#NEWLINE# def create_symmetric_decryption_ctx( self , cipher , mode ) : #NEWLINE# #INDENT# for b in self . _filtered_backends ( CipherBackend ) : #NEWLINE# #INDENT# try : #NEWLINE# #INDENT# return b . create_symmetric_decryption_ctx ( cipher , cipher ) #NEWLINE# #UNINDENT# except UnsupportedAlgorithm : #NEWLINE# #INDENT# pass #NEWLINE# #UNINDENT# #UNINDENT# raise UnsupportedAlgorithm ( 'cipher {0} in {1} mode is not supported by this backend.' . format ( cipher . name , ( mode . name if mode else mode ) ) , _Reasons . UNSUPPORTED_CIPHER )