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Update key management for database service

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Oleksii Zghurskyi
2025-08-19 16:24:51 +03:00
parent 1df21e88bd
commit 0118981e0a
8 changed files with 235 additions and 284 deletions
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Sources/DataRaft/Protocols/DatabaseServiceKeyProvider.swift
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@@ -1,124 +1,53 @@
import Foundation
import DataLiteCore
/// A protocol for supplying encryption keys to `DatabaseService` instances.
/// A protocol for providing encryption keys to a database service.
///
/// `DatabaseServiceKeyProvider` encapsulates all responsibilities for managing encryption keys
/// for one or more `DatabaseService` instances. It allows a database service to delegate key
/// retrieval, secure storage, rotation, and access control, enabling advanced security strategies
/// such as per-user key derivation, hardware-backed keys, biometric authentication, or ephemeral
/// in-memory secrets.
/// `DatabaseServiceKeyProvider` is responsible for managing encryption keys used
/// by a database service. This makes it possible to implement different strategies for storing
/// and retrieving keys: static, dynamic, hardware-backed, biometric, and others.
///
/// The provider is queried automatically by the database service whenever a new connection
/// is created or re-established (for example, during service initialization, after a reconnect,
/// or when the service requests a key rotation).
/// - The service requests a key when establishing or restoring a connection.
/// - If decryption fails, the service may ask the provider whether it should attempt to reconnect.
/// - If applying a key fails (for example, the key does not match or the
/// ``databaseService(keyFor:)`` method throws an error), this error is reported
/// to the provider through ``databaseService(_:didReceive:)``.
///
/// Error handling and diagnostics related specifically to encryption or key operations
/// (such as when a key is unavailable, authentication is denied, or decryption fails)
/// are reported to the provider via the optional ``databaseService(_:didReceive:)`` callback.
/// The provider is **not** notified of generic database or connection errors unrelated to
/// encryption.
/// - Important: The provider does not receive notifications about general database errors.
///
/// - Important: This protocol is **exclusively** for cryptographic key management.
/// It must not be used for generic database error handling or for concerns unrelated to
/// encryption, authorization, or key lifecycle.
/// ## Topics
///
/// ## Key Availability
/// ### Instance Methods
///
/// There are two distinct scenarios for returning a key:
///
/// - **No Encryption Needed:**
/// Return `nil` if the target database does not require encryption (i.e., should be opened
/// in plaintext mode). This is not an error; the database service will attempt to open the
/// database without a key. If the database is in fact encrypted, this will result in a
/// decryption error at the SQLite level (e.g., `SQLITE_NOTADB`), which is handled by the
/// database service as a normal failure.
///
/// - **Key Temporarily Unavailable:**
/// Also return `nil` if the key is *temporarily* unavailable for any reason (for example,
/// the user has not yet authenticated, the device is locked, a remote key is still loading,
/// or UI authorization has not been granted).
/// Returning `nil` in this case means the database service will not attempt to open
/// the database with a key. This will not trigger an error callback.
/// When the key later becomes available (for example, after user authentication or
/// successful network retrieval), **the provider is responsible for calling**
/// ``DatabaseService/reconnect()`` on the service to re-attempt the operation with the key.
///
/// - **Error Situations:**
/// Only throw an error if a *permanent* or *unexpected* failure occurs (for example,
/// a hardware security error, a fatal storage problem, or a cryptographic failure
/// that cannot be resolved by waiting or user action).
/// Thrown errors will be reported to the provider via the error callback, and may be
/// surfaced to the UI or logs.
///
/// - Tip: Never throw for temporary unavailability (such as "user has not unlocked" or
/// "still waiting for user action")—just return `nil` in these cases.
/// Use thrown errors only for non-recoverable or unexpected failures.
///
/// ## Error Callback
///
/// The method ``databaseService(_:didReceive:)`` will be called only for errors thrown by
/// ``databaseServiceKey(_:)`` or by the key application process (such as if the key fails
/// to decrypt the database).
