Make the SCRAM verifier the sole password credential; finish the account-registration relay

Credentials: the SCRAM-SHA-256 verifier is now the only password
credential. PLAIN and IDENTIFY verify the plaintext against it via
scram::verify_plain, exactly as a SCRAM login proves knowledge of it, so
an account provisioned from a verifier alone (external authority) works
over every mechanism, not only SCRAM. Removed the redundant argon2 hash
entirely: the field, the Credentials member, the AccountPasswordSet
field, hash_password/verify_password, and the argon2 crate. SASL SCRAM
already forces a PBKDF2 verifier into the store, so the hash never raised
the at-rest floor. OS RNG now comes from rand_core.

Registration: finished draft/account-registration over the ircd relay.
VERIFY confirms the emailed code, RESEND reissues it, STATUS reports
state, and REGISTER now emails the code and replies verification_required
on the relay path too, not only through NickServ.

Cargo.lock

@@ -26,18 +26,6 @@ dependencies = [
  "rustversion",
 ]
 
-[[package]]
-name = "argon2"
-version = "0.5.3"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "3c3610892ee6e0cbce8ae2700349fcf8f98adb0dbfbee85aec3c9179d29cc072"
-dependencies = [
- "base64ct",
- "blake2",
- "cpufeatures",
- "password-hash",
-]
-
 [[package]]
 name = "async-stream"
 version = "0.3.6"
@@ -189,27 +177,12 @@ version = "0.22.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "72b3254f16251a8381aa12e40e3c4d2f0199f8c6508fbecb9d91f575e0fbb8c6"
 
-[[package]]
-name = "base64ct"
-version = "1.8.3"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "2af50177e190e07a26ab74f8b1efbfe2ef87da2116221318cb1c2e82baf7de06"
-
 [[package]]
 name = "bitflags"
 version = "2.13.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "b4388bee8683e3d04af747c73422af53102d2bd24d9eadb6cbc100baef4b43f8"
 
-[[package]]
-name = "blake2"
-version = "0.10.6"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "46502ad458c9a52b69d4d4d32775c788b7a1b85e8bc9d482d92250fc0e3f8efe"
-dependencies = [
- "digest",
-]
-
 [[package]]
 name = "block-buffer"
 version = "0.10.4"
@@ -293,7 +266,6 @@ name = "echo"
 version = "0.0.1"
 dependencies = [
  "anyhow",
- "argon2",
  "axum",
  "axum-server",
  "base64",
@@ -317,6 +289,7 @@ dependencies = [
  "pbkdf2",
  "prost",
  "protoc-bin-vendored",
+ "rand_core",
  "regex",
  "rustls-pemfile",
  "serde",
@@ -859,17 +832,6 @@ version = "1.21.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "9f7c3e4beb33f85d45ae3e3a1792185706c8e16d043238c593331cc7cd313b50"
 
-[[package]]
-name = "password-hash"
-version = "0.5.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "346f04948ba92c43e8469c1ee6736c7563d71012b17d40745260fe106aac2166"
-dependencies = [
- "base64ct",
- "rand_core",
- "subtle",
-]
-
 [[package]]
 name = "pbkdf2"
 version = "0.12.2"

Cargo.toml

@@ -48,7 +48,7 @@ tokio = { version = "1", features = ["net", "io-util", "rt-multi-thread", "macro
 serde = { version = "1", features = ["derive"] }
 serde_json = "1"
 toml = "0.8"
-argon2 = { version = "0.5", features = ["std"] }
+rand_core = { version = "0.6", features = ["getrandom"] }
 base64 = "0.22"
 sha2 = "0.10"
 hmac = "0.12"

src/engine/db/account.rs

@@ -11,7 +11,6 @@ impl Db {
         let verified = !(self.email_enabled && email.is_some());
         let account = Account {
             name: name.to_string(),
-            password_hash: creds.password_hash,
             email,
             ts: now(),
             home: self.log.origin.clone(),
@@ -37,10 +36,10 @@ impl Db {
 
