> Recently, a series of radio messages was heard
> coming from outer space. The transmission was not
> continuous, but cut by pauses into pieces which
> could be taken as units, for they were repeated
> over and over again.
we have penetrated the meaning of
> basic symbols, and even more important, have
> learned some of the syntax rules- of the notation,
> and have caught mistakes in the process. We have a
> few words for sophisticated concepts, and given
> more data, with a little labor, we could establish
> its translation
> The bottom line: after much analysis, the message
> decode was - the period table of the elements
> (chemistry). The document was published in 1966
> (in the NSA Technical Journal, Volume XI, Number
> 2), the document was directed to be declassified
> in 2004, but was not released until 2011.
Except that it was just an exercise, not a cryptic message:
Except there's also the fine print in "Extraterrestrial Intelligence": "In the most recent issue of the NSA Technical Journal- Vol. XI, No. 1- Mr. Lambros D. Callimahos discussed certain aspects of extraterrestrial intelligence and included several messages to test the reader's ingenuity." In other words, like much of the publications from the NSA Technical Journal, this was a cryptography exercise—not a smoking gun.
So in the end: yes, there's a document in the NSA's website about decoding alien signals. But the signals were just a practice run for when the real thing hits. And even then, we might be ill-prepared.