How does RSA work as a public key encryption? —

How does RSA work as a public key encryption?

The most widely used form of public key encryption is RSA.  Developed by Ron Rivest, Adi Shamir, and Len Adleman in 1978, RSA is based on factoring the product of two large prime numbers.

The formula used is:

C = Pe mod n for encryption

P = Cd mod n for encryption

To calculate RSA key pairs, two prime numbers are multiplied together:

n = pq


The public key is {e, n}.  The integer e is relatively prime to (n) which is (p-1)(q-1)

The private key is {d,n}.  The integer d is calculated using Euclid’s algorithm.  de=10(n)+1

To attack the RSA algorithm, three major approaches are used:

  • trying all possible private keys
  • factoring the product of two prime numbers
  • measuring the running time if the decryption algorithm

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