     /// Provision a new account directly from pre-derived SCRAM verifiers (no
     /// plaintext), for bulk backfill from an external authority that stores
-    /// verifiers rather than passwords. `password_hash` is left empty — typed-
-    /// password login stays disabled until a real password is set — but SCRAM and
-    /// keycard login work at once. Refuses if the account already exists (so a
-    /// backfill can't clobber a fully-credentialed account). `scram512` empty =
+    /// verifiers rather than passwords. The verifier is the account's sole
+    /// password credential, so SCRAM, PLAIN, and IDENTIFY all work at once (see
+    /// `authenticate`). Refuses if the account already exists (so a backfill
+    /// can't clobber a fully-credentialed account). `scram512` empty =
     /// SCRAM-SHA-512 unavailable for this account (it falls back to 256).
     pub fn provision_account(&mut self, name: &str, scram256: &str, scram512: &str, email: Option<String>) -> Result<(), RegError> {
         if self.exists(name) {
@@ -51,7 +50,6 @@ impl Db {
         }
         let account = Account {
             name: name.to_string(),
-            password_hash: String::new(),
             email,
             ts: now(),
             home: self.log.origin.clone(),
@@ -84,15 +82,19 @@ impl Db {
     }
 
     #[cfg(test)]
-    pub(crate) fn test_hash(&self, name: &str) -> Option<String> {
-        self.accounts.get(&key(name)).map(|a| a.password_hash.clone())
+    pub(crate) fn test_verifier(&self, name: &str) -> Option<String> {
+        self.accounts.get(&key(name)).and_then(|a| a.scram256.clone())
     }
 
     /// Check credentials; on success return the account's canonical name (its
-    /// stored casing), else None.
+    /// stored casing), else None. The SCRAM-SHA-256 verifier is the sole password
+    /// credential, so PLAIN and IDENTIFY verify the plaintext against it exactly
+    /// as a SCRAM login proves knowledge of it (see `scram::verify_plain`).
     pub fn authenticate(&self, name: &str, password: &str) -> Option<&str> {
         let account = self.accounts.get(&self.resolved_key(name)?)?;
-        verify_password(password, &account.password_hash).then_some(account.name.as_str())
+        let verifier = account.scram256.as_deref()?;
+        crate::engine::scram::verify_plain(crate::engine::scram::Hash::Sha256, verifier, password)
+            .then_some(account.name.as_str())
     }
 
     /// The account's canonical name and its SCRAM verifier for `mech`, if any.
@@ -425,13 +427,11 @@ impl Db {
         self.log
             .append(Event::AccountPasswordSet {
                 account: account.to_string(),
-                password_hash: creds.password_hash.clone(),
                 scram256: creds.scram256.clone(),
                 scram512: creds.scram512.clone(),
             })
             .map_err(|_| RegError::Internal)?;
         let a = self.accounts.get_mut(&k).unwrap();
-        a.password_hash = creds.password_hash;
         a.scram256 = Some(creds.scram256);
         a.scram512 = Some(creds.scram512);
         Ok(())

src/engine/db/event.rs

@@ -15,7 +15,7 @@ pub enum Event {
     CertRemoved { account: String, fp: String },
     AccountEmailSet { account: String, email: Option<String> },
     AccountGreetSet { account: String, greet: String },
-    AccountPasswordSet { account: String, password_hash: String, scram256: String, scram512: String },
+    AccountPasswordSet { account: String, scram256: String, scram512: String },
     AccountDropped { account: String },
     AccountVerified { account: String },
     AjoinAdded { account: String, channel: String, key: String },
@@ -256,9 +256,8 @@ pub(crate) fn apply(accounts: &mut HashMap<String, Account>, channels: &mut Hash
                 a.greet = greet;
             }
         }
-        Event::AccountPasswordSet { account, password_hash, scram256, scram512 } => {
+        Event::AccountPasswordSet { account, scram256, scram512 } => {
             if let Some(a) = accounts.get_mut(&key(&account)) {
-                a.password_hash = password_hash;
                 a.scram256 = Some(scram256);
                 a.scram512 = Some(scram512);
             }

src/engine/db/mod.rs

@@ -18,9 +18,7 @@ pub fn build_badword_set(patterns: &[String]) -> regex::RegexSet {
 }
 use std::time::{Duration, Instant, SystemTime, UNIX_EPOCH};
 
-use argon2::password_hash::rand_core::{OsRng, RngCore};
-use argon2::password_hash::SaltString;
-use argon2::{Argon2, PasswordHash, PasswordHasher, PasswordVerifier};
+use rand_core::{OsRng, RngCore};
 use serde::{Deserialize, Serialize};
 use tokio::sync::broadcast;
 
