I'm using an extension method to decrypt a string which is encrypted by the server side php script using AES Algorithm.
The following is the extension method used
func aesDecrypt(key:String, iv:String, options:Int = kCCOptionPKCS7Padding) -> String? { if let keyData = key.data(using: String.Encoding.utf8), let data = NSData(base64Encoded: self, options: .ignoreUnknownCharacters), let cryptData = NSMutableData(length: Int((data.length)) + kCCBlockSizeAES128) { let keyLength = size_t(kCCKeySizeAES128) let operation: CCOperation = UInt32(kCCDecrypt) let algoritm: CCAlgorithm = UInt32(kCCAlgorithmAES128) let options: CCOptions = UInt32(options) var numBytesEncrypted :size_t = 0 let cryptStatus = CCCrypt(operation, algoritm, options, (keyData as NSData).bytes, keyLength, iv, data.bytes, data.length, cryptData.mutableBytes, cryptData.length, &numBytesEncrypted) if UInt32(cryptStatus) == UInt32(kCCSuccess) { cryptData.length = Int(numBytesEncrypted) let unencryptedMessage = String(data: cryptData as Data, encoding:String.Encoding.utf8) return unencryptedMessage } else { return nil } } return nil } This sometimes returns a null value
unencode = responseString?.aesDecrypt(key: "mykey", iv: "value"); I cannot figure out the exact reason why this happens.The responseString was not null when this happened.
Please advice