The latest versions of the FIDO Alliance user authentication specifications are available below. If you are new to FIDO, we recommend you first review the Specifications Overview before proceeding further.

In addition to meeting the technical requirements, the FIDO Alliance developed further security requirements that need to be implemented to enhance the security assurance of each device. These requirements are covered in the Authenticator Certification program found on the Certified Authenticator Levels page.

Older versions of the specifications can be found in the specification archive along with the Chinese translation of the UAF 1.0 specifications. The FIDO Specification Status and Intellectual Property Rights (IPR) of the FIDO Alliance specifications can be found here.


The FIDO Alliances publishes the following technical specifications for any implementer to download. In addition, the Alliance is providing support for implementers of FIDO authentication technology by operating the fido-dev@fidoalliance.org public discussion list. Please post any questions you may have about implementing the FIDO specifications in that forum.

The FIDO Alliance produces PDF-formatted specifications as a convenience for readers, however readers are advised to refer to the HTML-formatted specs if they encounter any formatting issues with the PDF-formatted specs. IF YOU ARE NOT YET A MEMBER OF THE FIDO ALLIANCE, AND YOU WOULD LIKE TO COMMENT ON OUR PUBLIC DRAFT SPECIFICATIONS, PLEASE USE THE CONTACT US FORM.

FIDO2 Specifications
CLIENT TO AUTHENTICATOR PROTOCOL (CTAP)
This Proposed Standard document describes the Client-to-Authenticator Protocol (CTAP) which uses USB, NFC, and / or BLE for communication between browsers or platforms and FIDO2 authenticators.

CTAP 2.1 Proposed Standard with Errata: HTML | PDF

CTAP 2.1 Errata: HTML | PDF

CTAP 2.2 Review Draft 01: HTML | PDF
W3C – Web Authentication:
An API for accessing Public Key Credentials
Level 2 (Webauthn)

This specification defines an API enabling the creation and use of strong, attested, scoped, public key-based credentials by web applications, for the purpose of strongly authenticating users.

Download: HTML
UAF Specifications
FIDO UAF Complete Specifications
This is a zip file containing the FIDO Alliance Universal Authentication Framework (UAF) specification files:

Change USB transport to conform to ISO7816-4
NFC (ISO7816-4) support
Bluetooth Low Energy support
Updated JavaScript 1.1 specification
Transports Extension specification
Expanded Metadata Service specification to include U2F

1.1 Proposed Standard: Files

1.2 Proposed Standard: Files
FIDO UAF Architectural Overview
This overview document describes the various protocol design considerations in detail and also describes the user flows in detail. It describes the layering and intention of each of the detailed protocol documents.
You should read this document first if you are new to UAF.

1.1 Proposed Standard: HTML | PDF
1.2 Proposed Standard: HTML | PDF
FIDO UAF Protocol Specification
This document defines the message formats and processing rules for all UAF protocol messages.

1.1 Proposed Standard: HTML | PDF
1.2 Proposed Standard: HTML | PDF
UAF Application API and Transport Binding Specification
This document describes the client-side APIs and interoperability profile for client applications to utilize FIDO UAF.

1.1 Proposed Standard: HTML | PDF
1.2 Proposed Standard: HTML | PDF
FIDO UAF Authenticator-specific Module API
This document defines Authenticator-specific Modules and the API provided to the FIDO client by ASMs.

1.1 Proposed Standard: HTML | PDF
1.2 Proposed Standard: HTML | PDF
FIDO UAF Authenticator Commands
This document describes Low-level functionality that UAF Authenticators should implement to support the UAF protocol.

1.1 Proposed Standard: HTML | PDF

1.2 Proposed Standard: HTML | PDF
FIDO ECDAA Algorithm
This document describes how to use Elliptic Curve (EC) Direct Anonymous Attestation (DAA) as a form of secure and private attestation for authenticators.

1.1 Proposed Standard: HTML | PDF

1.2 Review Draft: HTML | PDF

2.0 Implementation Draft: HTML | PDF
FIDO UAF APDU Commands
This document defines a mapping of FIDO UAF Authenticator commands to Application Protocol Data Units (APDUs) thus facilitating UAF authenticators based on Secure Elements.

1.1 Proposed Standard: HTML | PDF

1.2 Proposed Standard: HTML | PDF
UAF Registry of Predefined Values
This document describes implementation considerations and recommendations for creators of U2F devices and for relying parties implementing U2F support.

1.1 Proposed Standard: HTML | PDF
1.2 Proposed Standard: HTML | PDF
FIDO UAF Android This document defines the assertion format “APCV1CBOR” in order to use Android Protected Confirmation for FIDO UAF Transaction Confirmation.

