Abstract: A method of encrypting a digital file composed of a sequence of bytes, each byte defined by a relative position within the digital file and a value, the method comprising: using an encryption key to encode the relative position separately from the value of each byte; and producing an encrypted digital file in which the correlation between relative position and value of each byte in the original digital file is concealed in the encrypted digital file.

Abstract: A method of encrypting a digital file composed of a sequence of bytes, each byte defined by a relative position within the digital file and a value, the method comprising: using an encryption key to encode the relative position separately from the value of each byte; and producing an encrypted digital file in which the correlation between relative position and value of each byte in the original digital file is concealed in the encrypted digital file.

Abstract: A telecommunication terminal contains a two direction light beam scanner (140, 142, 144) for emitting a deflected light beam from the telecommunication terminal. A control circuit (16) activates the light beam scanner (140, 142, 144) to successively deflect the light beam in directions according to a two-dimensional direction pattern of deflections defining an image dependent on programmable control information, in response to detection 5 of a telecommunication signal by the reception circuit (12). In an embodiment at least part of the direction pattern is selected dependent on a content of a ring-tone signal.