Build and test the legacy jdk1.3 (build1-3) distribution on a modern host by running the genuine Sun JDK 1.3.1 inside an i386 / glibc-2.3.6 Docker container. Use this whenever the user wants to run "build1-3" / the "jdk1.3" or "Java 1.3" build, get a bcprov-jdk13 jar, reproduce a genuine-1.3 compile failure, or when a genuine JDK 1.3.1 won't start on the host ("can't find libjava.so", missing libstdc++-libc6.1-1.so.2, or a green-threads Classic VM segfault). Captures the container recipe, why glibc < 2.4 is mandatory, the uname/libstdc++/threads traps, and that the jdk1.3 source overlays have rotted (the real source floor is Java 1.4).
Build Maven-style -sources.jar and -javadoc.jar files for the legacy Ant distributions (jdk1.4 via build1-4, and jdk15to18 via build1-5to1-8) from the src.zip / src and javadoc artifacts the Ant build already produces. Use whenever the user wants source/javadoc jars for the jars in build/artifacts/jdk1.4/jars or build/artifacts/jdk1.5/jars — the Gradle build makes these automatically but the legacy Ant builds do not.
Build, sign, and test the legacy jdk15to18 (Java 5) distribution via the build1-5to1-8 script and ant/jdk15+.xml. Use this whenever the user wants to build/sign/run the "build1-5to1-8" version, get "sh build1-5to1-8 test" to pass, reproduce a genuine-Java-5 compile or test failure, or chase a "JCE cannot authenticate the provider BC" / NoSuchMethodError / NoClassDefFoundError that only shows up on a real JRE 5. Captures the build→sign→test ordering, the two different JDKs involved, the machine-only signing step, and the compile-time vs runtime Java-version traps that the modern Gradle build cannot surface.
Port a post-quantum signature algorithm into the BCPQC provider, end to end — lightweight engine plus JCA/JCE wiring, OID converter plumbing, BC↔BCPQC bridge, module-info, tests, and release notes. Use this skill whenever the user wants to add a new PQC signature scheme (FAEST, SNOVA, MAYO, HAWK, etc.) to BCPQC, port a reference C/Rust implementation into BC, or finish a half-wired PQC algorithm whose certs/keys can't be decoded through the standard BC provider. Reach for this skill even when the user only mentions the algorithm name and the verb is "add", "port", "wire up", or "integrate" — the file set and the BC-vs-BCPQC split that this skill captures are non-obvious and easy to half-finish.