What does it mean and how is a package or file signed with a private key?

Question

Cryptography

Hello, how is a file signed with a private key, what does it mean and how does it work, Next, how is it checked later? (PS I know what and how Symmetric and Asymmetric encryption public and private keys are and how they work) thanks in advance

Answer 1

A function is called, a private key and possibly a password are passed to it, the output is a stream of bytes, or a file.
Everything is checked against the hash by which everything is signed at the end. Moreover, you can calculate this hash from the public key.
This part is responsible for ensuring that the file has not changed since it was signed.
And you do not need to encrypt the content.
When decrypting, the same thing, only if it does not match, there will be garbage. What you will be informed
about And this is all very simplified.