Passwords & 2FA

• Password reuse. Large lists of leaked email and password pairs circulate, and attackers automatically try them on other sites (credential stuffing). One reused password can open many accounts.
• Phishing. A look-alike login page captures your password and any one-time code you type into it, often relaying both to the real site within seconds.
• Stolen vaults. If a password manager company is breached, attackers can copy encrypted vaults and guess master passwords offline, at their own pace. Only a strong master passphrase protects you then.
• SIM swapping. Someone persuades or bribes your mobile carrier to move your number to their SIM card, then receives your SMS login codes.
• Malware. No password manager can protect you on a compromised device that can read your screen, keystrokes or memory. Keep your system updated (see Operating systems).

Offline vault or cloud sync?

An offline manager such as KeePassXC stores your vault as one encrypted file that you keep and copy yourself. There is no account and no provider holding a copy of your vault. The cost is convenience: you move the file between devices and make your own backups.

A cloud manager encrypts the vault on your device before uploading it (vendors call this end-to-end or "zero-knowledge" encryption) and syncs it for you. You have to trust that its apps and servers behave as described. In 2026, researchers at ETH Zurich and USI showed that a malicious or compromised server could undermine that promise in Bitwarden, LastPass, Dashlane and 1Password, in the worst cases recovering passwords. The vendors have fixed many of the issues, accepted some as design choices, or disputed their severity. Self-hosting removes the third-party server but makes you responsible for keeping it patched.

These apps all read and write the open KeePass .kdbx format, so you can use KeePassXC on a computer and a different app on your phone with the same file. Sync it with a tool you trust, or keep it on one device and an encrypted backup.

Cloud managers are easier to set up and sync automatically across devices. All of them need an account, and all of them ask you to trust the provider's servers and app updates. If you use one, give it a long random master passphrase and turn on a second factor for the account itself.

A second factor is something you have in addition to the password. Any second factor is better than none, but they differ a lot in what they stop. The key question is whether the method is phishing-resistant: only FIDO2 security keys and passkeys check which website is asking, so a fake site gets nothing it can reuse.

A passkey replaces a password with a key pair. The private key stays in your password manager, phone or security key; the website only stores the public key. Your device offers a passkey only to the domain it was created for, so a look-alike phishing site gets nothing, and a breach of the website leaks nothing reusable.

Passkeys are now mainstream: the FIDO Alliance estimated about 5 billion in use in May 2026. There are two kinds. Synced passkeys live in a password manager or an Apple or Google account and copy themselves to your other devices. Device-bound passkeys are generated inside a hardware key (or a device's security chip) and never leave it, so they cannot be backed up.

Moving passkeys between managers

Until recently, passkeys could not be exported, which locked people into one provider. The FIDO Alliance published the Credential Exchange Format (CXF) as a Proposed Standard in August 2025; the matching Credential Exchange Protocol (CXP) is still a draft. Apple added CXP transfers in iOS 26 (September 2025) and Google added them to Android 14 and later through a Google Play services update by July 2026. Support in individual apps varies, so check your manager's documentation before counting on it.

An authenticator app stores a secret for each account and turns it into a six-digit code that changes every 30 seconds (TOTP). The secret is what matters: if you lose it without a backup, you are locked out; if someone copies it, they can generate your codes. Prefer apps that let you export encrypted backups and that do not require an account.

A FIDO2 security key is a small USB or NFC device that proves you hold it by signing a challenge for the exact site you registered with. It is the strongest second factor most people can get; CISA calls hardware FIDO keys the most effective option.

This guide still rates every key below as "use with caution" because of what a physical key reveals. Plugging in any USB device usually leaves its vendor and model in the operating system's logs (see Digital forensics), and a website can ask the key for an attestation that names its make and model, though not its serial number. If owning or using a key could itself draw attention to you, weigh that before buying one. Cheaper FIDO2 keys, such as the Token2 PIN+ range from Switzerland, work the same way for websites.

• Let the manager generate every password. Length matters more than symbols: NIST's 2025 guidelines require at least 15 characters for passwords used on their own and tell sites to drop mandatory symbol rules and forced periodic changes. Twenty or more random characters is an easy default.
• Make the master password a dice-generated passphrase of at least six random words, using EFF's wordlists. Do not invent it yourself: people are bad at randomness. It is the one password you must remember, and the one an attacker with a stolen vault will try to crack.
• Back up the vault. Keep an encrypted copy offline, for example on a USB drive (see Encryption), and check that you can open it. With a cloud manager, export from time to time.
• Save recovery codes for every account with 2FA, either in your vault or on paper stored safely.
• Autofill carefully. Keep browser extensions updated, turn off automatic filling on page load, and fill from the extension icon. In 2025 a researcher showed that invisible page elements could trick 11 password manager extensions into filling in data.
• Consider keeping 2FA secrets apart from passwords for your most important accounts, so that one compromised vault does not hand over both factors. This is a trade-off against convenience.
• Check for breached passwords with Pwned Passwords. It uses k-anonymity: only the first five characters of the password's hash leave your device.
• Keep crypto seed phrases out of cloud password managers. See Crypto for safer storage.
• If you stored passwords in Microsoft Authenticator: Microsoft removed password storage and autofill from the app in mid-2025; saved passwords stay in your Microsoft account and are reachable through Edge.

• Using a "unique pattern" such as a base word plus the site name. Once one password leaks, the others can be guessed. Every password should be random and unrelated.
• Keeping 2FA secrets in one app on one phone with no backup. Phones get lost, apps change owners (Raivo OTP) and vendors drop platforms (Authy desktop).
• Leaving a weak master password on a cloud vault. Vaults stolen from LastPass in 2022 were still being cracked in 2025.
• Typing a code or approving a prompt you did not start. Real-time phishing kits relay one-time codes instantly, and push bombing relies on you eventually tapping Approve.
• Registering only one hardware key, or leaving SMS enabled as a fallback after setting up a stronger method.
• Treating "zero-knowledge" as a guarantee. It describes how a vault is encrypted, not whether the provider's servers and app updates can be trusted.

• NIST SP 800-63B-4: Authentication and Authenticator Managementpages.nist.govThe 2025 US government rules on password length, blocklists and password managers.
• CISA: Mobile Communications Best Practice Guidance (December 2024)cisa.govAdvice for high-risk users: FIDO keys, dropping SMS codes, carrier PINs.
• CISA: Implementing Phishing-Resistant MFAcisa.govExplains push bombing, SIM swapping and why FIDO resists phishing.
• EFF: Dice-generated passphraseseff.org
• Zero Knowledge (About) Encryption, ETH Zurich and USI (2026)eprint.iacr.orgAttacks on four cloud password managers under a malicious server.
• FIDO Alliance: Credential Exchange Formatfidoalliance.org