Support blob-encrypted ciphers and match upstream's key id checks

src/api/core/accounts.rs

@@ -628,6 +628,8 @@ async fn post_password(data: Json<ChangePassData>, headers: Headers, conn: DbCon
                 err!("Invalid master password salt")
             }
 
+            validate_key_id_unchanged(&user, &unlock_data)?;
+
             (authentication_data.master_password_authentication_hash, unlock_data.master_key_wrapped_user_key)
         } else if let (Some(new_master_password_hash), Some(new_key)) = (data.new_master_password_hash, data.key) {
             (new_master_password_hash, new_key)
@@ -713,6 +715,21 @@ struct UnlockData {
     salt: String,
     kdf: KDFData,
     master_key_wrapped_user_key: String,
+    contained_key_id: Option<KeyId>,
+}
+
+/// A password or KDF change re-wraps the same user key, so a key id sent with it has to be the
+/// current one. Either may be missing: from a client that predates key ids, or a user whose key id
+/// isn't known yet. There is nothing to compare in those cases.
+///
+/// Ref: <https://github.com/bitwarden/server/blob/main/src/Core/KeyManagement/Models/Data/MasterPasswordUnlockData.cs>
+fn validate_key_id_unchanged(user: &User, unlock_data: &UnlockData) -> EmptyResult {
+    if let (Some(current), Some(contained)) = (&user.key_id, &unlock_data.contained_key_id)
+        && current != contained
+    {
+        err!("Invalid user key sent in master-password unlock data.")
+    }
+    Ok(())
 }
 
 #[derive(Deserialize)]
@@ -739,6 +756,8 @@ async fn post_kdf(data: Json<ChangeKdfData>, headers: Headers, conn: DbConn, nt:
         err!("Invalid master password salt")
     }
 
+    validate_key_id_unchanged(&headers.user, &data.unlock_data)?;
+
     let mut user = headers.user;
 
     set_kdf_data(&mut user, &data.unlock_data.kdf)?;
@@ -1036,8 +1055,9 @@ struct KeyIdData {
 #[post("/accounts/key-management/user-key-id", data = "<data>")]
 async fn post_user_key(data: Json<KeyIdData>, headers: Headers, conn: DbConn) -> EmptyResult {
     let mut user = headers.user;
+    // Only a backfill for accounts that have none. Afterwards the id changes with the key, in a rotation.
     if user.key_id.is_some() {
-        err_code!("Unexpected data", Status::UnprocessableEntity.code);
+        err!("User key id is already set.")
     }
 
     user.key_id = Some(data.into_inner().user_key_id);

src/api/core/ciphers.rs

@@ -23,7 +23,8 @@ use crate::{
         models::{
             Archive, Attachment, AttachmentId, Cipher, CipherId, Collection, CollectionCipher, CollectionGroup,
             CollectionId, CollectionUser, EventType, Favorite, Folder, FolderCipher, FolderId, Group, KeyId,
-            Membership, MembershipType, OrgPolicy, OrgPolicyType, OrganizationId, RepromptType, Send, UserId,
+            Membership, MembershipType, OrgPolicy, OrgPolicyType, OrganizationId, RepromptType, Send, User, UserId,
+            is_data_blob_encrypted,
         },
     },
     util::{NumberOrString, deser_opt_nonempty_str, save_temp_file},
@@ -189,12 +190,19 @@ async fn sync(data: SyncData, headers: Headers, client_version: Option<ClientVer
             // https://github.com/bitwarden/android/blob/release/2025.12-rc41/network/src/main/kotlin/com/bitwarden/network/model/MasterPasswordUnlockDataJson.kt#L22-L26
             "masterKeyEncryptedUserKey": headers.user.akey,
             "masterKeyWrappedUserKey": headers.user.akey,
-            "salt": headers.user.email
+            "salt": headers.user.email,
+            "containedKeyId": headers.user.key_id,
         })
     } else {
         Value::Null
     };
 
