    if args.filename:
+    elif args.filename:
+        pubkey = load_from_gpg(args.user_id)
+        s = Signer(user_id=user_id, created=pubkey['created'])
+        assert s.key_id == pubkey['key_id']
+
         data = open(args.filename, 'rb').read()
         sig, ext = s.sign(data), '.sig'
         if args.armor:
-            sig, ext = armor(sig, 'SIGNATURE'), '.asc'
+            sig = armor(sig, 'SIGNATURE')
+            ext = '.asc'
         open(args.filename + ext, 'wb').write(sig)
 
     s.close()