The process of authentication is distinct from that of
authorization. Whereas authentication is the process of verifying that "you are who you say you are", authorization is the process of verifying that "you are permitted to do what you are trying to do". While authorization often happens immediately after authentication (e.g., when logging into a computer system), this does not mean authorization presupposes authentication: an anonymous agent could be authorized to a limited action set. Similarly, the establishment of the authorization can occur long before the
authorization decision occurs. A user can be given access to secure systems based on user credentials that imply authenticity. A network administrator can give a user a
password, or provide the user with a key card or other access devices to allow system access. In this case, authenticity is implied but not guaranteed. Most secure internet communication relies on centralized authority-based trust relationships, such as those used in
HTTPS, where public
certificate authorities (CAs) vouch for the authenticity of websites. This same centralized trust model underpins protocols like OIDC (
OpenID Connect) where identity providers (e.g.,
Google) authenticate users on behalf of relying applications. In contrast, decentralized peer-based trust, also known as a
web of trust, is commonly used for personal services such as secure email or file sharing. In systems like
PGP, trust is established when individuals personally verify and sign each other’s cryptographic keys, without relying on a central authority. These systems use
cryptographic protocols that, in theory, are not vulnerable to
spoofing as long as the originator’s private key remains uncompromised. Importantly, even if the key owner is unaware of a compromise, the cryptographic failure still invalidates trust. However, while these methods are currently considered secure, they are not provably unbreakable—future mathematical or computational advances (such as
quantum computing or new algorithmic attacks) could expose vulnerabilities. If that happens, it could retroactively undermine trust in past communications or agreements. For example, a
digitally signed contract might be challenged if the signature algorithm is later found to be insecure..
Authentication factors The ways in which someone may be authenticated fall into three categories, based on what is known as the factors of authentication: something the user knows, something the user has, and something the user is. Each authentication factor covers a range of elements used to authenticate or verify a person's identity before being granted access, approving a transaction request, signing a document or other work product, granting authority to others, and establishing a chain of authority. Security research has determined that for a positive authentication, elements from at least two, and preferably all three, factors should be verified. The three factors (classes) and some of the elements of each factor are: • Knowledge: Something the user knows (e.g., a password,
partial password,
passphrase,
personal identification number (PIN),
challenge–response (the user must answer a question or pattern),
security question). • Ownership: Something the user has (e.g., wrist band,
ID card,
security token,
implanted device, cell phone with a built-in
hardware token,
software token, or cell phone holding a
software token). Outside of the legal system as well, fingerprints are easily
spoofable, with
British Telecom's top computer security official noting that "few" fingerprint readers have not already been tricked by one spoof or another. Hybrid or two-tiered authentication methods offer a compelling solution, such as private keys encrypted by fingerprint inside of a USB device.
Single-factor authentication As the weakest level of authentication, only a single component from one of the three categories of factors is used to authenticate an individual's identity. The use of only one factor does not offer much protection from misuse or malicious intrusion. This type of authentication is not recommended for financial or personally relevant transactions that warrant a higher level of security.
Multi-factor authentication Multi-factor authentication involves two or more authentication factors (something you know, something you have, or something you are). Two-factor authentication is a special case of multi-factor authentication involving exactly two factors. but this is still a two-factor authentication.
Authentication types –
National Cryptologic Museum Strong authentication The United States government's
National Information Assurance Glossary defines strong authentication as a layered authentication approach relying on two or more authenticators to establish the identity of an originator or receiver of information. The European Central Bank (ECB) has defined strong authentication as "a procedure based on two or more of the three authentication factors". The factors that are used must be mutually independent and at least one factor must be "non-reusable and non-replicable", except in the case of an inherence factor and must also be incapable of being stolen off the Internet. In the European, as well as in the US-American understanding, strong authentication is very similar to multi-factor authentication or 2FA, but exceeding those with more rigorous requirements. The
FIDO Alliance has been striving to establish technical specifications for strong authentication.
Continuous authentication Conventional computer systems authenticate users only at the initial log-in session, which can be the cause of a critical security flaw. To resolve this problem, systems need continuous user authentication methods that continuously monitor and authenticate users based on some biometric trait(s). A study used behavioural biometrics based on writing styles as a continuous authentication method. Recent research has shown the possibility of using smartphones sensors and accessories to extract some behavioral attributes such as touch dynamics,
keystroke dynamics and
gait recognition. These attributes are known as behavioral biometrics and could be used to verify or identify users implicitly and continuously on smartphones. The authentication systems that have been built based on these behavioral biometric traits are known as active or continuous authentication systems. The authentication of information can pose special problems with electronic communication, such as vulnerability to
man-in-the-middle attacks, whereby a third party taps into the communication stream, and poses as each of the two other communicating parties, in order to intercept information from each. Extra identity factors can be required to authenticate each party's identity. == See also ==