Android KeyStore

 

class MainActivity : AppCompatActivity() {

    @RequiresApi(Build.VERSION_CODES.M)
    override fun onCreate(savedInstanceState: Bundle?) {

        // Although you can define your own key generation parameter specification, it's
        // recommended that you use the value specified here.
//        val keyGenParameterSpec = MasterKeys.AES256_GCM_SPEC
//        val masterKeyAlias = MasterKeys.getOrCreate(keyGenParameterSpec)

        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        var secretKey : SecretKey? = null
        var alias = "1223"
        var ks : KeyStore = KeyStore.getInstance("AndroidKeyStore").apply {
            load(null)
        }

        if (ks.containsAlias(alias)) {
            //키가 존재할경우
            val secretKeyEntry = ks.getEntry(alias, null) as KeyStore.SecretKeyEntry
            secretKey = secretKeyEntry.secretKey
            Log.e("키가 있음", secretKey.toString())

            // 이 시크릿키를 가지고 뭔가 암호화 / 복호화?
        }
        else {
            //키가 없을경우
            val keyGenerator = KeyGenerator.getInstance(KeyProperties.KEY_ALGORITHM_AES, "AndroidKeyStore")
            val parameterSpec = KeyGenParameterSpec.Builder(
                alias,
                KeyProperties.PURPOSE_ENCRYPT or KeyProperties.PURPOSE_DECRYPT
            ).run {
                setBlockModes(KeyProperties.BLOCK_MODE_CBC)
                setEncryptionPaddings(KeyProperties.ENCRYPTION_PADDING_PKCS7)
                setDigests(KeyProperties.DIGEST_SHA256)
                setUserAuthenticationRequired(false)
                build()
            }
            keyGenerator.init(parameterSpec)
            secretKey = keyGenerator.generateKey()

            Log.e("키가 없어서 생성", secretKey.toString())

        }

        var iv: ByteArray
        var text = "우리나라 만세"
        //암호화 하는 부분
        val cipher_enc = Cipher.getInstance("AES/CBC/PKCS7Padding")
        cipher_enc.init(Cipher.ENCRYPT_MODE, secretKey)
        iv = cipher_enc.iv
        val byteEncryptedText = cipher_enc.doFinal(text.toByteArray())
        //복호화 하는 부분
        val cipher_dec = Cipher.getInstance("AES/CBC/PKCS7Padding")
        cipher_dec.init(Cipher.DECRYPT_MODE, secretKey, IvParameterSpec(iv))
        val byteDecryptedText = cipher_dec.doFinal(byteEncryptedText)
        Log.e("result","원본 : " + text)
        Log.e("result", "암호화 : "+ String(Base64.encode(byteEncryptedText, Base64.DEFAULT)))
        Log.e("result", "복호화 : "+ String(byteDecryptedText))

    }

}

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

- 참조

 

 

 

https://stackoverflow.com/questions/51469481/android-keystore-encrypt-and-decrypt-data

Android KeyStore Encrypt and Decrypt Data

 

https://linsoo.pe.kr/archives/28119

 

https://developer.android.com/training/articles/keystore?hl=ko 

Android Keystore 시스템  |  Android 개발자  |  Android Developers