The PGP specification lists the symmetric algorithms that can be used for encryption. The iWay PGP extension relies on the installed cryptographic providers to supply the necessary Cipher implementations. The IDEA implementation is missing by default because it is patented in many parts of the world and requires a license to run. The extended Bouncy Castle provider can be installed manually to add the IDEA implementation in the parts of the world that are not affected by this license. The user is responsible to confirm he complies with all the IDEA licensing terms.
The versions of the bcprov-<VERSION>.jar and bcprov-ext-<VERSION>.jar files must match.
The Bouncy Castle website usually provides only the latest version, so you may need to download the bcprov-ext-<VERSION>.jar file from another website.
If so, then replace bcprov-<VERSION>.jar with bcprov-ext-<VERSION>.jar in these locations also, since the lib\ext directory takes precedence.