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I am using cryptoSwift library for encryption and decryption. But it's working with only string 16 bytes. If i am passing small string or less than 16 bytes then getting nil result.
I am using Incremental operations use instance of Cryptor and encrypt/decrypt one part at a time.
Please help me here, is there anything which i am doing wrong.
Thanks in advance.
				do {
						// Encryption start
						let data =	Data.init(base64Encoded: "12345678901234567890123456789012".base64Encoded()!)
						let iv : Array<UInt8> = [0,0,0,0,0,0,0,0,0,0,0,0]
						let nIv = Data(iv)
						let gcmEnc = GCM(iv: nIv.bytes, mode: .detached)
						var enc = try? AES(key: data!.bytes, blockMode: gcmEnc, padding: .noPadding).makeEncryptor()
						let arrStr = ["My name is tarun"] // Working
						//let arrStr = ["tarun"] // Not working for this string
						var ciphertext = Array<UInt8>()
						for txt in arrStr{
								 let ciperText = try? enc?.update(withBytes: Array(txt.utf8)) // Getting nil for small string.
								 ciphertext.append(contentsOf: ciperText!)
						}
						var res = try? enc?.finish()
						gcmEnc.authenticationTag = self.randomGenerateBytes(count: 16)?.bytes
						res?.append(contentsOf: (gcmEnc.authenticationTag)!)
						let cipherData = Data(ciphertext) + Data(res!)
						let strEnc = String(decoding: cipherData, as: UTF8.self)
						print(strEnc)
				
						// Decryption start from here
						do {
								let gcmDec = GCM.init(iv: nIv.bytes, additionalAuthenticatedData: nil, tagLength: 16, mode: .detached)
								var aesDec = try! AES(key: data!.bytes, blockMode: gcmDec, padding: .noPadding).makeDecryptor()
								let tag_length = 16
								let encData = cipherData.subdata(in: 0..<cipherData.count - tag_length)
								let tag = cipherData.subdata(in: encData.count ..< cipherData.count)
								
								let decData = try? aesDec.update(withBytes: encData.bytes) //Getting nil here for small string
								let strData = String(decoding: decData!, as: UTF8.self)
								print(strData)
								
								do{
										var res = try? aesDec.finish(withBytes: tag.bytes)
										res?.append(contentsOf: tag)
										
								}catch{
										
								}
								
						} catch {
								// failed
						}
		}
		}
		func randomGenerateBytes(count: Int) -> Data? {
				let bytes = UnsafeMutableRawPointer.allocate(byteCount: count, alignment: 1)
				defer { bytes.deallocate() }
				let status = CCRandomGenerateBytes(bytes, count)
				guard status == kCCSuccess else { return nil }
				return Data(bytes: bytes, count: count)
		}
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