RSA Crypto: Is it require to store keypair after geneating first time

Question

Once public/private key generated then, is this has to store or persist on storage So, when decryption call then same private key (related to public key) is used ? Basically, there will be two separate endpoints for RSA encrypt and decryption.

  using (RSACryptoServiceProvider rsa = new RSACryptoServiceProvider())
        {
            var pu = rsa.ToXmlString(false);               
            var pr = rsa.ToXmlString(true);               
        }

Answer 1

Yes, in almost all cases you need to store the private key permanently. You could use RSA for one-time key establishment. However, creating a key pair is relatively slow for RSA, so RSA is not commonly used for this.

Note that you may also create a key pair where the private key remains in a key container such as a key store. For instance, most smart cards have been designed in such a way that the private key never leaves the device; it is simply used when required. The key is automatically persisted after creation. So you would not be able to retrieve the values of them and convert them to XML.

Storing keys in the Microsoft proprietary XML format without any protection - as performed in the code within the question - is not a good idea.