Also, is man-in-the-middle-attack for Alice and a CA ever stoppable? That's surely a fundamental problem in cryptography I guess? Basically if Eve is so omiscent that she can intercept and change all communication Alice ever does, then Alice is screwed? Same with web of trust, right?
You need a shared secret to agree on the shared secret to agree on the shared secret, etc? Are you saying, that, somehow, you need to a leap of faith and you need to trust something eg Facebook, CA, web of trust, or whatever?
They can exchange assymetric pub keys in a case if they can't really meet in private, but e. MITM attack for CA is stoppable if CA and certificate requester are authenticated for each other through shared secret, best would be for certificate requester to visit CA's office and show passport and exchange public keys.
The more channels Alice involves to get Bob's public key more Alice is confident about his key, thus protecting from Eve's tampering. About second shared key encrypted or signed by already shared key is not suffering from regression, because you do it very rarely, maybe once in a year, just to change crypto protocol, not for every day or message.
AES symmetric cipher may have some special attacks not exposed to public e.
RSA, DH might be broken for long time if somebody has invented fast discrete logarithming or number factorization algorithm, certainly they won't share it to public to have profit. Also Eve might have stolen Bob's private key thus can decrypt all messages without exposing herself. Such protocols, often using key-agreement protocolshave been developed with different security requirements for the secure channel, though some have attempted to remove the requirement for any secure channel at all.
Man-in-the-middle attack - Wikipedia
In such structures, clients and servers exchange certificates which are issued and verified by a trusted third party called a certificate authority CA.
If the original key to authenticate this CA has not been itself the subject of a MITM attack, then the certificates issued by the CA may be used to authenticate the messages sent by the owner of that certificate. Use of mutual authenticationin which both the server and the client validate the other's communication, covers both ends of a MITM attack, though the default behavior of most connections is to only authenticate the server.
However, these methods require a human in the loop in order to successfully initiate the transaction. It's worth noting that in a corporate environment, successful authentication as indicated by the browser's green padlock, does not always imply secure connection with the remote server.
Corporate security policies might contemplate the addition of custom certificates in workstation's web browsers in order to be able to inspect encrypted traffic. HTTP Public Key Pinningsometimes called "certificate pinning," helps prevent a MITM attack in which the certificate authority itself is compromised, by having the server provide a list of "pinned" public key hashes during the first transaction. Subsequent transactions then require one or more of the keys in the list must be used by the server in order to authenticate that transaction.
Tamper detection[ edit ] Latency examination can potentially detect the attack in certain situations,  such as with long calculations that lead into tens of seconds like hash functions. To detect potential attacks, parties check for discrepancies in response times.
Meet-in-the-Middle Attack | Cryptography | Crypto-IT
Say that two parties normally take a certain amount of time to perform a particular transaction. If one transaction, however, were to take an abnormal length of time to reach the other party, this could be indicative of a third party's interference inserting additional latency in the transaction.
Quantum Cryptographyin theory, provides tamper-evidence for transactions through the no-cloning theorem. Protocols based on quantum cryptography typically authenticate part or all of their classical communication with an unconditionally secure authentication scheme e.
Important evidence to analyze when performing network forensics on a suspected attack includes: Is the certificate signed by a trusted CA? Has the certificate been revoked?
Has the certificate been changed recently? Do other clients, elsewhere on the Internet, also get the same certificate? Notable instances[ edit ] A notable non-cryptographic man-in-the-middle attack was perpetrated by a Belkin wireless network router in Periodically, it would take over an HTTP connection being routed through it: The reply it sent, in place of the web page the user had requested, was an advertisement for another Belkin product. After an outcry from technically literate users, this 'feature' was removed from later versions of the router's firmware.