1. A method for speaker verification comprising using at least one hardware processor for: providing a development set comprising multiple voice samples of multiple speakers uttering a predefined development text; prompting a test text to a target speaker, wherein said test text is different from said development text, and recording a test sample of the target speaker uttering the test text; synthesizing a set of artificial voice samples based on said multiple voice samples, wherein each of said artificial voice samples simulates a different speaker of said multiple speakers uttering the test text; and verifying an identity of said target speaker based on said set of artificial voice samples and on said test sample of the target speaker.