Verifying signature on android in-app purchase message in Python on Google App Engine

The sample application on the android developers site validates the purchase json using java code. Has anybody had any luck working out how to validate the purchase in python. In particular in GAE?

The following are the relevant excerpts from the android in-app billing example program. This is what would need to be converted to python using PyCrypto which was re-written to be completely python by Google and is the only Security lib available on app engine. Hopefully Google is cool with me using the excerpts below.

private static final String KEY_FACTORY_ALGORITHM = "RSA";
private static final String SIGNATURE_ALGORITHM = "SHA1withRSA";
String base64EncodedPublicKey = "your public key here";

PublicKey key = Security.generatePublicKey(base64EncodedPublicKey);
verified = Security.verify(key, signedData, signature);

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 ...
    }
}
public static boolean verify(PublicKey publicKey, String signedData, String signature) {
    if (Consts.DEBUG) {
        Log.i(TAG, "signature: " + signature);
    }
    Signature sig;
    try {
        sig = Signature.getInstance(SIGNATURE_ALGORITHM);
        sig.initVerify(publicKey);
        sig.update(signedData.getBytes());
        if (!sig.verify(Base64.decode(signature))) {
            Log.e(TAG, "Signature verification failed.");
            return false;
        }
        return true;
    } catch ...
    }
    return false;
}