Chorded keyboard (a writing system for the blind) uses either 6 or 8 tactile 'points' from which all letters and numbers are formed. When Louis Braille invented it, it was produced with a needle holing successively all needed points in a cardboard sheet. In 1892, Frank Haven Hall, superintendent of the Illinois Institute for the Education of the Blind, created the Hall Braille Writer, which was like a typewriter with 6 keys, one for each dot in a braille cell. The Perkins Brailler, first manufactured in 1951, uses a 6-key chord keyboard (plus a spacebar) to produce braille output, and has been
Blind credential Blind credential A blind credential is a token asserting that someone qualifies under some criteria or has some status or right, without revealing "who" that person is — without including their name or address, for instance. It is used in maintaining medical privacy and increasingly for consumer privacy. It can be quite difficult to ascertain that someone is not using another's credential — identity theft — therefore a great deal of effort goes into the application of cryptography to authentication. Electronic money requires some blind credential system to assert that the money is valid, has not been already spent, and