Unvreakable Vase

The encrypted text we got given was

zmxhz3tkb2vzx3roaxnfzxzlbl9jb3vudf9hc19jcnlwdg9vb30=

Some fiddling around with the capitalisation of the base64 characters got us the actually-printable string

ZmxhZ3tkb2VzX3RoaXNfZXZlbl9jb3VudF9hc19jcnlwdG9vb30=

which decoded to yield the flag.

flag{does_this_even_count_as_cryptooo}