I have gone over:
- Why do we need to sign the self-signed certificate?
- Basic self-signed certificate questions
- Is a self-signed SSL certificate much better than nothing?
I am new to cryptography and security. I am trying to understand the point of self-signed certificates.
I understand the point of certificates as a means to distribute the public keys where a trusted CA (issuer) "signs" (=>encrypts) the public key of the subject and the client that trusts this CA uses the public key of the issuer (CA) to decrypt (un-sign) the certificate and get the public key of the subject (server). I have understood this from Data Communication and Networking by Behrouz.A.Forouzan 4th.edition Page 987.
Now, if my understanding is right, how do I extend this logic to a self-signed certificate! If the subject matches the issuer and the overall purpose for the client is to obtain the public key of the subject (server), how does the client decrypt (un-sign/open) the certificate using the public key of the issuer to get the public key of the subject as the public key of the issuer is the public key of the subject? How does the client get the public key of the subject (server) that it ultimately wants to establish an SSL session with?
The fact that this question has not been asked anywhere tells me that there must be something really basic that I have not understood. Please help me in understanding this.