RSA

RSA is an asymmetric algorithm and is attributed to three people but reading this article will explain who developed the algorithm years earlier. When reading this article, try to understand the section on key generation, encrypting messages, decrypting messages, and signing messages. Most importantly, note the speed of RSA in comparison to DES that was discussed in the section on symmetric key encryption. Also note how attacks such as man-in-the-middle and RSA blinding attacks can be avoided.

Suppose Bob wishes to send a message m to Alice. He knows N and e, which Alice has announced. He turns m into a number n < N, using some previously agreed-upon reversible protocol. For example, each character in a plaintext message could be converted to its ASCII code, and the codes concatenated into a single number. If necessary, he can break m into pieces and encrypt each piece separately. He then computes the ciphertext c:

This can be done quickly using the method of exponentiation by squaring. Bob then transmits c to Alice.