android 无效密钥规范异常？

i am using InApp Purchase api in my application ,where i have made an demo project ,in which i have taken one button,when we click on button i am getting this screen here

after then when i click on buy button an dialog shows that "payement sucessful",the image is here

显示此对话框后，我的应用程序被强制关闭。，我在这一行收到错误

public static PublicKey generatePublicKey(String encodedPublicKey) {
    try {
        byte[] decodedKey = Base64.decode(encodedPublicKey);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_FACTORY_ALGORITHM);
        return keyFactory.generatePublic(new X509EncodedKeySpec(decodedKey));
    } catch (NoSuchAlgorithmException e) {
        throw new RuntimeException(e);
    } catch (InvalidKeySpecException e) {
        Log.e(TAG, "Invalid key specification.");
        throw new IllegalArgumentException(e);
    } catch (Base64DecoderException e) {
        Log.e(TAG, "Base64DecoderException.", e);
        return null;
    }
}

here is my logcat