@@ -48,7 +46,6 @@ pub use echo_api::{
 #[derive(Debug, Clone, Serialize, Deserialize)]
 pub struct Account {
     pub name: String,
-    pub password_hash: String,
     pub email: Option<String>,
     pub ts: u64,
     // The node that first registered this account (its "home"). With `ts` it
@@ -833,10 +830,12 @@ fn valid_fp(fp: &str) -> bool {
 }
 
 // The expensive, password-derived half of an account, computed once at
-// registration. Split out from `register` so the derivation (argon2 + two SCRAM
+// registration. Split out from `register` so the derivation (two SCRAM
 // verifiers, ~1s at the default cost) can run off the reactor via spawn_blocking.
+// The SCRAM verifier is the sole password credential: SCRAM logins use it
+// directly, and PLAIN/IDENTIFY verify the plaintext against it (see
+// `scram::verify_plain`), so there is no separate password hash to keep in step.
 pub struct Credentials {
-    pub(crate) password_hash: String,
     pub(crate) scram256: String,
     pub(crate) scram512: String,
 }
@@ -1155,7 +1154,6 @@ impl Db {
     /// `register_prepared` then commits the result.
     pub fn derive_credentials(password: &str, iterations: u32) -> Option<Credentials> {
         Some(Credentials {
-            password_hash: hash_password(password)?,
             scram256: scram::make_verifier(Hash::Sha256, password, iterations),
             scram512: scram::make_verifier(Hash::Sha512, password, iterations),
         })
@@ -1204,16 +1202,6 @@ fn gen_code() -> String {
     b.iter().map(|x| ALPHABET[(*x % 32) as usize] as char).collect()
 }
 
-fn hash_password(password: &str) -> Option<String> {
-    let salt = SaltString::generate(&mut OsRng);
-    Argon2::default().hash_password(password.as_bytes(), &salt).ok().map(|h| h.to_string())
-}
-
-fn verify_password(password: &str, hash: &str) -> bool {
-    PasswordHash::new(hash)
-        .map(|parsed| Argon2::default().verify_password(password.as_bytes(), &parsed).is_ok())
-        .unwrap_or(false)
-}
 
 // The module-facing account/channel store. Every method forwards to Db's own
 // (fully-qualified so it is the inherent method, never this trait method), with

src/engine/db/tests.rs

@@ -28,15 +28,17 @@
 
     #[test]
     fn account_conflict_resolves_deterministically() {
-        let alice = |hash: &str, ts: u64, home: &str| Account {
-            name: "alice".into(), password_hash: hash.into(), email: None,
+        // `tag` (carried in the email field, a free identity slot here) labels
+        // which of the two competing registrations we're looking at.
+        let alice = |tag: &str, ts: u64, home: &str| Account {
+            name: "alice".into(), email: Some(tag.into()),
             ts, home: home.into(), scram256: None, scram512: None, certfps: vec![], verified: true, ajoin: vec![], suspension: None, memos: vec![], greet: String::new(), vhost: None, vhost_request: None, last_seen: ts, noexpire: false, expiry_warned: false, oper_note: None,
         };
         let converge = |first: &Account, second: &Account| {
             let (mut acc, mut ch, mut gr, mut bo, mut hc, mut nd) = (HashMap::new(), HashMap::new(), HashMap::new(), HashMap::new(), HostConfig::default(), NetData::default());
             apply(&mut acc, &mut ch, &mut gr, &mut bo, &mut hc, &mut nd, Event::AccountRegistered(Box::new(first.clone())));
             apply(&mut acc, &mut ch, &mut gr, &mut bo, &mut hc, &mut nd, Event::AccountRegistered(Box::new(second.clone())));
-            acc["alice"].password_hash.clone()
+            acc["alice"].email.clone().unwrap()
         };
         // Earlier registration wins, regardless of which claim applies first.
         let early = alice("EARLY", 100, "nodeB");
@@ -305,7 +307,7 @@
         db.scram_iterations = 4096;
         db.register("alice", "pw", None).unwrap();
         let bob = Account {
-            name: "bob".into(), password_hash: "x".into(), email: None,
+            name: "bob".into(), email: None,
             ts: 0, home: "peer".into(), scram256: None, scram512: None, certfps: vec![], verified: true, ajoin: vec![], suspension: None, memos: vec![], greet: String::new(), vhost: None, vhost_request: None, last_seen: 0, noexpire: false, expiry_warned: false, oper_note: None,
         };
         let entry = LogEntry { origin: "peer".into(), seq: 0, lamport: 1, event: Event::AccountRegistered(Box::new(bob)) };
@@ -342,6 +344,23 @@
         assert_eq!(db.certfps("bob"), &[kept][..], "kept cert survives");
     }
 
