1
$\begingroup$

Even after reading their paper I am still not able to understand why the scheme is secure and what an adversary should do to break it. This question might look stupid to most of you but I don't have mathematics background to delve this deep into cryptography.

$\endgroup$

1 Answer 1

1
$\begingroup$

The proposed scheme is IND-ID-CPA secure and is semantically secure in a random-oracle model.

From the paper:

The proof of security for our IBE system makes use of a weaker notion of security known as semantic security (also known as semantic security against a chosen plaintext attack). Semantic security is similar to chosen ciphertext security (IND-IDCCA) except that the adversary is more limited;

And detailing IND-ID-CPA:

We say that an identity-based encryption scheme $E$ is semantically secure (IND-ID-CPA) if no polynomially bounded adversary $A$ has a non-negligible advantage against the Challenger in the following IND-ID-CPA game:

The paper then goes into detail (which I suppose you've read). But basically the game involves the adversary not being able to better than guess the value of an encrypted bit for a chosen public key. The adversary has access as to as many other public/private keys as it wants.

The scheme is not IND-CCA secure. As per this answer here one way to attack the scheme would be to gain access to a "decryption oracle".

$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.