From a137dc395ccaa8f7d2003790f877777324716a41 Mon Sep 17 00:00:00 2001
From: brent s <r00t@square-r00t.net>
Date: Tue, 13 Mar 2018 11:14:41 -0400
Subject: [PATCH] adding re-signing

---
 re_sign.py    | 83 +++++++++++++++++++++++++++++++++++++++++++++++++++
 verifyfeed.py |  1 +
 2 files changed, 84 insertions(+)
 create mode 100755 re_sign.py

diff --git a/re_sign.py b/re_sign.py
new file mode 100755
index 0000000..a3859c0
--- /dev/null
+++ b/re_sign.py
@@ -0,0 +1,83 @@
+#!/usr/bin/env python3.6
+
+# stdlib
+import os
+import re
+# pypi
+import gpg
+import gpg.constants
+import gpg.errors
+
+# Re-sign all episode files that have an invalid signature.
+
+# The GPG home
+GNUPGHOME = '~/podcast/gpg'
+# The key ID to use to sign/verify. Must exist in the local keyring, trusted, etc.
+GPGKEY = '0x63D1CEA387C27A92E0D50AB8343C305F9109D4DC'
+# The "parent" path that contains both audio files and detached sigs.
+# It is assumed that the sigs for each episode file live in ../gpg/* (relative
+# to the media file(s)).
+# If you need to change this, check the signer class.
+EPPATH = '~/podcast/releases'
+FILEEXTS = ('mp3', 'ogg')
+
+class signer(object):
+    def __init__(self, key_id, gpg_home = '~/.gnupg',
+                 sig_ext = '.asc', gpg_armor = True):
+        os.environ['GNUPGHOME'] = os.path.abspath(os.path.expanduser(gpg_home))
+        self.sig_ext = sig_ext
+        self.gpg = gpg.Context()
+        # has to be an iterable
+        self.gpg.signers = []
+        self.key = self.gpg.get_key(key_id, True)
+        if self.key.can_sign:
+            self.gpg.signers.append(self.key)
+        self.gpg.armor = True
+
+    def chkSigValid(self, fpath, sigpath_base):
+        sigpath = '.'.join((sigpath_base, re.sub('^\.', '', self.sig_ext)))
+        with open(sigpath, 'rb') as sig, open(fpath, 'rb') as f, \
+                                         open(os.devnull, 'wb') as DEVNULL:
+            try:
+                self.gpg.verify(f, signature = sig, sink = DEVNULL,
+                                verify = self.gpg.signers)
+                return(True)
+            except (gpg.errors.BadSignatures, gpg.errors.GPGMEError,
+                    FileNotFoundError):
+                print('BAD/MISSING SIGNATURE: {0}'.format(fpath))
+                return(False)
+
+    def signEpFile(self, fpath, sigpath_base):
+        sigpath = '.'.join((sigpath_base, re.sub('^\.', '', self.sig_ext)))
+        with open(sigpath, 'wb') as f, open(fpath, 'rb') as s:
+            f.write(self.gpg.sign(s, mode = gpg.constants.SIG_MODE_DETACH)[0])
+        print('Signed/re-signed {0}'.format(fpath))
+        return()
+
+def getEpFiles(path, exts):
+    print('Building list of media files; please wait...')
+    fpaths = []
+    path = os.path.abspath(os.path.expanduser(path))
+    for root, dirs, files in os.walk(path):
+        for f in files:
+            if f.endswith(exts):
+                fpaths.append(os.path.join(root, f))
+    return(fpaths)
+
+def main(GPGHOME = GNUPGHOME, KEYID = GPGKEY,
+         EPSPATH = EPPATH, FILEEXT = FILEEXTS):
+    fpaths = getEpFiles(EPSPATH, FILEEXT)
+    sig = signer(KEYID, gpg_home = GPGHOME)
+    print('Verifying files (and signing if necessary)...')
+    for f in fpaths:
+        sigfilebase = os.path.abspath(
+                        os.path.join(
+                            os.path.dirname(f),
+                            os.path.join('..',
+                                         'gpg',
+                                         os.path.basename(f))))
+        if not sig.chkSigValid(f, sigfilebase):
+            sig.signEpFile(f, sigfilebase)
+
+if __name__ == '__main__':
+    main()
diff --git a/verifyfeed.py b/verifyfeed.py
index 9e4ad41..96d4260 100755
--- a/verifyfeed.py
+++ b/verifyfeed.py
@@ -11,6 +11,7 @@ try:
     from lxml import etree
 except ImportError:
     import xml.etree.ElementTree as etree
+# TODO: GPG verification too
 
 baseurl = 'https://sysadministrivia.com'