+    // Upstream omits this when unset rather than sending null.
+    let mut user_decryption = json!({ "masterPasswordUnlock": master_password_unlock });
+    if let Some(key_id) = &headers.user.key_id {
+        user_decryption["userKeyId"] = json!(key_id);
+    }
+
     Ok(Json(json!({
         "profile": user_json,
         "folders": folders_json,
@@ -204,10 +212,7 @@ async fn sync(data: SyncData, headers: Headers, client_version: Option<ClientVer
         "ciphers": ciphers_json,
         "domains": domains_json,
         "sends": sends_json,
-        "userDecryption": {
+        "userDecryption": user_decryption,
-            "masterPasswordUnlock": master_password_unlock,
-            "userKeyId": headers.user.key_id,
-        },
         "object": "sync"
     })))
 }
@@ -284,7 +289,8 @@ pub struct CipherData {
     Passport = 8
     */
     pub r#type: i32,
-    pub name: String,
+    // Absent on a blob-encrypted cipher, whose name is sealed inside `data`
+    pub name: Option<String>,
     pub notes: Option<String>,
     fields: Option<Value>,
 
@@ -298,6 +304,9 @@ pub struct CipherData {
     drivers_license: Option<Value>,
     passport: Option<Value>,
 
+    // The sealed blob of a v2 account's cipher, which replaces all of the fields above
+    data: Option<String>,
+
     favorite: Option<bool>,
     reprompt: Option<i32>,
 
@@ -319,6 +328,70 @@ pub struct CipherData {
     archived_date: Option<String>,
 }
 
+/// A field of a [`CipherData`] that fails upstream's model validation.
+#[derive(Debug)]
+pub struct CipherValidationError {
+    pub field: &'static str,
+    pub message: String,
+}
+
+impl From<CipherValidationError> for crate::Error {
+    fn from(e: CipherValidationError) -> Self {
+        Self::new_msg(e.message)
+    }
+}
+
+/// A user-owned cipher must be encrypted with the user's current key. Organization ciphers use the
+/// organization key, which has no id yet, and either id may be missing: from a client that predates
+/// the field, or a user whose key id isn't known yet. There is nothing to compare in those cases.
+///
+/// Ref: upstream's `CiphersController.ValidateCipherEncryptedByUser`
+fn validate_encrypted_by_user_key(data: &CipherData, user: &User, is_org_cipher: bool) -> EmptyResult {
+    if !is_org_cipher
+        && let (Some(cipher_key_id), Some(user_key_id)) = (&data.encrypted_by_key_id, &user.key_id)
+        && cipher_key_id != user_key_id
+    {
+        err!("Cipher was not encrypted with the current user key. Please try again.")
+    }
+    Ok(())
+}
+
+/// Upstream's `[StringLength(500000)]` on `CipherRequestModel.Data`
+const MAX_CIPHER_DATA_LENGTH: usize = 500_000;
+
+impl CipherData {
+    /// Whether the content is a single blob rather than the per-type fields. This parses `data`, so
+    /// callers that need the answer more than once should keep it.
+    pub fn is_blob(&self) -> bool {
+        self.data.as_deref().is_some_and(is_data_blob_encrypted)
+    }
+
+    /// Checks the content the way upstream's model validation does, before anything is saved.
+    /// `is_blob` is [`Self::is_blob`].
+    ///
+    /// Ref: <https://github.com/bitwarden/server/blob/main/src/Api/Vault/Models/Request/CipherRequestModel.cs>
+    pub fn validate_content(&self, is_blob: bool) -> Result<(), CipherValidationError> {
+        if let Some(data) = &self.data
+            && data.len() > MAX_CIPHER_DATA_LENGTH
+        {
+            return Err(CipherValidationError {
+                field: "Data",
+                message: format!("The field Data must be a string with a maximum length of {MAX_CIPHER_DATA_LENGTH}."),
+            });
+        }
+
+        // A blob carries the name inside it, so only the other formats need one
+        if !is_blob && self.name.as_deref().is_none_or(|n| n.trim().is_empty()) {
+            return Err(CipherValidationError {
+                field: "Name",
+                message: String::from("The Name field is required."),
+            });
+        }
+
+        Ok(())
+    }
+}
+
 #[derive(Debug, Deserialize)]
 #[serde(rename_all = "camelCase")]
 pub struct PartialCipherData {
@@ -355,13 +428,14 @@ async fn post_ciphers_create(
     if data.cipher.encrypted_for != headers.user.uuid {
         err_code!("Invalid user cipher", Status::UnprocessableEntity.code);
     }
+    validate_encrypted_by_user_key(&data.cipher, &headers.user, data.cipher.organization_id.is_some())?;
 
