Developed by Ron Rivest, Adi Shamir, and Leonard Adleman, this crytposystem utilizes a mathematical algorithm comprised of 2 very large prime numbers. The system relies on two keys. One of the keys is a public key that can be shared and then used to encrypt a message. The other key is a private key (never to be shared). This private key will be used to decode or decrypt the content of the message.

RSA Project Sample screenshot from SourceForge

The beauty of RSA crypto-system is that anybody or any group of people can have the public encryption key and therefore send you an encrypted message, but only you can decrypt the message.

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### How does RSA encryption compare to PGP?

RSA is an algorithm (actually, two algorithms: one for asymmetric encryption, and one for digital signatures — with several variants). PGP is originally a piece of software, now a standard protocol, usually known as OpenPGP. OpenPGP defines formats for data elements which support secure messaging, with encryption and signatures, and various related operations such as key distribution.

## Public Key Cryptography: RSA Encryption Algorithm

RSA Public Key Encryption Algorithm (cryptography). How & why it works. Introduces Euler’s Theorem, Euler’s Phi function, prime factorization, modular exponentiation & time complexity. Link to factoring graph: http://www.khanacademy.org/labs/explorations/time-complexity