2JKZifMP

1package com.bytepace.dimusco.utils
2
3import android.graphics.Bitmap
4import android.security.keystore.KeyGenParameterSpec
5import android.security.keystore.KeyProperties
6import com.bytepace.dimusco.DimuscoApp
7import java.io.*
8import java.security.KeyStore
9import javax.crypto.Cipher
10import javax.crypto.CipherInputStream
11import javax.crypto.KeyGenerator
12import javax.crypto.SecretKey
13import javax.crypto.spec.IvParameterSpec
14
15private const val KEY_ALIAS = "DimuscoKey"
16private const val KEY_STORE = "AndroidKeyStore"
17private const val CIPHER_MODE = "AES/CBC/PKCS7Padding"
18private const val FILE_ACCESS_MODE = "rw"
19private const val CBC_IV_SIZE = 16
20
21fun saveImage(filename: String, bitmap: Bitmap): Throwable? {
22    val bytes = ByteArrayOutputStream().use {
23        bitmap.compress(Bitmap.CompressFormat.PNG, 100, it)
24        return@use it.toByteArray()
25    }
26    return writeFile(filename, bytes)
27}
28
29fun writeFile(filename: String, bytes: ByteArray): Throwable? {
30    var throwable: Throwable? = null
31
32    try {
33        val file = File(DimuscoApp.getContext().filesDir, filename)
34        if (!file.exists()) file.parentFile.mkdirs()
35        RandomAccessFile(file, FILE_ACCESS_MODE).use { rFile ->
36            deleteFile(file)
37            val cipher = Cipher
38                .getInstance(CIPHER_MODE)
39                .apply {
40                    init(Cipher.ENCRYPT_MODE, getSecretKey())
41                }
42
43            val lock = rFile.channel.lock()
44
45            ByteArrayInputStream(bytes).use { bais ->
46                CipherInputStream(bais, cipher).use { cis ->
47                    FileOutputStream(file).use { out ->
48                        out.write(cipher.iv)
49                        out.write(cis.readBytes())
50                    }
51                }
52            }
53            lock.release()
54        }
55    } catch (e: java.lang.Exception) {
56        throwable = e
57    } finally {
58        return throwable
59    }
60}
61
62fun readFile(filename: String): ByteArray? {
63    val file = getFile(filename)
64    if (!file.exists()) return null
65
66    val bytes = FileInputStream(file).use { it.readBytes() }
67
68    val cipher = Cipher
69        .getInstance(CIPHER_MODE)
70        .apply {
71            init(
72                Cipher.DECRYPT_MODE,
73                getSecretKey(),
74                IvParameterSpec(bytes, 0, CBC_IV_SIZE)
75            )
76        }
77
78    return try {
79        ByteArrayInputStream(bytes).use { bais ->
80            CipherInputStream(bais, cipher).use { cis ->
81                cis.readBytes().drop(CBC_IV_SIZE).toByteArray()
82            }
83        }
84    } catch (e: java.lang.Exception) {
85        e.printStackTrace()
86        null
87    }
88}
89
90fun deleteFile(filename: String): Boolean {
91    return deleteFile(getFile(filename))
92}
93
94private fun deleteFile(file: File): Boolean {
95    return try {
96        when (file.isDirectory) {
97            true -> file.deleteRecursively()
98            else -> file.delete()
99        }
100    } catch (e: Exception) {
101        e.printStackTrace()
102        false
103    }
104}
105
106private fun getFile(filename: String): File {
107    return File("${DimuscoApp.getContext().filesDir}/$filename")
108}
109
110private fun getSecretKey(): SecretKey? {
111    val keyStore = KeyStore
112        .getInstance(KEY_STORE)
113        .apply { load(null) }
114
115    val keyEntry = keyStore.getEntry(KEY_ALIAS, null) as? KeyStore.SecretKeyEntry
116    return keyEntry?.secretKey ?: generateSecretKey()
117}
118
119private fun generateSecretKey(): SecretKey {
120    val spec = KeyGenParameterSpec
121        .Builder(KEY_ALIAS, KeyProperties.PURPOSE_ENCRYPT or KeyProperties.PURPOSE_DECRYPT)
122        .setBlockModes(KeyProperties.BLOCK_MODE_CBC)
123        .setEncryptionPaddings(KeyProperties.ENCRYPTION_PADDING_PKCS7)
124        .build()
125
126    KeyGenerator
127        .getInstance(KeyProperties.KEY_ALGORITHM_AES, KEY_STORE)
128        .apply {
129            init(spec)
130            return generateKey()
131        }
132}