# MoolKey password security glossary > 35 clear definitions covering passwords, cryptography, attacks, and authentication. Each entry starts with a direct answer, then explains the mechanism, common misunderstanding, and primary sources. Last reviewed: 2026-09-01 Canonical index: https://moolkey.com/glossary ## Contents - [Account takeover](https://moolkey.com/glossary/account-takeover) - [Authenticator app](https://moolkey.com/glossary/authenticator-app) - [Biometric authentication](https://moolkey.com/glossary/biometric-authentication) - [Brute force attack](https://moolkey.com/glossary/brute-force-attack) - [Credential stuffing](https://moolkey.com/glossary/credential-stuffing) - [Data breach](https://moolkey.com/glossary/data-breach) - [Deterministic password manager](https://moolkey.com/glossary/deterministic-password-manager) - [Dictionary attack](https://moolkey.com/glossary/dictionary-attack) - [End-to-end encryption](https://moolkey.com/glossary/end-to-end-encryption) - [Hashing](https://moolkey.com/glossary/hashing) - [Identity theft](https://moolkey.com/glossary/identity-theft) - [Key derivation function](https://moolkey.com/glossary/key-derivation-function) - [Keylogger](https://moolkey.com/glossary/keylogger) - [Master password](https://moolkey.com/glossary/master-password) - [Passkey](https://moolkey.com/glossary/passkey) - [Passphrase](https://moolkey.com/glossary/passphrase) - [Password autofill](https://moolkey.com/glossary/password-autofill) - [Password entropy](https://moolkey.com/glossary/password-entropy) - [Password hint](https://moolkey.com/glossary/password-hint) - [Password manager](https://moolkey.com/glossary/password-manager) - [Password rotation](https://moolkey.com/glossary/password-rotation) - [Password spraying](https://moolkey.com/glossary/password-spraying) - [Password vault](https://moolkey.com/glossary/password-vault) - [PBKDF2](https://moolkey.com/glossary/pbkdf2) - [Phishing](https://moolkey.com/glossary/phishing) - [PIN](https://moolkey.com/glossary/pin) - [Rainbow table](https://moolkey.com/glossary/rainbow-table) - [Salt](https://moolkey.com/glossary/salt) - [Security key](https://moolkey.com/glossary/security-key) - [Shoulder surfing](https://moolkey.com/glossary/shoulder-surfing) - [SIM swapping](https://moolkey.com/glossary/sim-swapping) - [Single sign-on](https://moolkey.com/glossary/single-sign-on) - [Social engineering](https://moolkey.com/glossary/social-engineering) - [Two-factor authentication](https://moolkey.com/glossary/two-factor-authentication) - [Zero-knowledge encryption](https://moolkey.com/glossary/zero-knowledge-encryption) ## Password entropy Category: Passwords Also called: entropy of a password, bits of entropy Canonical page: https://moolkey.com/glossary/password-entropy Password entropy measures how unpredictable a password is, expressed in bits. Each additional bit doubles the number of guesses an attacker needs. For a randomly generated password, entropy equals the length multiplied by log2 of the pool size. A 12-character password drawn from 86 possible symbols carries 77 bits. ### How password entropy is calculated The formula is `entropy = length x log2(pool size)`. Pool size is the number of distinct symbols each position could hold: 10 for digits, 26 for lowercase letters, 62 for alphanumerics, and around 86 once a typical symbol set is included. For a passphrase the same formula applies with words in place of characters. Five words drawn at random from the 1,296-word EFF list gives 5 x log2(1296) = 51.7 bits. ### How many bits are enough Below 45 bits offers little margin against fast offline guessing. Between 60 and 80 bits is a practical target for randomly generated secrets. Above 100 bits, brute force is unlikely to be the limiting risk; phishing, malware, and password reuse usually matter more. ### What people often get wrong Claim: "My password has 70 bits of entropy because it is 11 characters long." Correction: The formula only holds for passwords chosen at random. Tr0ub4dor&3 calculates to 70 bits but is worth closer to 28 in practice, because attackers guess a dictionary word plus standard substitutions rather than character by character. Further reading: [Calculate the entropy of any password](https://moolkey.com/tools/password-entropy-calculator) ### Sources - [EFF: Dice-generated passphrases](https://www.eff.org/dice): Wordlists and a verifiable method for choosing passphrase words at random. - [OWASP: Password Storage Cheat Sheet](https://cheatsheetseries.owasp.org/cheatsheets/Password_Storage_Cheat_Sheet.html): Practical guidance for salts, peppers, PBKDF2, Argon2id, and password hashes. - [NIST: SP 800-63B-4: Authentication and authenticator management](https://csrc.nist.gov/pubs/sp/800/63/b/4/final): Current requirements for passwords, authenticators, recovery, and rate limits. - [NIST: Computer Security Resource Center glossary](https://csrc.nist.gov/glossary): Canonical terminology used across US computer security guidance. --- ## Passphrase Category: Passwords Also called: diceware passphrase, word-based password Canonical page: https://moolkey.com/glossary/passphrase A passphrase is a password built from several randomly chosen words, such as "trout-canyon-mellow-drift". It carries less entropy per character than a random string but far more per unit of human effort, which makes it the right choice for the handful of secrets you must recall from memory. ### Why random selection is non-negotiable The strength of a passphrase comes entirely from the words being chosen by a machine, not by you. A self-invented phrase follows grammar, cultural reference, and personal association. Cracking tools model all three with song lyrics, book text, and scraped social media. Four genuinely random words from a 1,296-word list sit in a space of 2.8 trillion possibilities. A four-word sentence you composed yourself may sit in a space of a few million. ### Does a public wordlist weaken it No. This is the most common objection and it is wrong. Security comes from the number of equally likely combinations, not from the list being secret. Publishing the list lets anyone verify the entropy claim, which is a feature. ### Where passphrases beat random strings Master passwords, disk encryption, and anything typed on a television remote, games console, or car system. For the hundreds of accounts your software fills in for you, a random character password is denser and just as convenient. Further reading: [Generate a passphrase](https://moolkey.com/tools/passphrase-generator) ### Sources - [EFF: Dice-generated passphrases](https://www.eff.org/dice): Wordlists and a verifiable method for choosing passphrase words at random. - [NIST: SP 800-63B-4: Authentication and authenticator management](https://csrc.nist.gov/pubs/sp/800/63/b/4/final): Current requirements for passwords, authenticators, recovery, and rate limits. - [NIST: Computer Security Resource Center glossary](https://csrc.nist.gov/glossary): Canonical terminology used across US computer security guidance. --- ## Master password Category: Passwords Also called: master key, primary password Canonical page: https://moolkey.com/glossary/master-password A master password is the one secret that unlocks a password manager. In a vaulted manager it decrypts the stored vault; in a deterministic manager it is an input to the calculation that recreates every other password. Either way, it is the only password you have to remember, and losing it is usually unrecoverable. ### What makes a good master password It has to be strong enough to resist an offline attack and memorable enough that you will never forget it. Those requirements pull in opposite directions. A six-word random