+    // An account provisioned from a SCRAM verifier alone (external authority)
+    // must authenticate over the PLAIN / IDENTIFY path (db.authenticate), not
+    // only over SCRAM — the verifier is the sole credential, so a backfilled
+    // member can still `/msg NickServ IDENTIFY`.
+    #[test]
+    fn provisioned_account_authenticates_over_plain() {
+        let mut db = Db::open(tmp("prov-plain"), "N1");
+        db.scram_iterations = 4096;
+        let creds = Db::derive_credentials("hunter2", 4096).unwrap();
+        db.provision_account("ext", &creds.scram256, "", None).unwrap();
+
+        // The verifier is the only credential on file, and PLAIN/IDENTIFY works.
+        assert!(db.test_verifier("ext").is_some(), "provisioned: verifier is the credential");
+        assert_eq!(db.authenticate("ext", "hunter2"), Some("ext"), "right password logs in");
+        assert!(db.authenticate("ext", "wrong").is_none(), "wrong password rejected");
+    }
+
     // A peer with an empty log converges from a node that has already compacted.
     #[test]
     fn compacted_node_still_converges() {

src/engine/mod.rs

@@ -566,8 +566,8 @@ impl Engine {
     }
 
     #[cfg(test)]
-    pub(crate) fn test_account_hash(&self, name: &str) -> Option<String> {
-        self.db.test_hash(name)
+    pub(crate) fn test_account_verifier(&self, name: &str) -> Option<String> {
+        self.db.test_verifier(name)
     }
 
     #[cfg(test)]
@@ -1133,6 +1133,8 @@ fn sasl_success(agent: &str, client: &str, account: String) -> Vec<NetAction> {
 // Outcome of a registration attempt, rendered to the right wire response below.
 enum RegOutcome {
     Ok,
+    /// Registered, but an emailed code must be confirmed before it's verified.
+    VerifyRequired,
     Exists,
     RateLimited,
     Frozen,
@@ -1147,6 +1149,7 @@ fn reg_reply(reply: &RegReply, outcome: RegOutcome, account: &str) -> Vec<NetAct
         RegReply::Relay { reqid, kind } => {
             let (status, code, message) = match outcome {
                 RegOutcome::Ok => ("success", "*", "Account registered."),
+                RegOutcome::VerifyRequired => ("verification_required", "VERIFICATION_REQUIRED", "Registered — check your email for a code, then VERIFY."),
                 RegOutcome::Exists => ("error", "ACCOUNT_EXISTS", "That account name is already registered."),
                 RegOutcome::RateLimited => ("error", "TEMPORARILY_UNAVAILABLE", "Too many registrations, please wait a moment."),
                 RegOutcome::Frozen => ("error", "TEMPORARILY_UNAVAILABLE", "Registrations are temporarily frozen by network staff."),
@@ -1165,8 +1168,10 @@ fn reg_reply(reply: &RegReply, outcome: RegOutcome, account: &str) -> Vec<NetAct
         RegReply::NickServ { agent, uid, nick } => {
             let notice = |text: String| NetAction::Notice { from: agent.clone(), to: uid.clone(), text };
             match outcome {
-                RegOutcome::Ok => vec![
-                    // Registering identifies you to the nick right away (drives 900).
+                // Registering identifies you to the nick right away (drives 900).
+                // VerifyRequired still logs you in; the emailed-code notice is
+                // appended by complete_register.
+                RegOutcome::Ok | RegOutcome::VerifyRequired => vec![
                     NetAction::Metadata { target: uid.clone(), key: "accountname".to_string(), value: nick.clone() },
                     notice(format!("Your nick \x02{nick}\x02 is now registered and you're logged in. Welcome!")),
                 ],

