1. A method for voice transformation, comprising: transforming a source speech of a person using transformation parameters, wherein the transforming comprises modifying the source speech to sound as if the source speech were spoken by a different person; and encoding information on the transformation parameters in an output speech using steganography, wherein the source speech can be reconstructed using the output speech and the information on the transformation parameters, and wherein at least one of the transforming and the encoding is performed by a processor.