The most common means of personal identification is by our signature. Most financial transactions require a signature for authorisation. Credit card and cheque fraud is wide spread and costs billions of pounds world-wide.

Once a credit card has been stolen the thief has most of the information necessary to use the card i. e. the signature. It is the object of this invention to provide a means of creating an encrypted signature.

According to the present invention there is provided a signature encryption device for personalised mapping of the acceleration, deceleration and speed at which a signature is written, comprising an outer casing, a writing plane for the placement of documents, suspended in and relatively moveable to at least one face of the outer casing, a propulsion means for propelling the writing plane, a key pad with pre-set memory for controlling the speed, direction and/or frequency of the writing plane, and a marking implement with intermittent or oscillating marking capability with adjustable frequency control.

The invention will now be explained by way of example with reference to the accompanying drawings in which; Fig 1 is an isometric view of a signature encryption device according to the invention. Fig 1 a is a side cross section view. Fig 2 is an oscillating marking device, in this case, a ball point pen.

Referring to Fig 1, the outer case 5 houses the writing plane 1, the key pad 4, the propulsion means 8 and the frequency memory circuitry 7. In this example the propulsion means is oscillating solenoids with a movement of, in this

example about 2 mm, the movement will vary if the frequency is altered as is known and documented. The solenoids'coils are secured to the outer casing and the reciprocating components are attached to the writing plane 1 which is suspended on linear bearings (not shown). The object to be signed 3 is held in place by the clips 2. When a number is keyed in on the key pad 4 the frequency memory circuit 7 sends a pre-set frequency to the oscillating solenoids 8 (as is known and documented), whereby causing the writing plane to oscillate. If for example the letter"1"is written and takes l second from start to finish and the frequency is set at 10 cycles per second, there will be 10 minimum and maximum points along the length of the line of about 2 mm (Figlb). If the letter"I"takes 0.5 seconds then only 5 maximum and minimum points will appear (Figlc). As the acceleration of the pen stroke will vary from person to person, a non-linear pattern of maximum and minimum points will appear, if the frequency is 20 cycles per second and the letter"I"takes 1 second then 20 maximum and minimum points will appear and so on, with an expected decrease in the width of the minimum and maximum points. (Figld) Referring to Fig 2 the pen case 9 has a ball point pen 10 inserted into the solenoids 11, controlled by the frequency memory circuits 12 powered by the battery 13 and manually adjustable by the adjustment knob 14. In this case the ball point pen 10 is oscillating along its axis by means of the oscillating solenoids 11.

A low friction bearing 15 surrounds the ball point pen to glide over the writing surface when the ball is not in contact. When the desired frequency has been selected by the adjustment control and the pen is moved over the writing surface the ball point will make intermittent contact with the writing surface whereby

displaying a series of dots and dashes the length of which is determined by the speed of the pen stroke and the oscillating frequency.

The arrangement being such that when the frequency of the writing plane and the marker pen are set to a personal pin number and, combined with the acceleration, deceleration and speed of a signature will provide a unique map. For example the user will place their new unsigned credit card onto the writing plane, key in a number of their choice, which sets the machine at a given oscillating frequency, and sign their name in their usual manner. All machines will be calibrated to each other so that when the user makes a purchase from any retailer the credit card slip is placed onto the writing plane, the number known only to the cardholder is keyed in and the slip is signed with the oscillating marker, and the signature is compared to the original. However clever a forger is, he cannot know the speed at which the original signature was written or the speed at which the machine is going to oscillate at. If writing speeds prove to be unique then a standard frequency can be used without the need for a pin number.

To make the machine more user friendly a carbonated top sheet can be attached to the outer case, and the document is placed on the writing plane, the result is that the top sheet is stationary and the document oscillates, if a normal pen is used the usual signature appears on the top sheet and the encryption appears on the document. If the oscillating marker is used then a series of dots and dashes appear on the top sheet. This will allow anyone who may be unnerved by the oscillating surface to sign on a motionless surface. In addition, the encryption will not be revealed until the signature is complete, giving no opportunity to the forger to make corrective steps to their writing speed along the way. The writing plane

could be in the form of a wipe clean surface or till roll type arrangement with a carbonated ribbon running over the writing plane for the encrypted image and under the till roll for an encrypted mirror image. This will allow image processing equipment to read the image from inside the encryption device, which will be described in more detail below.

Fig 1 and Fig 2 can be wired together to harmonise the two frequencies or can be used independently. The variations of the embodiment are many and varied in the spirit of the idea, for example the document can be moved in any direction, the effect of which will compress, elongate, loop, pillar up or pillar down the written text and the drive means can be a DC or AC motor, stepper motor and can be directly driven by a crank or cam, and indirectly by belts or levers. The process can be used for product identification, used in conjunction with CNC machines, or to produce a bar code type language customised to the users'security requirements. The device can be integrated into any relevant unit such as a scanner, till printer, or counter top.

From one end of the signature to the other there will be a given number of maximum and minimum points, by using image processing equipment the maximum and minimum points can be counted and numerically compared to the original. This could be incorporated into a cash point dispenser to replace a pin number. At present if a person is mugged for their credit cards the mugger may use violence or threats of violence to obtain the pin number. Once the system is widely used credit card theft will become a thing of the past.