By the way, I also tried this:

public static class SecKeychainAttributeList extends Structure { public int count; public Structure[] attr; }

and then setting up the call like this:

SecKeychainAttribute attr = new SecKeychainAttribute(); ... SecKeychainAttributeList attrList = new SecKeychainAttributeList(); attrList.attr = attr.toArray(1);

That avoided the NullPointerException, but gave me this instead:

java.lang.IllegalArgumentException: Native type undefined for class com.sun.jna.Structure