Opportunistic encryption of DMs sent via notification client

notifications_client.py

@@ -11,6 +11,7 @@ import html
 import time
 import sys
 import select
+from random import randint
 from utils import getNicknameFromActor
 from utils import getDomainFromActor
 from utils import getFullDomain
@@ -26,6 +27,8 @@ from follow import sendUnfollowRequestViaServer
 from posts import sendPostViaServer
 from announce import sendAnnounceViaServer
 from pgp import pgpDecrypt
+from pgp import hasLocalPGPkey
+from pgp import pgpEncryptToActor
 
 
 def _waitForKeypress(timeout: int, debug: bool) -> str:
@@ -320,6 +323,32 @@ def _notificationNewDM(session, toHandle: str,
     subject = None
     commentsEnabled = True
     subject = None
+
+    # if there is a local PGP key then attempt to encrypt the DM
+    # using the PGP public key of the recipient
+    if hasLocalPGPkey():
+        sayStr = \
+            'Local PGP key detected...' + \
+            'Fetching PGP public key for ' + toHandle
+        _sayCommand(sayStr, sayStr, screenreader, systemLanguage, espeak)
+        paddedMessage = newMessage
+        if len(paddedMessage) < 32:
+            # add some padding before and after
+            # This is to guard against cribs based on small messages, like "Hi"
+            for before in range(randint(1, 16)):
+                paddedMessage = ' ' + paddedMessage
+            for after in range(randint(1, 16)):
+                paddedMessage += ' '
+        cipherText = \
+            pgpEncryptToActor(paddedMessage, toHandle)
+        if not cipherText:
+            sayStr = toHandle + ' has no PGP public key'
+            _sayCommand(sayStr, sayStr, screenreader, systemLanguage, espeak)
+        else:
+            newMessage = cipherText
+            sayStr = 'Message encrypted'
+            _sayCommand(sayStr, sayStr, screenreader, systemLanguage, espeak)
+
     sayStr = 'Sending'
     _sayCommand(sayStr, sayStr, screenreader, systemLanguage, espeak)
     if sendPostViaServer(__version__,

pgp.py

@@ -6,7 +6,9 @@ __maintainer__ = "Bob Mottram"
 __email__ = "bob@freedombone.net"
 __status__ = "Production"
 
+import os
 import subprocess
+from pathlib import Path
 from person import getActorJson
 
 
@@ -300,7 +302,7 @@ def _pgpImportPubKey(recipientPubKey: str) -> str:
     return keyId
 
 
-def pgpEncrypt(content: str, recipientPubKey: str) -> str:
+def _pgpEncrypt(content: str, recipientPubKey: str) -> str:
     """ Encrypt using your default pgp key to the given recipient
     """
     keyId = _pgpImportPubKey(recipientPubKey)
@@ -321,18 +323,22 @@ def pgpEncrypt(content: str, recipientPubKey: str) -> str:
     return encryptResult
 
 
-def _getPGPPublicKeyFromActor(handle: str) -> str:
+def _getPGPPublicKeyFromActor(handle: str, actorJson=None) -> str:
     """Searches tags on the actor to see if there is any PGP
     public key specified
     """
-    actorJson = getActorJson(handle, False, False, True)
+    if not actorJson:
+        actorJson = getActorJson(handle, False, False, True)
     if not actorJson:
         return None
     if not actorJson.get('attachment'):
         return None
     if not isinstance(actorJson['attachment'], list):
         return None
+    # search through the tags on the actor
     for tag in actorJson['attachment']:
+        if not isinstance(tag, dict):
+            continue
         if not tag.get('value'):
             continue
         if '--BEGIN PGP PUBLIC KEY BLOCK--' in tag['value']:
@@ -340,6 +346,27 @@ def _getPGPPublicKeyFromActor(handle: str) -> str:
     return None
 
 
+def hasLocalPGPkey() -> bool:
+    """Returns true if there is a local .gnupg directory
+    """
+    homeDir = str(Path.home())
+    gpgDir = homeDir + '/.gnupg'
+    if os.path.isfile(gpgDir):
+        return True
+    return False
+
+
+def pgpEncryptToActor(content: str, toHandle: str) -> str:
+    """PGP encrypt a message to the given actor or handle
+    """
+    # get the actor and extract the pgp public key from it
+    recipientPubKey = _getPGPPublicKeyFromActor(toHandle)
+    if not recipientPubKey:
+        return None
+    # encrypt using the recipient public key
+    return _pgpEncrypt(content, recipientPubKey)
+
+
 def pgpDecrypt(content: str, fromHandle: str) -> str:
     """ Encrypt using your default pgp key to the given recipient
     fromHandle can be a handle or actor url
@@ -363,5 +390,5 @@ def pgpDecrypt(content: str, fromHandle: str) -> str:
     (decryptResult, err) = proc.communicate()
     if not decryptResult:
         return content
-    decryptResult = decryptResult.decode('utf-8')
+    decryptResult = decryptResult.decode('utf-8').strip()
     return decryptResult

tests.py

@@ -3000,8 +3000,7 @@ def testFunctions():
         'E2EEremoveDevice',
         'setOrganizationScheme',
         'fill_headers',
-        '_nothing',
-        "pgpEncrypt"
+        '_nothing'
     ]
     excludeImports = [
         'link',