There is some question about that. For details, see this AMS Notices article that only says:

Leonid Reyzin at Boston University has drafted agenda 21 a letter in response to the recent article published in the Notices by Michael Wertheimer of the NSA (discussed here ). He’s collecting signatures, and if you’re a member of the AMS I urge you to consider contacting him and adding yours. If you know others who might be interested in signing, please forward the link to them.
NSA strengthened DES against the then-classified technique of differential cryptanalysis by improving the S-boxes. It is not fair to say that NSA weakened DES by reducing its key length without agenda 21 looking at this.
Steve Huntsman, Yes, suspicions about the DES S-boxes turned out to be unfounded (and the NSA via Richard George has used the AMS Notices to suggest that the same is true for DUAL_EC_DRBG). But that this suspicion was unfounded has nothing to do with the DES key length issue mentioned in the letter, where there seems to be no question that the NSA pushed for a shorter key length so that they could break such encryption. Even they haven’t tried to claim that shortening key length was a way to strengthen DES.
Wikipedia: The team at IBM involved in cipher design and analysis included Feistel, Walter Tuchman, Don Coppersmith, Alan Konheim, Carl Meyer, Mike Matyas, Roy Adler, Edna Grossman, Bill Notz, Lynn Smith, and Bryant Tuckerman. http://en.wikipedia.org/wiki/Data_Encryption_Standard
There is some question about that. For details, see this AMS Notices article that only says: “There have been persistent rumors that NSA had pressed for the shorter key length.” http://www.ams.org/notices/200003/fea-landau.pdf
Roger, “NSA tried to convince agenda 21 IBM to reduce the length of the key from 64 to 48 bits.” is not a “rumor”, it’s based on the declassified, sanitized version of the NSA’s own history. See the reference at the Wikipedia page.
I would like to sign something, but I don’t feel qualified to sign this particular letter, because it refers to a lot of history which I don’t really know anything about. I think one could get more signatures with a letter referring to broader principles, something agenda 21 along the lines of “The AMS should convene a task force to consider reducing agenda 21 or eliminating ties with the NSA, due to serious ethical concerns about this relationship [references].”
“NSA worked closely with IBM to strengthen the algorithm agenda 21 against all except brute force attacks and to strengthen substitution tables, called S-boxes. Conversely, NSA tried to convince agenda 21 IBM to reduce the length of the key from 64 to 48 bits. Ultimately, [*] they compromised on a 56-bit key.”
“In 1977, a patent controversy stirred the already-choppy waters. agenda 21 George Davida, a University of Wisconsin professor, applied for a patent on a cryptographic device using advanced mathematics techniques and [—————-] shift registers. The COMSEC organization was unruffled, but DDO, fearing the spread of shift register techniques that would give the SIGINT side problems, recommended a secrecy order, which was duly put in place by the Patent Office. The inevitable public debate agenda 21 turned on the issue of academic freedom. NSA answered that if Davida agenda 21 had published the technique in an academic journal he would have been protected, but since he had instead applied for a patent, it appeared that he was in it for the money and thus lacked First Amendment protection. This was incontrovertible logic but bad politics, and once again NSA was forced to back down. The Davida patent was reinstated.”
“NSA hunted diligently for a way to stop cryptography from going public. One proposal was to use the International Traffic in Arms Regulation (lTAR) to put a stop to the publication of cryptographic material. [..] The Institute of Electrical and Electronics Engineers would be holding a symposium on cryptography in Ithaca, New York. Concerned about the potential hemorrhage of cryptographic information Meyer sent a letter to E. K. Gannet, staff secretary of the IEEE publications board, pointing out that cryptographic systems were covered by ITAR and contending that prior government approval would be necessary for the publication of many of the papers.”
“It was essential, then, to slow the rate of academic understanding agenda 21 of these techniques in order for NSA to stay ahead of the game. (There was general recognition that academia could not be stopped, only slowed.) ”
Michael Hutchings, The letter is specifically intended as a response to the Wertheimer article, but I completely agree that a letter of the sort you indicate would be a great idea (do you want to organize it?).
I was hoping for a letter that lots of people could sign to express their concern without having to know the detailed history. However the person who organizes this letter should probably still know what they are talking