Support for PGP Email Support (DeltaChat Compatible) (#1205)

all-plugin-requirements.txt

@@ -11,3 +11,6 @@ gntp
 # Provides mqtt:// support
 # use v1.x due to https://github.com/eclipse/paho.mqtt.python/issues/814
 paho-mqtt < 2.0.0
+
+# Pretty Good Privacy (PGP) Provides mailto:// and deltachat:// support
+PGPy

apprise/plugins/email.py

@@ -27,28 +27,42 @@
 # POSSIBILITY OF SUCH DAMAGE.
 
 import dataclasses
+import os
 import re
 import smtplib
 import typing as t
 from email.mime.text import MIMEText
 from email.mime.application import MIMEApplication
 from email.mime.multipart import MIMEMultipart
+from email.mime.base import MIMEBase
 from email.utils import formataddr, make_msgid
 from email.header import Header
 from email import charset
+import hashlib
 
 from socket import error as SocketError
 from datetime import datetime
+from datetime import timedelta
 from datetime import timezone
 
+from ..apprise_attachment import AppriseAttachment
 from .base import NotifyBase
 from ..url import PrivacyMode
-from ..common import NotifyFormat, NotifyType
+from ..common import NotifyFormat, NotifyType, PersistentStoreMode
 from ..conversion import convert_between
-from ..utils import is_ipaddr, is_email, parse_emails, is_hostname
+from ..utils import is_ipaddr, is_email, parse_emails, is_hostname, parse_bool
 from ..locale import gettext_lazy as _
 from ..logger import logger
 
+try:
+    import pgpy
+    # Pretty Good Privacy (PGP) Support enabled
+    PGP_SUPPORT = True
+
+except ImportError:
+    # Pretty Good Privacy (PGP) Support disabled
+    PGP_SUPPORT = False
+
 # Globally Default encoding mode set to Quoted Printable.
 charset.add_charset('utf-8', charset.QP, charset.QP, 'utf-8')
 
@@ -355,6 +369,10 @@ class NotifyEmail(NotifyBase):
     # Support attachments
     attachment_support = True
 
+    # There is no reason a PGP Public Key should exceed 8K in size
+    # If it is more than this, then it is not accepted
+    max_pgp_public_key_size = 8000
+
     # Default Notify Format
     notify_format = NotifyFormat.HTML
 
@@ -439,6 +457,12 @@ class NotifyEmail(NotifyBase):
             'type': 'string',
             'map_to': 'smtp_host',
         },
+        'pgp': {
+            'name': _('PGP Encryption'),
+            'type': 'bool',
+            'map_to': 'use_pgp',
+            'default': False,
+        },
         'mode': {
             'name': _('Secure Mode'),
             'type': 'choice:string',
@@ -451,6 +475,14 @@ class NotifyEmail(NotifyBase):
             'type': 'list:string',
             'map_to': 'reply_to',
         },
+        'pgpkey': {
+            'name': _('PGP Public Key Path'),
+            'type': 'string',
+            'private': True,
+            # By default persistent storage is referenced
+            'default': '',
+            'map_to': 'pgp_key',
+        },
     })
 
     # Define any kwargs we're using
@@ -463,7 +495,7 @@ class NotifyEmail(NotifyBase):
 
     def __init__(self, smtp_host=None, from_addr=None, secure_mode=None,
                  targets=None, cc=None, bcc=None, reply_to=None, headers=None,
-                 **kwargs):
+                 use_pgp=None, pgp_key=None, **kwargs):
         """
         Initialize Email Object
 
@@ -500,6 +532,29 @@ class NotifyEmail(NotifyBase):
         self.smtp_host = \
             smtp_host if isinstance(smtp_host, str) else ''
 
+        # pgp hash
+        self.pgp_public_keys = {}
+
+        self.use_pgp = use_pgp if not None \
+            else self.template_args['pgp']['default']
+
+        if self.use_pgp and not PGP_SUPPORT:
+            self.logger.warning(
+                'PGP Support is not available on this installation; '
+                'ask admin to install PGPy')
+
+        # Our template object is just an AppriseAttachment object
+        if pgp_key:
+            self.pgp_key = AppriseAttachment(asset=self.asset)
+            # Add our definition to our pgp_key reference
+            self.pgp_key.add(pgp_key)
+            # Enforce maximum file size
+            self.pgp_key[0].max_file_size = self.max_pgp_public_key_size
+
+        else:
+            # No key; use auto-generation
+            self.pgp_key = None
+
         # Now detect secure mode
         if secure_mode:
             self.secure_mode = None \
@@ -733,6 +788,10 @@ class NotifyEmail(NotifyBase):
                 'There are no Email recipients to notify')
             return False
 
