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. This is what renders the --check-fips command unnecessary. 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.
Note
FIPS 140-2 is a regulation that will be deprecated in May 2026. At that point, auditors typically recommend that authenticators certified under FIPS 140-2 not be deployed in new deployments. They can continue to be used in existing deployments, but authenticators deployed in new environments must have a valid certificate that is not expired. FIPS 140-2 is being replaced by FIPS 140-3, therefore any new submissions must fulfill the FIPS 140-3 requirements.
NIST Version Certification
The YubiKey 5 cryptographic module is FIPS 140-2 certified, both Level 1 and Level 2 (Physical Security Level 3) and in certification process for FIPS 140-3.
Per NIST document FIPS 140-3 Transition Effort, YubiKey 5 FIPS Series certification is affected:
The YubiKey 5 FIPS Series hardware with the 5.4 firmware is certified as an authenticator under both FIPS 140-2 Level 1 and Level 2. It meets the highest authenticator assurance level 3 (AAL3) of NIST SP800-63B guidance. To use security keys from the YubiKey 5 FIPS Series as a Level 2, more stringent initialization is required than for Level 1. Guidance for Level 2 is detailed in FIPS 140-2 Level 2 Changes and Configuration. Guidance for Level 3 is set out in FIPS 140-3 Changes.
Effective September 22, 2026, this certification will be moved to the Historical List.
FIPS 140-3 certification based on YubiKey 5 FIPS Series firmware version 5.7.4 is in coordination phase. YubiKey 5 FIPS Series is not yet certified FIPS 140-3, but it shares the cryptographic module major functions.
YubiKey 5 Firmware Support for Cryptographic Module Major Functions
The following table lists the FIPS cryptographic modules and protocols supported with the YubiKey 5 firmware versions.
| 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) | 140-3 | 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
The 5.7.4 is not a FIPS key, but it shares the cryptographic module major functions.
The YubiKey 5 FIPS Series hardware with the 5.4 firmware is certified as an authenticator under both FIPS 140-2 Level 1 and Level 2. It meets the highest authenticator assurance level 3 (AAL3) of NIST SP800-63B guidance. To use security keys from the YubiKey 5 FIPS Series as a Level 2, more stringent initialization is required than for Level 1. Guidance for Level 2 is detailed in FIPS 140-2 Level 2 Changes and Configuration. Guidance for Level 3 is set out in FIPS 140-3 Changes.
FIPS AAGUID and 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:
Form Factor
|
YubiKey Value
|
Security Key
Value, FW 5.4+
|
FIPS YubiKey
Value, FW 5.4+
|
|---|---|---|---|
| UNDEFINED | 0x00 | N/A | N/A |
| Keychain, USB-A | 0x01 | 0x41 | 0x81 |
| Nano, USB-A | 0x02 | N/A | 0x82 |
| Keychain, USB-C | 0x03 | 0x43 | 0x83 |
| Nano, USB-C | 0x04 | N/A | 0x84 |
Keychain with
Lightning, USB-C
|
0x05 | N/A | x85 |
Credentials and Permitted Values
The table below lists the credentials required, allowed values, and credential owner for the supported applications as of FIPS 140-2 Level 2.
| Application | Credential | Permitted Values | Credential
Owner
|
|---|---|---|---|
| OATH | Authentication
Key
|
14-64 byte HMAC
SHA1/SHA256 key
|
Crypto Officer |
One Time Password
(OTP)
|
Access Code:
OTP Slot 1
OTP Slot 2
|
6 byte access codes
6 byte access codes
|
Crypto Officer |
| OpenPGP | User Password
(PW1)
|
6-127 byte PIN | Authenticated
User
|
Admin Password
(PW3)
|
8-127 byte PIN | Crypto Officer | |
| PIV Smart Card | Management Key | 3-key TDES key | Crypto Officer |
| PUK | 6-8 byte PIN | Crypto Officer | |
| PIN | 6-8 byte PIN | Authenticated
User
|
|
| WebAuthn | PIN | 6 to 32 byte PIN | Authenticated
User
|
The instructions for the individual applications are provided in the following topics:
- FIDO Configuration with FIPS (WebAuthn)
- OTP Configuration with FIPS
- OATH Configuration with FIPS
- OpenPGP
- PIV Configuration with FIPS
For more information on secure channel requirements from NIST, see NIST SP 800-63-C and NIST SP 800-63B.