Cipher With ECB Mode Should Not Be Used

android encryption rsa android-keystore
Bryan picture Bryan · Mar 15, 2016 · Viewed 8.2k times · Source

I am trying to use a Cipher with an RSA key pair along with the "AndroidKeyStore". In all of the Android documentation I can find, the examples show Cipher.getInstance("RSA/ECB/OAEPWithSHA-256AndMGF1Padding") or Cipher.getInstance("RSA/ECB/PKCS1Padding"). Both of which come up with the same warning on Android Studio:

ECB Encryption should not be used

Cipher#getInstance should not be called with ECB as the cipher mode or without setting the cipher mode because the default mode on android is ECB, which is insecure.

Obviously I cannot omit it, or set the mode to None, because the default is ECB. If ECB mode is insecure, which mode should I be using?

If I use any other mode (that I know of) I get a NoSuchAlgorithmException: No provider found for RSA/{mode}/OAEPWithSHA-256AndMGF1Padding. Could the padding be the problem?

Either way, according to the Android KeyStore System documentation, ECB mode seems to be the only cipher block mode that it supports while using RSA.

Answer

Alex Klyubin picture Alex Klyubin · Mar 15, 2016

This looks like bug in Android Lint used by Android Studio to find issues. The intention of that warning is to warn about the use of ECB block mode with symmetric ciphers, such as AES. However, there's no point in warning about this for RSA, because RSA/ECB/... Cipher accepts/processes only one block of input.

I suggest you file a bug in https://code.google.com/p/android/ against Android Lint.

Related questions

RSA Encryption Decryption in Android

I am implementing a demo for RSA Encryption and Decryption in Android. I can Perform Encryption very well, but In Decryption I get an Exception: >>java.security.InvalidKeyException: unknown key type passed to RSA. KeyPairGenerator kpg; KeyPair kp; …

Read More
RSA Encryption: Difference between Java and Android

I am using RSA to encrypt username and password on Android and decrypt them on server (tomcat 6, java 1.6). Android Encryption: PublicKey pubKey = readPublicKeyFromFile(mod, ex); Cipher cipher = Cipher.getInstance("RSA"); cipher.init(Cipher.ENCRYPT_MODE, pubKey); byte[] cipherData = cipher.doFinal(…

Read More
Android Encrypting String using RSA Public key

I am working in a project where I have to encrypt password using RSA public key. I tried many samples and solutions from SO like as follows Android RSA encryption from public string RSA using SpongyCastle But none of the …

Read More