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1private val storage = Storage(context)
2
3fun createMasterKey(keyPassword: String? = null) {
4    if (SystemServices.hasMarshmallow()) {
5        createAndroidSymmetricKey()
6    } else {
7        createDefaultSymmetricKey()
8    }
9}
10
11private fun createAndroidSymmetricKey() {
12    keyStoreWrapper.createAndroidKeyStoreSymmetricKey(MASTER_KEY)
13}
14
15private fun createDefaultSymmetricKey() {
16    val symmetricKey = keyStoreWrapper.generateDefaultSymmetricKey()
17    val masterKey = keyStoreWrapper.createAndroidKeyStoreAsymmetricKey(MASTER_KEY)
18    val encryptedSymmetricKey = CipherWrapper(CipherWrapper.TRANSFORMATION_ASYMMETRIC).wrapKey(symmetricKey, masterKey.public)
19    storage.saveEncryptionKey(encryptedSymmetricKey)
20}
21
22// ---------
23
24fun encrypt(data: String, keyPassword: String? = null): String {
25    return if (SystemServices.hasMarshmallow()) {
26        encryptWithAndroidSymmetricKey(data)
27    } else {
28        encryptWithDefaultSymmetricKey(data)
29    }
30}
31
32fun decrypt(data: String, keyPassword: String? = null): String {
33    return if (SystemServices.hasMarshmallow()) {
34        decryptWithAndroidSymmetricKey(data)
35    } else {
36        decryptWithDefaultSymmetricKey(data)
37    }
38}
39
40private fun encryptWithAndroidSymmetricKey(data: String): String {
41    val masterKey = keyStoreWrapper.getAndroidKeyStoreSymmetricKey(MASTER_KEY)
42    return CipherWrapper(CipherWrapper.TRANSFORMATION_SYMMETRIC).encrypt(data, masterKey)
43}
44
45private fun decryptWithAndroidSymmetricKey(data: String): String {
46    val masterKey = keyStoreWrapper.getAndroidKeyStoreSymmetricKey(MASTER_KEY)
47    return CipherWrapper(CipherWrapper.TRANSFORMATION_SYMMETRIC).decrypt(data, masterKey)
48}
49
50private fun encryptWithDefaultSymmetricKey(data: String): String {
51    val masterKey = keyStoreWrapper.getAndroidKeyStoreAsymmetricKeyPair(MASTER_KEY)
52    val encryptionKey = storage.getEncryptionKey()
53    val symmetricKey = CipherWrapper(CipherWrapper.TRANSFORMATION_ASYMMETRIC).unWrapKey(encryptionKey, ALGORITHM_AES, Cipher.SECRET_KEY, masterKey?.private) as SecretKey
54    return CipherWrapper(CipherWrapper.TRANSFORMATION_SYMMETRIC).encrypt(data, symmetricKey)
55}
56
57private fun decryptWithDefaultSymmetricKey(data: String): String {
58    val masterKey = keyStoreWrapper.getAndroidKeyStoreAsymmetricKeyPair(MASTER_KEY)
59    val encryptionKey = storage.getEncryptionKey()
60    val symmetricKey = CipherWrapper(CipherWrapper.TRANSFORMATION_ASYMMETRIC).unWrapKey(encryptionKey, ALGORITHM_AES, Cipher.SECRET_KEY, masterKey?.private) as SecretKey
61    return CipherWrapper(CipherWrapper.TRANSFORMATION_SYMMETRIC).decrypt(data, symmetricKey)
62}