Send a challenge to a YubiKey, and read the response. Cross-platform application for configuring any YubiKey over all USB interfaces. Hi, I use Challenge-Response on one of the two slots of my Yubikey (5 I think) for unlocking KeePassXC and it works out of the box with KeePass2Android, with a pretty high number of iterations. In my experience you can not use YubiChallenge with Keepass2Android - it clashes with its internal Yubikey Neo support, each stealing the NFC focus from the other. You will have done this if you used the Windows Logon Tool or Mac Logon Tool. Jestem w posiadaniu Yubikey 5 NFC - wersja 5. For most configurations, you should be able to use the Applications > OTP menu in YubiKey Manager to. Remove your YubiKey and plug it into the USB port. Challenge-response is a fine way for a remote or otherwise secured system to authenticate. This just just keepassx/keepassx#52 rebased against keepassxc. Happy to see YubiKey support! I bought the Pro version as a thank you ️🙏🏻. Extended Support via SDK Challenge-Response (HMAC-SHA1) Get the plugin from AUR: keepass-plugin-keechallenge AUR; In KeePass additional option will show up under Key file / provider called Yubikey challenge-response; Plugin assumes slot 2 is used; SSH agent. :)OTP, OATH-HOTP, Challenge-Response, and Static Password) that is loaded in each slot. You can also follow the steps written below for how the setup process usually looks when you want to directly add your YubiKey to a service. AppImage version works fine. Yay! Close database. Yubikey with KeePass using challenge-response vs OATH-HOTP. Protects against phishing, since the challenge-response step uses a signed challenge; the phishing site won't have the key, so the response step will fail. Time based OTPs- extremely popular form of 2fa. OATH. Yubico Login for Windows adds the Challenge-Response capability of the YubiKey as a second factor for authenticating to local Windows accounts. So I use my database file, master password, and Yubikey challenge-response to unlock the database, all good. In the password prompt, enter the password for the user account listed in the User Name field and click Pair. HMAC-SHA1 takes a string as a challenge and returns a response created by hashing the string with a stored secret. select challenge response. kdbx) with YubiKey. Configure a Yubikey Neo with Challenge-Response on Slot 2; Save a database using the Keechallenge plugin as a key provider; Make sure that both the . Configure a static password. Note. Challenge-response does not return a different response with a single challenge. Advantages of U2F include: A Yubikey response may be generated in a straightforward manner with HMAC-SHA1 and the Yubikey's secret key, but generating the Password Safe Yubikey response is a bit more involved because of null characters and operating system incompatibilities. You now have a pretty secure Keepass. Re-enter password and select open. This is a similar but different issue like 9339. In order to authenticate successfully, the YubiKey has to answer an incoming challenge with the correct response, which it can only produce using the secret. yubico/challenge-<key-serial> that contains a challenge response configuration for the key. I agree - for redundancy there has to be second option to open vault besides Yubikey (or any other hardware token). Select HMAC-SHA1 mode. Two-step Login. Real-time challenge-response schemes like U2F address OTP vulnerabilities such as phishing and various forms of man-in-the-middle attacks. This credential can also be set to require a touch on the metal contact before the response is sent to the requesting software. To further simplify for Password Safe users, Yubico offers a pre. Yubikey challenge-response already selected as option. However, various plugins extend support to Challenge Response and HOTP. Now register a connected YubiKey with your user account via challenge-response: ykpamcfg -2. Challenge-response isn't much stronger than using a key-file on a USB stick, or using a static password with a YubiKey (possibly added to a password you remember). Steps to ReproduceAuthentication Using Challenge-Response; MacOS X Challenge-Response; Two Factor PAM Configuration; Ubuntu FreeRadius YubiKey; YubiKey and FreeRADIUS 1FA via PAM; YubiKey and FreeRADIUS via PAM; YubiKey and OpenVPN via PAM; YubiKey and Radius via PAM; YubiKey and SELinux; YubiKey and SSH via PAMPay attention to the challenge padding behavior of the Yubikey: It considers the last byte as padding if and only if the challenge size is 64 bytes long (its maximum), but then also all preceding bytes of the same value. ), and via NFC for NFC-enabled YubiKeys. Then in Keepass2: File > Change Master Key. Good for adding entropy to a master password like with password managers such as keepassxc. You could have CR on the first slot, if you want. If