Intel Celeron G3900 CPU Dual Core 2.8GHz TDP 51W 2MB LGA 1151 CPU

### General & Basics

Q1: What is the YubiKey 5C NFC?**
A: The YubiKey 5C NFC is a hardware authentication device that provides strong, phishing-resistant multi-factor authentication (MFA) and passwordless login. It helps secure your online accounts from unauthorized access, even if your password is compromised.

Q2: What are the main connection methods?
A: It has two ways to connect:
1. USB-C: Plug it directly into the USB-C port on computers, laptops, and some mobile devices.
2. NFC (Near Field Communication):** Tap it on the back of NFC-enabled smartphones (Android and iOS) for wireless authentication.

Q3: Is this key durable for everyday carry?
A: Yes. It is built with glass-fiber reinforced plastic, has an **IP68 rating** (water and dust resistant), is crush-resistant, has no batteries or moving parts, and is rated for over 100,000 USB insertion cycles. It's designed to live on a keyring.

### Security & Technical Specifications

Q4: What authentication protocols does it support?
A: It is a multi-protocol key supporting:
* **FIDO2/WebAuthn** (including hardware-bound passkeys)
* **FIDO U2F**
* **Yubico OTP**
* **OATH-TOTP** & **OATH-HOTP** (requires Yubico Authenticator app)
* **Smart card (PIV)**
* **OpenPGP**
* Secure Static Passwords

**Q5: How many accounts or "passkeys" can it store?**
**A:**
* **FIDO2 (passkeys):** Up to 100 resident credentials.
* **OATH (TOTP) slots:** 64
* **PIV certificates:** 24
* **OTP seeds:** 2

**Q6: What are the cryptographic specifications?**
**A:** It supports RSA (up to 4096), ECC (P-256, P-384), and modern curves like Ed25519, X25519, secp256k1, and brainpool curves.

**Q7: Is this key FIPS certified?**
**A:** No, this specific model (YubiKey 5C NFC) is **not FIPS 140-2 certified**. Yubico offers separate "FIPS Series" keys for users who require that certification.

### Compatibility & Usage

**Q8: Which devices and operating systems does it work with?**
**A:** It works with devices that have a USB-C port or support NFC. Compatible operating systems include **Windows, macOS, ChromeOS, and Linux**.

**Q9: Which popular online services support it?**
**A:** It works with hundreds of services, including:
* **Google, Microsoft, Facebook, Twitter (X)**
* **Password managers:** 1Password, Bitwarden Premium, Keeper
* **Business/IT:** Okta, Duo Security, Ping Identity, AWS IAM, Azure AD
* **Cloud storage:** Dropbox, Salesforce

Look for the **"Works with YubiKey"** logo on service websites.

**Q10: Can I use it on my iPhone or Android phone?**
**A:** Yes.
* **iPhone (iOS):** Works via **NFC** (tap on back of phone). Also works via USB-C on newer iPad models.
* **Android:** Works via **USB-C** and **NFC**.

**Q11: Do I need any special software?**
**A:** For basic FIDO2/U2F logins (the most common method), no software is needed—it works via your web browser. However, to manage OATH-TOTP codes (like Google Authenticator codes) stored on the key, you need the free **Yubico Authenticator App** (desktop and mobile).

### Purchasing & Logistics

**Q12: Does it require batteries or an internet connection?**
**A:** No. The key is powered by the USB port or the NFC field from your phone. It has no battery and requires no network connection, ensuring it works even offline.

**Q13: What is the warranty and return policy?**
**A:** The page indicates a **45-day consumer returns** policy for the Hong Kong store. It ships from Singapore.

**Q14: Where is it manufactured?**
**A:** It is securely manufactured in Sweden.

**Q15: Is there a subscription required to use the key?**
**A:** No. The key itself is a one-time purchase. However, the page mentions a **YubiEnterprise Subscription** for businesses with 500+ users who want to get keys via a subscription model.

### Troubleshooting & Advanced

**Q16: What is the difference between the YubiKey 5C NFC and other YubiKey models?**
**A:** The main difference is the connector:
* **YubiKey 5C NFC:** USB-C + NFC (most versatile for modern computers and phones).
* **YubiKey 5 NFC:** USB-A + NFC (for traditional USB-A ports).
* **YubiKey 5Ci:** USB-C + Lightning (for older iPhones).
* **Security Key C NFC:** A lower-cost, FIDO2/U2F-only version (lacks OTP, PIV, OpenPGP).

**Q17: Can I use this as my only authentication method (passwordless)?**
**A:** Yes, for services that support **FIDO2/WebAuthn passwordless login** (e.g., Microsoft, Google). You can register the key as a "passkey" and log in by simply inserting and tapping the key, without entering a password.

**Q18: What should I do if I lose my YubiKey?**
**A:** You should always **register at least two YubiKeys** as backup for your important accounts. If you lose one, you can use the backup key to log in and remove the lost key from your account settings. Yubico cannot recover accounts for you, as the key is a local, offline device.