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<pre>
!!! Overview
[{$pagename}] ([CTAP]) [specification] describes an [Application Layer] [protocol] for communication between a [WebAuthn Authenticator] and another client/platform, as well as bindings of this [application] [protocol] to a variety of transport [protocols] using different physical media.


[{$pagename}] [CTAP2] [Specification] is from the [FIDO Alliance]. [{$pagename}] specifies a [protocol] for communication between a [Client Device] with [cryptographic] capabilities (aka [WebAuthN][authenticator]) and a host computer that wishes to use these capabilities for security functions including strong user [authentication]. A person could use his/her phone or another portable security key as the [FIDO Authenticator] to transparently and securely log on to notebooks, desktops, connected cars, and other devices.[2]


[FIDO2] [clients|FIDO Client], such as [browsers] implementing the W3C Web Authentication ([Web Authentication API]) specification, to perform [authentication] using pairwise [Public Key]/[Private Key] pairs securely held by [authenticators] speaking the [{$pagename}] protocol (rather than [passwords]). Use of three transports for communicating with authenticators is specified in the [{$pagename}] specification: 
* [USB] Human Interface Device (USB HID)
* [Near Field Communication] ([NFC])
* [Bluetooth] Smart/[Bluetooth Low Energy] ([BLE]).

The [Application Layer] [protocol] defines requirements for such transport [protocols]. Each transport binding defines the details of how such transport layer connections should be set up, in a manner that meets the requirements of the [Application Layer] [protocol].

!! [{$pagename}] [CTAP2]
[CTAP2] devices provide additional capabilities.


!! More Information
There might be more information for this subject on one of the following:
[{ReferringPagesPlugin before='*' after='\n' }]
----
* [#1] - [Client to Authenticator Protocol (CTAP)|https://fidoalliance.org/specs/fido-v2.0-id-20180227/fido-client-to-authenticator-protocol-v2.0-id-20180227.html|target='_blank'] - based on information obtained 2018-05-08- 
* [#2] - [The latest versions of the FIDO Alliance specifications|https://fidoalliance.org/download/|target='_blank'] - based on information obtained 2018-06-02- 









































































































































































































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