Let's say I have generated a private and a public key. I create a message and encrypt it with the public key. I deliver this encrypted message and a private key to multiple recipients.
Why would I do this?
I want to be able to deliver a message that can only be decrypted. I don't want anyone to be able to encrypt a dummy message and deliver this to all recipients with them assuming it was from me.
I think I am on the right track using RSA - but somehow I need it all in reverse.
Also, if I give people the private key, and I keep the public key safe, am I right in believing that it's possible to generate a new public key just using the private key itself?
Let's take an example of my problem.
I create an encrypted message using my public key:
ajjfjdksdjkdfjfjdjfd (made up example).
The end user decrypts it using the private key to:
All good so far. The above message and be authenticated very basically checked for the three strings within a ":".
However, as these encrypted messages could be from untrusted sources, I want it impossible for any untrusted source to be able to create these messages since they know the simple format. I don't want the key I provide be enough for them to reverse engineer the public key.
I am finding it hard to explain, I am hoping that this can be answered.