|
|
@@ -0,0 +1,66 @@
|
|
|
+// CryptoSwift
|
|
|
+//
|
|
|
+// Copyright (C) 2014-2018 Marcin Krzyżanowski <marcin@krzyzanowskim.com>
|
|
|
+// This software is provided 'as-is', without any express or implied warranty.
|
|
|
+//
|
|
|
+// In no event will the authors be held liable for any damages arising from the use of this software.
|
|
|
+//
|
|
|
+// Permission is granted to anyone to use this software for any purpose,including commercial applications, and to alter it and redistribute it freely, subject to the following restrictions:
|
|
|
+//
|
|
|
+// - The origin of this software must not be misrepresented; you must not claim that you wrote the original software. If you use this software in a product, an acknowledgment in the product documentation is required.
|
|
|
+// - Altered source versions must be plainly marked as such, and must not be misrepresented as being the original software.
|
|
|
+// - This notice may not be removed or altered from any source or binary distribution.
|
|
|
+//
|
|
|
+
|
|
|
+final class StreamDecryptor: Cryptor, Updatable {
|
|
|
+ private let blockSize: Int
|
|
|
+ private var worker: CipherModeWorker
|
|
|
+ private let padding: Padding
|
|
|
+ // Accumulated bytes. Not all processed bytes.
|
|
|
+ private var accumulated = Array<UInt8>(reserveCapacity: 16)
|
|
|
+
|
|
|
+ private var lastBlockRemainder = 0
|
|
|
+
|
|
|
+ init(blockSize: Int, padding: Padding, _ worker: CipherModeWorker) throws {
|
|
|
+ self.blockSize = blockSize
|
|
|
+ self.padding = padding
|
|
|
+ self.worker = worker
|
|
|
+ }
|
|
|
+
|
|
|
+ // MARK: Updatable
|
|
|
+ public func update(withBytes bytes: ArraySlice<UInt8>, isLast: Bool) throws -> Array<UInt8> {
|
|
|
+ accumulated = Array(bytes)
|
|
|
+
|
|
|
+ var plaintext = Array<UInt8>(reserveCapacity: bytes.count)
|
|
|
+ for chunk in accumulated.batched(by: blockSize) {
|
|
|
+ plaintext += worker.decrypt(block: chunk)
|
|
|
+ }
|
|
|
+
|
|
|
+ // omit unecessary calculation if not needed
|
|
|
+ if padding != .noPadding {
|
|
|
+ lastBlockRemainder = plaintext.count.quotientAndRemainder(dividingBy: blockSize).remainder
|
|
|
+ }
|
|
|
+
|
|
|
+ if isLast {
|
|
|
+ // CTR doesn't need padding. Really. Add padding to the last block if really want. but... don't.
|
|
|
+ plaintext = padding.remove(from: plaintext, blockSize: blockSize)
|
|
|
+ }
|
|
|
+
|
|
|
+ if var finalizingWorker = worker as? FinalizingModeWorker, isLast == true {
|
|
|
+ plaintext = try finalizingWorker.finalize(encrypt: plaintext.slice)
|
|
|
+ }
|
|
|
+
|
|
|
+ return plaintext
|
|
|
+ }
|
|
|
+
|
|
|
+ public func seek(to position: Int) throws {
|
|
|
+ guard var worker = self.worker as? SeekableModeWorker else {
|
|
|
+ fatalError("Not supported")
|
|
|
+ }
|
|
|
+
|
|
|
+ try worker.seek(to: position)
|
|
|
+ self.worker = worker
|
|
|
+
|
|
|
+ accumulated = []
|
|
|
+ }
|
|
|
+}
|
Marcin Krzyzanowski