标签：#authentication

Someone on your leadership team asked a reasonable question: should we adopt passkeys? You searched for answers and found implementation tutorials - WebAuthn server libraries, credential storage schemas, ceremony diagrams. They assume you've already decided. None of that helps you answer the question you were actually asked. This article is a decision guide. The question isn't how to implement passkey login. It's whether you should, when the timing makes sense, and for which users first. Implementation details matter eventually - but they don't belong at the front of the decision. You've seen Apple's demos and Google's Chrome nudges. Your security team may have sent a memo about phishing-resistant authentication. You know the term. What you don't have is a clear way to evaluate whether passkeys fit your product, your users, and your team's capacity to ship and support them. By the end of this article, you'll have scored your app against a readiness checklist, mapped show-stoppers that can block adoption, and drafted a one-page recommendation for leadership. Plain Terms: Passkeys, Passwords, and MFA Before scoring your app, you and stakeholders need to mean the same thing when you say "passkey", "password", and "MFA". Vendor decks use these loosely. A PM might say "passkeys replace passwords" while security means "phishing-resistant credentials". Both can be true. Passwords are shared secrets the user types; your server checks a hash. They leak via breaches and phishing sites. Users forget them, reuse them, and call support. MFA adds a second factor - app push, SMS, hardware key, or biometric. It cuts credential-stuffing and many phishing attacks, but adds friction, lost-device tickets, and cross-platform complexity. Passkeys are cryptographic key pairs on the user's device. The private key never leaves the device or synced passkey manager. Sign-in means unlocking with biometrics or a PIN; your server stores only the public key and verifies a signature. On web, the b

Every identity migration guide eventually reaches the same paragraph, and it's always a little apologetic: "users will need to reset their passwords." It gets treated like a law of nature. It isn't. It's a choice, usually forced by a tool that didn't want to do the harder thing. The harder thing is verifying your users' existing password hashes in place, so they sign in after the move with exactly the credentials they had before and never notice anything happened. Whether you can do it comes down to one question: can you get the old hashes, and can the new system verify them? Password hashes are more portable than people think A password hash isn't a secret algorithm. bcrypt is bcrypt. A bcrypt hash carries its own cost factor and salt inside the string, so anything that implements bcrypt can verify a hash any other bcrypt system produced. The same is true of the PBKDF2 format ASP.NET Identity uses: documented, versioned, self-describing. If you know what you're holding, you can check a password against it without ever knowing the password. So a migration that preserves logins doesn't need the plaintext (nobody has it) and doesn't need to re-hash everyone up front. It needs to obtain the stored hashes and verify against them on sign-in, upgrading each one to its own format quietly the first time a user logs in. That last part is lazy migration: carry the old hash, verify it once, replace it transparently. Over a few weeks of normal logins your user table re-hashes itself and the legacy formats age out, with zero resets and zero support tickets. The dual-path bit The wrinkle is that different sources hand you different formats, and a good importer verifies both: From self-hosted Duende / ASP.NET Identity: the V3 PBKDF2 hashes (and any legacy bcrypt) verify natively and rehash on first sign-in. This is the easy case, because it's the same scheme the destination already uses. Most teams are surprised it's that clean. From Auth0: bcrypt hashes verify verbatim. The catch

AWS recently introduced Amazon Cognito multi-region replication, which automatically replicates user identities and user pool configurations from a primary region to a secondary one. This enables applications to continue authenticating users from a replica region during outages, without requiring custom replication and failover mechanisms. By Renato Losio

1. Introduction As the golden standard of secure remote access , the Secure Shell (SSH) protocol has several layers of protection. One of them involves recording and keeping track of the known servers on the client side. known_hosts By default, the known_hosts file for a given user is located at: cat /home/user_name/.ssh/known_hosts github.com ssh-rsa *** github.com ecdsa-sha2-nistp256 *** github.com ssh-ed25519 *** Basically, the file contains a list with several columns, separated by whitespace: Identifying host data Host key type Host key value Optional comment The first column can be hashed or cleartext, depending on the setting of HashKnownHosts in /etc/ssh/ssh_config . When hashed, the first field of each line starts with |1| , a HASH_MAGIC marker. After the latter, the field continues with a random 160-bit string, otherwise known as a salt, followed by a 160-bit SHA1 hash. Each of these is encoded in base64 . The main idea is to hide the IP address or hostname data, which would otherwise be directly visible Either way, known_hosts contains a mapping between a server as identified by its characteristics and its key . ## Known Hosts Checking When connecting to a remote host, SSH checks the known_hosts file of the client to confirm the address or hostname for the server match the key we get from it . If there is a match, the session setup can continue. Otherwise, we get an error. The entry for 192.168.6.66 in the known_hosts file doesn’t match the (Elliptic Curve Digital Signature Algorithm, ECDSA ) key we got back from the server at that address . Critically, if we don’t know what caused the error, we should heed the text in capital letters: something nasty can indeed be happening . On the other hand, the reasons for such an issue can be valid and trivial: dynamic IP address changed hostname reinstalled system reinstalled SSH Docker container misconfigured DHCP relocated client In fact, there can be many more. ## Bypass Known Hosts The error text when connectin