passphrase resolves the tension, giving roughly 62 bits in a form the human brain can hold. It must also be unique. A master password reused anywhere else means one unrelated breach exposes everything. ### Why you usually cannot recover it In a zero-knowledge design, the provider never receives your master password in any usable form, so there is nothing for support to reset. This is a deliberate property, not an oversight: if a provider could reset it, so could anyone who compromised the provider. ### What people often get wrong Claim: "My password manager can email me a reset link if I forget it." Correction: Some offer emergency access or recovery codes you set up in advance, but no zero-knowledge manager can recover the master password itself. If it could, its encryption would be reversible by the provider. Further reading: [How to choose a master password](https://moolkey.com/blog/how-to-choose-a-strong-master-password) ### Sources - [OWASP: Password Storage Cheat Sheet](https://cheatsheetseries.owasp.org/cheatsheets/Password_Storage_Cheat_Sheet.html): Practical guidance for salts, peppers, PBKDF2, Argon2id, and password hashes. - [NIST: SP 800-63B-4: Authentication and authenticator management](https://csrc.nist.gov/pubs/sp/800/63/b/4/final): Current requirements for passwords, authenticators, recovery, and rate limits. - [NIST: Computer Security Resource Center glossary](https://csrc.nist.gov/glossary): Canonical terminology used across US computer security guidance. --- ## Zero-knowledge encryption Category: Cryptography Also called: zero-knowledge architecture, zero-access encryption Canonical page: https://moolkey.com/glossary/zero-knowledge-encryption Zero-knowledge encryption means the service provider never possesses the key required to read your data. Encryption and decryption happen on your device with a key derived from a secret you never transmit. The provider stores ciphertext it cannot open. That protection comes from mathematics, not policy. ### How to tell whether a claim is real Three questions separate a real zero-knowledge design from marketing. Can the provider reset your password and still give you your data? If yes, they hold a key. Can they show you a preview of your content in a web dashboard without you entering your passphrase? If yes, they hold a key. Do they publish where key derivation happens and let it be audited? If not, you are trusting a claim rather than a design. ### What it does not protect against Zero-knowledge protects data at rest on the provider's servers. It does nothing about malware on your own device, a phishing page that captures your passphrase as you type it, or metadata such as which services you hold accounts with. Treat it as one strong guarantee, not a complete threat model. Further reading: [What a zero-knowledge password manager really means](https://moolkey.com/blog/what-is-a-zero-knowledge-password-manager) ### Sources - [OWASP: Password Storage Cheat Sheet](https://cheatsheetseries.owasp.org/cheatsheets/Password_Storage_Cheat_Sheet.html): Practical guidance for salts, peppers, PBKDF2, Argon2id, and password hashes. - [NIST: Computer Security Resource Center glossary](https://csrc.nist.gov/glossary): Canonical terminology used across US computer security guidance. --- ## PBKDF2 Category: Cryptography Also called: Password-Based Key Derivation Function 2 Canonical page: https://moolkey.com/glossary/pbkdf2 PBKDF2 is a key derivation function that converts a password into a cryptographic key by applying a hash function repeatedly, commonly 600,000 times. The repetition is the point: it costs you a fraction of a second once and makes an attacker pay that delay for every guess. ### Why the iteration count matters Each doubling of the iteration count halves an attacker's guessing rate. Going from 1,000 iterations to 600,000 slows them by a factor of 600, which is worth roughly nine extra bits of password entropy without the user changing anything. OWASP currently recommends at least 600,000 iterations for PBKDF2-HMAC-SHA256. Older software using 1,000 or 10,000 iterations is measurably weaker against modern GPUs. ### PBKDF2 versus bcrypt, scrypt, and Argon2 PBKDF2 is compute-hard but not memory-hard, which means specialised hardware can parallelise it efficiently. Argon2id and scrypt additionally require large amounts of memory per guess, which frustrates that hardware. PBKDF2's advantage is universal availability: it is built into the Web Crypto API in every browser, so it runs client-side with no dependencies. Further reading: [Why 600,000 iterations](https://moolkey.com/blog/pbkdf2-600k-iterations-explained) ### Sources - [OWASP: Password Storage Cheat Sheet](https://cheatsheetseries.owasp.org/cheatsheets/Password_Storage_Cheat_Sheet.html): Practical guidance for salts, peppers, PBKDF2, Argon2id, and password hashes. - [NIST: Computer Security Resource Center glossary](https://csrc.nist.gov/glossary): Canonical terminology used across US computer security guidance. --- ## Key derivation function Category: Cryptography Also called: KDF Canonical page: https://moolkey.com/glossary/key-derivation-function A key derivation function turns a human-chosen password into a fixed-length cryptographic key. Because passwords are short and predictable while keys must be neither, a KDF stretches the input through thousands of expensive operations, making each attacker guess costly. PBKDF2, bcrypt, scrypt, and Argon2 are the common choices. ### Why not just hash the password once A single SHA-256 pass takes microseconds, which means an attacker with a GPU can test tens of billions of candidate passwords per second. A KDF deliberately makes that one operation take a meaningful fraction of a second, collapsing the attacker's throughput by five or six orders of magnitude. ### The three hardness properties Compute-hard functions cost CPU time (PBKDF2). Memory-hard functions additionally demand large amounts of RAM per guess, which defeats the cheap parallelism of GPUs and custom silicon (scrypt, Argon2). Argon2id combines both and is the current recommendation where it is available. ### Sources - [OWASP: Password Storage Cheat Sheet](https://cheatsheetseries.owasp.org/cheatsheets/Password_Storage_Cheat_Sheet.html): Practical guidance for salts, peppers, PBKDF2, Argon2id, and password hashes. - [NIST: Computer Security Resource Center glossary](https://csrc.nist.gov/glossary): Canonical terminology used across US computer security guidance. --- ## Salt Category: Cryptography Also called: cryptographic salt, password salt Canonical page: https://moolkey.com/glossary/salt A salt is a unique value combined with a password before hashing. It ensures two people with the same password get different stored hashes, which defeats precomputed attacks such as rainbow tables and forces an attacker to crack every account separately rather than all of them at once. ### Why salts do not need to be secret Salts are usually stored in plaintext alongside the hash, and that is fine. Their job is uniqueness, not confidentiality. A unique salt removes the attacker's ability to reuse work across accounts. A salt fails if it is reused or predictable across users. ### Salt versus pepper A pepper is a secret value added to every password hash and stored separately from the database, often in application configuration or a hardware module. A leaked database without the pepper is much harder to attack. Peppers complement salts; they do not replace them. ### Sources - [OWASP: Password Storage Cheat Sheet](https://cheatsheetseries.owasp.org/cheatsheets/Password_Storage_Cheat_Sheet.html): Practical guidance for salts, peppers, PBKDF2, Argon2id, and password hashes. - [NIST: Computer Security