P4Ant is bundled with an older version of 2010.1 P4Java which did not support connecting to SSL servers.
To connect to an SSL Perforce Server use the latest version of P4Java instead. The P4Java download can be found in the Tools & Api section
For example, either alter your taskdef element's classpath attribute to use the new p4java.jar or replace the p4java.jar that you copied to
Your java installation may also need to have the unlimited strenght JCE installed. See Using P4Java and P4Eclipse with SSL enabled Perforce Servers
Your Perforce task must specify protocol="p4javassl"
jobview="reportedBy=jbrown project=snorkle release=2014"/>