     // This check is usually only needed in update_cipher_from_data(), but we
     // need it here as well to avoid creating an empty cipher in the call to
     // cipher.save() below.
     enforce_personal_ownership_policy(Some(&data.cipher), &headers, &conn).await?;
 
-    let mut cipher = Cipher::new(data.cipher.r#type, data.cipher.name.clone());
+    let mut cipher = Cipher::new(data.cipher.r#type, String::new());
     cipher.user_uuid = Some(headers.user.uuid.clone());
     cipher.save(&conn).await?;
 
@@ -389,12 +463,7 @@ async fn post_ciphers(data: Json<CipherData>, headers: Headers, conn: DbConn, nt
         err_code!("Invalid user cipher", Status::UnprocessableEntity.code);
     }
 
-    if let Some(cipher_key_id) = &data.encrypted_by_key_id
+    validate_encrypted_by_user_key(&data, &headers.user, data.organization_id.is_some())?;
-        && let Some(user_key_id) = &headers.user.key_id
-        && cipher_key_id != user_key_id
-    {
-        err_code!("Invalid key cipher", Status::UnprocessableEntity.code);
-    }
 
     // The web/browser clients set this field to null as expected, but the
     // mobile clients seem to set the invalid value `0001-01-01T00:00:00`,
@@ -402,7 +471,7 @@ async fn post_ciphers(data: Json<CipherData>, headers: Headers, conn: DbConn, nt
     // needed when creating a new cipher, so just ignore it unconditionally.
     data.last_known_revision_date = None;
 
-    let mut cipher = Cipher::new(data.r#type, data.name.clone());
+    let mut cipher = Cipher::new(data.r#type, String::new());
     update_cipher_from_data(&mut cipher, data, &headers, None, &conn, &nt, UpdateType::SyncCipherCreate).await?;
 
     Ok(Json(cipher.to_json(&headers.host, &headers.user.uuid, None, CipherSyncType::User, &conn).await?))
@@ -451,6 +520,9 @@ pub async fn update_cipher_from_data(
 
     enforce_personal_ownership_policy(Some(&data), headers, conn).await?;
 
+    let is_blob = data.is_blob();
+    data.validate_content(is_blob)?;
+
     // Check that the client isn't updating an existing cipher with stale data.
     // And only perform this check when not importing ciphers, else the date/time check will fail.
     if ut != UpdateType::None
@@ -550,24 +622,35 @@ pub async fn update_cipher_from_data(
         _ => err!("Invalid type"),
     };
 
