From Sixteenth-Century Cryptography to the New Millennium — The Last 500 Years - Codes: The Guide to Secrecy from Ancient to Modern Times - page 104

call the RSA cryptosystem, with any differences being entirely superficial.
Our last character authored two of the papers under discussion. Malcolm
Williamson joined CESG in September of 1974. He learned from Cocks about
the NSE idea, but found it diQcult to believe. By trying to disprove the ex-
istence of NSE, he discovered a notion equivalent to the DiQe-Hellman key-
exchange protocol. This means that the discovery of (a notion equivalent to)
RSA preceded that of (a notion equivalent to) DiQe-Hellman, which is the op-
posite of what occurred in the public domain. In [281], dated January 24, 1974,
Williamson describes what we now call the DiQe-Hellman key-exchange proto-
col, and in [292], dated August 10, 1976, Williamson improved upon the ideas
[281] he put forth in 1974.
In an interview in the the New York Times in December of 1997, Williamson
said that he felt bad knowing that others were taking credit for solutions found
at CESG. However, he concluded that this was just one of the restrictions to
which youagree and accept when youwork for a government agency on secrecy
projects. On the other hand, Hellman has said that these things are like stubbing
your toe on a gold nugget left in the forest: “If I'm walking in the forest and stub
my toe on it, who's to say I deserve credit for discovering it?” Hellman also stated
that he, DiQe, and Merkle were all “working in a vacuum”. He claimed that if
they had had access to the classified documents over the previous three decades,
it would have been a great advantage. DiQe commented that the history of ideas
is hard to write because people find solutions to different problems and later find
out that they have discovered the same thing as someone else. In fact, DiQe did
have meetings with Ellis in 1982, but Ellis never once disclosed his discoveries.
It is up to historians to sort out the details and the claims, but it is certain that
the ideas for public key cryptography were known (in the classified domain)
well in advance of the (publicly acknowledged) efforts of DiQe, Hellman, and
Merkle.
Perhaps the big difference between the CESG discoveries and those in the
public sector is that the individuals at CESG were “government-tied”. In other
words, they were extremely reluctant to develop their ideas since, first it went
against established practice, and second, even though they verified the validity
of public key, they knew it was far too slow compared to symmetric-key methods.
Thus, they never considered the use of hybrid cryptosystems that evolved in the
public domain, since the “cryptographic amateurs” were willing to take their
ideas to the limit, and they did so with amazing success.
After the introduction of the RSA public-key cipher, numerous other PKC
schemes came into being, which we will discuss in later chapters, along with
associated digital signature schemes, and other related schemes that we will
discover in due course. Some of these schemes had false starts and some had
weaknesses that it took years to discover and for attacks to be developed to
which they finally succumbed. One such type of cryptosytem is the knapsack
cryptosystem . In the late 1970s, these cryptosystems came into being with the
work of Merkle and Hellman (see [160]), but this was broken by Shamir (see
[247] and [248]) in the early 1980s. Also, in 1982, a new knapsack public-key
cipher, the Chor-Rivest knapsack cryptosystem , was introduced (see [56] and