a secret phrase, or a combination of letters and numbers, used to get access to a computer or a computer file (= be able to start using it)

The encrypted file is now widely available online, along with the passphrase to open it. 加密文件及打开这种文件的密码现在很容易在网上找到。

The network is only ever as secure as the passphrase used to protect it. 网络的安全程度取决于用来保护它的密码。