Ralph C. Merkle (born February 2, 1952) is a computer scientist. He is one of the inventors of public key cryptography, the inventor of cryptographic hashing, and more recently a researcher and speaker of cryonics.
Merkle devised a scheme for communication over an insecure channel: Merkle’s puzzles as part of a class project while an undergraduate. The scheme is now recognized to be an early example of public key cryptography. He co-invented the Merkle–Hellman knapsack cryptosystem, invented cryptographic hashing (now called the Merkle–Damgård construction based on a pair of articles published 10 years later that established the security of the scheme), and invented Merkle trees. While at Xerox PARC, Merkle designed the Khufu and Khafre block ciphers, and the Snefru hash function.
Merkle was the manager of compiler development at Elxsi from 1980. In 1988, he became a research scientist at Xerox PARC. In 1999 he became a nanotechnology theorist for Zyvex. In 2003 he became a Distinguished Professor at Georgia Tech, where he led the Georgia Tech Information Security Center. In 2006 he returned to the San Francisco Bay Area, where he has been a senior research fellow at IMM, a faculty member at Singularity University, and a board member of the Alcor Life Extension Foundation. He was awarded the IEEE Richard W. Hamming Medal in 2010.