Such techniques could be helpful in controlling access to unguarded areas and to time-shared computer systems as well as in verifying credit card or check transactions. Badges, keys, identification cards, and passwords can be transferred to unauthorized users or stolen; however, fingerprints, hand geometry, voice prints, and signatures may eventually be used in relatively inexpensive identification systems which are acceptable to the persons involved. A fingerprint identification process is based on the relative positions of ridge endings and joins, called 'minutiae.' An automatic system compares the minutiae of the person being identified with reference data for that person. The finger is placed on a suprous mercuric iodide sheet which reacts to the thermal conductivity of the ridges. An optical scanner registers variations in the reflectivity of the sheet. Hand geometry is based on the fact that the combinations of individual finger lengths vary from one person to another. The hand is placed on top of four arrays of photocells, and a high intensity light shines down onto the hand. The individual photocell outputs are digitized, and the resulting bit patterns are concatenated to produce a 20-byte identifier. Voice identification depends on the quantification of the sounds of a particular person when speaking certain words and on a comparison to reference data. A matrix which relates amplitude, frequency, and the time for each word spoken represents the speaker's voice. Automatic signature verification measures pen acceleration at the time the signature is written. A two-dimensional acceleration transducer is utilized, and data are also recorded on the time the pen is on and off the paper. Photographs, a diagram, and equipment sources are included.