Methods, systems, and apparatus are disclosed which enable flexible insertion of forensic watermarks into a digital content signal using a common customization function. The common customization function flexibly employs a range of different marking techniques that are applicable to a wide range of forensic marking schemes. These customization functions are also applicable to pre-processing and post-processing operations that may be necessary for enhancing the security and transparency of the embedded marks, as well as improving the computational efficiency of the marking process. The common customization function supports a well-defined set of operations specific to the task of forensic mark customization that can be carried out with a modest and preferably bounded effort on a wide range of devices. This is accomplished through the use of a generic transformation technique for use as a “customization” step for producing versions of content forensically marked with any of a multiplicity of mark messages.