src/engine/register.rs

@@ -130,14 +130,66 @@ impl Engine {
         }
     }
 
-    // Authority side of the IRCv3 account-registration relay. Hands the work to
-    // the link layer (which derives the password off-thread) via DeferRegister.
+    // Authority side of the IRCv3 account-registration relay (draft/account-
+    // registration). REGISTER hands off to the link layer (which derives the
+    // password off-thread) via DeferRegister; VERIFY/RESEND/STATUS are answered
+    // here directly against the emailed-code flow.
     pub(crate) fn account_request(&mut self, reqid: String, kind: String, account: String, p2: String, p3: String) -> Vec<NetAction> {
-        if !kind.eq_ignore_ascii_case("REGISTER") {
-            return Vec::new(); // VERIFY / RESEND / STATUS: later
+        if kind.eq_ignore_ascii_case("REGISTER") {
+            let email = if p2.is_empty() || p2 == "*" { None } else { Some(p2) };
+            return vec![NetAction::DeferRegister { account, password: p3, email, reply: RegReply::Relay { reqid, kind } }];
+        }
+
+        // Relay-only replies, built directly (REGISTER goes through complete_register).
+        let resp = |status: &str, code: &str, message: &str| {
+            vec![NetAction::AccountResponse {
+                reqid: reqid.clone(),
+                kind: kind.clone(),
+                account: account.clone(),
+                status: status.to_string(),
+                code: code.to_string(),
+                message: message.to_string(),
+            }]
+        };
+        // Identity is the website's in external mode; the relay shouldn't manage it.
+        if self.db.external_accounts() {
+            return resp("error", "ACCOUNT_REGISTRATION_DISABLED", "Accounts are managed on the website.");
+        }
+
+        match kind.to_ascii_uppercase().as_str() {
+            // VERIFY <account> <code> — confirm the emailed code.
+            "VERIFY" => {
+                let code = if !p2.is_empty() { p2 } else { p3 };
+                if self.db.account(&account).is_none() {
+                    resp("error", "ACCOUNT_UNKNOWN", "No such account.")
+                } else if self.db.take_code(&account, db::CodeKind::Confirm, &code) {
+                    let _ = self.db.verify_account(&account);
+                    resp("success", "*", "Account verified.")
+                } else {
+                    resp("error", "INVALID_CODE", "That verification code is wrong or has expired.")
+                }
+            }
+            // RESEND <account> — issue and email a fresh confirmation code.
+            "RESEND" => match self.db.account(&account).map(|a| (a.verified, a.email.clone())) {
+                None => resp("error", "ACCOUNT_UNKNOWN", "No such account."),
+                Some((true, _)) => resp("error", "ALREADY_VERIFIED", "That account is already verified."),
+                Some((false, None)) => resp("error", "NO_EMAIL", "No email address is on file for that account."),
+                Some((false, Some(addr))) => {
+                    let code = self.db.issue_code(&account, db::CodeKind::Confirm);
+                    let mail = echo_api::email::confirm(self.db.email_brand(), self.db.email_accent(), self.db.email_logo(), &account, &code);
+                    let mut out = resp("verification_required", "VERIFICATION_REQUIRED", "A new confirmation code has been emailed.");
+                    out.push(NetAction::SendEmail { to: addr, subject: mail.subject, text: mail.text, html: Some(mail.html) });
+                    out
+                }
+            },
+            // STATUS <account> — report registration/verification state.
+            "STATUS" => match self.db.account(&account).map(|a| a.verified) {
+                None => resp("error", "ACCOUNT_UNKNOWN", "No such account."),
+                Some(true) => resp("success", "VERIFIED", "Account is registered and verified."),
+                Some(false) => resp("verification_required", "VERIFICATION_REQUIRED", "Account is registered but not yet verified."),
+            },
+            _ => Vec::new(),
         }
-        let email = if p2.is_empty() || p2 == "*" { None } else { Some(p2) };
-        vec![NetAction::DeferRegister { account, password: p3, email, reply: RegReply::Relay { reqid, kind } }]
     }
 