+        elif self.use_pgp and not PGP_SUPPORT:
+            self.logger.warning('PGP Support unavailable')
+            return False
+
         messages: t.List[EmailMessage] = []
 
         # Create a copy of the targets list
@@ -831,6 +890,40 @@ class NotifyEmail(NotifyBase):
                         mixed.attach(app)
                 base = mixed
 
+            if self.use_pgp:
+                self.logger.debug("Securing email with PGP Encryption")
+                # Set our header information to include in the encryption
+                base['From'] = formataddr(
+                    (None, self.from_addr[1]), charset='utf-8')
+                base['To'] = formataddr((None, to_addr), charset='utf-8')
+                base['Subject'] = Header(title, self._get_charset(title))
+
+                # Apply our encryption
+                encrypted_content = self.pgp_encrypt_message(base.as_string())
+                if not encrypted_content:
+                    self.logger.warning('Unable to PGP encrypt email')
+                    # Unable to send notification
+                    return False
+
+                # prepare our messsage
+                base = MIMEMultipart(
+                    "encrypted", protocol="application/pgp-encrypted")
+
+                # Store Autocrypt header (DeltaChat Support)
+                base.add_header(
+                    "Autocrypt",
+                    "addr=%s; prefer-encrypt=mutual" % formataddr(
+                        (False, to_addr), charset='utf-8'))
+
+                # Set Encryption Info Part
+                enc_payload = MIMEText("Version: 1", "plain")
+                enc_payload.set_type("application/pgp-encrypted")
+                base.attach(enc_payload)
+
+                enc_payload = MIMEBase("application", "octet-stream")
+                enc_payload.set_payload(encrypted_content)
+                base.attach(enc_payload)
+
             # Apply any provided custom headers
             for k, v in self.headers.items():
                 base[k] = Header(v, self._get_charset(v))
@@ -901,38 +994,269 @@ class NotifyEmail(NotifyBase):
                         message.to_addrs,
                         message.body)
 
-                    self.logger.info(
+                    self.logger.info('Sent Email to %s', message.recipient)
-                        f'Sent Email notification to "{message.recipient}".')
+
                 except (SocketError, smtplib.SMTPException, RuntimeError) as e:
                     self.logger.warning(
-                        f'Sending email to "{message.recipient}" failed. '
+                        'Sending email to "%s" failed.', message.recipient)
-                        f'Reason: {e}')
+                    self.logger.debug(f'Socket Exception: {e}')
 
                     # Mark as failure
                     has_error = True
 
         except (SocketError, smtplib.SMTPException, RuntimeError) as e:
             self.logger.warning(
-                f'Connection error while submitting email to {self.smtp_host}.'
+                'Connection error while submitting email to "%s"',
-                f' Reason: {e}')
+                self.smtp_host)
+            self.logger.debug(f'Socket Exception: {e}')
 
             # Mark as failure
             has_error = True
 
         finally:
             # Gracefully terminate the connection with the server
-            if socket is not None:  # pragma: no branch
+            if socket is not None:
                 socket.quit()
 
+        # Reduce our dictionary (eliminate expired keys if any)
+        self.pgp_public_keys = {
+            key: value for key, value in self.pgp_public_keys.items()
+            if value['expires'] > datetime.now(timezone.utc)}
+
         return not has_error
 