valid, the Yubico PAM module extracts the OTP string and sends it to the Yubico authentication server or else it. 5 Challenge-response mode 11 2. Then “HMAC-SHA1”. (Verify with 'ykman otp info') Repeat both or only the last step if you have a backup key (strongly recommended). Download and install YubiKey Manager. so and pam_permit. This also works on android over NFC or plugged in to charging port. The YubiKey 5Ci is like the 5 NFC, but for Apple fanboys. Instead they open the file browser dialogue. All three modes need to be checked: And now apps are available. All of these YubiKey options rely on an shared secret key, or in static password mode, a shared static password. If you have a YubiKey with Challenge-Response authentication support, take a look at the Yubico Login for Windows Configuration Guide, which will allow you to set up MFA on. The LastPass Mobile Device Application supports YubiKey two-factor authentication via both direct connection (USB, Lightning, etc. Hello, I am thinking of getting a yubikey and would like to use it for KeepassXC. The YubiKey needs to be configured with our Personalization Tools for HMAC-SHA1 challenge-response with variable input in slot 2. devices. First, configure your Yubikey to use HMAC-SHA1 in slot 2. USB Interface: FIDO. Initial YubiKey Personalization Tool Screen Note that triggering slot 2 requires you to hold the YubiKey's touch sensor for 2+ seconds; slot 1 is triggered by touching it for just 1-2 seconds. Its my understanding this is a different protocol " HOTP hardware challenge response Then your Yubikey works, not a hardware problem. This does not work with. KeePass enables users to store passwords in a highly-encrypted database, which can only be unlocked with one master password and/or a key file. Open J-Jamet pinned this issue May 6, 2022. Manage certificates and PINs for the PIV application; Swap the credentials between two configured. The first command (ykman) can be skipped if you already have a challenge-response credential stored in slot 2 on your YubiKey. Post navigation. The 5Ci is the successor to the 5C. KeeChallenge encrypts the database with the secret HMAC key (S). Posts: 9. PORTABLE PROTECTION – Extremely durable, waterproof, tamper resistant,A YubiKey have two slots (Short Touch and Long Touch), which may both be configured for different functionality. You will then be asked to provide a Secret Key. 2. 4. To use the YubiKey for multi-factor authentication you need to. serial-btn-visible: The YubiKey will emit its serial number if the button is pressed during power-up. In the password prompt, enter the password for the user account listed in the User Name field and click Pair. HMAC Challenge/Response - spits out a value if you have access to the right key. so, pam_deny. CLA INS P1 P2 Lc Data; 0x00: 0x01 (See below) 0x00 (varies) Challenge data: P1: Slot. Build the package (without signing it): make builddeb NO_SIGN=1 Install the package: dpkg -i DEBUILD/yubikey-luks_0. KeeChallenge 1. Optionally, an extra String purpose may be passed additionally in the intent to identify the purpose of the challenge. No need to fall back to a different password storage scheme. Strong security frees organizations up to become more innovative. Press Ctrl+X and then Enter to save and close the file. The U2F application can hold an unlimited number of U2F credentials and is FIDO certified. Mutual Auth, Step 2: output is YubiKey Authentication Response (to be verified by the client (off-card) application) and the result of Client Authentication. This is a similar but different issue like 9339. You can add up to five YubiKeys to your account. Open it up with KeePass2Android, select master key type (password + challenge-response), type in password, but. " -> click "system file picker" select xml file, then type password and open database. 0 from the DMG, it only lists "Autotype". 9. 5 Debugging mode is disabled. (smart card), OATH-HOTP and OATH-TOTP (hash-based and time-based one-time passwords), OpenPGP, YubiOTP, and challenge-response. In other words, Slot 2 can store a Yubico OTP credential, or a Challenge-Response credential. If they gained access to your YubiKey then they could use it there and then to decrypt your. BTW: Yubikey Challenge/Response is not all that safe, in that it is vulnerable to replay attacks. 