At EMnify we have configured OpenVPN to be encrypted as follow:
OpenVPN's default encryption algorithm BF-CBC (Blowfish, block-cipher) with a 128-bit (variable) key size.
Message authentication is what's referred to as HMAC. Using a HMAC is to ensure the encrypted data hasn't been altered in transit. OpenVPN's default setting is SHA-1.
TLS stands for Transport Layer Security which is a cryptographic protocol used to increase security over computer networks. TLS is the successor of SSL although is sometimes still referred to as SSL.