Question

I currently use bouncy castle to generate a RSA key pair and export them into files. Currently, the keys are exported in DER format. I would like to know if it is possible to export them in .PEM format instead.

Answer 1

Depending on your code (which you are not showing) just use PemWriter.

public class PEMWriter
extends org.bouncycastle.util.io.pem.PemWriter

Or convert outside with

 openssl x509 inform=DER in=in.der outform=PEM out=out.pem