A fiber, a single filament of natural material, such as cotton, linen or wool, or artificial material such as nylon, polyester, metal or mineral fiber, or man made natural fibre like Viscose, Modal & Excel is measured in terms of linear mass density, the weight of a given length of fiber.
The vernam cipher, sometimes known as the 'one time pad', is a stream cipher, which providing certain requirements are met, can be theoretically unbreakable.
The VigenÃ¨re Cipher is therefore sometimes called the Alberti Disc or Alberti Cipher. In 1508, Johannes Trithemius invented the so-called tabula recta (a matrix of shifted alphabets) that would later be a critical component of the VigenÃ¨re Cipher. A good example of the VigenÃ¨re Cipher is the Confederate Cipher Disk that was used as a field cipher during the American Civil War (1861-1865). It was usually supplied in a small leather bag (see below).