Supporting encryption and authentication mode such as GCM

[Takashi Kato]

Security is getting more and more important these days. CBC or CTR mode is not enough to protect privacy. TLS 1.3 requires GCM mode which can add authentication data to encrypt. Luckily, libtomcrypt originally supports these mode (encauth) so it won't be such pain in the ass to implement.

See https://github.com/libtom/libtomcrypt

[Takashi Kato]

GCM is supported. Maybe CCM and others need to be supported but this is for later.