The present invention relates to a method of generating an array of random bits. The method generates unique arrays of random bits using carbon nanotube field effect transistor fabrication technology and can be used for security applications. The method includes: modifying a substrate to form a modified surface having a pattern selected from a group including: trenches, rigs, and a combination thereof; depositing a compound on the trenches and/or the rigs; and applying a dispersion of carbon nanomaterials onto the modified surface to form an array of random bits. The first system includes setting an array of random bits based on carbon nanomaterials as a digital signature by measuring electric charge flowing through each individual bit. The second system includes protecting an array of random bits against iterative unauthorized accessing mechanisms.