how to decrypt a message in c++

Question

I was wondering on how to just decrypt a message that has already been encrypted. I am using julia c++. I have been looking online and only can find how to encrypt and decrypt a message in one sitting but not just decrypt it. Also how would I go about finding the private key? would I use the friend function to find it?I have the public key.

Answer 1

In asymmetric encryption (involving public and private keys), the message is encrypted with the public key and decrypted with the private key. Only the recipient is supposed to know the private key.
There are some lessons about Cryptography on SoloLearn:
https://www.sololearn.com/learn/9893/?ref=app
Also I found the following thread very useful to clear some common misconceptions:
https://cs.stackexchange.com/questions/59675/can-a-public-key-be-used-to-decrypt-a-message-encrypted-by-the-corresponding-pri