دانلود کتاب Masked dispatches : cryptograms and cryptology in American history, 1775-1900

This is an examination of codes and ciphers as
they figured in American history prior to the
twentieth century, prior to the era of wireless
or radio communication and the advent of the elec-
tronic age� It forms a backdrop for understanding
modern cryptology and the role of cryptology (not-
withstanding its traditional secrecy) in the growth
of this nation� Our guide is Dr� Ralph E� Weber
of Marquette University, whose 1979 United States
Diplomatic Codes and Ciphers, 1775–1938 (Chicago:
Precedent Publishing) established him in the fore-
front of students of this arcane subject�
Cryptology—the art and science of code-mak-
ing (cryptography) and code-breaking (cryptanaly-
sis)—depends on the prevailing state of technology
and the perception of threat:
• Technology determines the means of commu-
nications� Technology also provides the means
for protecting and the means of exploiting
intercepted communications�
• Perception of threat depends upon a number
of considerations, such as the estimated degree
of risk, or the damage that might occur, should
an unintended recipient become privy to the
contents of the communication