FIDO CTAP 2.1

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    FIDO Alliance
    
    
  

  
Client to Authenticator Protocol for FIDO2 security keys, defining USB, NFC, and BLE communication with authenticators.

  
  
FIDO CTAP 2.1 (Client to Authenticator Protocol) defines how a host such as a browser or operating system talks to an external FIDO2 authenticator over USB, NFC, or Bluetooth Low Energy. Together with WebAuthn it enables phishing-resistant, passwordless sign-in using public-key credentials that never leave the security key. The 2.1 revision added enterprise attestation, credential management, and always-uv (user verification) policies for managed deployments.

  
  

    
    CTAP 2.1
    
    
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    Published 2018
    
    
  






  
  

    
    




    
    

    
    

    
    

      
Standard Details

      

        

          
            
            
            
CategoryFIDO Alliance

            
            
            
Year Published2018

            
            
            
            
StatusActive

          
        

      

    


    
    

    
    

    
    
    
    

      
Compliant Card Types

      

        
        
          

            
FIDO2 Security Key (Card Form)

            Dual-Interface
          

          
Hardware authenticator supporting FIDO2/WebAuthn for passwordless login, available in USB, NFC, and smart card form factors.

        
        
      

    

    
    

    
    
    
    

    
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