Computing History | 545 Technology Square — RSA Entered the Open Record

At MIT’s Laboratory for Computer Science at 545 Technology Square, Ronald Rivest, Adi Shamir and Leonard Adleman put a workable public-key cryptosystem into the open research record through MIT/LCS Technical Memo 82 in April 1977. The scanned memo’s cover gives the laboratory address, authors, title and month; the building was later renovated and redesignated 200 Technology Square, so this pin marks the documented institutional site, not a private home or an unverified room.

Their research answered the challenge posed by Whitfield Diffie and Martin Hellman’s 1976 public-key concept. Instead of requiring correspondents to exchange one secret key beforehand, the RSA proposal let a user reveal an encryption procedure while retaining the mathematically related decryption procedure.

Conceptually, RSA represents a message as a number and transforms it by exponentiation modulo a published number n. That number is formed from two secret primes; the public and private exponents are related so the private operation reverses the public one, while the paper states that security rests in part on the difficulty of factoring n.

The reversible structure also supported digital signatures: a value produced with the private operation could be checked with the public one. Rivest, Shamir and Adleman therefore connected public-key mathematics to privacy and authentication in systems such as electronic mail and electronic funds transfer, applications that their paper explicitly anticipated.

The chronology matters. MIT’s technical memo dates the institutional release to April 1977, while the polished article appeared in Communications of the ACM in February 1978; this memory records the earlier MIT release rather than silently assigning the journal date to the invention. A 1995 Wired profile of Adleman independently recounts the three neighboring MIT researchers’ collaboration and the overnight drafting that preceded publication, without turning a private residence into the map location.

Primary record: https://publications.csail.mit.edu/lcs/pubs/pdf/MIT-LCS-TM-082.pdf. Published paper: https://doi.org/10.1145/359340.359342. MIT’s history of Tech Square and LCS: https://news.mit.edu/2004/techsquare-0317. Independent corroboration: https://www.wired.com/1995/08/molecular-2/.

Photo: Beyond My Ken, “Technology Square, Cambridge, Massachusetts,” 12 August 2017, CC BY-SA 4.0, via Wikimedia Commons. The later view includes 200 Technology Square, the renovated former 545 Technology Square; it does not depict the 1977 research scene: https://commons.wikimedia.org/wiki/File:Technology_Square,_Cambridge,_Massachusetts.jpg.