     // Cheap gate run before the expensive derivation: reject an already-taken name
@@ -166,20 +218,25 @@ impl Engine {
         };
         let addr = email.clone();
         let outcome = match self.db.register_prepared(account, creds, email) {
-            Ok(()) => RegOutcome::Ok,
+            Ok(()) if self.db.is_verified(account) => RegOutcome::Ok,
+            Ok(()) => RegOutcome::VerifyRequired,
             Err(RegError::Exists) => RegOutcome::Exists,
             Err(RegError::Internal) => RegOutcome::Internal,
         };
-        let ok = matches!(outcome, RegOutcome::Ok);
+        let needs_verify = matches!(outcome, RegOutcome::VerifyRequired);
         let mut out = reg_reply(&reply, outcome, account);
         self.track_accounts(&out);
-        // If this created an unverified account (email confirmation applies), email a code.
-        if ok && !self.db.is_verified(account) {
-            if let (Some(addr), RegReply::NickServ { agent, uid, .. }) = (addr, &reply) {
+        // Unverified (email confirmation applies): email a code, on either the
+        // NickServ or the account-registration relay path. The relay reply
+        // already carries verification_required; NickServ users get a notice.
+        if needs_verify {
+            if let Some(addr) = addr {
                 let code = self.db.issue_code(account, db::CodeKind::Confirm);
                 let mail = echo_api::email::confirm(self.db.email_brand(), self.db.email_accent(), self.db.email_logo(), account, &code);
                 out.push(NetAction::SendEmail { to: addr, subject: mail.subject, text: mail.text, html: Some(mail.html) });
-                out.push(NetAction::Notice { from: agent.clone(), to: uid.clone(), text: "A confirmation code has been emailed to you. Confirm with \x02CONFIRM <code>\x02.".to_string() });
+                if let RegReply::NickServ { agent, uid, .. } = &reply {
+                    out.push(NetAction::Notice { from: agent.clone(), to: uid.clone(), text: "A confirmation code has been emailed to you. Confirm with \x02CONFIRM <code>\x02.".to_string() });
+                }
             }
         }
         out

src/engine/scram.rs

@@ -8,15 +8,17 @@
 //!
 //! Passwords are used as raw UTF-8 (no SASLprep), matching that stack.
 
-use argon2::password_hash::rand_core::{OsRng, RngCore};
+use rand_core::{OsRng, RngCore};
 use base64::{engine::general_purpose::STANDARD, Engine as _};
 use hmac::{Hmac, Mac};
 use sha2::{Digest, Sha256, Sha512};
 use subtle::ConstantTimeEq;
 
-// Provisioning cost. High on purpose: the client bears the Hi() work each login,
-// the server only at REGISTER, and the verifier must not be a weaker
-// password-equivalent than the argon2 hash beside it.
+// Provisioning cost. High on purpose: over SCRAM the client bears the Hi() work
+// each login and the server only at REGISTER; over PLAIN/IDENTIFY the server
+// bears it (see `verify_plain`). This verifier is the sole password credential,
+// so its cost is the account's whole at-rest password strength — exceeds OWASP's
+// PBKDF2-HMAC-SHA256 floor (600k) with headroom.
 pub const DEFAULT_ITERATIONS: u32 = 1_200_000;
 const SALT_LEN: usize = 16;
 
@@ -121,6 +123,23 @@ pub fn make_verifier(hash: Hash, password: &str, iterations: u32) -> String {
     )
 }
 
