鑰匙

key / CL:把[ba3]

key / also pr. [yao4]

spoon

used in 鑰匙|钥匙[yao4 shi5]

One key opens one lock. / There is a different solution for each problem. (idiom)

public key (in encryption)

Today is the key to the past.

private key (in encryption)

master key / skeleton key / passkey

to make a key

keycard

keyhole

keychain