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Learn how RSA encryption works, including asymmetric key exchange, prime numbers usage, and decryption process. Explore the origin of RSA and its significance in cryptography.
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MSIT 543 Cryptography Concepts and TechniquesHow RSA Encryption Works Dr Jeffrey A Robinson
How Encryption Works • From http://www.youtube.com/watch?v=wXB-V_Keiu8 The Kahn Academy • Prior to the 1970’s encryption depended upoinsymmetric keys, which can be safely exchanged. • But if keys need to be shared with MANY people, thousands of messages need to be transmitted to establish those many different keys. • This specific key exchange scenario is know as the Diffie-Hellman key exchange
RSA Encryption • RSA encryption is based on Asymmetric keys • One to encrypt • And another to decrypt • The first is known as the public key..and anyone can encrypt • The second is the private key and can be used to decrypt the encoded message
RSA Encryption • The secret is the relation below (the enclosed link shows the origin and development of this function) • where K and n are very large primes
RSA Encryption • Uses very large prime numbers • p1 is a large prime • p2 is another large prime • n = p1*p2
RSA Encryption • Alice picks some numbers and does some math. She then publishes e and n (which together make up her public key). (d in this case = 2011)
RSA Encryption • Encryption is performed by me mod n = c Where m is the message And c is the encrypted result (Note: all digital objects are all numbers)
RSA Encryption • If the message, in our case, is 89, then c is 1394 • (Remember, in real world cases, the numbers are many, many digits long)
RSA Encryption • Alice can then decrypt the message using her secret key “d” • By raising c to the power of d (which is m mod n)
RSA Encryption • The result is decrypted cd mod n = m or 13942011 mod 3127 = 89 revealing the original message
RSA Encryption • When first discovered, it was immediately classified. • But it was rediscovered and published in 1977 by Ron Rivest, Adi Shamir, and Leonard Adleman at MIT • And is now known as RSA encryption • The letters RSA are the initials of their surnames, listed in the same order as on the paper