+/// Verify a plaintext password against a stored verifier, for the PLAIN /
+/// NickServ IDENTIFY path where the server holds the plaintext. Recomputes the
+/// StoredKey the same way a SCRAM client would and compares it constant-time.
+///
+/// The verifier is the account's sole password credential, so this is the whole
+/// PLAIN/IDENTIFY check — SCRAM logins prove knowledge of the same verifier
+/// without the server seeing the plaintext. The cost is one `Hi()` (PBKDF2) at
+/// the verifier's own iteration count.
+pub fn verify_plain(hash: Hash, encoded: &str, password: &str) -> bool {
+    let Some(v) = parse_verifier(encoded) else {
+        return false;
+    };
+    let salted = hi(hash, password.as_bytes(), &v.salt, v.iterations);
+    let stored_key = h(hash, &hmac(hash, &salted, b"Client Key"));
+    stored_key.ct_eq(&v.stored_key).unwrap_u8() == 1
+}
+
 pub fn parse_verifier(encoded: &str) -> Option<Verifier> {
     let (mut iterations, mut salt, mut stored_key, mut server_key) = (None, None, None, None);
     for part in encoded.split(',') {
@@ -297,4 +316,39 @@ mod tests {
     fn channel_binding_rejected() {
         assert!(parse_client_first("p=tls-unique,,n=user,r=abc").is_none());
     }
+
+    // A verifier produced by an *external account authority* — a website that
+    // owns member identity when running with `[auth] external = true` and hands
+    // us a `v=1,i=,s=,sk=,sv=` verifier over the Accounts API, never a password —
+    // must authenticate here byte-for-byte. That interop is the whole reason a
+    // provisioned member can log in over SCRAM against an account we only ever
+    // received a verifier for. This vector was generated by such an authority's
+    // own SCRAM code for the password below; if either side's derivation drifts
+    // (iteration count, salt encoding, key labels), this stops passing.
+    #[test]
+    fn external_authority_verifier_authenticates() {
+        const VERIFIER: &str = "v=1,i=1200000,s=jV9Tm09E7bT1s59EeQaMEw==,\
+            sk=O4Sbg4ZsB0L2HAmTI2NlKu7rOL7tXBBMSIAjLeapOXA=,\
+            sv=ghy7LNgX58CzMLRciK2OkfTu+ODC+iJAgibRMBXSH0c=";
+        const PASSWORD: &str = "correct horse battery staple";
+
+        let v = parse_verifier(VERIFIER).expect("authority verifier parses");
+        assert_eq!(v.iterations, DEFAULT_ITERATIONS, "authority uses the same default cost");
+
+        // Play a real SCRAM-SHA-256 client against it, with a fixed client nonce.
+        let cf = parse_client_first("n,,n=member,r=cnonce123").unwrap();
+        let (server_first, full_nonce) = server_first(&cf.cnonce, &v);
+        let prove = |pw: &str| {
+            let salted = hi(Hash::Sha256, pw.as_bytes(), &v.salt, v.iterations);
+            let client_key = hmac(Hash::Sha256, &salted, b"Client Key");
+            let stored_key = h(Hash::Sha256, &client_key);
+            let without_proof = format!("c=biws,r={full_nonce}");
+            let auth_message = format!("{},{},{}", cf.client_first_bare, server_first, without_proof);
+            let client_sig = hmac(Hash::Sha256, &stored_key, auth_message.as_bytes());
+            let client_final = format!("{without_proof},p={}", STANDARD.encode(xor(&client_key, &client_sig)));
+            verify_final(Hash::Sha256, &v, &cf.client_first_bare, &server_first, &cf.gs2_header, &full_nonce, &client_final)
+        };
+        assert!(prove(PASSWORD).is_some(), "the real password authenticates against the authority's verifier");
+        assert!(prove("wrong").is_none(), "a wrong password is rejected");
+    }
 }

src/engine/tests.rs

@@ -410,7 +410,7 @@
 
         // An earlier claim from another node wins and takes the name over.
         let winner = db::Account {
-            name: "alice".into(), password_hash: "OTHER".into(), email: None,
+            name: "alice".into(), email: None,
             ts: 0, home: "peer".into(), scram256: None, scram512: None, certfps: vec![], verified: true, ajoin: vec![], suspension: None, memos: vec![], greet: String::new(), vhost: None, vhost_request: None, last_seen: 0, noexpire: false, expiry_warned: false, oper_note: None,
         };
         let entry = LogEntry::for_test("peer", 0, 1, db::Event::AccountRegistered(Box::new(winner)));
@@ -599,6 +599,43 @@
         assert!(e.db.is_verified("newbie"), "confirmed after CONFIRM");
     }
 