+    def pgp_generate_keys(self, path=None):
+        """
+        Generates a set of keys based on email configured
+        """
+        if path is None:
+            if self.store.mode == PersistentStoreMode.MEMORY:
+                # Not possible - no write permissions
+                return False
+
+            # Set our path
+            path = self.store.path
+
+        try:
+            # Create a new RSA key pair with 2048-bit strength
+            key = pgpy.PGPKey.new(
+                pgpy.constants.PubKeyAlgorithm.RSAEncryptOrSign, 2048)
+
+        except NameError:
+            # PGPy not installed
+            self.logger.debug('PGPy not installed; ignoring PGP file: %s')
+            return False
+
+        # Prepare our uid
+        name, email = self.names[self.from_addr[1]], self.from_addr[1]
+        uid = pgpy.PGPUID.new(name, email=email)
+
+        # Filenames
+        file_prefix = email.split('@')[0].lower()
+        pub_path = os.path.join(path, f'{file_prefix}-pub.asc')
+        prv_path = os.path.join(path, f'{file_prefix}-prv.asc')
+
+        if os.path.isfile(pub_path):
+            self.logger.warning(
+                'PGP generation aborted; Public key already exists: %s',
+                pub_path)
+            return True
+
+        # Add the user ID to the key
+        key.add_uid(uid, usage={
+            pgpy.constants.KeyFlags.Sign,
+            pgpy.constants.KeyFlags.EncryptCommunications},
+            hashes=[pgpy.constants.HashAlgorithm.SHA256],
+            ciphers=[pgpy.constants.SymmetricKeyAlgorithm.AES256],
+            compression=[pgpy.constants.CompressionAlgorithm.ZLIB])
+
+        try:
+            # Write our keys to disk
+            with open(pub_path, 'w') as f:
+                f.write(str(key.pubkey))
+
+        except OSError as e:
+            self.logger.warning('Error writing PGP file %s', pub_path)
+            self.logger.debug(f'I/O Exception: {e}')
+
+            # Cleanup
+            try:
+                os.unlink(pub_path)
+                self.logger.trace('Removed %s', pub_path)
+
+            except OSError:
+                pass
+
+        try:
+
+            with open(prv_path, 'w') as f:
+                f.write(str(key))
+
+        except OSError as e:
+            self.logger.warning('Error writing PGP file %s', prv_path)
+            self.logger.debug(f'I/O Exception: {e}')
+            try:
+                os.unlink(pub_path)
+                self.logger.trace('Removed %s', pub_path)
+
+            except OSError:
+                pass
+
+            try:
+                os.unlink(prv_path)
+                self.logger.trace('Removed %s', prv_path)
+
+            except OSError:
+                pass
+
+            return False
+
+        self.logger.info(
+            'Wrote PGP Keys for %s/%s',
+            os.path.dirname(pub_path),
+            os.path.basename(pub_path))
+        return True
+
+    def pgp_pubkey(self, email=None):
+        """
+        Returns a list of filenames worth scanning for
+        """
+        if self.pgp_key is not None:
+            # If our code reaches here, then we fetch our public key
+            pgp_key = self.pgp_key[0]
+            if not pgp_key:
+                # We could not access the attachment
+                self.logger.error(
+                    'Could not access PGP Public Key {}.'.format(
+                        pgp_key.url(privacy=True)))
+                return False
+
+            return pgp_key.path
+
+        elif not self.store.path:
+            # No path
+            return None
+
+        fnames = [
+            'pgp-public.asc',
+            'pgp-pub.asc',
+            'public.asc',
+            'pub.asc',
+        ]
+
+        # Prepare our key files
+        emails = [self.from_addr[1]]
+        if email:
+            emails.append(email)
+
+        for email in emails:
+            _entry = email.split('@')[0].lower()
+            fnames.insert(0, f'{_entry}-pub.asc')
+
+            # Lowercase email (Highest Priority)
+            _entry = email.lower()
+            fnames.insert(0, f'{_entry}-pub.asc')
+
+        return next(
+            (os.path.join(self.store.path, fname)
+             for fname in fnames
+             if os.path.isfile(os.path.join(self.store.path, fname))),
+            None)
+
+    def pgp_public_key(self, path=None, email=None):
+        """
+        Opens a spcified pgp public file and returns the key from it which
+        is used to encrypt the message
+        """
+        if path is None:
+            path = self.pgp_pubkey(email=email)
+
+            if not path:
+                if self.pgp_generate_keys(path=self.store.path):
+                    path = self.pgp_pubkey(email=email)
+                    if path:
+                        # We should get a hit now
+                        return self.pgp_public_key(path=path)
+
+                self.logger.warning('No PGP Public Key could be loaded')
+                return None
+
+        # Persistent storage key
+        ps_key = hashlib.sha1(
+            os.path.abspath(path).encode('utf-8')).hexdigest()
+        if ps_key in self.pgp_public_keys:
+            # Take an early exit
+            return self.pgp_public_keys[ps_key]['public_key']
+
+        try:
+            with open(path, 'r') as key_file:
+                public_key, _ = pgpy.PGPKey.from_blob(key_file.read())
+
+        except NameError:
+            # PGPy not installed
+            self.logger.debug(
+                'PGPy not installed; skipping PGP support: %s', path)
+            return None
+
+        except FileNotFoundError:
+            # Generate keys
+            self.logger.debug('PGP Public Key file not found: %s', path)
+            return None
+
+        except OSError as e:
+            self.logger.warning('Error accessing PGP Public Key file %s', path)
+            self.logger.debug(f'I/O Exception: {e}')
+            return None
+
+        self.pgp_public_keys[ps_key] = {
+            'public_key': public_key,
+            'expires':
+            datetime.now(timezone.utc) + timedelta(seconds=86400)
+        }
+        return public_key
+
+    # Encrypt message using the recipient's public key
+    def pgp_encrypt_message(self, message, path=None):
+        """
+        If provided a path to a pgp-key, content is encrypted
+        """
+
+        # Acquire our key
+        public_key = self.pgp_public_key(path=path)
+        if not public_key:
+            # Encryption not possible
+            return False
+
+        try:
+            message_object = pgpy.PGPMessage.new(message)
+            encrypted_message = public_key.encrypt(message_object)
+            return str(encrypted_message)
+
+        except pgpy.errors.PGPError:
+            # Encryption not Possible
+            self.logger.debug(
+                'PGP Public Key Corruption; encryption not possible')
+
+        except NameError:
+            # PGPy not installed
+            self.logger.debug('PGPy not installed; Skipping PGP encryption')
+
+        return None
+
     def url(self, privacy=False, *args, **kwargs):
         """
         Returns the URL built dynamically based on specified arguments.
         """
 
