Method getIv

app/src/main/java/eu/faircode/email/CloudSync.java:778–784

(long revision)

    }

    private static byte[] getIv(long revision) {
        byte[] iv = ByteBuffer.allocate(12)
                .putLong(revision) // 8 bytes
                .putInt(0) // 4 bytes
                .array();
        return iv;
    }

    private static byte[] getAd(String key, long revision) throws NoSuchAlgorithmException {
        byte[] k = MessageDigest.getInstance("SHA256").digest(key.getBytes());