-    let type_data = if let Some(mut data) = type_data_opt {
+    if let Some(blob) = data.data.filter(|_| is_blob) {
-        // Remove the 'Response' key from the base object.
+        // A blob holds all of the content, the name included, so nothing is kept outside it. The name
-        data.as_object_mut().unwrap().remove("response");
+        // column can't be null, so it's left empty; `to_json` reports it as null, as upstream does.
-        // Remove the 'Response' key from every Uri.
+        // TODO: Make `ciphers.name` nullable and store `None` here instead.
-        if data["uris"].is_array() {
+        cipher.name = String::new();
-            data["uris"] = clean_cipher_data(data["uris"].clone());
+        cipher.notes = None;
-        }
+        cipher.fields = None;
-        data
+        cipher.password_history = None;
+        cipher.data = blob;
     } else {
+        let Some(mut type_data) = type_data_opt else {
             err!("Data missing")
         };
+        // Remove the 'Response' key from the base object.
+        type_data.as_object_mut().unwrap().remove("response");
+        // Remove the 'Response' key from every Uri.
+        if type_data["uris"].is_array() {
+            type_data["uris"] = clean_cipher_data(type_data["uris"].clone());
+        }
 
-    cipher.key = data.key;
+        // `validate_content` made sure there is a name
-    cipher.name = data.name;
+        cipher.name = data.name.unwrap_or_default();
         cipher.notes = data.notes;
         cipher.fields = data.fields.map(|f| clean_cipher_data(f).to_string());
-    cipher.data = type_data.to_string();
         cipher.password_history = data.password_history.map(|f| f.to_string());
+        cipher.data = type_data.to_string();
+    }
+
+    cipher.key = data.key;
     cipher.reprompt = data.reprompt.filter(|r| *r == RepromptType::None as i32 || *r == RepromptType::Password as i32);
 
     cipher.save(conn).await?;
@@ -664,7 +747,7 @@ async fn post_ciphers_import(data: Json<ImportData>, headers: Headers, conn: DbC
         let folder_id = relations_map.get(&index).and_then(|i| folders.get(*i).cloned());
         cipher_data.folder_id = folder_id;
 
-        let mut cipher = Cipher::new(cipher_data.r#type, cipher_data.name.clone());
+        let mut cipher = Cipher::new(cipher_data.r#type, String::new());
         update_cipher_from_data(&mut cipher, cipher_data, &headers, None, &conn, &nt, UpdateType::None).await?;
     }
 
@@ -732,6 +815,8 @@ async fn put_cipher(
         err!("Cipher is not write accessible")
     }
 
+    validate_encrypted_by_user_key(&data, &headers.user, cipher.organization_uuid.is_some())?;
+
     update_cipher_from_data(&mut cipher, data, &headers, None, &conn, &nt, UpdateType::SyncCipherUpdate).await?;
 
     Ok(Json(cipher.to_json(&headers.host, &headers.user.uuid, None, CipherSyncType::User, &conn).await?))

src/api/core/organizations.rs

@@ -1891,7 +1891,7 @@ async fn post_org_import(
         cipher_data.folder_id = None;
         // Replace the client-provided, unvalidated organizationId with the real target org
         cipher_data.organization_id = Some(org_id.clone());
-        let mut cipher = Cipher::new(cipher_data.r#type, cipher_data.name.clone());
+        let mut cipher = Cipher::new(cipher_data.r#type, String::new());
         update_cipher_from_data(
             &mut cipher,
             cipher_data,

src/db/models/cipher.rs

@@ -63,6 +63,22 @@ pub struct Cipher {
     pub reprompt: Option<i32>,
 }
 
+/// Whether `data` is a sealed cipher blob rather than the legacy per-type JSON.
+///
+/// Ciphers of v2 accounts are encrypted as a single blob that carries everything, name included,
+/// and is opaque to us. It is recognized the same way upstream does, by a top-level
+/// `format_version` key that the legacy JSON never has.
+///
+/// Ref: <https://github.com/bitwarden/server/blob/main/src/Core/Vault/Entities/Cipher.cs>
+pub fn is_data_blob_encrypted(data: &str) -> bool {
+    serde_json::from_str::<Value>(data).is_ok_and(|d| is_blob_value(&d))
+}
+
+/// [`is_data_blob_encrypted`] for `data` that was already parsed.
+fn is_blob_value(data: &Value) -> bool {
+    data.get("format_version").is_some()
+}
+
 pub enum RepromptType {
     None = 0,
     Password = 1,
@@ -110,6 +126,11 @@ impl Cipher {
                     .insert(format!("Ciphers[{index}].Notes"), serde_json::to_value([&max_note_size_msg]).unwrap());
             }
 
