Trust Store vs Key Store - creating with keytool

I understand that the keystore would usually hold private/public keys and the trust store only public keys (and represents the list of trusted parties you intend to communicate with). Well, that's my first assumption, so if that's not correct, I probably haven't started very well...

I was interested though in understanding how / when you distinguish the stores when using keytool.

So, far I've created a keystore using

keytool -import -alias bob -file bob.crt -keystore keystore.ks

which creates my keystore.ks file. I answer yes to the question do I trust bob but it is unclear to me if this has created a keystore file or a truststore file? I can set up my application to use the file as either.

-Djavax.net.ssl.keyStore=keystore.ks -Djavax.net.ssl.keyStorePassword=x
-Djavax.net.ssl.trustStore=keystore.ks -Djavax.net.ssl.trustStorePassword=x

and with System.setProperty( "javax.net.debug", "ssl") set, I can see the certificate under trusted certifications (but not under the keystore section). The particular certificate I'm importing has only a public key and I intend to use it to send stuff over an SSL connection to Bob (but perhaps that's best left for another question!).

Any pointers or clarifications would be much appreciated. Is the output of keytool the same whatever you import and its just convention that says one is a keystore and the other a trust store? What's the relationship when using SSL etc?

The terminology is a bit confusing indeed, but both javax.net.ssl.keyStore and javax.net.ssl.trustStore are used to specify which keystores to use, for two different purposes. Keystores come in various formats and are not even necessarily files (see this question), and keytool is just a tool to perform various operations on them (import/export/list/...).

The javax.net.ssl.keyStore and javax.net.ssl.trustStore parameters are the default parameters used to build KeyManagers and TrustManagers (respectively), then used to build an SSLContext which essentially contains the SSL/TLS settings to use when making an SSL/TLS connection via an SSLSocketFactory or an SSLEngine. These system properties are just where the default values come from, which is then used by SSLContext.getDefault(), itself used by SSLSocketFactory.getDefault() for example. (All of this can be customized via the API in a number of places, if you don't want to use the default values and that specific SSLContexts for a given purpose.)

The difference between the KeyManager and TrustManager (and thus between javax.net.ssl.keyStore and javax.net.ssl.trustStore) is as follows (quoted from the JSSE ref guide):

> TrustManager: Determines whether the > remote authentication credentials (and > thus the connection) should be > trusted. > > KeyManager: Determines which > authentication credentials to send to > the remote host.

(Other parameters are available and their default values are described in the JSSE ref guide. Note that while there is a default value for the trust store, there isn't one for the key store.)

Essentially, the keystore in javax.net.ssl.keyStore is meant to contain your private keys and certificates, whereas the javax.net.ssl.trustStore is meant to contain the CA certificates you're willing to trust when a remote party presents its certificate. In some cases, they can be one and the same store, although it's often better practice to use distinct stores (especially when they're file-based).

To explain in common usecase/purpose or layman way:

> TrustStore : Used to store the certificates > of trusted entities. A process can maintain a store of certificates of all the trusted parties > which it trusts. > > keyStore : Used to store the server keys (both public and private) > along with the signed certificate.

During the SSL handshake,

1. A client tries to access https://

2. And thus, Server responds by providing a SSL certificate (which is stored in its keyStore)

3. Now, the client receives the SSL certificate and verifies it via trustStore (i.e the client's trustStore already has pre-defined set of certificates which it trusts.). Its like : Can I trust this server ? Is this the same server whom I am trying to talk to ? No middle man attacks ?

4. Once, the client verifies that it is talking to server which it trusts, then SSL communication can happen over a shared secret key.

Note : I am not talking here anything about client authentication on server side. If a server wants to do a client authentication too, then the server also maintains a trustStore to verify client. Then it becomes mutual TLS.

There is no difference between keystore and truststore files. Both are files in the proprietary JKS file format. The distinction is in the use: To the best of my knowledge, Java will only use the store that is referenced by the -Djavax.net.ssl.trustStore system property to look for certificates to trust when creating SSL connections. Same for keys and -Djavax.net.ssl.keyStore. But in theory it's fine to use one and the same file for trust- and keystores.

Keystore is used by a server to store private keys, and Truststore is used by third party client to store public keys provided by server to access. I have done that in my production application. Below are the steps for generating java certificates for SSL communication:

1. Generate a certificate using keygen command in windows:

keytool -genkey -keystore server.keystore -alias mycert -keyalg RSA -keysize 2048 -validity 3950

2. Self certify the certificate:

keytool -selfcert -alias mycert -keystore server.keystore -validity 3950

3. Export certificate to folder:

keytool -export -alias mycert -keystore server.keystore -rfc -file mycert.cer

4. Import Certificate into client Truststore:

keytool -importcert -alias mycert -file mycert.cer -keystore truststore

These are the steps to create a Truststore in your local machine using Keytool. Steps to create truststore for a URL in your local machine.

1. Hit the url in the browser using chrome

2. Check for the "i" icon to the left of the url in the chrome and click it

3. Check for certificate option and click it and a Dialog box will open

4. check the "certificate path" tab for the number of certificates available to create the truststore

5. Go the "details" tab -> click"Copy to File" -> Give the path and the name for the certificate you want to create.

6. Check if it has parent certificates and follow the point "5".

7. After all the certificates are being create open Command Prompt and navigate to the path where you created the certificates.

8. provide the below Keytool command to add the certificates and create a truststore.

Sample: 
   keytool -import -alias abcdefg -file abcdefg.cer -keystore cacerts
		where "abcdefg" is the alias name and "abcdefg.cer" is the actual certificate name and "cacerts" is the truststore name

9. Provide the keytool command for all the certificates and add them to the trust store.

   	keytool -list -v -keystore cacerts

keystore simply stores private keys, wheras truststore stores public keys. You will want to generate a java certificate for SSL communication. You can use a keygen command in windows, this will probably be the most easy solution.