the Java keystore contains certificate information
To be more precise it contains public keys or key pairs
(public and private key). The keystore is protected by
a password and every private key is also protected by a password.
However you are able to change or remove passwords. It's up to you.
A Java keystore is like a detached keystore of a web browser i.e.
Mozilla -> Edit -> Preferences -> Advanced -> Certificates,
Chrome -> Settings -> Advanced Settings -> HTTPS/SSL
A Certificate Manager of such manages your certificates, peoples public keys, server or Certificate Authority certificates which are also public keys. They are stored in the keystore of a browser.
but this information is public (i.e. other machine certificates which
you want the local machine to trust)
Public are only keys that don't need any protection, they are
the public keys. Private keys are not public and protected by a password.
You decide when to use the keys and when stolen it is not easy extract informations from. So a keystore is a security enchancement.
But you speak generally about the level of trust, or Trust metrics.
To do this you need to know, that a private keys can theoretically
also be guessed, so your security is not 100%. A todays supercomputer listed at
Top500 Supercomputer Sites with 33,862.7 Tera Flops/s could bruteforce you private key. Theoretically, your computer/laptop can be stolen or your keystore can be stolen and your passwords can be read by a trojan.
You will end up asking, how high is the risk if my keystore would be stolen and decrypted and what can I do to prevent it. This is often also a question of effort and price.
If your risk is high, then you need to store your keystore on a detached disk (i.e. pen drive), use long complex passwords and use a special protected machine to connect from.