Resource Center glossary](https://csrc.nist.gov/glossary): Canonical terminology used across US computer security guidance. --- ## Hashing Category: Cryptography Also called: password hashing, cryptographic hash Canonical page: https://moolkey.com/glossary/hashing Hashing converts data of any size into a fixed-length fingerprint using a one-way function. You cannot reverse a hash back into the original input. Sites store password hashes rather than passwords so that a database leak does not immediately hand over everyone's credentials, provided the hashing was done properly. ### Hashing is not encryption Encryption is reversible with the right key; hashing is not reversible at all. If a service can email you your existing password, it is storing it encrypted or in plaintext rather than hashed. Treat that as a warning. ### Fast hashes versus password hashes SHA-256 and MD5 are designed to be fast, which makes them excellent for file integrity and terrible for passwords: speed is exactly what an attacker wants. Password storage needs a deliberately slow function such as bcrypt, scrypt, Argon2, or PBKDF2 with a high iteration count. ### What people often get wrong Claim: "Hashed passwords in a breach are safe." Correction: Only if they were salted and slow-hashed. When an unsalted SHA-1 database of common passwords leaks, attackers can recover a large fraction of it within hours. ### Sources - [OWASP: Password Storage Cheat Sheet](https://cheatsheetseries.owasp.org/cheatsheets/Password_Storage_Cheat_Sheet.html): Practical guidance for salts, peppers, PBKDF2, Argon2id, and password hashes. - [NIST: Computer Security Resource Center glossary](https://csrc.nist.gov/glossary): Canonical terminology used across US computer security guidance. --- ## Deterministic password manager Category: Passwords Also called: stateless password manager, vault-free password manager Canonical page: https://moolkey.com/glossary/deterministic-password-manager A deterministic password manager recreates each password by calculation rather than retrieving it from storage. The same Master Key plus the same site name always produces the same password, so a stored list of generated credentials is not required. Hosted products may still keep non-secret account metadata. ### How it differs from a vaulted manager A vaulted manager encrypts your passwords and syncs the encrypted blob between devices. A deterministic manager does not store generated passwords, though a hosted product may keep non-secret metadata such as the site name and a version number. A breach of a vaulted manager exposes an encrypted vault; a breach of a deterministic one can expose account metadata instead of a stored credential list. ### The honest trade-offs Changing a password requires a version counter, since the calculation would otherwise always produce the same result. Importing existing passwords is impossible because they were not generated by the formula. A forgotten master key is unrecoverable because there is no encrypted copy to fall back on. Further reading: [How deterministic password management works](https://moolkey.com/how-moolkey-works) ### Sources - [OWASP: Password Storage Cheat Sheet](https://cheatsheetseries.owasp.org/cheatsheets/Password_Storage_Cheat_Sheet.html): Practical guidance for salts, peppers, PBKDF2, Argon2id, and password hashes. - [NIST: SP 800-63B-4: Authentication and authenticator management](https://csrc.nist.gov/pubs/sp/800/63/b/4/final): Current requirements for passwords, authenticators, recovery, and rate limits. - [NIST: Computer Security Resource Center glossary](https://csrc.nist.gov/glossary): Canonical terminology used across US computer security guidance. --- ## Password vault Category: Passwords Also called: encrypted vault, password database Canonical page: https://moolkey.com/glossary/password-vault A password vault is the encrypted container holding the credentials a traditional password manager has saved. It is decrypted locally with a key derived from your master password, then synced between devices in encrypted form. The vault makes autofill and recovery possible. It also makes the provider a target. ### Why a vault is a concentration of risk A vault is valuable enough to attack patiently. When the encrypted vaults themselves leak, as happened in the 2022 LastPass incident, the attacker gets unlimited offline attempts against every vault. The strength of your master password and the iteration count in use at the time become the remaining barriers. ### What a vault buys you in return Autofill, secure notes, credit cards, TOTP codes, sharing, and account recovery all depend on there being something stored. These are real benefits, and for many people they outweigh the concentration risk. The choice is a genuine trade-off, not a right answer. Further reading: [Vaulted versus deterministic](https://moolkey.com/compare) ### Sources - [OWASP: Password Storage Cheat Sheet](https://cheatsheetseries.owasp.org/cheatsheets/Password_Storage_Cheat_Sheet.html): Practical guidance for salts, peppers, PBKDF2, Argon2id, and password hashes. - [NIST: SP 800-63B-4: Authentication and authenticator management](https://csrc.nist.gov/pubs/sp/800/63/b/4/final): Current requirements for passwords, authenticators, recovery, and rate limits. - [NIST: Computer Security Resource Center glossary](https://csrc.nist.gov/glossary): Canonical terminology used across US computer security guidance. --- ## Password manager Category: Passwords Canonical page: https://moolkey.com/glossary/password-manager A password manager gives every account its own strong password so that one breach cannot cascade into ten. Most store passwords in an encrypted vault; some recompute them on demand from a master key. Either way, the goal is the same: remove the human habit of reusing one memorable password everywhere. ### Why reuse is the problem worth solving Credential-stuffing attacks take email-and-password pairs from one breach and replay them against other services. Reuse is what turns a leak at a forum you forgot about into a compromised email account. Your email account can then reset everything else. ### The two architectures Vaulted managers (1Password, Bitwarden, Dashlane, Keeper) encrypt and sync stored credentials. Deterministic managers (MoolKey, LessPass, Spectre) recompute generated credentials from a Master Key instead of storing a generated credential list. Vaults offer autofill and recovery; deterministic tools trade those conveniences for a smaller stored-secret surface. Further reading: [How password managers work, in depth](https://moolkey.com/blog/how-do-password-managers-work) ### Sources - [OWASP: Credential Stuffing Prevention Cheat Sheet](https://cheatsheetseries.owasp.org/cheatsheets/Credential_Stuffing_Prevention_Cheat_Sheet.html): How password reuse is replayed at scale and how services can limit the damage. - [NIST: SP 800-63B-4: Authentication and authenticator management](https://csrc.nist.gov/pubs/sp/800/63/b/4/final): Current requirements for passwords, authenticators, recovery, and rate limits. - [NIST: Computer Security Resource Center glossary](https://csrc.nist.gov/glossary): Canonical terminology used across US computer security guidance. --- ## Brute force attack Category: Attacks Canonical page: https://moolkey.com/glossary/brute-force-attack A brute force attack tries every possible password in sequence until one works. Its cost grows exponentially with password length, which is why length matters more than any composition rule. In practice, attackers rarely brute force blindly. They exhaust likely candidates first, then fall back to exhaustive search. ### Online versus offline An online attack runs against