Using SSL

Configuring the PostgreSQL® server for SSL is covered in the main documentation, so it will not be repeated here. There are also instructions in the source certdir Before trying to access your SSL enabled server from Java, make sure you can get to it via psql. You should see output like the following if you have established a SSL connection.

$ ./bin/psql -h localhost -U postgres
psql (14.5)
SSL connection (protocol: TLSv1.2, cipher: ECDHE-RSA-AES256-GCM-SHA384, bits: 256, compression: off)
Type "help" for help.

postgres=#

PostgreSQL® provides a way for developers to customize how an SSL connection is established. This may be used to provide a custom certificate source or other extensions by allowing the developer to create their own SSLContext instance. The connection URL parameters sslfactory allow the user to specify which custom class to use for creating the SSLSocketFactory . The class name specified by sslfactory must extend javax.net.ssl.SSLSocketFactory and be available to the driver’s classloader.

This class must have a zero argument constructor or a single argument constructor preferentially taking a Properties argument. There is a simple org.postgresql.ssl.DefaultJavaSSLFactory provided which uses the default java SSLFactory.

Information on how to actually implement such a class is beyond the scope of this documentation. Places to look for help are the JSSE Reference Guide and the source to the NonValidatingFactory provided by the JDBC driver.

There are a number of connection parameters for configuring the client for SSL. See SSL Connection parameters

The simplest being ssl=true , passing this into the driver will cause the driver to validate both the SSL certificate and verify the hostname (same as verify-full ).

Note

This is different from libpq which defaults to a non-validating SSL connection.

In this mode, when establishing a SSL connection the JDBC driver will validate the server’s identity preventing “man in the middle” attacks. It does this by checking that the server certificate is signed by a trusted authority, and that the host you are connecting to is the same as the hostname in the certificate.

If you require encryption and want the connection to fail if it can’t be encrypted then set sslmode=require this ensures that the server is configured to accept SSL connections for this Host/IP address and that the server recognizes the client certificate. In other words if the server does not accept SSL connections or the client certificate is not recognized the connection will fail.

Note

In this mode we will accept all server certificates.

If sslmode=verify-ca , the server is verified by checking the certificate chain up to the root certificate stored on the client.

If sslmode=verify-full , the server host name will be verified to make sure it matches the name stored in the server certificate.

The SSL connection will fail if the server certificate cannot be verified. verify-full is recommended in most security-sensitive environments.

The default SSL Socket factory is the LibPQFactory. In the case where the certificate validation is failing you can try sslcert= and LibPQFactory will not send the client certificate. If the server is not configured to authenticate using the certificate it should connect.

The location of the client certificate, the PKCS-8 client key and root certificate can be overridden with the sslcert , sslkey , and sslrootcert settings respectively. These default to /defaultdir/postgresql.crt, /defaultdir/postgresql.pk8, and /defaultdir/root.crt respectively where defaultdir is ${user.home}/.postgresql/ in *nix systems and %appdata%/postgresql/ on windows.

As of version 42.2.9 PKCS-12 is also supported. In this archive format the client key and the client certificate are in one file, which needs to be set with the sslkey parameter. For the PKCS-12 format to be recognized, the file extension must be “.p12” (supported since 42.2.9) or “.pfx” (since 42.2.16). (In this case the sslcert parameter is ignored.)

Finer control of the SSL connection can be achieved using the sslmode connection parameter. This parameter is the same as the libpq sslmode parameter and currently implements the following

sslmode Eavesdropping Protection MITM Protection
disable No No I don’t care about security and don’t want to pay the overhead for encryption
allow Maybe No I don’t care about security but will pay the overhead for encryption if the server insists on it
prefer Maybe No I don’t care about encryption but will pay the overhead of encryption if the server supports it
require Yes No I want my data to be encrypted, and I accept the overhead. I trust that the network will make sure I always connect to the server I want.
verify-ca Yes Depends on CA policy I want my data encrypted, and I accept the overhead. I want to be sure that I connect to a server that I trust.
verify-full Yes Yes I want my data encrypted, and I accept the overhead. I want to be sure that I connect to a server I trust, and that it’s the one I specify.

NOTE

If you are using Java’s default mechanism (not LibPQFactory) to create the SSL connection you will need to make the server certificate available to Java, the first step is to convert it to a form Java understands.

openssl x509 -in server.crt -out server.crt.der -outform der

From here the easiest thing to do is import this certificate into Java’s system truststore.

keytool -keystore $JAVA_HOME/lib/security/cacerts -alias postgresql -import -file server.crt.der

The default password for the cacerts keystore is changeit . Setting the alias to postgresql is not required. You may apply any name you wish.

If you do not have access to the system cacerts truststore you can create your own truststore.

keytool -keystore mystore -alias postgresql -import -file server.crt.der

When starting your Java application you must specify this keystore and password to use.

java -Djavax.net.ssl.trustStore=mystore -Djavax.net.ssl.trustStorePassword=mypassword com.mycompany.MyApp

In the event of problems extra debugging information is available by adding -Djavax.net.debug=ssl to your command line.

In some situations it may not be possible to configure your Java environment to make the server certificate available, for example in an applet. For a large scale deployment it would be best to get a certificate signed by recognized certificate authority, but that is not always an option. The JDBC driver provides an option to establish a SSL connection without doing any validation, but please understand the risk involved before enabling this option.

A non-validating connection is established via a custom SSLSocketFactory class that is provided with the driver. Setting the connection URL parameter sslfactory=org.postgresql.ssl.NonValidatingFactory will turn off all SSL validation.