(idiomatic) A piece of cake; an extremely simple thing, something trivial, a cinch, easy as pie.

朝飯前: A piece of cake; an extremely simple thing.

put away

to lose (something) / to get rid of / to lose (someone) (wife, child, etc.)

lose a person, suffer the death of another person

(cryptography) key exchange - an exchange of peers' keys at initialization phase of connection.

(cryptography) public key

(cryptography) secret key

(Internet slang) protected account (on social media, especially Twitter and Instagram)

black key (of a piano, etc.)