1.2 Proposed Standard: HTML | PDF
FIDO UAF WebAuthentication Assertion Format
This document defines the assertion format “WAV1CBOR” in order to use Web Authentication assertions through the FIDO UAF protocol.

1.2 Proposed Standard: HTML | PDF
FIDO UAF ERRATA
This errata is being published to address certain issues that have been identified in the UAF v1.1 Specification. All Specifications and errata are required to be approved by the FIDO Board prior to publication.

1.1 Implementation Draft: PDF
FIDO Metadata
FIDO Authenticator Metadata Statements
This document defines the authenticator metadata. This metadata, in turn, describes FIDO authenticator form factors, characteristics, and capabilities. The metadata is used to inform relying party interactions with, and make policy decisions about, the authenticators.

1.1 Proposed Standard: HTML | PDF

3.0 Proposed Standard: HTML | PDF
FIDO Authenticator Metadata Service
Baseline method for relying parties to obtain FIDO Metadata statements.

1.1 Proposed Standard: HTML | PDF

3.0 Proposed Standard: HTML | PDF
FIDO2 and UAF Common Files
FIDO Registry of Predefined Values
This document defines all the strings and constants common to all FIDO specifications.

1.1 Proposed Standard: HTML | PDF

2.2 Proposed Standard: HTML | PDF
FIDO AppID and Facet Specification
This document defines the scope of user credentials and how a trusted computing base that supports application isolation may make access control decisions about which keys can be used by which applications and web origins.

1.1 Proposed Standard: HTML | PDF

2.1 Proposed Standard: HTML | PDF
FIDO Security Reference
Provides an analysis of FIDO security based on detailed analysis of security threats pertinent to the FIDO protocols based on its goals, assumptions, and inherent security measures.

1.1 Proposed Standard: HTML | PDF

2.1 Proposed Standard: HTML | PDF
FIDO Technical Glossary
Defines the technical terms and phrases used in FIDO Alliance specifications and documents.

1.1 Proposed Standard: HTML | PDF

2.1 Proposed Standard: HTML | PDF
FIDO ECDAA Algorithm

This document describes how to use Elliptic Curve (EC) Direct Anonymous Attestation (DAA) as a form of secure and private attestation for authenticators.

1.1 Proposed Standard: HTML | PDF

2.1 Proposed Standard: HTML | PDF
U2F SPECIFICATIONS
FIDO U2F Complete Specifications
This is a zip file containing the U2F 1.2 Specifications public snapshot of FIDO Alliance Universal 2nd Factor (U2F) specs approved July 11th, 2017. Included in the latest U2F 1.2 specifications are:

Change USB transport to conform to ISO7816-4
NFC (ISO7816-4) support
Bluetooth Low Energy support
Updated JavaScript 1.1 specification
Transports Extension specification
Expanded Metadata Service specification to include U2F
You should read this document first if you are new to U2F.

1.2 Proposed Standard: Files
FIDO U2F Architectural Overview
This overview document describes the various design considerations which go into the protocol in detail and describes the user flows in detail. It describes the layering and intention of each of the detailed protocol documents. It describes the various privacy considerations in the protocol design through the document and summarizes these at the end
You should read this document first if you are new to U2F.

1.0 Proposed Standard: HTML

1.2 Proposed Standard: PDF

1.2 Proposed Standard: HTML

1.2 Proposed Standard: PDF
FIDO U2F JavaScript API
This document describes the client side API in the web browser for accessing U2F capabilities. An online service or website can levearge U2F by using this API on the client side and pairing it with a server which can verify U2F messages on the server side. (Later specifications will describe APIs in non-browser contexts).


1.0 Proposed Standard: HTML

1.2 Proposed Standard: PDF

1.2 Proposed Standard: Files

1.2 Proposed Standard: Files
FIDO U2F Raw Message Formats
This document describes the binary format of request messages which go from the FIDO U2F server to the FIDO U2F token and the binary format of the response messages from the token to the server. These messages are encoded by the browser (FIDO client) for communication over a particular transport (such as USB) to the cryptographic core of the token which performs key generation and signing. A header file with standard values is also specified.

1.0 Proposed Standard: HTML

1.2 Proposed Standard: PDF

1.2 Proposed Standard: HTML

1.2 Proposed Standard: PDF
FIDO U2F HID Protocol
This document describes how the browser (FIDO client) frames the binary raw messages coming from the javascript API for transport over USB-HID to a U2F token. The binary raw messages are described in the ‘FIDO U2F Raw Message Formats’ document. A header file with standard values is also specified. [Later specifications will specify how the javascript APIs frames raw messages over other (non-USB) transports].

