Authentication - Information Content

Information Content

The authentication of information can pose special problems (especially man-in-the-middle attacks), and is often wrapped up with authenticating identity.

Literary forgery can involve imitating the style of a famous author. If an original manuscript, typewritten text, or recording is available, then the medium itself (or its packaging — anything from a box to e-mail headers) can help prove or disprove the authenticity of the document.

However, text, audio, and video can be copied into new media, possibly leaving only the informational content itself to use in authentication.

Various systems have been invented to allow authors to provide a means for readers to reliably authenticate that a given message originated from or was relayed by them. These involve authentication factors like:

• A difficult-to-reproduce physical artifact, such as a seal, signature, watermark, special stationery, or fingerprint.
• A shared secret, such as a passphrase, in the content of the message.
• An electronic signature; public-key infrastructure is often used to cryptographically guarantee that a message has been signed by the holder of a particular private key.

The opposite problem is detection of plagiarism, where information from a different author is passed off as a person's own work. A common technique for proving plagiarism is the discovery of another copy of the same or very similar text, which has different attribution. In some cases, excessively high quality or a style mismatch may raise suspicion of plagiarism.