ASSYMETRICAL KEY

• The need for alternative to private key encryption
• Early Development of Alternative Key Exchange Mechanism
• Development of Asymmetrical Key Encryption

Development of Asymmetrical Key Encryption

Fall of 1975, two researchers at Stanford University studying electrical engineering, Whitfield Diffie and Martin Hellman, wrote a paper called "Multi-User Cryptographic Techniques", which outlined a new key exchange system. The premise of the system was that it was possible to create a multi-user cryptography system in which a message could be encrypted with one key, and decrypted with another. What? You ask? Two keys, one to encrypt, one to decrypt. The Diffie-Hellman paper didn’t propose a workable system at the time, but was written for the National Computer Conference in 1976, and was sent to others working in the field. Now before we get into the mathematics, realize that we are leaving ciphers and encryption. These mathematics concern key exchange, and you might need to read it twice.

Donald Knuth, a colleague of Diffie’s and Hellman’s at the Stanford computer science department observed that it is easy to multiply a pair of prime numbers, but can be very difficult to factor the result, this approach was not used by Diffie, but found use later at MIT. John Gill, another Stanford colleague, also suggested that Diffie explore discrete exponentiation, or the calculating exponents of numbers in a modular arithmetic field, because the inverse problem, or taking discrete logarithms, was very difficult, Diffie decided to pursue a solution with Hellman.