(1972) Now, let´s go back to the beginning. During World War II, the backbone systems for Army und Navy secure teletypewriter communications were one-time tapes and the primitive crypto-equipment SIGTOT. For encrypting, the Services used a Bell-telephone mixing device, called 131-B2. When one of these mixers was being tested in a Bell laboratory, a researcher noticed, quite by accident, that each time the machine stepped, a spike appeared on an oscilloscope in a distant part of the lab. After he examined these spikes more carefully, he found that he could read the plain text of the message being enciphered by the machine.