jars

As the Bouncy Castle release page shows, their code is released in several different packages which include & exclude different parts of the Bouncy Castle offering. Spongy Castle follows a similar breakdown into smaller jars, though it partitions those jars so that no code is repeated - for instance, unlike bcprov-jdk15on, scprov-jdk15on doesn't include any of the classes from the 'lightweight' API, which are only included in sc-light-jdk15on.

This kind of hierarchy is easily resolved by a dependency-management tool like Maven, but if you're manually including your own jars, you'll need to ensure you include all the sub-dependencies (an indented item in this list depends on all it's ancestors):

• sc-light-jdk15on - lightweight API that excludes JCA/JCE support
  • scprov-jdk15on - JCA/JCE support
    • scpg-jdk15on - PGP support (also requires sc-bzip2)
    • scpkix-jdk15on - several APIs around Public-Key Infrastructure
      • scmail-jdk15on - S/MIME support (also requires javax.mail:mail and javax.activation:activation)

As an example, scmail-jdk15on requires scpkix-jdk15on, scprov-jdk15on, and sc-light-jdk15on.