How to make SSL certificates trusted by your machine

Created by Steve Place, Modified on Wed, 08 Nov 2023 at 11:48 AM by Steve Place

You need all the certificates in your certificate chain in your truststore. You can test whether they are or not with the following command:

openssl s_client -connect your.server:port -CApath /path/to/certs

A successful output of the above command might look like this:

CONNECTED(00000003)
depth=2 C = US, O = DigiCert Inc, OU = www.digicert.com, CN = DigiCert Global Root CA
verify return:1
depth=1 C = US, O = DigiCert Inc, CN = DigiCert SHA2 Secure Server CA
verify return:1
depth=0 C = US, ST = Some-State, O = Organization, CN = your.server
verify return:1
---
Certificate chain
 0 s:C = US, ST = Some-State, O = Organization, CN = your.server
   i:C = US, O = DigiCert Inc, CN = DigiCert SHA2 Secure Server CA
---
Server certificate
-----BEGIN CERTIFICATE-----
...
-----END CERTIFICATE-----
---
No client certificate CA names sent
Peer signing digest: SHA512
Peer signature type: RSA
Server Temp Key: ECDH, P-256, 256 bits
---
SSL handshake has read 2055 bytes and written 441 bytes
Verification: OK
---
New, TLSv1.2, Cipher is ECDHE-RSA-AES256-GCM-SHA384
Server public key is 2048 bit
Secure Renegotiation IS supported
Compression: NONE
Expansion: NONE
No ALPN negotiated
SSL-Session:
    Protocol  : TLSv1.2
    Cipher    : ECDHE-RSA-AES256-GCM-SHA384
    ...
---

Note the line Verification: OK.

An unsuccessful output might look like:

CONNECTED(00000003)
depth=0 C = US, ST = Some-State, O = Some-Organization, CN = your.server
verify error:num=20:unable to get local issuer certificate
verify return:1
depth=0 C = US, ST = Some-State, O = Some-Organization, CN = your.server
verify return:1
---
Certificate chain
 0 s:/C=US/ST=Some-State/O=Some-Organization/CN=your.server
   i:/C=US/ST=Some-State/O=Some-Organization/CN=Some-CA
---
Server certificate
-----BEGIN CERTIFICATE-----
[encoded certificate data]
-----END CERTIFICATE-----
---
No client certificate CA names sent
---
SSL handshake has read 1484 bytes and written 456 bytes
Verification error: unable to get local issuer certificate
---
New, TLSv1.2, Cipher is ECDHE-RSA-AES256-GCM-SHA384
Server public key is 2048 bit
Secure Renegotiation IS supported
Compression: NONE
Expansion: NONE
No ALPN negotiated
SSL-Session:
    Protocol  : TLSv1.2
    Cipher    : ECDHE-RSA-AES256-GCM-SHA384
    Session-ID: 5F4E3C1D9F5B8CD16AEF23A6EF837B396FBAE4D763C3F8F1F5B9D66407A77F0F
    Session-ID-ctx: 
    Master-Key: E3CC7EE7BFD36FAD9BDC2C6A6A9FECB6E3EC4637D8FCC4B9A5B9A5D9E7A8BBCF3EACAE5B67B6ECEA5B633AD5E7E6C3F3
    Start Time: 1594825600
    Timeout   : 7200 (sec)
    Verify return code: 20 (unable to get local issuer certificate)

Note the line verify error:num=20:unable to get local issuer certificate.

If your certificate(s) is/are not in the truststore, you can copy it to the truststore with the following command:

keytool -import -trustcacerts -file /path/to/myCert.crt -keystore /path/to/my-truststore.jks

The -trustcacerts argument is important because it imports all certificates from $JAVA_HOME/lib/security/cacerts to my-truststore.jks.