YubiKey 5Ci


Note: This article lists the technical specifications of the YubiKey 5Ci. If you're looking for setup instructions for your YubiKey 5Ci, see https://www.yubico.com/start.

The YubiKey 5Ci has six distinct applications, which are all independent of each other and can be used simultaneously. Note: Some software such as GPG can lock the CCID USB interface, preventing another software from accessing applications that use that mode.


The YubiKey 5Ci uses a USB 2.0 interface. All of the applications are available through this interface.



The FIDO2 application allows for secure single and multi-factor authentication, and can store up to 25 resident credentials. These credentials, which are protected by a PIN, enable passwordless login, where the YubiKey, unlocked by a PIN and authorized by touch, can log you in to your accounts without entering a username or password. The FIDO2 application is FIDO certified.

USB Interface: FIDO
More about FIDO 2
Enhancements to FIDO 2 Support


The OTP applet contains two programmable slots, each can hold one of the following credentials:

  • Yubico OTP
  • HMAC-SHA1 Challenge-Response
  • Static Password

USB Interface: OTP


The U2F application can hold an unlimited number of U2F credentials and is FIDO certified.

USB Interface: FIDO


The YubiKey 5 series can hold up to 32 OATH credentials and supports both OATH-TOTP (time based) and OATH-HOTP (counter based). Accessing this applet requires Yubico Authenticator.

USB Interface: CCID

PIV (Smart Card)

This application provides a PIV compatible smart card. On Windows, the smart card functionality can be enhanced with the YubiKey Smart Card Minidriver.

Default Values:

  • PIN: 123456
  • PUK: 12345678
  • Management Key: 010203040506070801020304050607080102030405060708

Supported Algorithms:

  • RSA 1024
  • RSA 2048
  • ECC P256
  • ECC P384

Slot Information:

  • Slot 9a: Authentication
  • Slot 9b: Management Key
  • Slot 9c: Digital Signature
  • Slot 9d: Key Management
  • Slot 9e: Card Authentication
  • Slot f9: Attestation
  • Slots 82-95: Retired Key Management

USB Interface: CCID
More info about PIV


This application implements version 3.4 of the OpenPGP Smart Card specification which can be used with GnuPG. For key sizes over 2048 bits, GnuPG version 2.0 or higher is required.
Enhancements to OpenPGP 3.4 Support

Supported Algorithms:

  • RSA 1024
  • RSA 2048
  • RSA 3072
  • RSA 4096
  • secp256r1
  • secp256k1
  • secp384r1
  • secp521r1
  • brainpoolP256r1
  • brainpoolP384r1
  • brainpoolP512r1
  • curve25519
    • x25519 (decipher only)
    • ed25519 (sign / auth only)

USB Interface: CCID

Physical Specifications

Form Factor

Connectors: USB-C, Lightning
Dimensions: 12mm x 40.3mm x 5mm.
Weight: 2.8g


Operational range: 0 °C to 40 °C (32 °F to 104 °F)
Storage range: -20 °C to 85 °C (-4 °F to 185 °F)