a live login form, where rate limiting and lockouts cap the attacker at perhaps 100 attempts per second. An offline attack runs against a stolen database on the attacker's own hardware, where a GPU cluster reaches 100 billion attempts per second against a fast hash. Always assume the offline case when judging a password. ### Why length beats complexity Adding one character multiplies the search space by the entire pool size, roughly 86 times for a mixed-character password. Adding a symbol type only widens that pool once. A 16-character random password from an 86-character pool exceeds 100 bits and sits outside practical brute-force reach under current assumptions. ### Sources - [OWASP: Credential Stuffing Prevention Cheat Sheet](https://cheatsheetseries.owasp.org/cheatsheets/Credential_Stuffing_Prevention_Cheat_Sheet.html): How password reuse is replayed at scale and how services can limit the damage. - [CISA: Secure Our World](https://www.cisa.gov/secure-our-world): Public guidance for recognizing phishing and protecting high-value accounts. - [NIST: Computer Security Resource Center glossary](https://csrc.nist.gov/glossary): Canonical terminology used across US computer security guidance. --- ## Dictionary attack Category: Attacks Canonical page: https://moolkey.com/glossary/dictionary-attack A dictionary attack starts with a curated list of real words, names, and previously breached passwords. It then applies rules such as capitalising the first letter, appending a year, or swapping a for 4. This is much faster than brute force because human password choices are less random than they appear. ### Why leet substitutions do not help Every serious cracking tool applies substitution rules automatically. Turning 'password' into 'p@ssw0rd' adds under one bit of real strength, because the rule is in the toolkit's default configuration. The word is the weakness; disguising it changes almost nothing. ### The rule that follows from this If a human chose it, assume a dictionary attack may find it. Strength should come from random selection: either random characters or random words drawn by a machine from a list you did not curate. Further reading: [Test a password against these patterns](https://moolkey.com/tools/password-strength-checker) ### Sources - [OWASP: Password Storage Cheat Sheet](https://cheatsheetseries.owasp.org/cheatsheets/Password_Storage_Cheat_Sheet.html): Practical guidance for salts, peppers, PBKDF2, Argon2id, and password hashes. - [CISA: Secure Our World](https://www.cisa.gov/secure-our-world): Public guidance for recognizing phishing and protecting high-value accounts. - [NIST: Computer Security Resource Center glossary](https://csrc.nist.gov/glossary): Canonical terminology used across US computer security guidance. --- ## Credential stuffing Category: Attacks Canonical page: https://moolkey.com/glossary/credential-stuffing Credential stuffing takes username-and-password pairs leaked from one site and tries them automatically across many others. It requires no password cracking; it exploits reuse. Even a low success rate can be profitable at scale, so attackers move quickly when new credential dumps appear. ### Why this is the attack that actually reaches you Most people are not singled out by someone cracking their password. They are caught in an automated sweep. A password that is unique to one site stops the stolen pair from working elsewhere, though it does not stop phishing or malware. ### What limits the damage A unique password per site is the primary defence. Two-factor authentication is the secondary one: even a correct password fails without the second factor. Breach monitoring services tell you which credentials to rotate first. ### Sources - [OWASP: Credential Stuffing Prevention Cheat Sheet](https://cheatsheetseries.owasp.org/cheatsheets/Credential_Stuffing_Prevention_Cheat_Sheet.html): How password reuse is replayed at scale and how services can limit the damage. - [CISA: Secure Our World](https://www.cisa.gov/secure-our-world): Public guidance for recognizing phishing and protecting high-value accounts. - [NIST: Computer Security Resource Center glossary](https://csrc.nist.gov/glossary): Canonical terminology used across US computer security guidance. --- ## Rainbow table Category: Attacks Canonical page: https://moolkey.com/glossary/rainbow-table A rainbow table is a precomputed structure that maps hashes back to the passwords that produced them, trading storage for speed. Against unsalted hashes it turns cracking into a lookup. Salting defeats it entirely, because every account's hash would need its own table. ### Why they matter less than they used to Two things reduced their relevance. Salting became standard, which makes precomputation useless. And GPU cracking became so fast that computing hashes on demand is often cheaper than storing and searching terabytes of tables. Rainbow tables remain a good illustration of why salt exists. ### Sources - [OWASP: Password Storage Cheat Sheet](https://cheatsheetseries.owasp.org/cheatsheets/Password_Storage_Cheat_Sheet.html): Practical guidance for salts, peppers, PBKDF2, Argon2id, and password hashes. - [CISA: Secure Our World](https://www.cisa.gov/secure-our-world): Public guidance for recognizing phishing and protecting high-value accounts. - [NIST: Computer Security Resource Center glossary](https://csrc.nist.gov/glossary): Canonical terminology used across US computer security guidance. --- ## Passkey Category: Authentication Also called: FIDO2 credential, WebAuthn credential Canonical page: https://moolkey.com/glossary/passkey A passkey replaces a password with a public and private key pair. The private key never leaves your device and is unlocked by your fingerprint, face, or device PIN; the site only ever stores the public key. Because nothing secret is transmitted, passkeys cannot be phished, reused, or stolen in a database breach. ### How signing in works The site sends a random challenge. Your device signs it with the private key after you authenticate locally, and returns the signature. The site verifies it against the stored public key. No shared secret ever crosses the network, which removes the entire class of attacks based on capturing one. ### Where passkeys fall short today Coverage is incomplete. Many sites still require a password as a fallback, and that fallback remains the weakest link. Syncing across ecosystems is improving but can still be awkward, and recovery generally routes through your platform account, which becomes a new point of concentration. ### What people often get wrong Claim: "Passkeys mean I no longer need a password manager." Correction: Eventually, perhaps. Today almost every site that offers passkeys keeps password login enabled as a fallback, so the password still has to be strong and unique. Further reading: [Passkeys versus password managers](https://moolkey.com/blog/passkeys-vs-password-managers) ### Sources - [FIDO Alliance: Passkeys](https://fidoalliance.org/passkeys/): How device-held key pairs replace shared passwords and resist phishing. - [W3C: Web Authentication: Level 3](https://www.w3.org/TR/webauthn-3/): The web standard behind passkeys and FIDO2 security keys. - [NIST: SP 800-63B-4: Authentication and authenticator management](https://csrc.nist.gov/pubs/sp/800/63/b/4/final): Current requirements for passwords, authenticators, recovery, and rate limits. - [OWASP: Multifactor Authentication Cheat Sheet](https://cheatsheetseries.owasp.org/cheatsheets/Multifactor_Authentication_Cheat_Sheet.html): A comparison of authentication factors, recovery paths, and common attack routes. --- ## Two-factor authentication Category: Authentication Also called: 2FA, multi-factor