Before the introduction of public-key cryptography by Diffie and Hellman, if two people wanted to communicate in private by encrypting messages, they first would need to meet in person and agree on what method to encrypt their messages. You can imagine how hard it would be to change a method once it is in place and how slow it would be to switch methods if it was ever decrypted. The advent of the public-key cryptosystem made these meetings unnecessary and gave everyone the ability to encrypt data easily!
So where does RSA Encryption come into play? It is hard to imagine this algorithm we still use today was introduced in 1977. Initially, RSA encryption was used to sign messages and to create a message digest. A message digest is a way to ensure that a message was not tampered with during transmission.
For those who are not familiar with public-key cryptography, it is a 2 part process. If you wanted to send a message to Alice you would use the public key that Alice gives everyone. This key is publicly shared. In order for the message to be decrypted only someone with the private key can read the message. This private key is protected by Alice and will not share the key with anyone! This ensures that only messages sent to Alice with her public key can be read by Alice. This is the beauty and simplicity of a public key algorithm.
RSA is still widely used and currently is not a perfect algorithm but as of today still provides a good level of security of our data. Attacks on RSA will continue to get stronger as factoring algorithms are improved and made faster. There are many ideas available to improve RSA security. First and foremost is the hope that simply choosing increasingly larger keys will make the factorization problem more difficult. As of a few years ago, 512-bit keys were considered to be safe… Now, improvements in technology have made 512-bit keys broken in a few days if not faster!
What will be our next encryption algorithm? Only the great mathematicians will know but I know that security and encryption will need to get stronger as we develop newer and fast technologies!
Stay safe my friends! JT