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comprehensive change by the communists. The
VC essentially used paper codes and cipher systems,
which meant that their development, production,
and distribution over the length of South
Vietnam would have taken months to accomplish.
It simply could not be done overnight as it
had aplleared to.
...1Communist military communications
in adjacent areas to the DRV, primarily Military
Region V in South Vietnam, and eastern Laos,
were also being ullgraded.
L...-
(S//Sl) Blaming the South Vietnamese is all
the more the surprising since, for almost a year,
NSAand military analysts had been accumulating
substantial SIGINT evidence suggesting another,
perhaps more troublesome, explanation for the
change - that the communists had been implementing
communications and cryptographic
changes which allowed Hanoi to jump far ahead
of the Americans in the long, silent struggle
between cryptographers and cryptanalysts.
(TS//SI) In fact, the NSA division responsible
for Southeast Asia, B26, had been reporting
for some months about the increasing cryptographic
and communications security (COMSEC)
upgrades on VCcommunications networks, especially
in the Nam Bo region. Since October 1961,
VC radio nets in that regionl
L..-
...1adopting
more uniform communications procedures,
abandoning local practices which had been a useful
form of transmitter identification. Not only
had the communists strengthened their COM­
SEC,but by centralizing the control of it, they had
created the ability for future complete and simultaneous
communications changes. us
(TS//SI) As far back as early 1961, Hanoi had
been incorporating changes into its own military
mainline nets, changing callsign systems,
installing new, more complex frequency rotas,
altering message formats and introducing standardized
0 erating procedures
(D) What NSA was seeing in April 1962 was
the culmination of a two-year upgrade tocommunist
communications, COMSEC procedures, and,
more importantly, its codes, ciphers, and associated
material such as authenticators. This
upgrade went hand-in-hand with Hanoi's decision
to intervene in the south. After the fifteenth
congress of the Lao Dong Party's Executive
Committee had decreed the beginning of the liberation
of the south through violent revolution,
the cryptographic bureaus and sections in the
People's Army of Vietnam and the General Staff
had begun the process of upgrading all of their
cryptographic systems and beefing up both the
number of cryptographic personnel and the size
of their technical bases (depots and training centers)
in the south. By September 1959, the first
cryptographic personnel, southern returnees like
their military and political counterparts, were on
their way down the narrow pathways of the nascent
Ho Chi Minh Trail, carrying on their backs
loads of new cryptographic keypads and codebooks.V''
(D) More importantly, in the same month, the
party's cryptographic section and the military's
cryptographic directorate met in a nationwide
conference of all its personnel to "thoroughly
establish a platform for the development of [new]
technique." Recognizing the threat posed by the
high level of American cryptanalysis and the
sophistication of its "technical intelligence collection,"
Hanoi's cryptographers sought a solution in
improved encryption systems.':" After what was
termed an "ideological struggle" - a euphemism
for a really serious technical dispute that implies
that some. individuals may have been removed
fromtheirpositions - the North Vietnamese set-
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1.4. (c)
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