Title: Theory / Unimportant / CS / Softw / Security / YubiKey

Name: YubiKey
Definition: a hardware authentication device manufactured by Yubico
Page: https://en.wikipedia.org/wiki/YubiKey
Context: Gerrit

Name: One time password
Definition: a password that is valid for only one login session or transaction, on a computer system or other digital device
Page: https://en.wikipedia.org/wiki/One-time_password
Context: Gerrit
Example: SMS
Name2: One-time pin
Example2: Hardware token
Abbreviation: OTP
Example3: app authenticator
Name3: Dynamic password
Example4: paper printed

Name: Universal 2nd Factor
Definition: Open standard for identifying someone by something he has, a key that respond to public key cryptography challenges by storing a private key
Page: https://en.wikipedia.org/wiki/Universal_2nd_Factor
Context: Gerrit
Abbreviation: U2F

Name: Time-based One-Time Password
Definition: a computer algorithm that generates a one-time password (OTP) which uses the current time as a source of uniqueness
Page: https://en.wikipedia.org/wiki/Time-based_One-Time_Password

Question: What is the main advantage of OTP
Answer: Not succeptible to replay attack
Page: https://en.wikipedia.org/wiki/Time-based_One-Time_Password

Question: Requirement for OTP
Answer: Generated by a cryptographic hash function
Page: https://en.wikipedia.org/wiki/Time-based_One-Time_Password
Answer2: have a source of randomness or good pseudorandomness, or time measure
Answer3: Device generating them can be lost, broken, stolen

Name: S/key
Definition: OTP that consists in having a seed s a cryptographic hash function f, and the i-th key is \(f^{1000-i}(s)\).
\(f^{1000}(s)\) is assumed to be transmitted securely.
The i-th code \(c_i\) is checked by ensuring that, \(f(c_i)=c_{i-1}\).
Page: https://en.wikipedia.org/wiki/S/KEY

Name: Two factor authentification
Definition: An authentification protocol that require the user to show two proofs, ideally belonging to different kind of authenification mechanism
Page: https://en.wikipedia.org/wiki/Multi-factor_authentication
Abbreviation: 2FA