Why do people use bouncycastle instead of Java’s built in JCE provider? What is the difference?

Why do people use bouncycastle instead of Java Cryptography Extension? What is the difference?

Answer

BouncyCastle has many more cipher suites and algorithms than the default JCE provided by Sun.

In addition to that, BouncyCastle has lots of utilities for reading arcane formats like PEM and ASN.1 that no sane person would want to rewrite themselves.