authentication, MFA Canonical page: https://moolkey.com/glossary/two-factor-authentication Two-factor authentication requires a second proof of identity in addition to your password, typically a time-based code from an app, a hardware security key, or a biometric check. A stolen password is no longer enough on its own, though phishable codes can still be relayed. ### The factors ranked by strength Hardware security keys using FIDO2 are strongest, because they verify the site's identity and cannot be relayed by a phishing page. Authenticator apps generating TOTP codes are strong and universally available. SMS codes are the weakest common option, vulnerable to SIM swapping, but still far better than no second factor. ### Where to enable it first Your email account, before anything else. Email is the reset channel for every other account you own, which makes it the single highest-value target. Then financial accounts, then your password manager, then everything else. ### Sources - [OWASP: Multifactor Authentication Cheat Sheet](https://cheatsheetseries.owasp.org/cheatsheets/Multifactor_Authentication_Cheat_Sheet.html): A comparison of authentication factors, recovery paths, and common attack routes. - [W3C: Web Authentication: Level 3](https://www.w3.org/TR/webauthn-3/): The web standard behind passkeys and FIDO2 security keys. - [NIST: SP 800-63B-4: Authentication and authenticator management](https://csrc.nist.gov/pubs/sp/800/63/b/4/final): Current requirements for passwords, authenticators, recovery, and rate limits. --- ## Phishing Category: Attacks Canonical page: https://moolkey.com/glossary/phishing Phishing tricks you into giving your credentials to an attacker, usually through a convincing copy of a login page reached from an email or message. It bypasses password strength entirely. A 32-character random password typed into a fake site is exposed as quickly as a weak one. ### Why strong passwords do not help Phishing does not guess your password; it asks you for it. This is why the security advice shifts here: check the domain before typing, use a password manager that refuses to autofill on the wrong domain, and prefer passkeys or hardware keys, which cryptographically verify the site's identity for you. ### The autofill defence A password manager's autofill is a quiet anti-phishing feature. It matches on the exact domain, so if it declines to fill a page that looks familiar, that hesitation is a signal worth trusting more than your own eyes. ### Sources - [CISA: Secure Our World](https://www.cisa.gov/secure-our-world): Public guidance for recognizing phishing and protecting high-value accounts. - [W3C: Web Authentication: Level 3](https://www.w3.org/TR/webauthn-3/): The web standard behind passkeys and FIDO2 security keys. - [NIST: Computer Security Resource Center glossary](https://csrc.nist.gov/glossary): Canonical terminology used across US computer security guidance. --- ## End-to-end encryption Category: Cryptography Also called: E2EE Canonical page: https://moolkey.com/glossary/end-to-end-encryption End-to-end encryption encrypts data on the sending device and decrypts it only on the receiving device. The service provider, the network, and any server in between handle ciphertext they cannot read. The provider transports your data without being able to inspect its contents. ### How it relates to zero-knowledge The terms overlap but are not identical. End-to-end encryption describes data in transit between parties. Zero-knowledge describes an architecture where the provider cannot read data at rest either. A service can be end-to-end encrypted for messages while still holding keys to other data it stores for you. ### What still leaks Metadata. Who you communicate with, when, how often, and from where usually remains visible to the provider even when content does not. For a password manager, the equivalent metadata is the list of services you hold accounts with. ### Sources - [NIST: Computer Security Resource Center glossary](https://csrc.nist.gov/glossary): Canonical terminology used across US computer security guidance. - [OWASP: Password Storage Cheat Sheet](https://cheatsheetseries.owasp.org/cheatsheets/Password_Storage_Cheat_Sheet.html): Practical guidance for salts, peppers, PBKDF2, Argon2id, and password hashes. --- ## Shoulder surfing Category: Attacks Canonical page: https://moolkey.com/glossary/shoulder-surfing Shoulder surfing means stealing a credential by watching it being entered over a shoulder, through a security camera, or from across a café. Long passwords take longer to type and expose more of the entry sequence, so physical privacy matters as much as password strength here. ### Where it still happens Cash machines and payment terminals, phone unlock screens on public transport, and shared or open-plan offices. PIN entry is the most exposed moment in most people's day, which is one reason a PIN's protection depends more on lockouts than on the number itself. ### Practical defences Cover the keypad with your other hand to block both human observers and overhead cameras. Prefer biometric unlock in public, keeping the PIN as the fallback. Never reuse your card PIN as your phone PIN, since the phone one is observed far more often. ### Sources - [NIST: SP 800-63B-4: Authentication and authenticator management](https://csrc.nist.gov/pubs/sp/800/63/b/4/final): Current requirements for passwords, authenticators, recovery, and rate limits. - [CISA: Secure Our World](https://www.cisa.gov/secure-our-world): Public guidance for recognizing phishing and protecting high-value accounts. - [NIST: Computer Security Resource Center glossary](https://csrc.nist.gov/glossary): Canonical terminology used across US computer security guidance. --- ## PIN Category: Authentication Also called: personal identification number Canonical page: https://moolkey.com/glossary/pin A PIN is a short numeric code protecting a card, phone, or device. Four digits allow only 10,000 combinations, so most of a PIN's security comes from the attempt limit and from avoiding the small set of numbers that many other people choose. ### Why human PIN choice is the weak point Analysis of 3.4 million exposed four-digit PINs found that 1234 alone accounted for over 10% of them, and the ten most common covered roughly 20%. A further large cluster follows the MMDD shape of a date or sits in the 19xx range of birth years. A thief with three attempts and a guess list does far better than 3 in 10,000. ### Six digits where you can Moving from four digits to six multiplies the space by 100, from 10,000 to 1,000,000 combinations. Phones and banking apps generally allow it. Cards often do not, in which case randomness matters even more. Further reading: [Generate a random PIN](https://moolkey.com/tools/pin-generator) ### Sources - [NIST: SP 800-63B-4: Authentication and authenticator management](https://csrc.nist.gov/pubs/sp/800/63/b/4/final): Current requirements for passwords, authenticators, recovery, and rate limits. - [OWASP: Multifactor Authentication Cheat Sheet](https://cheatsheetseries.owasp.org/cheatsheets/Multifactor_Authentication_Cheat_Sheet.html): A comparison of authentication factors, recovery paths, and common attack routes. --- ## Data breach Category: Attacks Also called: security breach, data leak Canonical page: https://moolkey.com/glossary/data-breach A data breach is an incident where an organisation's stored data is accessed or removed by someone unauthorised. For passwords, the exposed data is usually a database of hashes. Those hashes are only as protective as the method that created them, and weak hashing can turn a breach into rapid password disclosure. ### What actually leaks Rarely plaintext