Quiz Entry - updated: 2026.10.22
What distinguishes single-factor authentication (SFA), multi-factor authentication (MFA) and hardware-based MFA (HW-MFA), with typical examples?
SFA uses one factor (password, PIN, code list, SMS confirmation); MFA combines factors of different kinds (a multi-factor software OTP authenticator, or two single-factor means of different factor types); HW-MFA puts the multi-factor protection into dedicated hardware (an OTP device or a cryptographic smartcard).
| Class | Examples (NIST-style authenticator types) | Why it is stronger or weaker |
|---|---|---|
| SFA | Memorized secret (password, PIN); look-up secret (a printed list of codes, Strichliste); out-of-band authenticator (confirmation via SMS) | One stolen or phished secret is enough |
| MFA | Multi-factor OTP software authenticator (an app that generates codes after a PIN or fingerprint unlock); or two single-factor means with different factors | An attacker needs to defeat two different kinds of proof |
| HW-MFA | Multi-factor OTP device (a hardware token with PIN); multi-factor cryptographic device (a smartcard with PIN) | The secret lives in tamper-resistant hardware and cannot be copied off it |
The jump from MFA to HW-MFA is about where the secret lives. An authenticator app runs on a general-purpose phone that malware could compromise; a smartcard keeps its private key inside a chip that never releases it.
Go deeper:
One-time password (Wikipedia) — software and hardware OTP generators, and SMS delivery.- Smart card (Wikipedia) — how cryptographic smartcards keep keys on the chip.