Style fix: always have an explicit return.

pdfminer/pdfdocument.py

@@ -284,7 +284,8 @@ class PDFXRefStream(PDFBaseXRef):
 ##
 class PDFStandardSecurityHandler(object):
 
-    PASSWORD_PADDING = b'(\xbfN^Nu\x8aAd\x00NV\xff\xfa\x01\x08..\x00\xb6\xd0h>\x80/\x0c\xa9\xfedSiz'
+    PASSWORD_PADDING = (b'(\xbfN^Nu\x8aAd\x00NV\xff\xfa\x01\x08'
+                        b'..\x00\xb6\xd0h>\x80/\x0c\xa9\xfedSiz')
     supported_revisions = (2, 3)
 
     def __init__(self, docid, param, password=b''):
@@ -292,12 +293,14 @@ class PDFStandardSecurityHandler(object):
         self.param = param
         self.password = password
         self.init()
+        return
 
     def init(self):
         self.init_params()
         if self.r not in self.supported_revisions:
             raise PDFEncryptionError('Unsupported revision: param=%r' % self.param)
         self.init_key()
+        return
 
     def init_params(self):
         self.v = int_value(self.param.get('V', 0))
@@ -306,11 +309,13 @@ class PDFStandardSecurityHandler(object):
         self.o = str_value(self.param['O'])
         self.u = str_value(self.param['U'])
         self.length = int_value(self.param.get('Length', 40))
+        return
 
     def init_key(self):
         self.key = self.authenticate(self.password)
         if self.key is None:
             raise PDFPasswordIncorrect
+        return
 
     def is_printable(self):
         return bool(self.p & 4)
@@ -364,6 +369,8 @@ class PDFStandardSecurityHandler(object):
         key = self.compute_encryption_key(password)
         if self.verify_encryption_key(key):
             return key
+        else:
+            return None
 
     def verify_encryption_key(self, key):
         # Algorithm 3.6
@@ -424,12 +431,15 @@ class PDFStandardSecurityHandlerV4(PDFStandardSecurityHandler):
         self.cfm['Identity'] = self.decrypt_identity
         if self.strf not in self.cfm:
             raise PDFEncryptionError('Undefined crypt filter: param=%r' % self.param)
+        return
 
     def get_cfm(self, name):
         if name == 'V2':
             return self.decrypt_rc4
         elif name == 'AESV2':
             return self.decrypt_aes128
+        else:
+            return None
 
     def decrypt(self, objid, genno, data, attrs=None, name=None):
         if not self.encrypt_metadata and attrs is not None:
@@ -465,10 +475,13 @@ class PDFStandardSecurityHandlerV5(PDFStandardSecurityHandlerV4):
         self.u_hash = self.u[:32]
         self.u_validation_salt = self.u[32:40]
         self.u_key_salt = self.u[40:]
+        return
 
     def get_cfm(self, name):
         if name == 'AESV3':
             return self.decrypt_aes256
+        else:
+            return None
 
     def authenticate(self, password):
         password = password.encode('utf-8')[:127]
@@ -486,6 +499,7 @@ class PDFStandardSecurityHandlerV5(PDFStandardSecurityHandlerV4):
             hash = SHA256.new(password)
             hash.update(self.u_key_salt)
             return AES.new(hash.digest(), mode=AES.MODE_CBC, IV=b'\x00' * 16).decrypt(self.ue)
+        return None
 
     def decrypt_aes256(self, objid, genno, data):
         return AES.new(self.key, mode=AES.MODE_CBC, IV=data[:16]).decrypt(data[16:])
@@ -515,6 +529,7 @@ class PDFDocument(object):
         security_handler_registry[4] = PDFStandardSecurityHandlerV4
         if SHA256 is not None:
             security_handler_registry[5] = PDFStandardSecurityHandlerV5
+
     debug = 0
 
     def __init__(self, parser, password=b'', caching=True, fallback=True):