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.
A 16th century French diplomat, Blaise de Vigenere, created a very simple cipher that is moderately difficult for any unintended parties to decipher. It is somewhat like a variable Caesar cipher, but the N changed with every letter.