0), and I cannot reopen the database without my YubiKey, that is still only possible with YubiKey. This library makes it easy to use. YubiKey 2. When generating keys from passphrase, generate 160 bit keys for modes that support it (OATH-HOTP and HMAC challenge response). Choose PAM configuration In order for KeePassXC to properly detect your Yubikey, you must setup one of your two OTP slots to use a Challenge Response. Yes, the response is totally determined by the secret key and challenge, so both keys will compute identical responses. If the Yubikey is plugged in, the sufficient condition is met and the authentication succeeds. Select Challenge-response credential type and click Next. KeePass is a light-weight and easy-to-use open source password manager compatible with Windows, Linux, Mac OS X, and mobile devices with USB ports. Ensure that the challenge is set to fixed 64 byte (the yubikey does some odd formatting games when a variable length is used, so that's unsupported at the moment). Trochę kombinowałem z ustawieniami w Yubico Manager. And unlike passwords, challenge question answers often remain the same over the course of a. In this case, the cryptographic operation will be blocked until the YubiKey is touched (the duration of touch does not matter). In practice, two-factor authentication (2FA). Get Updates. 40, the database just would not work with Keepass2Android and ykDroid. Note: We did not discuss TPM (Trusted Platform Module) in the section. For this tutorial, we use the YubiKey Manager 1. Use "client" for online validation with a YubiKey validation service such as the YubiCloud, or use "challenge-response" for offline validation using YubiKeys with HMAC-SHA-1 Challenge-Response configurations. Perform a challenge-response style operation using either YubicoOTP or HMAC-SHA1 against a configured YubiKey slot. The YubiKey will wait for the user to press the key (within 15 seconds) before answering the challenge. Then “HMAC-SHA1”. Each operates differently. Scan yubikey but fails. The size of the the response buffer is 20 bytes, this is inherent to SHA1 but can by changed by defining RESP_BUF_SIZE. The YubiKey 5 Cryptographic Module (the module) is a single-chip module validated at FIPS 140-2 Security Level 1. Private key material may not leave the confines of the yubikey. USB Interface: FIDO. Initial YubiKey Personalization Tool ScreenNote that triggering slot 2 requires you to hold the YubiKey's touch sensor for 2+ seconds; slot 1 is triggered by touching it for just 1-2 seconds. Now register a connected YubiKey with your user account via challenge-response: ykpamcfg -2. Defaults to client. Challenge-response is compatible with Yubikey devices. configuration functionality into client-side applications accessing the Yubikey challenge-response and serial number functionality introduced in Yubikey 2. Features. The U2F application can hold an unlimited number of U2F credentials and is FIDO certified. debug Turns on debugging to STDOUT mode=[client|challenge-response] Set the mode of operation, client for OTP validation and challenge-response for challenge-response validation, client is the default. Description. I think. 3. Which is probably the biggest danger, really. If you have already setup your Yubikeys for challenge. Two YubiKeys with firmware version 2. Select Open. Is a lost phone any worse than a lost yubikey? Maybe not. The YubiKey will wait for the user to press the key (within 15 seconds) before answering the challenge. In KeePass' dialog for specifying/changing the master key (displayed when. FIDO2 standard now includes hmac-secret extension, which provides similar functionality, but implemented in a standard way. the Challenge-Response feature turns out to be a totally different feature than what accounts online uses. Apps supporting it include e. First, configure your Yubikey to use HMAC-SHA1 in slot 2. HMAC-SHA1 Challenge-Response; Static Password; OATH-HOTP; USB Interface: OTP. From the secret it is possible to generate the Response required to decrypt the database. Manage certificates and PINs for the PIV ApplicationYubiKey in Challenge/Response mode does not require network access in the preboot environment The sections below will walk us through how two-factor authentication using Yubikey in Challenge/Response mode can be implemented to work seamlessly with FDE implementations. Manage certificates and PINs for the PIV application; Swap the credentials between two configured. And it has a few advantages, but more about them later. Another application using CR is the Windows logon tool The Yubico Authenticator does not use CR in any way. Click Interfaces. KeePass natively supports only the Static Password function. e. The proof of concept for using the YubiKey to encrypt the entire hard drive on a Linux computer has been developed by Tollef Fog Heen, a long time YubiKey user and Debian package maintainer. Open it up with KeePass2Android, select master key type (password + challenge-response), type in password, but. Open Yubikey Manager, and select. OATH. A YubiKey has two slots (Short Touch and Long Touch). To use the YubiKey for multi-factor authentication you need to. You now have a pretty secure Keepass. To enable challenge-response on your Yubikey in slot 2, type the following command: ykman otp chalresp -g 2 This configures slot 2 for challenge-response, and leaves slot 1 alone. Paste the secret key you made a copy of earlier into the box, leave Variable Length Challenge? unchecked, and. Hence, a database backup can be opened if you also store its XML file (or even any earlier one). This permits OnlyKey and Yubikey to be used interchangeably for challenge-response with supported applications. 