YubiKey 5 FIPS Series Features

NIST classified the YubiKey 5 Series FIPS as “composite authenticators”. As such, no device in that series can be taken out of the FIPS-approved mode after initialization without zeroizing the function. This means that once the YubiKey is correctly configured, it remains in the correct configuration. As long as the crypto officer ensures that the YubiKey 5 Series FIPS devices are correctly configured at initialization, they remain in FIPS-approved mode. See Deploying the YubiKey 5 FIPS Series.

Initialization is a bit different depending on the FIPS version you are using. Each version requires more stringent initialization than the previous level. See YubiKey Firmware 5.7.x Changes for FIPS 140-3, FIPS 140-2 Level 2 Configuration, or FIPS 140-2 Level 1 Configuration.

NIST Version Certification

The YubiKey 5 cryptographic module applies across YubiKey firmware versions.

  • YubiKey 5 FIPS Series firmware version 5.7.4 is is certified as an authenticator under FIPS 140-3, Level 2.
  • YubiKey 5 FIPS Series hardware with 5.4.3 and 5.4.2 firmware is certified as an authenticator under FIPS 140-2, both Level 1 and Level 2 (Physical Security Level 3).

The YubiKey 5 FIPS Series meets the highest authenticator assurance Level 3 (AAL3) of NIST SP800-63B guidance.

Note

  • Effective May 22 2026, YubiKey 5 FIPS Series firmware 5.7.4 was NIST certified for FIPS 140-3.
  • YubiKey 5 FIPS Series 5.4.x FIPS 140-2 certification moved to the Sunset List, May 2026 and will be moved to the Historical List, September 22, 2026.

Per NIST document FIPS 140-3 Transition Effort, YubiKey 5 FIPS Series certification is affected as follows:

  • Existing deployments - No change. Authenticators certified under FIPS 140-2 can continue to be used in existing deployments after sunset.
  • New deployments - FIPS 140-2 is being replaced by FIPS 140-3. New submissions must fulfill the FIPS 140-3 requirements. Authenticators deployed in new environments must have a valid certificate that is not expired. Auditors typically recommend that authenticators certified under FIPS 140-2 are not used in new deployments.

Supported Cryptographic Module Major Functions

The following table lists the FIPS cryptographic modules and protocols supported for the YubiKey 5 FIPS Series firmware versions.

Cryptographic Functions and NIST Version per Firmware Version
Function Firmware Versions
5.7.4 5.4.3 5.4.2
FIDO Universal 2nd Factor (U2F)
FIDO2 WebAuthn 140-3 140-2 140-2
OATH OTP authentication 140-3 140-2 140-2
One Time Password (Yubico OTP)
140-2 140-2
OpenPGP (version 3.4) 140-3 140-2
PIV-compatible smart card 140-3 140-2 140-2
SCP03 140-3 140-2 140-2
SCP11 140-3
YubiHSM Auth 140-3 140-2

Note

  1. Do not use U2F with FIPS. Instead use the FIDO2. U2F is disabled on FIPS 140-3 keys. Be sure to disable U2F on FIPS 140-2 keys. See U2F with FIPS.
  2. For Yubico OTP, YubiKeys are labeled, enabled, and usable on FIPS 140-3 devices. However, it is not certified as FIPS.

FIPS Form Factors

Form factor is set during manufacturing and returned as a one-byte value. Currently defined values for this are set out in the Form Factor table below. These FIPS YubiKey values apply since YubiKey firmware 5.4.

FIPS Form Factor Byte Values
YubiKey Undefined 5 NFC 5 Nano 5C NFC 5C Nano 5Ci
Connections
N/A
NFC +
USB-A
Nano
USB-A
NFC +
USB-C
Nano
USB-C
Lightning +
USB-C
Value 0x00 0x01 0x02 0x03 0x04 0x05
FIPS Value N/A 0x81 0x82 0x83 0x84 0x85

Credentials and Permitted Values

For FIPS 140-3 Level 2 and FIPS 140-2 Level 2, the table below lists the credentials required, allowed values, and credential owner for the supported applications.

Credentials Required and Allowed
Application
Credential
Credential
Owner

 Permitted Values FIPS
140-3
140-2
OATH
Authentication
Key
Crypto
Officer
14-64 byte HMAC SHA1,
SHA256 key
One Time
Password (OTP)
OTP Slot 1
OTP Slot 2
Crypto
Officer


6 byte
access codes
OpenPGP
User Password
(PW1)
Authenticated
User
8-127 byte
PIN
6-127 byte
PIN
Admin Password
(PW3)
Crypto
Officer
8-127 byte
PIN
6-127 byte
PIN
PIV Smart Card Management Key
Crypto
Officer
AES-128,
AES-192,
AES-256
3-key TDES,
AES-128,192,
AES-256 key
PUK
Authenticated
User
8 byte PIN
6-8 byte
PIN
PIN
Authenticated
User
8 byte PIN
6-8 byte
PIN
WebAuthn PIN
Authenticated
User
8-63 byte
PIN
6-32 byte
PIN

The instructions for the individual applications are provided in the following topics:

For more information on secure channel requirements from NIST, see NIST Special Publication 800-63-C and NIST Special Publication 800-63B.