1. Encryption takes plaintext and turns it into unreadable ciphertext.
2. A wildcard certificate can be used on multiple servers in the same domain. Therefore, when you install it, the name of the server will be inserted into the X509.
3. The old private key is required to decrypt the data. Keys work in pairs and the old public key encrypted the data, therefore, he needs the corresponding private key to decrypt it.
4. A digital signature provides non-repudiation and integrity of the email. He needs to sign it with his private key. There is only one private key.
5. A digital signature provides both integrity, so you know that it has not been tampered with, and non-repudiation as it was signed using the one and only ...