2 Audience Programmers and systems integrators. Update: Feel like a bit of a dope for not checking earlier, but if you go to the KeePassXC menu, then click About KeePassXC, at the bottom of the resulting window it lists "Extensions". Therefore, it is not possible to generate or use any database (. It does exactly what it says, which is authentication with a. In this video I show you how to use a YubiKey with KeePass for an added layer of security using challenge response in order to be able to open your KeePass d. Second, as part of a bigger piece of work by the KeepassXC team and the community, refactor all forms of additional factor security into AdditionalFactorInfo as you suggested, this would be part of a major "2. To use the YubiKey for multi-factor authentication you need to. Program an HMAC-SHA1 OATH-HOTP credential. Yubikey needs to somehow verify the generated OTP (One Time Password) when it tries to authenticate the user. Send a challenge to a YubiKey, and read the response. The tool works with any YubiKey (except the Security Key). The best part is, I get issued a secret key to implant onto any yubikey as a spare or just to have. When communicating with the YubiKey over NFC, the Challenge-Response function works as expected, and the APDUs will behave in the same manner as. Next, select Long Touch (Slot 2) -> Configure. x). Features. 4. 0 ! We have worked long and hard to bring you lots of new features and bug fixes in a well-rounded release. In the list of options, select Challenge Response. Update the settings for a slot. Keepassium is better then StrongBox because Keepassium works with autofill and yubikey. In addition to FIDO2, the YubiKey 5 series supports: FIDO U2F, PIV (smart card), OpenPGP, Yubico OTP, OATH-TOTP, OATH-HOTP, and challenge-response. Setup. Save a copy of the secret key in the process. Click Challenge-Response 3. This credential can also be set to require a touch on the metal contact before the response is sent to the requesting software. YubiKey Personalization Tool shows whether your YubiKey supports challenge-response in the. When you unlock the database: KeeChallenge loads the challenge C from the XML file and sends it to the YubiKey. Works in the Appvm with the debian-11 default template but not with debian-11-minimal custom template i made. This library. Send a challenge to a YubiKey, and read the response. kdbx and the corresponding . Yubico Login for Windows adds the Challenge-Response capability of the YubiKey as a second factor for authenticating to local Windows accounts. Yes you can clone a key, if you are using hmac-sha1, download the yubikey personalisation tool. Keepass2Android and. YubiKey 4 Series. The YubiKey then enters the password into the text editor. HMAC-SHA1 Challenge-Response; Static Password; OATH-HOTP; USB Interface: OTP. This app should be triggered using an implicit intent by any external application wishing to perform challenge-response. 4. I added my Yubikeys challenge-response via KeepassXC. Configure yubikey for challenge-response mode in slot 2 (leave yubico OTP default in slot 1). This document describes how to use both tools. "Type" a. Maybe some missing packages or a running service. If you instead use Challenge/Response, then the Yubikey's response is based on the challenge from the app. Mind that the Database Format is important if you want to use Yubikey over NFC to unlock database on Android devices. Overall, I'd generally recommend pursuing the Challenge-Response method, but in case you'd rather explore the others, hopefully the information above is helpful. Use Yubico Authenticator for Android with YubiKey NEO devices and your Android phones that are NFC-enabled. Used KeePassXC to Change Master Key and configure YubiKey Challenge-Response. The YubiKey can be configured with two different C/R modes — the standard one is a 160 bits HMAC-SHA1, and the other is a YubiKey OTP mimicking mode, meaning two subsequent calls with the same challenge will result in different responses. WebAuthn / U2F: WebAuthn is neither about encryption, nor hashing. 2. 