passwords. Usually a table of email addresses paired with password hashes, plus whatever else the service stored. The severity depends almost entirely on the hashing: an unsalted SHA-1 database is effectively cracked within hours, while bcrypt or Argon2 with a proper cost factor buys years. Breaches also expose details people forget are stored, including password hints, security question answers, and partial payment information. Those records can matter as much as the password itself. ### Why one breach becomes many Attackers do not stop at the breached service. They take the recovered email-and-password pairs and replay them everywhere, which is why a leak at a forum you forgot about can end with your email account compromised. Unique passwords sever that chain completely. Further reading: [Check whether a password has been breached](https://moolkey.com/tools/password-breach-check) ### Sources - [Have I Been Pwned: Pwned Passwords](https://haveibeenpwned.com/Passwords): A searchable corpus of password hashes exposed in known data breaches. - [OWASP: Password Storage Cheat Sheet](https://cheatsheetseries.owasp.org/cheatsheets/Password_Storage_Cheat_Sheet.html): Practical guidance for salts, peppers, PBKDF2, Argon2id, and password hashes. - [CISA: Secure Our World](https://www.cisa.gov/secure-our-world): Public guidance for recognizing phishing and protecting high-value accounts. - [NIST: Computer Security Resource Center glossary](https://csrc.nist.gov/glossary): Canonical terminology used across US computer security guidance. --- ## Account takeover Category: Attacks Also called: ATO Canonical page: https://moolkey.com/glossary/account-takeover Account takeover happens when an attacker moves from accessing your account to controlling it. They may change the password, recovery email, and second factor so you cannot get back in. Credential stuffing, phishing, and SIM swapping are common routes to that outcome. ### The chain that leads there Almost every takeover follows the same route: a password is obtained (through a breach, a phishing page, or reuse), it works somewhere, and the attacker then locks down the recovery paths. The critical link is usually your email account, because whoever controls it can reset everything else. ### What actually stops it A unique password per site removes replay. Two-factor authentication means a correct password alone is not enough. An authenticator app or hardware key removes SIM swapping as a route in. Protect the email account first because it can reset almost everything else. ### Sources - [OWASP: Credential Stuffing Prevention Cheat Sheet](https://cheatsheetseries.owasp.org/cheatsheets/Credential_Stuffing_Prevention_Cheat_Sheet.html): How password reuse is replayed at scale and how services can limit the damage. - [OWASP: Multifactor Authentication Cheat Sheet](https://cheatsheetseries.owasp.org/cheatsheets/Multifactor_Authentication_Cheat_Sheet.html): A comparison of authentication factors, recovery paths, and common attack routes. - [CISA: Secure Our World](https://www.cisa.gov/secure-our-world): Public guidance for recognizing phishing and protecting high-value accounts. - [NIST: Computer Security Resource Center glossary](https://csrc.nist.gov/glossary): Canonical terminology used across US computer security guidance. --- ## Authenticator app Category: Authentication Also called: TOTP app, 2FA app Canonical page: https://moolkey.com/glossary/authenticator-app An authenticator app generates a six-digit code that changes every thirty seconds, computed from a secret shared with the site at setup and the current time. Because the code is derived locally and never sent over the network in advance, it cannot be intercepted the way an SMS code can. ### How TOTP works When you scan the QR code, the site gives your app a shared secret. Both sides then compute HMAC over that secret and the current 30-second time window, truncating the result to six digits. No network traffic is involved at code-generation time, which is why the app works in aeroplane mode. ### Why it beats SMS SMS codes travel over a network that can be redirected. In a SIM swap, an attacker convinces a carrier to move your number to a new SIM and receives the codes meant for you. Authenticator apps avoid that route because the shared secret stays on your device. ### The backup problem Losing the phone means losing every code unless you saved the recovery codes at setup. Save them somewhere separate from the phone, and treat that step as part of enabling 2FA rather than an optional extra. ### Sources - [IETF: RFC 6238: Time-Based One-Time Password Algorithm](https://datatracker.ietf.org/doc/html/rfc6238): The standard that defines rotating time-based authenticator codes. - [OWASP: Multifactor Authentication Cheat Sheet](https://cheatsheetseries.owasp.org/cheatsheets/Multifactor_Authentication_Cheat_Sheet.html): A comparison of authentication factors, recovery paths, and common attack routes. - [NIST: SP 800-63B-4: Authentication and authenticator management](https://csrc.nist.gov/pubs/sp/800/63/b/4/final): Current requirements for passwords, authenticators, recovery, and rate limits. --- ## Security key Category: Authentication Also called: hardware key, FIDO2 key, YubiKey Canonical page: https://moolkey.com/glossary/security-key A security key is a small physical device that authenticates you using public-key cryptography. Its decisive advantage over every code-based method is origin binding: the key checks the site's actual domain before signing, so a phishing page gets nothing even if you were fully convinced by it. ### Why phishing simply fails against it Codes can be relayed. If a convincing fake page asks for your six-digit code, you might type it, and the attacker forwards it to the real site within the window. A security key cannot be tricked this way because the signature is tied to the requesting domain. A signature for the fake domain is worthless at the real one. ### The practical trade-offs You have to carry it, and you should own two: one in use and one stored safely. Losing your only key without a backup method creates a genuine lockout risk. Coverage is also uneven, with strong support on major platforms and patchier support elsewhere. ### Sources - [W3C: Web Authentication: Level 3](https://www.w3.org/TR/webauthn-3/): The web standard behind passkeys and FIDO2 security keys. - [FIDO Alliance: Passkeys](https://fidoalliance.org/passkeys/): How device-held key pairs replace shared passwords and resist phishing. - [NIST: SP 800-63B-4: Authentication and authenticator management](https://csrc.nist.gov/pubs/sp/800/63/b/4/final): Current requirements for passwords, authenticators, recovery, and rate limits. - [OWASP: Multifactor Authentication Cheat Sheet](https://cheatsheetseries.owasp.org/cheatsheets/Multifactor_Authentication_Cheat_Sheet.html): A comparison of authentication factors, recovery paths, and common attack routes. --- ## SIM swapping Category: Attacks Also called: SIM swap attack, SIM jacking Canonical page: https://moolkey.com/glossary/sim-swapping SIM swapping is when an attacker convinces your mobile carrier to move your phone number onto a SIM they control. Every SMS verification code then arrives on their device instead of yours. It is the single strongest argument against using SMS as a second factor for anything valuable. ### How the attack runs It is social engineering against the carrier, not a technical exploit. The attacker gathers enough personal detail, often from previous breaches, to pass the carrier's identity check. They then report a lost phone and request a transfer. The first sign for the victim is usually a phone that suddenly loses signal. ### How to