Implement ReKey on async db

src/SQLite.cs

@@ -244,6 +244,8 @@ CreateTablesResult CreateTables<T, T2, T3, T4, T5> (CreateFlags createFlags = Cr
 		List<T> Query<T> (string query, params object[] args) where T : new();
 		List<object> Query (TableMapping map, string query, params object[] args);
 		List<T> QueryScalars<T> (string query, params object[] args);
+		void ReKey (string key);
+		void ReKey (byte[] key);
 		void Release (string savepoint);
 		void Rollback ();
 		void RollbackTo (string savepoint);
@@ -259,8 +261,7 @@ CreateTablesResult CreateTables<T, T2, T3, T4, T5> (CreateFlags createFlags = Cr
 	/// An open connection to a SQLite database.
 	/// </summary>
 	[Preserve (AllMembers = true)]
-	public partial class SQLiteConnection : IDisposable
-		, ISQLiteConnection
+	public partial class SQLiteConnection : ISQLiteConnection
 	{
 		private bool _open;
 		private TimeSpan _busyTimeout;

src/SQLiteAsync.cs

@@ -110,6 +110,8 @@ Task<CreateTablesResult> CreateTablesAsync<T, T2, T3, T4, T5> (CreateFlags creat
 		Task<List<T>> QueryAsync<T> (string query, params object[] args) where T : new();
 		Task<List<object>> QueryAsync (TableMapping map, string query, params object[] args);
 		Task<List<T>> QueryScalarsAsync<T> (string query, params object[] args);
+		Task ReKeyAsync (string key);
+		Task ReKeyAsync (byte[] key);
 		Task RunInTransactionAsync (Action<SQLiteConnection> action);
 		Task SetBusyTimeoutAsync (TimeSpan value);
 		AsyncTableQuery<T> Table<T> () where T : new();
@@ -121,8 +123,7 @@ Task<CreateTablesResult> CreateTablesAsync<T, T2, T3, T4, T5> (CreateFlags creat
 	/// <summary>
 	/// A pooled asynchronous connection to a SQLite database.
 	/// </summary>
-	public partial class SQLiteAsyncConnection
-		: ISQLiteAsyncConnection
+	public partial class SQLiteAsyncConnection : ISQLiteAsyncConnection
 	{
 		readonly SQLiteConnectionString _connectionString;
 
@@ -1265,6 +1266,30 @@ public Task<IEnumerable<object>> DeferredQueryAsync (TableMapping map, string qu
 		{
 			return ReadAsync (conn => (IEnumerable<object>)conn.DeferredQuery (map, query, args).ToList ());
 		}
+
+		/// <summary>
+		/// Change the encryption key for a SQLCipher database with "pragma rekey = ...".
+		/// </summary>
+		/// <param name="key">Encryption key plain text that is converted to the real encryption key using PBKDF2 key derivation</param>
+		public Task ReKeyAsync (string key)
+		{
+			return WriteAsync<object> (conn => {
+				conn.ReKey (key);
+				return null;
+			});
+		}
+
+		/// <summary>
+		/// Change the encryption key for a SQLCipher database.
+		/// </summary>
+		/// <param name="key">256-bit (32 byte) or 384-bit (48 bytes) encryption key data</param>
+		public Task ReKeyAsync (byte[] key)
+		{
+			return WriteAsync<object> (conn => {
+				conn.ReKey (key);
+				return null;
+			});			
+		}
 	}
 
 	/// <summary>