1 Inserting the YubiKey for the first time (Windows XP) 15. Verifying OTPs is the job of the validation server, which stores the YubiKey's AES. install software for the YubiKey, configure the YubiKey for the Challenge-Response mode, store the password for YubiKey Login and the Challenge-Response secret in dom0, enable YubiKey authentication for every service you want to use it for. Description Use the Password Manager KeePassXC with Yubikey Challenge-Response mode. run: sudo nano /etc/pam. Posted: Fri Sep 08, 2017 8:45 pm. Mode of operation. There are a number of YubiKey functions. HMAC-SHA1 Challenge-Response* PIV; OpenPGP** *Native OTP support excludes HMAC-SHA1 Challenge-Response credentials **The YubiKey's OpenPGP feature can be used over USB or NFC with third-party application OpenKeyChain app, which is available on Google Play. Quite for a while the yubikey supports a challenge response mode, where the computer can send a challenge to the yubikey and the yubikey will answer with a response, that is calculated using HMAC-SHA1. It will become a static password if you use single phrase (Master Password). YubiKey: This method uses HMAC-SHA1 and Yubico OTP for authentication. In order to use OnlyKey and Yubikey interchangeably both must have the same HMAC key set. Commit? (y/n) [n]: y $ Challenge-Response An off-the-shelf YubiKey comes with OTP slot 1 configured with a Yubico OTP registered for the YubiCloud, and OTP slot 2 empty. Open up the Yubikey NEO Manager, insert a YubiKey and hit Change Connection Mode. The YubiKey Personalization Tool can help you determine whether something is loaded. Add a "Recovery" box to the challenge-response area that allows a hex string to be entered and used for the challenge response computation. I confirmed this using the Yubico configuration tool: when configured for a fixed length challenge my yubikey does NOT generate the NIST response, but it does if I set it to variable length. Use Small Challenge (Boolean) Set when the HMAC challenge will be less than 64-bytes. 4. Ensure that the challenge is set to fixed 64 byte (the Yubikey does some odd formatting games when a variable length is used, so that's unsupported at the moment). fast native implementation using yubico-c and ykpers; non-blocking API, I/O is performed in a separate thread; thread-safe library, locking is done inside; no additional JavaScript, all you need is the . 2 and 2x YubiKey 5 NFC with firmware v5. 0" release of KeepassXC. Plug in the primary YubiKey. Something user knows. Although it doesn't affect FIDO directly, there is what I would consider a de-facto standard procedure with challenge-response procedures for the Yubikey,. Get popup about entering challenge-response, not the key driver app. Yubikey already works as a challenge:response 2FA with LUKS with linux full-disk encryption so I guess implementing it in zuluCrypt (full-disk + container encryption) shouldn't be very hard. The SDK is designed to enable developers to accomplish common YubiKey OTP application configuration tasks: Program a slot with a Yubico OTP credential; Program a slot with a static password; Program a slot with a challenge-response credential; Calculate a response code for a challenge-response credential; Delete a slot’s configuration 3 Configuring the YubiKey. YubiKey modes. The yubico-pam module needs a second configured slot on the Yubikey for the HMAC challenge. Configuring the OTP application. The YubiKey 5 series can hold up to 32 OATH credentials and supports both OATH-TOTP (time based) and OATH-HOTP. 0. js. conf to make following changes: Change user and group to “root” to provide the root privileges to radiusd daemon so that it can call and use pam modules for authentication. Initialize the Yubikey for challenge response in slot 2. Bitwarden Pricing Chart. If you ever lose your YubiKey, you will need that secret to access your database and to program the. How user friendly it is depends on. CryptoI'd much prefer the HMAC secret to never leave the YubiKey - especially as I might be using the HMAC challenge/response for other applications. The newer method was introduced by KeePassXC. Challenge-response - Provides a method to use HMAC-SHA1 challenge-response. Existing yubikey challenge-response and keyfiles will be untouched. U2F. I searched the whole Internet, but there is nothing at all for Manjaro. A YubiKey with configuration slot 2 available; YubiKey Manager; KeePass version 2. USB Interface: FIDO. I then opened KeePassXC and clicked “Continue” twice, not changing any of the default database settings. Encrypting a KeePass Database Enable Challenge/Response on the Yubikey. Program an HMAC-SHA1 OATH-HOTP credential. For my copy, version 2. HMAC-SHA1 Challenge-Response; Static Password; OATH-HOTP; USB Interface: OTP. This option is only valid for the 2. :)The slots concept really only applies to the OTP module of the YubiKey. Na 2-slot long touch - challenge-response. KeeChallenge works using the HMAC-SHA1 challenge response functionality built into the Yubikey. The tool works with any YubiKey (except the Security Key). There are two slots, the "Touch" slot and the "Touch and Hold" slot. YubiKey slot 2 is properly configured for HMAC-SHA1 challenge-response with YubiKey Personalization Tool. Management - Provides ability to enable or disable