+            if let Err(e) = cipher.validate_content(cipher.is_blob()) {
+                validation_errors
+                    .insert(format!("Ciphers[{index}].{}", e.field), serde_json::to_value([e.message]).unwrap());
+            }
+
             // Validate the password history if it contains `null` values and if so, return a warning
             if let Some(Value::Array(password_history)) = &cipher.password_history {
                 for pwh in password_history {
@@ -154,6 +175,11 @@ impl Cipher {
     ) -> Result<Value, crate::Error> {
         use crate::util::{format_date, validate_and_format_date};
 
+        // Parsed once here, since `data` can be large and this runs for every cipher in a sync.
+        // `LowerCase` only lowercases the first letter of each key, so it keeps `format_version`.
+        let type_data = serde_json::from_str::<LowerCase<Value>>(&self.data).map(|d| d.data);
+        let is_blob_encrypted = type_data.as_ref().is_ok_and(is_blob_value);
+
         let mut attachments_json: Value = Value::Null;
         if let Some(cipher_sync_data) = cipher_sync_data {
             if let Some(attachments) = cipher_sync_data.cipher_attachments.get(&self.uuid)
@@ -189,14 +215,12 @@ impl Cipher {
             (false, false, false)
         };
 
-        let fields_json: Vec<_> = self
+        // Like upstream, a cipher that was stored without fields or password history reports them as
-            .fields
+        // null rather than as an empty list; clients keep the two apart.
-            .as_ref()
+        let fields_json: Option<Vec<_>> = self.fields.as_ref().map(|s| {
-            .and_then(|s| {
             serde_json::from_str::<Vec<LowerCase<Value>>>(s)
                 .inspect_err(|e| warn!("Error parsing fields {e:?} for {}", self.uuid))
                 .ok()
-            })
                 .map(|d| {
                     d.into_iter()
                         .map(|mut f| {
@@ -218,16 +242,13 @@ impl Cipher {
                         })
                         .collect()
                 })
-            .unwrap_or_default();
+                .unwrap_or_default()
+        });
 