/// It will *not* be called for generic database or connection errors.
///
/// Implement this method if you wish to log, recover from, or respond to permanent key-related
/// failures (such as prompting the user, resetting state, or displaying errors).
public protocol DatabaseServiceKeyProvider: AnyObject {
/// Returns the encryption key to be applied to the given database service.
/// - ``databaseService(keyFor:)``
/// - ``databaseService(shouldReconnect:)``
/// - ``databaseService(_:didReceive:)``
public protocol DatabaseServiceKeyProvider: AnyObject, Sendable {
/// Returns the encryption key for the specified database service.
///
/// This method is invoked by the `DatabaseService` during connection initialization,
/// reconnection, or explicit key rotation. Implementations may return a static key,
/// derive it from external data, fetch it from secure hardware, or perform required
/// user authentication.
/// May return `nil` if the encryption key is currently unavailable or if the database
/// does not require encryption.
///
/// - Parameter service: The requesting database service.
/// - Returns: A `Connection.Key` representing the encryption key, or `nil` if encryption is
/// not required for this database or the key is temporarily unavailable. Returning `nil`
/// will cause the database service to attempt opening the database in plaintext mode.
/// If the database is actually encrypted, access will fail with a decryption error.
/// - Throws: Only throw for unrecoverable or unexpected errors (such as hardware failure,
/// fatal storage issues, or irrecoverable cryptographic errors). Do **not** throw for
/// temporary unavailability; instead, return `nil` and call ``DatabaseService/reconnect()``
/// later when the key becomes available.
///
/// - Note: This method may be called multiple times during the lifecycle of a service,
/// including after a failed decryption attempt or key rotation event.
func databaseServiceKey(_ service: DatabaseService) throws -> Connection.Key?
/// - Parameter service: The service requesting the key.
/// - Returns: The encryption key or `nil`.
/// - Throws: An error if the key cannot be retrieved.
func databaseService(keyFor service: DatabaseServiceProtocol) throws -> Connection.Key?
/// Notifies the provider that the database service encountered an error
/// related to key retrieval or application.
/// Indicates whether the service should attempt to reconnect if applying the key fails.
///
/// This method is called **only** when the service fails to retrieve or apply an
/// encryption key (e.g., if ``databaseServiceKey(_:)`` throws, or if the key fails
/// to decrypt the database due to a password/key mismatch).
///
/// Use this callback to report diagnostics, trigger recovery logic, prompt the user
/// for authentication, or update internal state.
/// By default, this method does nothing; implement it only if you need to respond
/// to key-related failures.
/// - Parameter service: The database service.
/// - Returns: `true` to attempt reconnection. Defaults to `false`.
func databaseService(shouldReconnect service: DatabaseServiceProtocol) -> Bool
/// Notifies the provider of an error that occurred while retrieving or applying the key.
///
/// - Parameters:
/// - service: The database service reporting the error.
/// - error: The error encountered during key retrieval or application.
func databaseService(_ service: DatabaseService, didReceive error: Error)
/// Informs the service whether it should attempt to reconnect automatically.
///
/// Return `true` if the service should retry connecting (for example, if the key may
/// become available shortly). By default, returns `false`.
///
/// - Parameter service: The database service.
/// - Returns: `true` to retry, `false` to abort.
func databaseServiceShouldReconnect(_ service: DatabaseService) -> Bool
func databaseService(_ service: DatabaseServiceProtocol, didReceive error: Error)
}
public extension DatabaseServiceKeyProvider {
/// Default no-op implementation for key-related error reporting.
func databaseService(_ service: DatabaseService, didReceive error: Error) {}
/// Default implementation disables automatic reconnect attempts.
func databaseServiceShouldReconnect(_ service: DatabaseService) -> Bool {
false
}
func databaseService(shouldReconnect service: DatabaseServiceProtocol) -> Bool { false }
func databaseService(_ service: DatabaseServiceProtocol, didReceive error: Error) {}
}