reduce the risk Move your second factor off SMS wherever possible and use an authenticator app or security key. Add a port-out PIN or account lock with your carrier; many carriers support one. Remove your phone number as a recovery method on accounts that let you use something else. ### Sources - [FBI: Criminals Increasing SIM Swap Schemes](https://www.ic3.gov/PSA/2022/PSA220208): How SIM swap fraud works and which account protections reduce the risk. - [OWASP: Multifactor Authentication Cheat Sheet](https://cheatsheetseries.owasp.org/cheatsheets/Multifactor_Authentication_Cheat_Sheet.html): A comparison of authentication factors, recovery paths, and common attack routes. - [CISA: Secure Our World](https://www.cisa.gov/secure-our-world): Public guidance for recognizing phishing and protecting high-value accounts. - [NIST: Computer Security Resource Center glossary](https://csrc.nist.gov/glossary): Canonical terminology used across US computer security guidance. --- ## Password rotation Category: Passwords Also called: password expiry, forced password change Canonical page: https://moolkey.com/glossary/password-rotation Password rotation means changing passwords at fixed intervals, typically every 60 or 90 days. Modern guidance has reversed on this: NIST SP 800-63B now recommends against arbitrary expiry, because forced changes push people toward predictable patterns like Spring2026 followed by Summer2026. ### Why scheduled expiry backfires A person forced to invent a new password every quarter does not generate a new random one. They increment. The observable result across large organisations is a population of passwords following visible patterns, which is far easier to attack than a stable set of strong unique ones. ### When you should rotate On evidence, not on a calendar. Change a password immediately if it appeared in a breach, if you reused it somewhere that was breached, if you shared it and the sharing has ended, or if you suspect any compromise of the device you typed it on. ### What people often get wrong Claim: "Changing my passwords every 90 days makes me safer." Correction: It usually makes you less safe. NIST reversed this guidance because forced rotation produces predictable sequences. Rotate in response to evidence of exposure instead. ### Sources - [NIST: SP 800-63B-4: Authentication and authenticator management](https://csrc.nist.gov/pubs/sp/800/63/b/4/final): Current requirements for passwords, authenticators, recovery, and rate limits. - [NIST: Computer Security Resource Center glossary](https://csrc.nist.gov/glossary): Canonical terminology used across US computer security guidance. --- ## Password autofill Category: Passwords Canonical page: https://moolkey.com/glossary/password-autofill Autofill is a password manager entering your saved credentials into a login form for you. Beyond convenience, it is a quiet anti-phishing control: a manager matches on the exact domain, so if it declines to fill a page that looks familiar to you, that refusal is worth more than your own judgement. ### The security argument for it Human eyes are poor at spotting a lookalike domain, particularly on a phone where the URL bar is truncated. Software comparing strings is not. Treat a manager that will not autofill as a warning rather than an inconvenience, and check the address before typing anything. ### Where autofill has been risky Researchers have repeatedly demonstrated attacks where hidden form fields harvest autofilled credentials, and where fills on embedded frames leak to the wrong origin. Reputable managers have hardened against these, but it is a reason to prefer explicit fill on click over silent fill on page load. ### Sources - [NIST: SP 800-63B-4: Authentication and authenticator management](https://csrc.nist.gov/pubs/sp/800/63/b/4/final): Current requirements for passwords, authenticators, recovery, and rate limits. - [NIST: Computer Security Resource Center glossary](https://csrc.nist.gov/glossary): Canonical terminology used across US computer security guidance. --- ## Biometric authentication Category: Authentication Also called: fingerprint login, Face ID, biometrics Canonical page: https://moolkey.com/glossary/biometric-authentication Biometric authentication uses a physical characteristic such as a fingerprint, face, or iris to verify you. On modern devices the biometric template stays in secure hardware and unlocks a locally stored key. It is a convenient replacement for typing a PIN, not a replacement for the PIN itself. ### Biometrics unlock, they do not authenticate remotely Your fingerprint is not transmitted to any website. It releases a key held in your device's secure element, and that key does the cryptographic work. This is why a device PIN always exists as a fallback: the biometric is a convenient gate in front of it, not a substitute for it. ### The property that makes them different You cannot change your fingerprint. A leaked password is replaceable; a compromised biometric template is not. This is the argument for keeping biometrics as a local unlock mechanism rather than as a shared credential sent to services. ### Sources - [NIST: SP 800-63B-4: Authentication and authenticator management](https://csrc.nist.gov/pubs/sp/800/63/b/4/final): Current requirements for passwords, authenticators, recovery, and rate limits. - [W3C: Web Authentication: Level 3](https://www.w3.org/TR/webauthn-3/): The web standard behind passkeys and FIDO2 security keys. - [OWASP: Multifactor Authentication Cheat Sheet](https://cheatsheetseries.owasp.org/cheatsheets/Multifactor_Authentication_Cheat_Sheet.html): A comparison of authentication factors, recovery paths, and common attack routes. --- ## Keylogger Category: Attacks Canonical page: https://moolkey.com/glossary/keylogger A keylogger records keystrokes and captures passwords at the moment you type them. A 32-character random password is captured as easily as a weak one. This is why keeping the device clean matters alongside choosing a strong password. ### Why strength is irrelevant here A keylogger does not guess. It reads. This is the same reason phishing beats strong passwords: both attacks capture the secret rather than compute it. The relevant defences are keeping the device clean, using autofill instead of typing, and adding a second factor so a captured password is not sufficient. ### What limits the damage Two-factor authentication limits some of the damage because a recorded password alone may not complete a login. Autofill reduces exposure because the password is never typed. If you suspect a device is compromised, change passwords from a different device. Otherwise the keylogger may capture the replacements too. ### Sources - [CISA: Secure Our World](https://www.cisa.gov/secure-our-world): Public guidance for recognizing phishing and protecting high-value accounts. - [OWASP: Multifactor Authentication Cheat Sheet](https://cheatsheetseries.owasp.org/cheatsheets/Multifactor_Authentication_Cheat_Sheet.html): A comparison of authentication factors, recovery paths, and common attack routes. - [NIST: Computer Security Resource Center glossary](https://csrc.nist.gov/glossary): Canonical terminology used across US computer security guidance. --- ## Password spraying Category: Attacks Canonical page: https://moolkey.com/glossary/password-spraying Password spraying inverts the usual attack: instead of guessing many passwords for one account, it tries one common password against thousands of accounts. Each account sees only a single failed attempt, so ordinary lockout rules may not trigger. In a large population, one of those guesses may work. ### Why lockouts do not catch it Account lockout triggers on repeated failures against