+    // draft/account-registration over the ircd relay: REGISTER defers, replies
+    // verification_required and emails a code; VERIFY confirms; STATUS reports it.
+    #[test]
+    fn account_registration_relay_verify_flow() {
+        let path = std::env::temp_dir().join("echo-acctreg-relay.jsonl");
+        let _ = std::fs::remove_file(&path);
+        let mut db = Db::open(&path, "test");
+        db.scram_iterations = 4096;
+        db.set_email_enabled(true);
+        let mut e = Engine::new(vec![Box::new(NickServ { uid: "42SAAAAAA".into(), guest_nick: "Guest".into(), guest_seq: 0 })], db);
+
+        // REGISTER <account> <email> :<password> relayed from the ircd.
+        let reg = e.account_request("r1".into(), "REGISTER".into(), "neo".into(), "neo@example.org".into(), "trinity".into());
+        let (account, password, email, reply) = reg.iter().find_map(|a| match a {
+            NetAction::DeferRegister { account, password, email, reply } => Some((account.clone(), password.clone(), email.clone(), reply.clone())),
+            _ => None,
+        }).expect("relay register defers");
+        let out = e.complete_register(&account, Db::derive_credentials(&password, 4096), email, reply);
+        assert!(out.iter().any(|a| matches!(a, NetAction::AccountResponse { status, .. } if status == "verification_required")), "{out:?}");
+        assert!(!e.db.is_verified("neo"), "unverified until the code is confirmed");
+        let body = out.iter().find_map(|a| match a { NetAction::SendEmail { text, .. } => Some(text.clone()), _ => None }).expect("a code is emailed on the relay path too");
+        let code = body.split("CONFIRM ").nth(1).unwrap().split_whitespace().next().unwrap().to_string();
+
+        // VERIFY with the code succeeds; a stale/duplicate VERIFY then fails.
+        let ok = e.account_request("r2".into(), "VERIFY".into(), "neo".into(), code, String::new());
+        assert!(ok.iter().any(|a| matches!(a, NetAction::AccountResponse { status, .. } if status == "success")), "{ok:?}");
+        assert!(e.db.is_verified("neo"), "verified after VERIFY");
+        let again = e.account_request("r3".into(), "VERIFY".into(), "neo".into(), "000000".into(), String::new());
+        assert!(again.iter().any(|a| matches!(a, NetAction::AccountResponse { code, .. } if code == "INVALID_CODE")), "{again:?}");
+
+        // STATUS reports verified; VERIFY on an unknown account is a clean error.
+        let st = e.account_request("r4".into(), "STATUS".into(), "neo".into(), String::new(), String::new());
+        assert!(st.iter().any(|a| matches!(a, NetAction::AccountResponse { code, .. } if code == "VERIFIED")), "{st:?}");
+        let unknown = e.account_request("r5".into(), "VERIFY".into(), "ghost".into(), "x".into(), String::new());
+        assert!(unknown.iter().any(|a| matches!(a, NetAction::AccountResponse { code, .. } if code == "ACCOUNT_UNKNOWN")), "{unknown:?}");
+    }
+
     // GHOST renames off a session using a nick the caller owns.
     #[test]
     fn nickserv_ghost() {

src/gossip.rs

@@ -345,7 +345,7 @@ mod tests {
 
         let mut converged = false;
         for _ in 0..100 {
-            let (ha, hb) = (a.lock().await.test_account_hash("alice"), b.lock().await.test_account_hash("alice"));
+            let (ha, hb) = (a.lock().await.test_account_verifier("alice"), b.lock().await.test_account_verifier("alice"));
             if ha.is_some() && ha == hb {
                 converged = true;
                 break;

src/grpc.rs

@@ -252,7 +252,7 @@ impl Accounts for AccountsService {
         if let Err(status) = self.engine.lock().await.authority_pre_check(&msg.name) {
             return Ok(Response::new(reply(status, "cannot register that name right now")));
         }
-        // Expensive Argon2/SCRAM derivation runs off the shared engine lock, same
+        // Expensive SCRAM verifier derivation runs off the shared engine lock, same
         // as an IRC-originated REGISTER (see link.rs's DeferRegister handling).
         let iterations = self.engine.lock().await.scram_iterations();
         let password = msg.password.clone();
@@ -441,7 +441,6 @@ mod tests {
     fn to_wire_filters_credentials_and_maps_directory_events() {
         let acct = Account {
             name: "alice".into(),
-            password_hash: "secret-hash".into(),
             email: Some("alice@example.com".into()),
             ts: 111,
             home: "A".into(),
@@ -473,7 +472,7 @@ mod tests {
 
         let pw_change = LogEntry::for_test(
             "A", 1, 2,
-            Event::AccountPasswordSet { account: "alice".into(), password_hash: "x".into(), scram256: "x".into(), scram512: "x".into() },
+            Event::AccountPasswordSet { account: "alice".into(), scram256: "x".into(), scram512: "x".into() },
         );
         assert!(to_wire(&pw_change).is_none(), "credential changes must never replicate");