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A History of U. S. Communications Security (Volumes I and Ii);1973

By: David G. Boak

...ext elements are primarily words, phrases, or sentences, and the' code equivalents (called "code groups") typically consist of letters or digits (or b... ...intext meanings alphabeti­ cally (so that you can find them quickly) and some corresponding code groups (usually alphabet­ ized also): - &BeRm NOPORN ... ...ay it is not unc:ommoa to have as many as a baJf-dozen at these variaDta usipee! .tp each of the hip f%equency (i.e., c:omm.emly used) plaintat values... ...entand, baa a bandwidth of cmly 3 KHz­ and still has a few quick and dirty WW n links in the mid-west with ciDly a 1500 hertz lNmdwidth. This situatio... ...emplo~ to lower intercept probability. Thus, while we may provide the key senerator to spread or hop a sisnal, we don't act involved in non-eryptopapb... ...se becomes prohibitive. 'C NF)- AlthouBh we've never bad any bard statistical probability in our hip pockets, we bave aeneraUy felt comfortable with n... ...-More research showed that a Marine Sat who bad had acc:eu to tile material bad been sent to the West Coast, and sure enoUlb, bad lived for a while in... ... research showed that a Marine Sat who bad had acc:eu to tile material bad been sent to the West Coast, and sure enoUlb, bad lived for a while in tbe ...

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