available application on YubiKey. Actual BehaviorNo option to input challenge-response secret. This is a different approach to. If the correct YubiKey is inserted, the response must match with the expected response based on the presented challenge. Remove the YubiKey challenge-response after clicking the button. So it's working now. YubiKey/docs/users-manual/application-otp":{"items":[{"name":"application-concepts-overview. We start out with a simple challenge-response authentication flow, based on public-key cryptography. Authenticator App. See examples/configure_nist_test_key for an example. The “YubiKey Windows Login Configuration Guide” states that the following is needed. YubiKey challenge-response USB and NFC driver. The YubiKey class is defined in the device module. Test your YubiKey with Yubico OTP. mode=[client|challenge-response] Mode of operation, client for OTP validation and challenge-response for challenge-response validation. 1 Introduction. Command APDU info. YubiKey SDKs. Extended Support via SDK. auth required pam_yubico. KeePassXC, in turn, also supports YubiKey in. Things to do: Add GUI Signals for letting users know when enter the Yubikey Rebased 2FA code by Kyle Manna #119 (diff);. Additionally, KeeChallenge encrypts the S with the pre-calculated challenge-response pair, and stored the encrypted secret and challenge in the XML file. Deletes the configuration stored in a slot. HOTP - extremely rare to see this outside of enterprise. Open Yubikey Manager, and select Applications -> OTP. Need help: YubiKey 5 NFC + KeePass2Android. That said the Yubikey's work fine on my desktop using the KeepasXC application. Make sure to copy and store the generated secret somewhere safe. ykpersonalize -2 -ochal-resp -ochal-hmac -ohmac-lt64 -oserial-api-visible Mode of operation. Last edited by LockBot on Wed Dec 28, 2022 12:16 pm, edited 1 time in total. Qt 5. The YubiKey secures the software supply chain and 3rd party access with phishing-resistant MFA. To confirm that you want to commit that new configuration to slot 1, press the y key and then the Enter key. Challenge response uses raw USB transactions to work. Programming the Yubikey with Challenge-Response mode HMAC-SHA1 (fixed 64 byte input!) using the Yubikey Personalization Tool seems to be incompatible using "standard. The OTP module has a "touch" slot and a "touch and hold" slot and it can do any two of the following: - YubiOTP - Challenge-Response - HOTP - Static Password In other words, you can have Challenge Response in slot 2 and YubiOTP in slot 1, etc. 2+) is shown with ‘ykpersonalize -v’. HMAC-SHA1 Challenge-Response; Static Password; OATH-HOTP; USB/NFC Interface: OTP OATH. Using keepassdx 3. If you install another version of the YubiKey Manager, the setup and usage might differ. If you choose to authenticate locally then you configure slot 2 of your Yubikey in challenge response mode ( following the other tutorial ) The password prompt depends on how you configure sshd / pam _____-Tom. OATH. Configure a slot to be used over NDEF (NFC). Open Terminal. KeeWeb connects to YubiKeys using their proprietary HMAC-SHA1 Challenge-Response API, which is less than ideal. Need it so I can use yubikey challenge response on the phone. HMAC-SHA1 Challenge-Response; Static Password; OATH-HOTP; USB Interface: OTP. UseKey (ReadOnlyMemory<Byte>) Explicitly sets the key of the credential. I love that the Challenge-Response feature gives me a secret key to backup my hardware key and being able to freely make spares is a godsend for use with KeepassXC, but. The YubiKey is given your password as a Challenge, where it performs some processing using the Challenge and the secret it has, providing the Response back to ATBU. A YubiKey with configuration slot 2 available; YubiKey Manager; KeePass version 2 (version should be 2. Among the top highlights of this release are. When the secret key is implanted, the challenge response is duplicated to each yubikey I implant it onto. Configure a slot to be used over NDEF (NFC). Posted: Fri Sep 08, 2017 8:45 pm. 2. None of the other Authenticator options will work that way with KeePass that I know of. You will have done this if you used the Windows Logon Tool or Mac Logon Tool. xml file are accessible on the Android device. First, program a YubiKey for challenge response on Slot 2: ykpersonalize -2 -ochal-resp -ochal-hmac -ohmac-lt64 -oserial-api-visible. YubiKey Personalization Tool shows whether your YubiKey supports challenge-response in the lower right. Challenge response uses raw USB transactions to work. Program a challenge-response credential. NET SDK and the YubiKey support the following encryption and hashing algorithms for challenge-response: Yubico OTP (encryption) HMAC SHA1 as defined in RFC2104 (hashing) For Yubico OTP challenge-response, the key will receive a 6-byte challenge. md","path.