The invention relates to a method for dying and/or lightening keratin fibres using direct cationic disulphide dyes of formula (I) a cosmetic composition including same and a device with a plurality of compartments including same: Formula (I) in which: R R R R R R Q Q X Y and An are such as defined in the description and n p = 0 or 1. The dyeing method and the composition according to the invention make it possible in particular to achieve lasting dyeing of keratin fibres that is intense chromatic and/or uniform with or without the use of an oxidising agent.
