YubiKey 5Ci

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.

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

Applications
FIDO2
The FIDO2 application allows for resident credentials to be stored and allows for password-less login on sites and devices that support it. The credentials can be protected with a PIN for convenient and strong two factor authentication. The FIDO2 application is FIDO certified.
USB Interface: FIDO
More about FIDO 2
Enhancements to FIDO 2 Support

OTP
The OTP applet contains two
programmable slots, each can hold one of the following credentials:
· Yubico OTP
· HMAC-SHA1 Challenge-Response
· Static Password
· OATH-HOTP
USB Interface: OTP
U2F
The U2F application can hold an unlimited number of U2F credentials and is FIDO certified
USB Interface: FIDO
OATH
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.

• PIN: 123456
• PUK: 12345678
• Management Key:0102030405060708010203040506/ 7080102030405060708

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
OpenPGP
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

o x25519 (decipher only)
o ed25519 (sign / auth only)

USB Interface: CCID
Physical Specifications
Form Factor
Connectors: USB-C, Lightning Dimensions: 12mm x 40.3mm x 5mm. Weight: 2.9g
Temperatures
Operational range: 0 °C to 40 °C (32 °F to 104 °F)
Storage range: -20 °C to 85 °C (-4 °F to 185 °F)