Android 8.0: IllegalBlocksizeException when using RSA/ECB/OAEPWithSHA-512AndMGF1Padding

Question

I usually find answers for most of our issues here but this time I need to ask :-).

We have encountered a problem with RSA encryption / decryption in one of our Apps run

Answer 1

A possible solution is described here in the comment #15 from Sep 8, 2017 07:08PM:

https://issuetracker.google.com/issues/36708951#comment15

I changed the Cipher-Initialisation from

Cipher cipher = Cipher.getInstance("RSA/ECB/OAEPWithSHA-256AndMGF1Padding");
cipher.init(Cipher.DECRYPT_MODE, this.getPrivateKey(context));

to

OAEPParameterSpec sp = new OAEPParameterSpec("SHA-256", "MGF1", new MGF1ParameterSpec("SHA-1"), PSource.PSpecified.DEFAULT);
Cipher cipher = Cipher.getInstance("RSA/ECB/OAEPWithSHA-256AndMGF1Padding");
cipher.init(Cipher.DECRYPT_MODE, this.getPrivateKey(context), sp);

I tested this on Android 6 up to Android 8 (emulator) and the issue seems to be gone. You should also change the Cipher.ENCRYPT_MODE-Implementation.