one account. Spraying makes one attempt per account, so no threshold is ever crossed. Detection has to happen at the network level, by noticing many single failures from one source, which many systems do not do. ### The defence is population-wide Individually, avoid common passwords because spraying only works when your password is on the attacker's short list. Organisations should screen new passwords against known-breached lists when they are set. Further reading: [Check whether your password is on those lists](https://moolkey.com/tools/password-breach-check) ### Sources - [OWASP: Credential Stuffing Prevention Cheat Sheet](https://cheatsheetseries.owasp.org/cheatsheets/Credential_Stuffing_Prevention_Cheat_Sheet.html): How password reuse is replayed at scale and how services can limit the damage. - [NIST: SP 800-63B-4: Authentication and authenticator management](https://csrc.nist.gov/pubs/sp/800/63/b/4/final): Current requirements for passwords, authenticators, recovery, and rate limits. - [CISA: Secure Our World](https://www.cisa.gov/secure-our-world): Public guidance for recognizing phishing and protecting high-value accounts. - [NIST: Computer Security Resource Center glossary](https://csrc.nist.gov/glossary): Canonical terminology used across US computer security guidance. --- ## Social engineering Category: Attacks Canonical page: https://moolkey.com/glossary/social-engineering Social engineering attacks the person rather than the system. It includes phishing emails, pretext phone calls, fake support agents, and SIM swapping. In each case, the attacker uses persuasion to route around a technical control and convince someone to grant access. ### Why it works on careful people Effective social engineering manufactures urgency and authority, such as a message that appears to come from your bank and says your account will be frozen within the hour. Under time pressure, people stop verifying. The defence is procedural: never act on an inbound message. Start contact yourself through a number or address you already had. ### The controls that still hold Security keys resist phishing because origin binding prevents a fake site from receiving a usable credential. Codes, passwords, and one-time links can still be relayed by an attacker talking to you in real time. ### Sources - [CISA: Secure Our World](https://www.cisa.gov/secure-our-world): Public guidance for recognizing phishing and protecting high-value accounts. - [W3C: Web Authentication: Level 3](https://www.w3.org/TR/webauthn-3/): The web standard behind passkeys and FIDO2 security keys. - [NIST: Computer Security Resource Center glossary](https://csrc.nist.gov/glossary): Canonical terminology used across US computer security guidance. --- ## Single sign-on Category: Authentication Also called: SSO, sign in with Google, social login Canonical page: https://moolkey.com/glossary/single-sign-on Single sign-on lets one identity provider vouch for you across many services through a button such as 'Sign in with Google' or 'Sign in with Apple'. It reduces the number of passwords you hold and concentrates the consequences: whoever controls that provider account can reach every connected service. ### The genuine benefits Fewer passwords means fewer chances to reuse one. The identity provider is usually better defended than a small site would be, and it can enforce strong second factors centrally. For organisations, revocation is also immediate because disabling one account closes every connected service. ### The concentration cost Losing the provider account can cut off every connected service, and providers do suspend accounts. Some services also make it hard to detach a social login later. Protect the SSO account itself with a security key and keep its recovery methods current. ### Sources - [NIST: SP 800-63C-4: Federation and assertions](https://csrc.nist.gov/pubs/sp/800/63/c/4/final): Current guidance for federated identity and single sign-on. - [OWASP: Multifactor Authentication Cheat Sheet](https://cheatsheetseries.owasp.org/cheatsheets/Multifactor_Authentication_Cheat_Sheet.html): A comparison of authentication factors, recovery paths, and common attack routes. - [NIST: SP 800-63B-4: Authentication and authenticator management](https://csrc.nist.gov/pubs/sp/800/63/b/4/final): Current requirements for passwords, authenticators, recovery, and rate limits. --- ## Identity theft Category: Attacks Canonical page: https://moolkey.com/glossary/identity-theft Identity theft is the use of personal details such as your name, date of birth, address, or government ID number to impersonate you. The goal is often to open credit or access an existing account. A compromised email or financial account can expose much of the information an impersonator needs. ### How password security connects to it An email account is a dossier. It holds statements, delivery addresses, tax documents, and the reset links for everything else. A single reused password that leaks in an unrelated breach can therefore open a path to a full identity profile, which is why email deserves your strongest password and second factor. ### What to do first if it happens Regain and secure the email account before anything else because it controls the recovery of other accounts. Then contact affected financial institutions, place a fraud alert or credit freeze where that is available in your country, and document each step. Most remediation processes require a paper trail. ### Sources - [CISA: Secure Our World](https://www.cisa.gov/secure-our-world): Public guidance for recognizing phishing and protecting high-value accounts. - [OWASP: Credential Stuffing Prevention Cheat Sheet](https://cheatsheetseries.owasp.org/cheatsheets/Credential_Stuffing_Prevention_Cheat_Sheet.html): How password reuse is replayed at scale and how services can limit the damage. - [NIST: Computer Security Resource Center glossary](https://csrc.nist.gov/glossary): Canonical terminology used across US computer security guidance. --- ## Password hint Category: Authentication Also called: security question, knowledge-based authentication Canonical page: https://moolkey.com/glossary/password-hint Password hints and security questions let you recover access by proving you know something personal. Their answers are often guessable or public on social media. Unlike a password, a biographical fact cannot be changed after exposure. Current NIST guidance does not permit knowledge-based questions for digital authentication. ### Why they undermine strong passwords A recovery mechanism is an alternative way in, so an account is only as strong as its weakest route. A 20-character random password guarded by 'What was your first pet's name?' is protected by the pet's name. Breaches have also leaked hint fields in plaintext, handing attackers the answer directly. ### How to handle a mandatory one Where you cannot skip it, do not answer truthfully. Generate a random string and store it as if it were a second password. The field only has to match; the answer does not have to be true. ### What people often get wrong Claim: "Security questions add a layer of protection." Correction: They usually subtract one. They create a second, weaker way into the account, and their answers are often discoverable or unchangeable. ### Sources - [NIST: SP 800-63B-4: Authentication and authenticator management](https://csrc.nist.gov/pubs/sp/800/63/b/4/final): Current requirements for passwords, authenticators, recovery, and rate limits. - [OWASP: Multifactor Authentication Cheat Sheet](https://cheatsheetseries.owasp.org/cheatsheets/Multifactor_Authentication_Cheat_Sheet.html): A comparison of authentication factors, recovery paths, and common attack routes.