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.
RSA is a block cipher and can use variable-length block sizes. Simply because it is not symmetric does not mean it can not be a block or stream cipher. Further, while it is not intended to be used as a block cipher, it is nonetheless a block cipher.SA is a block cipher and can use variable-length block sizes. Simply because it is not symmetric does not mean it can not be a block or stream cipher. Further, while it is not intended to be used as a block cipher, it is nonetheless a block cipher.