-        let password_history_json: Vec<_> = self
+        let password_history_json: Option<Vec<_>> = self.password_history.as_ref().map(|s| {
-            .password_history
-            .as_ref()
-            .and_then(|s| {
             serde_json::from_str::<Vec<LowerCase<Value>>>(s)
                 .inspect_err(|e| warn!("Error parsing password history {e:?} for {}", self.uuid))
                 .ok()
-            })
                 .map(|d| {
                     // Check every password history item if they are valid and return it.
                     // If a password field has the type `null` skip it, it breaks newer Bitwarden clients
@@ -248,65 +269,8 @@ impl Cipher {
                         })
                         .collect()
                 })
-            .unwrap_or_default();
+                .unwrap_or_default()
-
+        });
-        // Get the type_data or a default to an empty json object '{}'.
-        // If not passing an empty object, mobile clients will crash.
-        let mut type_data_json = serde_json::from_str::<LowerCase<Value>>(&self.data)
-            .inspect_err(|_| warn!("Error parsing data field for {}", self.uuid))
-            .map_or_else(|_| Value::Object(serde_json::Map::new()), |d| d.data);
-
-        // NOTE: This was marked as *Backwards Compatibility Code*, but as of January 2021 this is still being used by upstream
-        // Set the first element of the Uris array as Uri, this is needed several (mobile) clients.
-        if self.atype == 1 {
-            // Upstream always has an `uri` key/value
-            type_data_json["uri"] = Value::Null;
-            if let Some(uris) = type_data_json["uris"].as_array_mut()
-                && !uris.is_empty()
-            {
-                // Fix uri match values first, they are only allowed to be a number or null
-                // If it is a string, convert it to an int or null if that fails
-                for uri in &mut *uris {
-                    if uri["match"].is_string() {
-                        let match_value = match uri["match"].as_str().unwrap_or_default().parse::<u8>() {
-                            Ok(n) => json!(n),
-                            _ => Value::Null,
-                        };
-                        uri["match"] = match_value;
-                    }
-                }
-                type_data_json["uri"] = uris[0]["uri"].clone();
-            }
-
-            // Check if `passwordRevisionDate` is a valid date, else convert it
-            if let Some(pw_revision) = type_data_json["passwordRevisionDate"].as_str() {
-                type_data_json["passwordRevisionDate"] = json!(validate_and_format_date(pw_revision));
-            }
-        }
-
-        // Fix secure note issues when data is invalid
-        // This breaks at least the native mobile clients
-        if self.atype == 2 {
-            match type_data_json {
-                Value::Object(ref t) if t.get("type").is_some_and(Value::is_number) => {}
-                _ => {
-                    type_data_json = json!({"type": 0});
-                }
-            }
-        }
-
-        // Fix invalid SSH Entries
-        // This breaks at least the native mobile client if invalid
-        // The only way to fix this is by setting type_data_json to `null`
-        // Opening this ssh-key in the mobile client will probably crash the client, but you can edit, save and afterwards delete it
-        if self.atype == 5
-            && (type_data_json["keyFingerprint"].as_str().is_none_or(str::is_empty)
-                || type_data_json["privateKey"].as_str().is_none_or(str::is_empty)
-                || type_data_json["publicKey"].as_str().is_none_or(str::is_empty))
-        {
-            warn!("Error parsing ssh-key, mandatory fields are invalid for {}", self.uuid);
-            type_data_json = Value::Null;
-        }
 
         let collection_ids = if let Some(cipher_sync_data) = cipher_sync_data {
             if let Some(cipher_collections) = cipher_sync_data.cipher_collections.get(&self.uuid) {
@@ -403,10 +367,83 @@ impl Cipher {
             _ => err!(format!("Cipher {} has an invalid type {}", self.uuid, self.atype)),
         };
 
-        json_object[key] = type_data_json;
+        if is_blob_encrypted {
+            // The blob holds all of the content, so it is sent back as-is and the structured fields
+            // stay null, as upstream does. Only the name needs clearing, the others are never stored.
+            json_object["data"] = json!(self.data);
+            json_object["name"] = Value::Null;
+        } else {
+            json_object[key] = self.legacy_type_data_json(type_data);
+        }
         Ok(json_object)
     }
 
