Cross-platform Authentication is often used to facilitate delivery of personalized services to the Digital Subject regardless of the device used. Of course many times this ability is used in an less appropriate manner.
Typically, Cross-platform Authentication is associated with HTTP Authentication but could also be Multiple-channel Authentication.
Generic Security Service Application Program Interface is one Cross-platform Authentication which can be implemented over HTTP using Simple and Protected GSSAPI Negotiation Mechanism.
Often an Authentication Agent would be used to implement Cross-platform Authentication