czXym0sF

1package np.com.sarbagyastha.file_encrypter
2
3import android.util.Base64
4import androidx.annotation.NonNull
5import io.flutter.embedding.engine.plugins.FlutterPlugin
6import io.flutter.plugin.common.MethodCall
7import io.flutter.plugin.common.MethodChannel
8import io.flutter.plugin.common.MethodChannel.MethodCallHandler
9import io.flutter.plugin.common.MethodChannel.Result
10import io.flutter.plugin.common.PluginRegistry.Registrar
11import kotlinx.coroutines.CoroutineScope
12import kotlinx.coroutines.Dispatchers.IO
13import kotlinx.coroutines.Dispatchers.Main
14import kotlinx.coroutines.launch
15import kotlinx.coroutines.withContext
16import java.io.FileInputStream
17import java.io.FileOutputStream
18import javax.crypto.Cipher
19import javax.crypto.CipherInputStream
20import javax.crypto.CipherOutputStream
21import javax.crypto.KeyGenerator
22import javax.crypto.spec.IvParameterSpec
23import javax.crypto.spec.SecretKeySpec
24
25class FileEncrypterPlugin : FlutterPlugin, MethodCallHandler {
26    private lateinit var channel: MethodChannel
27    private lateinit var result: Result
28    private val algorithm = "AES"
29    private val transformation = "AES/CBC/PKCS5Padding"
30
31    override fun onAttachedToEngine(@NonNull flutterPluginBinding: FlutterPlugin.FlutterPluginBinding) {
32        channel = MethodChannel(flutterPluginBinding.binaryMessenger, "file_encrypter")
33        channel.setMethodCallHandler(this)
34    }
35
36    companion object {
37        @JvmStatic
38        fun registerWith(registrar: Registrar) {
39            val channel = MethodChannel(registrar.messenger(), "file_encrypter")
40            channel.setMethodCallHandler(FileEncrypterPlugin())
41        }
42    }
43
44    override fun onMethodCall(@NonNull call: MethodCall, @NonNull result: Result) {
45        this.result = result
46        CoroutineScope(IO).launch {
47            when (call.method) {
48                "encrypt" -> encrypt(call.argument("inFileName"), call.argument("outFileName"))
49                "decrypt" -> decrypt(call.argument("key"), call.argument("inFileName"), call.argument("outFileName"))
50                else -> withContext(Main) {
51                    result.notImplemented()
52                }
53            }
54        }
55    }
56
57    override fun onDetachedFromEngine(@NonNull binding: FlutterPlugin.FlutterPluginBinding) {
58        channel.setMethodCallHandler(null)
59    }
60
61    private suspend fun successResult(data: String?) {
62        withContext(Main) {
63            result.success(data)
64        }
65    }
66
67    private suspend fun errorResult(message: String?) {
68        withContext(Main) {
69            result.error("", message, message)
70        }
71    }
72
73    private suspend fun encrypt(inFileName: String?, outFileName: String?) {
74        val cipher = Cipher.getInstance(transformation)
75        val secretKey = KeyGenerator.getInstance("AES").generateKey()
76
77        try {
78            FileOutputStream(outFileName!!).use { fileOut ->
79                cipher.init(Cipher.ENCRYPT_MODE, secretKey)
80                CipherOutputStream(fileOut, cipher).use { cipherOut ->
81                    fileOut.write(cipher.iv)
82                    val buffer = ByteArray(8192)
83                    FileInputStream(inFileName!!).use { fileIn ->
84                        var byteCount = fileIn.read(buffer)
85                        while (byteCount != -1) {
86                            cipherOut.write(buffer, 0, byteCount)
87                            byteCount = fileIn.read(buffer)
88                        }
89                    }
90                }
91            }
92        } catch (e: Exception) {
93            e.printStackTrace()
94            errorResult(e.message)
95            return
96        }
97
98        val keyString = Base64.encodeToString(secretKey.encoded, Base64.DEFAULT)
99        successResult(keyString)
100    }
101
102    private suspend fun decrypt(key: String?, inFileName: String?, outFileName: String?) {
103        val cipher = Cipher.getInstance(transformation)
104        val encodedKey = Base64.decode(key, Base64.DEFAULT)
105        val secretKey = SecretKeySpec(encodedKey, 0, encodedKey.size, algorithm)
106
107        try {
108            FileInputStream(inFileName!!).use { fileIn ->
109                val fileIv = ByteArray(16)
110                fileIn.read(fileIv)
111                cipher.init(Cipher.DECRYPT_MODE, secretKey, IvParameterSpec(fileIv))
112                CipherInputStream(fileIn, cipher).use { cipherIn ->
113                    val buffer = ByteArray(8192)
114                    FileOutputStream(outFileName!!).use { fileOut ->
115                        var byteCount = cipherIn.read(buffer)
116                        while (byteCount != -1) {
117                            fileOut.write(buffer, 0, byteCount)
118                            byteCount = cipherIn.read(buffer)
119                        }
120                    }
121                }
122            }
123        } catch (e: Exception) {
124            e.printStackTrace()
125            errorResult(e.message)
126            return
127        }
128        successResult(null)
129    }
130}
131