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    <p>I've come up with this possible attack, based on my understanding of the protocol, inspired by <a href="http://en.wikipedia.org/wiki/Needham-Schroeder_protocol#An_attack_on_the_protocol" rel="nofollow">Lowe's Attack to Needham-Shroeder Public Key Protocol</a>:</p> <ul> <li>Alice wants to reconnect. Calculates its committment ca and sends to Bob. The message is captured by Mallory.</li> <li>Mallory answers. She does not know the shared secret, so she invents one. Calculates cb and sends to Alice.</li> <li>At this step, Alice cannot verify the shared secret yet. So she sends DHpubA and ChallA.</li> <li>Mallory ignores the messages from Alice and disappears.</li> </ul> <p>Now Mallory has a valid DHpubA, ChallA and the corresponding (valid) ca.</p> <ul> <li>Mallory sends ca to Bob.</li> <li>Bob answers with cb.</li> <li>Mallory sends a valid set of DhpubA, ChallA</li> <li>Bob sends his DhpubB and ChallB</li> </ul> <p>Since Bob can validate Mallory's messages, she is authenticated as Alice. Obviously Mallory does not know DHprivA, se she cannot calculate the current session key, but nevertheless you have a security flaw since Bob thinks he's talking to Alice. </p> <p><strong>General advice</strong>: avoid implementing you own cryptographic solution and don't trust security reviews from anyone else than an established security firm.</p> <p>If you feel that your security requirements are not satisfied by standard mainstream crypto, try stating your requirements and asking whether is there a security procotol that matches them. </p>
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    1. POSecurity review of an authenticated Diffie Hellman variant
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    1. USGiacomo Verticale
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    1. COI must state again: this is NOT my invention. This is the implementation of a protocol proposed in "Key agreement in peer-to-peer wireless networks". I only want to review if ADDITIONS to this protocol render their security proof useless.
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    2. COThanks for this evaluation. This gives some insight why you are not allowed to transfer sensitive data on the unencrypted channel after key exchange. This attack would be able to intercept. But in this scenarion it would not be a threat, as channels are 1) authenticated afterwards and 2) enryption starts early. Anyway i will give some second thought to it as it may impose restrictions on the cipher negotiation protocol.
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    3. COCan you give a pointer for the paper you are citing?
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      1. USGiacomo Verticale
 

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