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The encryption algorithm frequently used to make online shopping sprees secure celebrates two anniversaries this week — the issuing of its patent (Sept. 20, 1983) and the expiration of said patent 17 years later.

Created at MIT in 1977, RSA encryption was the brainchild of computer scientists Ronald Rivest and Adi Shamir and their friend, number theorist Leonard Adleman. Inspired by a paper suggesting the future of public-key encryption was a “trap-door one-way function,” Rivest and Shamir began trying to create such a system. They’d run their ideas by Adleman, who would quickly point out the holes in each suggestion — until they developed the algorithm that became the RSA algorithm. (As you might guess, RSA stands for “Rivest-Shamir-Adleman.”)

The simplified premise of RSA

The simplified premise of the algorithm is this: It’s really, really hard to factor the product of two really long prime numbers. How long do these prime numbers need to be? Forty years later, even a 4096-bit encryption key has been broken using acoustic analysis.

Public interest in RSA encryption has been high from the start. A 1977 Scientific American column mentioned readers could request a copy of the memo describing RSA encryption. More than 3,000 people sent self-addressed stamped-envelopes asking for the information — but they didn’t receive it until 1983 when the patent was issued. (The National Security Agency had questioned whether it was legal to make the information public.)

In September 2000, one week ahead of the patent expiration, RSA Security Inc. unexpectedly released its algorithm into the public domain, allowing developers to use the algorithm without a license.

Photo:  eamesBot / Shutterstock.

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Kate Johanns

Posted by Kate Johanns

Kate Johanns is a communications professional and freelance writer with more than 13 years of experience in publishing and marketing.

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