DER encoded RSA private key

DER encoded RSA private key is an RSA private key format that stores the same information as PEM encoded RSA private key, but encoded in DER format instead of PEM format.

Examples
To view the contents of a file: openssl rsa -noout -text -inform DER -in example-der.key

To convert to PEM encoded RSA private key format: openssl rsa -inform DER -in example-der.key -out example-pem.key

Software

 * OpenSSL