In computing, I'm used to talk about "authenticating against a server". However, it came to my attention that many people use "with" instead of "against" in that sentence, and the Google test seems to prove them right.

Are both valid expressions? Do they mean exactly the same? Do you know any dictionary or style guide out there that states either that one of them is the only valid expression or that one of them is better than the other one?

1 Answer 1


Generally, a user authenticates to something with something. A user is proving he or she is entitled to access something based on something he or she has. For example,

The user must authenticate to the host with Active Directory credentials.

In more complicated scenarios 'against' might be useful. For example,

The user will be authenticating against the Active Directory's Kerberos server.

The definition of against as "compared or contrasted with" is being used rather than "in opposition to".

The user must authenticate to the host with Active Directory credentials because authentication is against the Kerberos server.

In a way, 'against' is thinking from the server's point of view. A user provides credentials and the server compares them to its user table.

I use Microsoft Manual of Style and couldn't find a recommended style. I use 'to' and 'with' when I'm writing for end-users and I use 'against' when writing for administrators.

  • 1
    If I may put it this way: You authenticate to a server, just like you have connected to this server beforehand. Commented Oct 27, 2015 at 19:13
  • 1
    And you are authenticating against the Stack Exchange user tables.
    – Val
    Commented Aug 17, 2016 at 15:45

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