Is a master key in the old JBOK wallet simply a private key (with a different name) ie is it the same format as a private key? I am trying to scan individual bytes to look for it as this wallet was not born encrypted....OR does it just generate a master key on the fly when you encrypt ?
It is not a private key nor is it stored in any way similar to a private key. The master key is generated when you encrypt. It is never stored unencrypted.
The thing to look for is a record that begins with
mkey