         # Define an URL parameters
-        params = {}
+        params = {
+            'pgp': 'yes' if self.use_pgp else 'no',
+        }
+
+        # Store oure public key back into your URL
+        if self.pgp_key is not None:
+            params['pgp_key'] = NotifyEmail.quote(
+                self.pgp_key[0].url(privacy=privacy), safe=':')
 
         # Append our headers into our parameters
         params.update({'+{}'.format(k): v for k, v in self.headers.items()})
@@ -1044,7 +1368,7 @@ class NotifyEmail(NotifyBase):
         """
         return (
             self.secure_protocol if self.secure else self.protocol,
-            self.user, self.password, self.host,
+            self.user, self.password, self.host, self.smtp_host,
             self.port if self.port
             else SECURE_MODES[self.secure_mode]['default_port'],
         )
@@ -1053,8 +1377,7 @@ class NotifyEmail(NotifyBase):
         """
         Returns the number of targets associated with this notification
         """
-        targets = len(self.targets)
+        return len(self.targets) if self.targets else 1
-        return targets if targets > 0 else 1
 
     @staticmethod
     def parse_url(url):
@@ -1086,6 +1409,16 @@ class NotifyEmail(NotifyBase):
             # value if invalid; we'll attempt to figure this out later on
             results['host'] = ''
 
+        # Get PGP Flag
+        results['use_pgp'] = \
+            parse_bool(results['qsd'].get(
+                'pgp', NotifyEmail.template_args['pgp']['default']))
+
+        # Get PGP Public Key Override
+        if 'pgpkey' in results['qsd'] and results['qsd']['pgpkey']:
+            results['pgp_key'] = \
+                NotifyEmail.unquote(results['qsd']['pgpkey'])
+
         # The From address is a must; either through the use of templates
         # from= entry and/or merging the user and hostname together, this
         # must be calculated or parse_url will fail.

test/var/pgp/corrupt-pub.asc

@@ -0,0 +1,18 @@
+-----BEGIN PGP PUBLIC KEY BLOCK-----
+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+=ZY2q
+-----END PGP PUBLIC KEY BLOCK-----

test/var/pgp/valid-pub.asc

@@ -0,0 +1,18 @@
+-----BEGIN PGP PUBLIC KEY BLOCK-----
+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+=ZY2q
+-----END PGP PUBLIC KEY BLOCK-----