Man-in-the-middle attack - Wikipedia
AttAcks on crypto system are “passive attacks” (called “traffic analysis” in which the “meet-in-the-middle attack” (is a knownplain text attack in which the attacker problems. Given a group of people, what is the probability of two people in the. Download Citation on ResearchGate | Probability to meet in the middle | This Walks and a Refined Analysis of Attacks on the Discrete Logarithm Problem. Download Citation on ResearchGate | Probability to meet in the middle | This Walks and a Refined Analysis of Attacks on the Discrete Logarithm Problem.
Authentication provides some degree of certainty that a given message has come from a legitimate source. Tamper detection merely shows evidence that a message may have been altered. Authentication[ edit ] All cryptographic systems that are secure against MITM attacks provide some method of authentication for messages.
Most require an exchange of information such as public keys in addition to the message over a secure channel. 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.
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. 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?
Meet-in-the-middle attack - Wikipedia
Has the certificate been changed recently? Do other clients, elsewhere on the Internet, also get the same certificate? It usually refers to observing repetitions that are likely to occur given enough applications of a particular function or algorithm.
- 3-subset meet-in-the-middle attack
- Collision attacks
- Meet-in-the-middle attack
The phenomenon extends most obviously to hash functions. Let's say we use a bit MD5 hash to verify the integrity of a message. There are possible hash codes. But after we have hashed "only" random messages the square root ofthen just by chance it is more likely than not that some pair of those messages will have the same hash code. With SHA-1, a bit hash, then a pair only becomes likely after around messages.
Note that we're just talking about collisions that naturally would occur by random chance; we're not referring to active attacks against these particular hash functions. A similar phenomenon occurs if we encrypt a large number of blocks using certain block cipher modes.
In OFB output feedback mode, then after encrypting in the order of blocks, it's likely that we'll re-use part of the previous cipher stream. At present, this is an inconceivably large amount of data; in 20 or 30 years, it may well be a realistic amount of data to encrypt with a given key. Meet-in-the-middle attacks In a meet-in-the-middle attack, Group A is typically some pre-calculated set of encrypted blocks, and Group B is a set of "real" encrypted blocks. The idea is to use the pre-calculated set of blocks to try and find at least one "real" encrypted block that you can decrypt.
A typical version of the attack is as follows: