Checking Passphrase for private key:
openssl rsa -check -in keyfilename
openssl rsa -des3 -in keyfilename -out newkeyfilename
Installing or trusting certificates:
Extensions .crt, .pem and .cer are interchangeable, just change the file name extension, they have the same form. Try this:
sudo cp mycert.cer /usr/share/ca-certificates/mycert.pem
sudo dpkg-reconfigure ca-certificates
Getting the RSA public and private key from conf file.