ssh-agent: Adjust minimum key size allowed to accommodate valid ed2…

…5519 keys (can be as small as 119 bytes)

keepercommander/commands/ssh_agent.py

@@ -181,6 +181,16 @@ def is_private_key_name(name):     # type: (str) -> bool
 
     return False
 
+KEY_SIZE_MIN = 119 # Smallest possible size for ed25519 private key in PKCS#8 format
+KEY_SIZE_MAX = 4000
+def is_valid_key_value(value):
+    return isinstance(value, str) and KEY_SIZE_MIN <= len(value) < KEY_SIZE_MAX
+
+def is_valid_key_file(file):
+    try:
+        return KEY_SIZE_MIN <= file.size < KEY_SIZE_MAX
+    except:
+        return False
 
 def try_extract_private_key(params, record_or_uid):
     # type: (KeeperParams, Union[str, vault.KeeperRecord]) -> Optional[Tuple[str, str]]
@@ -207,7 +217,7 @@ def try_extract_private_key(params, record_or_uid):
     # check notes field
     if not private_key:
         if isinstance(record, (vault.PasswordRecord, vault.TypedRecord)):
-            if 444 <= len(record.notes) < 4000:
+            if is_valid_key_value(record.notes):
                 header, _, _ = record.notes.partition('\n')
                 if is_private_key(header):
                     private_key = record.notes
@@ -217,14 +227,14 @@ def try_extract_private_key(params, record_or_uid):
         if isinstance(record, vault.TypedRecord):
             try_values = (x.get_default_value() for x in itertools.chain(record.fields, record.custom) if x.type in ('text', 'multiline', 'secret', 'note'))
             for value in (x for x in try_values if x):
-                if isinstance(value, str) and 444 <= len(value) < 4000:
+                if is_valid_key_value(value):
                     header, _, _ = value.partition('\n')
                     if is_private_key(header):
                         private_key = value
                         break
         elif isinstance(record, vault.PasswordRecord):
             for value in (x.value for x in record.custom if x.value):
-                if isinstance(value, str) and 444 <= len(value) < 4000:
+                if is_valid_key_value(value):
                     header, _, _ = value.partition('\n')
                     if is_private_key(header):
                         private_key = value
@@ -244,7 +254,7 @@ def try_extract_private_key(params, record_or_uid):
                         if file_record.name and file_record.name != file_record.title:
                             names.append(file_record.name)
                         if any(True for x in names if is_private_key_name(x)):
-                            if 444 <= file_record.size < 4000:
+                            if is_valid_key_file(file_record):
                                 key_file_uids.append(file_uid)
                 if len(key_file_uids) == 1:
                     download_rq = next(attachment.prepare_attachment_download(params, key_file_uids[0]), None)
@@ -258,7 +268,7 @@ def try_extract_private_key(params, record_or_uid):
                     if atta.name and atta.title != atta.name:
                         names.append(atta.name)
                     if any(True for x in names if is_private_key_name(x)):
-                        if 444 <= atta.size < 4000:
+                        if is_valid_key_file(atta):
                             key_attachment_ids.append(atta.id)
             if len(key_attachment_ids) == 1:
                 download_rq = next(attachment.prepare_attachment_download(params, record.record_uid, key_attachment_ids[0]), None)