YubiKey Checker

Validate YubiKey OTP tokens to check authenticity and decode information instantly.

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About This Tool

This YubiKey Checker tool allows you to validate YubiKey OTP (One-Time Password) tokens using the Yubico validation protocol. Simply paste a YubiKey OTP (44 characters starting with 'cccccc') and the tool will verify its authenticity, decode the embedded information including the YubiKey ID, timestamp, counter values, and session usage. The tool performs both format validation and real API verification against Yubico's servers to ensure the token is genuine and not replayed. Perfect for developers, system administrators, and security professionals who need to verify YubiKey tokens in their applications or troubleshoot authentication issues.

How to Use

  1. Locate a YubiKey OTP token (44 characters, typically starting with 'cccccc')
  2. Paste the OTP into the input field
  3. Click the 'Validate YubiKey' button
  4. View the validation results including status, decoded information, and detailed analysis
  5. For invalid tokens, check the error message and ensure you're using a valid YubiKey OTP
How to use yubikey checker

Frequently Asked Questions

Find Quick Answers

What is a YubiKey OTP?
A YubiKey OTP (One-Time Password) is a 44-character token generated by a YubiKey hardware device when you press its button. It starts with a fixed prefix (like 'cccccc') followed by encrypted data that includes the device ID, timestamp, counter, and session information.
How does the validation work?
The tool first validates the OTP format (44 characters, correct structure), then sends it to Yubico's validation servers using the Yubico Validation Protocol v2.0. The server responds with whether the OTP is valid, replayed, or invalid, along with decoded information from the token.
Do I need a Yubico API key to use this tool?
No, the tool comes with a built-in API key for basic validation. For production use or high-volume validation, administrators may need to configure their own Yubico API credentials in the development tasks.
What information is decoded from a YubiKey OTP?
A valid YubiKey OTP contains the YubiKey's public ID (first 12 characters), timestamp (when the button was pressed), session counter (increments when device powers on), usage counter (increments with each press), and a random number for uniqueness.
Can this tool detect replayed tokens?
Yes, the Yubico validation protocol checks if the token has been used before. If a token is replayed, the validation will return 'REPLAYED' status instead of 'OK'.

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