1.0 Proposed Standard: HTML

1.2 Proposed Standard: PDF

1.2 Proposed Standard: HTML

1.2 Proposed Standard: PDF
FIDO U2F Bluetooth® protocol
This document describes the communication protocol between a FIDO client and FIDO authenticators over Bluetooth technology and Bluetooth Smart.

1.2 Proposed Standard: HTML

1.2 Proposed Standard: PDF
FIDO U2F NFC Protocol
This document describes the communication protocol between a FIDO client and FIDO authenticators over Near Field Communication (NFC).

1.2 Proposed Standard: HTML

1.2 Proposed Standard: PDF
FIDO U2F Transport Extensions
This standard describes one way relying parties may learn which transports an authenticator supports, by allowing authenticator vendors to embed hardware features as an optional extension in the authenticator’s attestation certificate.

1.2 Proposed Standard: HTML

1.2 Proposed Standard: PDF
FIDO U2F Implementation Considerations
This document describes implementation considerations and recommendations for creators of U2F devices and for relying parties implementing U2F support.

1.0 Proposed Standard: HTML

1.0 Proposed Standard: PDF

1.2 Proposed Standard: HTML

1.2 Proposed Standard: PDF
FIDO AppID and Facet Specification
This document defines the scope of user credentials and how a trusted computing base which supports application isolation may make access control decisions about which keys can be used by which applications and web origins.

1.0 Proposed Standard: HTML

1.0 Proposed Standard: PDF

1.2 Proposed Standard: HTML

1.2 Proposed Standard: PDF
FIDO Security Reference
Provides an analysis of FIDO security based on detailed analysis of security threats pertinent to the FIDO protocols based on its goals, assumptions, and inherent security measures.

1.0 Proposed Standard: HTML

1.0 Proposed Standard: PDF

1.2 Proposed Standard: HTML

1.2 Proposed Standard: PDF
FIDO Technical Glossary
Defines the technical terms and phrases used in FIDO Alliance specifications and documents.

1.0 Proposed Standard: HTML

1.0 Proposed Standard: PDF

1.2 Proposed Standard: HTML

1.2 Proposed Standard: PDF
FIDO U2F Readme
This is a README for the U2F 1.2 Implementation Draft public snapshot of the Universal Second Factor (U2F) specs as of July 11, 2017.

1.0 Proposed Standard: TXT

1.2 Proposed Standard: TXT

About FIDO Specification Status and Intellectual Property Rights (IPR)

Summary of IPR Status of the Specifications on this site:

SpecificationSpecification Status
U2F 1.0Proposed Standard Expanded to the World
U2F 1.1

Proposed Standard Expanded to the World
U2F 1.2Proposed Standard Expanded to the World
UAF 1.0Proposed Standard Expanded to the World
UAF 1.1Proposed Standard Expanded to the World
FIDO2 Submission to W3CProposed Standard Expanded to the World
FIDO2 CTAPProposed Standard Expanded to the World
FIDO Device Onboard 1.0Proposed Standard Expanded to the World
FIDO Device Onboard 1.1Proposed Standard Expanded to the World

Explanation of IPR Status FIDO Alliance specifications progress through various stages, Pre-Draft, Working Draft, Review Draft and Proposed Standard. The Promise, the agreement FIDO Alliance Member organizations make to grant a royalty-free license of their patent rights for compliant implementations, is applied differently based on the specification stage. The Promise does not apply for Pre-Draft, Working Draft and Review Draft specification stages. At Proposed Standard stage, the Promise is provided by all FIDO Alliance members of the relevant Technical Working Group to the entire world. For any FIDO Alliance specifications issued as Proposed Standard before January 1, 2020, the Promise is a covenant not to assert patent rights against compliant implementations and is provided by all the then FIDO Alliance members to the entire world. It is understood that the above is a brief summary and that the actual terms are provided in the FIDO Alliance Membership Agreement, which should be consulted for any specific case.

Patent Notices The FIDO Alliance Membership Agreement provides Members the opportunity to make withdrawals of Granted Claims from the Promise under certain conditions. The FIDO Alliance Membership Agreement should be consulted for the specific conditions. The Board is pleased to report to the public that it has received no such notice pertaining to any of the Specifications published on this site. Implementers interested in learning more about what this means are encouraged to review our IPR Summary and/or section 6 of the FIDO Alliance Membership Agreement.