+    /// The per-type data (`login`, `card`, …) of a legacy cipher, from `type_data` as parsed from
+    /// `self.data`, with fixups for values that are known to break clients.
+    fn legacy_type_data_json(&self, type_data: Result<Value, serde_json::Error>) -> Value {
+        use crate::util::validate_and_format_date;
+
+        // Get the type_data or a default to an empty json object '{}'.
+        // If not passing an empty object, mobile clients will crash.
+        let mut type_data_json = type_data
+            .inspect_err(|_| warn!("Error parsing data field for {}", self.uuid))
+            .unwrap_or_else(|_| Value::Object(serde_json::Map::new()));
+
+        // NOTE: This was marked as *Backwards Compatibility Code*, but as of January 2021 this is still being used by upstream
+        // Set the first element of the Uris array as Uri, this is needed several (mobile) clients.
+        if self.atype == 1 {
+            // Upstream always has an `uri` key/value
+            type_data_json["uri"] = Value::Null;
+            if let Some(uris) = type_data_json["uris"].as_array_mut()
+                && !uris.is_empty()
+            {
+                // Fix uri match values first, they are only allowed to be a number or null
+                // If it is a string, convert it to an int or null if that fails
+                for uri in &mut *uris {
+                    if uri["match"].is_string() {
+                        let match_value = match uri["match"].as_str().unwrap_or_default().parse::<u8>() {
+                            Ok(n) => json!(n),
+                            _ => Value::Null,
+                        };
+                        uri["match"] = match_value;
+                    }
+                }
+                type_data_json["uri"] = uris[0]["uri"].clone();
+            }
+
+            // Check if `passwordRevisionDate` is a valid date, else convert it
+            if let Some(pw_revision) = type_data_json["passwordRevisionDate"].as_str() {
+                type_data_json["passwordRevisionDate"] = json!(validate_and_format_date(pw_revision));
+            }
+        }
+
+        // Fix secure note issues when data is invalid
+        // This breaks at least the native mobile clients
+        if self.atype == 2 {
+            match type_data_json {
+                Value::Object(ref t) if t.get("type").is_some_and(Value::is_number) => {}
+                _ => {
+                    type_data_json = json!({"type": 0});
+                }
+            }
+        }
+
+        // Fix invalid SSH Entries
+        // This breaks at least the native mobile client if invalid
+        // The only way to fix this is by setting type_data_json to `null`
+        // Opening this ssh-key in the mobile client will probably crash the client, but you can edit, save and afterwards delete it
+        if self.atype == 5
+            && (type_data_json["keyFingerprint"].as_str().is_none_or(str::is_empty)
+                || type_data_json["privateKey"].as_str().is_none_or(str::is_empty)
+                || type_data_json["publicKey"].as_str().is_none_or(str::is_empty))
+        {
+            warn!("Error parsing ssh-key, mandatory fields are invalid for {}", self.uuid);
+            type_data_json = Value::Null;
+        }
+
+        type_data_json
+    }
+
     pub async fn update_users_revision(&self, conn: &DbConn) -> Vec<UserId> {
         let mut user_uuids = Vec::new();
         match self.user_uuid {

src/db/models/mod.rs

@@ -21,7 +21,7 @@ mod user;
 pub use self::archive::Archive;
 pub use self::attachment::{Attachment, AttachmentId};
 pub use self::auth_request::{AuthRequest, AuthRequestId};
-pub use self::cipher::{Cipher, CipherId, RepromptType};
+pub use self::cipher::{Cipher, CipherId, RepromptType, is_data_blob_encrypted};
 pub use self::collection::{Collection, CollectionCipher, CollectionId, CollectionUser};
 pub use self::device::{Device, DeviceId, DeviceType, DeviceWithAuthRequest, PushId};
 pub use self::emergency_access::{EmergencyAccess, EmergencyAccessId, EmergencyAccessStatus, EmergencyAccessType};

src/db/models/user.rs

@@ -555,7 +555,18 @@ pub struct UserId(String);
 )]
 #[deref(forward)]
 #[from(forward)]
-pub struct KeyId(String);
+pub struct KeyId(#[serde(deserialize_with = "deserialize_key_id")] String);
+
+/// Rejects a key id from a request that isn't 16 bytes as lowercase hex, as upstream's `[KeyId]` does.
+///
+/// Ref: <https://github.com/bitwarden/server/blob/main/src/Core/KeyManagement/Models/Data/KeyId.cs>
+fn deserialize_key_id<'de, D: serde::Deserializer<'de>>(deserializer: D) -> Result<String, D::Error> {
+    let key_id = <String as serde::Deserialize>::deserialize(deserializer)?;
+    if key_id.len() != 32 || !key_id.bytes().all(|b| matches!(b, b'0'..=b'9' | b'a'..=b'f')) {
+        return Err(serde::de::Error::custom("Key id must be a 32 character lowercase hex-encoded string."));
+    }
+    Ok(key_id)
+}
 
 impl SsoUser {
     pub async fn save(&self, conn: &DbConn) -> EmptyResult {